Trauma and Critical Care Flashcards

Question

The most appropriate treatment for a duodenal hematoma that occurs from blunt trauma is A. Exploratory laparotomy and bypass of the duodenum B. Exploratory laparotomy and evacuation of the hematoma C. Exploratory laparotomy to rule out associated injuries D. Observation

Answer 1

Answer: D Duodenal hematomas arc caused by a direct blow to the abdomen and occur more often in children than adults. Blood accumulates between the seromuscular and submucosal layers, eventually causing obstruction. The diagnosis is suspected by the onset of vomiting following blunt abdominal trauma; barium examination of the duodenum reveals either the coiled spring sign or obstruction. Most duodenal hematomas in children can be managed nonoperatively with nasogastric suction and parenteral nutrition. Resolution of the obstruction occurs in the majority of patients if this therapy is continued for 7 to 14 days. If surgical intervention becomes necessary, evacuation of the hematoma is associated with equal success but fewer complications than bypass procedures. Despite few existing data on adults, there is no reason to believe that their hematomas should be treated differently from those of children. A new approach is laparoscopic evacuation if the obstruction persists more than 7 days.

Answer 2

Answer: C Optimal management of pancreatic trauma is determined by where the parenchymal damage is located and whether the intrapancreatic common bile duct and main pancreatic duct remain intact. Patients with pancreatic contusions (defined as injuries that leave the ductal system intact) can be treated nonoperatively or with closed suction drainage if undergoing laparotomy for other indications. Patients with proximal pancreatic injuries, defined as those that lie to the right of the superior mesenteric vessels, are also managed with closed suction drainage. In contrast, distal pancreatic injuries are managed based upon ductal integrity. Pancreatic duct disruption can be identified through direct exploration of the parenchymal laceration, operative pancreatography, endoscopic retrograde pancreatography (ERCP), or magnetic resonance cholangiopancreatography (MRCP). Patients with distal ductal disruption undergo distal pancreatectomy, preferably with splenic preservation. An alternative, which preserves both the spleen and distal transected end of the pancreas, is either a Roux-en-Y pancreaticojejunostomy or pancreaticogastrostomy. If the patient is physiologically compromised, distal pancreatectomy with splenectomy is the preferred approach.

Answer 3

Answer: D Numerous large retrospective and several prospective studies have now clearly demonstrated that primary repair is safe and effective in the majority of patients with penetrating injuries. Colostomy is still appropriate in a few patients, but the current dilemma is how to select them. Exteriorized repair is probably no longer indicated since most patients who were once candidates for this treatment are now successfully managed by primary repair. Two methods have been advocated that result in 75 to 90% of penetrating colonic injuries being safely treated by primary repair. The first is to repair all perforations not requiring resection. If resection is required due to the local extent of the injury, and it is proximal to the middle colic artery, the proximal portion of the right colon up to and including the injury is resected and an ileocolostomy performed. If resection is required distal to the middle colic artery, an end colostomy is created and the distal colon oversewn and left within the abdomen. The theory behind this approach is that an ileocolostomy heals more reliably than colocolostomy, because in the trauma patient who has suffered shock and may be hypovolemic, assessing the adequacy of the blood supply of the colon is much less reliable than in elective procedures. The blood supply of the terminal ileum is never a problem. The other approach is to repair all injuries regardless of the extent and location (including colocolostomy), and reserve colostomy for patients with protracted shock and extensive contamination. The theory used to support this approach is that systemic factors are more important than local factors in determining whether a suture line will heal. Both of these approaches are reasonable and result in the majority of patients being treated by primary repairs. When a colostomy is required, regardless of the theory used to reach that conclusion, performing a loop colostomy proximal to a distal repair should be avoided because a proximal colostomy does not protect a distal suture line. All suture lines and anastomoses are performed with the running single-layer technique.

Answer 4

Answer: A When undergoing laparotomy for trauma, the best policy is to explore all penetrating wounds to the kidneys. However, over 90% of blunt injuries are treated nonoperatively; the indications for surgery include parenchymal injuries leading to hypotension and evidence of renovascular injury. If laparotomy is performed in the setting of blunt kidney injury for other reasons, expanding or pulsatile perinephric hematomas should be explored. Injuries to the ureters are uncommon but may occur in patients with pelvic fractures and penetrating trauma. An injury may not be identified until a complication (ie, a urinoma) becomes apparent. If an injury is suspected during operative exploration but is not clearly identified, methylene blue or indIgo carmine is administered IV with observation for extravasation. Bladder injuries are subdivided into those with intraperitoneal extravasation and those with extraperitoneal extravasation. Extraperitoneal ruptures are treated nonoperatively with bladder decompression for 2 weeks, whereas injuries with intraperitoneal extravasation can be closed primarily. Urethral injuries are managed by bridging the defect with a Foley catheter, with or without direct suture repair. Strictures are not uncommon but can be managed electively.

Answer 5

Answer: D In comatose or obtundcd patients, the diagnosis is more difficult to secure. A compatible history, firmness of the compartment to palpation, and diminished mobility of the joint are suggestive. The presence or absence of a pulse distal to the affected compartment is notoriously unreliable in the diagnosis of a compartment syndrome. A frozen joint and myoglobinuria are late signs and suggest a poor prognosis. As in the abdomen, compartment pressure can be measured. The small, hand-held Stryker device is a convenient tool for this purpose. Pressures greater than 45 mm Hg usually require operative intervention. Patients with pressures between 30 and 45 mm Hg should be carefully evaluated and closely watched. (See Schwartz 10th ed.,p. 215.)

Answer 6

Answer: B Mortality in patients with severe head injury more than doubles after the age of 55 years. Moreover, 25% of patients with a normal GCS score of 15 had intracranial bleeding, with an associated mortality of 50%. Just as there is no absolute age that predicts outcome, admission GCS score is a poor predictor of individual outcome. Therefore, the majority of trauma centers advocate an initial aggressive approach with re-evaluation at the 72-hour mark to determine subsequent care. Secondly, one of the most common sequelae of blunt thoracic trauma is rib fractures. In fact, in one study, 50% of patients older than 65 years sustained rib fractures from a fall of <6 ft, compared with only 1% of patients younger than 65 years. Concurrent pulmonary contusion is noted in up to 35% of patients, and pneumonia complicates the injuries in 10 to 30% of patients with rib fractures.

Answer 7

ANSWER: D COMMENTS: In the ICU, management of pain can be difficult and is often complicated by an inability to communicate with the patient and by the patient’s physiologic instability, comorbid conditions, or delirium. Several methods have been developed to help assess sedation, including the Riker Sedation-Agitation Scale and the Ramsay Scale. This patient has both renal and hepatic dysfunction, which makes lorazepam an incorrect choice. It has a slow onset and intermediate half-life. In this situation, a faster-acting drug is preferable because the patient is obviously agitated. A Diprivan and fentanyl drip is the best answer because Diprivan is a general anesthetic agent with a rapid onset and ultrashort duration of action. Side effects of this medication include a risk for hypotension, high cost, pain on injection, and potential for hypertriglyceridemia. It has no analgesic effect and therefore additional medication is required to control the pain. Fentanyl is a better choice for analgesia because of the patient’s renal failure and its rapid onset of action relative to morphine, which can take 5 to 10 min. The use of four-point restraints without additionally sedating the patient is not a good option. Again, PCA is not a good option for a patient intubated and needing further sedation because of agitation. Moreover, morphine and its active metabolites (morphine-3-glucuro- nide and morphine-6-glucuronide) can accumulate in patients with renal insufficiency. Finally, placing an epidural catheter in an agitated patient would be difficult and dangerous to the patient and staff.

Answer 8

ANSWER: B COMMENTS: The best choice is cisatracurium, a nondepolarizing neuromuscular blocker and one of the most commonly used paralytics in the ICU. It, along with atracurium, is metabolized by plasma ester hydrolysis and Hofmann elimination and is therefore the best choice in this patient with both hepatic and renal dysfunction. Pancuronium is long acting but contraindicated in patients with coronary artery disease because it has a vagolytic effect and induces tachycardia. Vecuronium is intermediate acting (30 min) but is cleared by the kidney and liver. Succinylcholine is a short- acting depolarizing neuromuscular blocker, usually for facilitation of endotracheal intubation. Rocuronium has a rapid onset and intermediate duration thus making it a better choice for short procedures, as opposed to the needs of this patient, who must be sedated for a longer period.

Answer 9

ANSWER: C COMMENTS: The incidence of complications after arterial catheterization seems to be operator independent, unlike the case with pulmonary artery (PA) catheterization. Known risk factors include intermittent punctures, age younger than 10 years, prolonged catheterization (>4 days), anticoagulant therapy, and use of a catheter larger than 20 gauge or made of polypropylene rather than Teflon. The radial artery is the site most frequently used for catheterization, provided that the ulnar artery and palmar arterial arch are patent. Therefore the Allen test should be performed before attempting radial artery catheterization. A normal test result consists of a palmar blush within 7s after the ulnar artery is released. Most patients with arterial thrombosis remain asymptomatic. Symptoms can be minimized by placing lines in arteries with good collateral circulation. Most thrombi (43%) are present at the time of catheter removal and another 30% develop within 24 h. A higher incidence of thrombosis occurs within the first 24h when surgical cutdown is performed (48% vs. 23% with percutaneous placement), but the incidence of thrombosis at 1 week is the same for both methods of placement. Brachial artery cannulation has a high incidence of embolic occlusion of the distal arteries (5%–41%) and should therefore be avoided. Infection remains the most common complication. Predisposing factors are prolonged catheterization, surgical cutdown, local inflammation, pre- existing bacteremia, and failure to change the saline flush fluid, transducer, and flush tubing every 48 h. The need for intermittent arterial catheter replacement is not established and indeed is controversial. The aortic mean arterial pressure (MAP) and diastolic arterial pressure are slightly higher than the radial MAP and diastolic arterial pressure. However, systolic pressure is consistently higher in the radial artery than in the aorta. This discrepancy increases with distal progression, smaller arterial caliber, and age and is explained by the reflection of pressure waves from capillary beds, which results in augmentation of the systolic and reduction of the diastolic values measured.

Answer 10

ANSWER: B COMMENTS: The indications for PA catheters and their value in patients with sepsis or hemodynamic instability are uncertain, but they may be useful in the management of patients unresponsive to the use of fluids and vasoactive agents. Dysrhythmias occur in 12%–67% of patients undergoing catheterization but are usually self-limited, premature ventricular contractions. Complete heart block can develop in patients with preexisting left bundle branch block. A prophylactic pacing wire should be used in these patients. Prophylactic lidocaine and full inflation of the balloon may prevent ventricular ectopy. Hemoptysis in patients with a PA catheter sug- gests the diagnosis of perforation or rupture. Mechanisms involved in PA rupture include (1) overinflation of the balloon, (2) incomplete balloon inflation (<75%) with the exposed tip being forced through the wall, and (3) pulmonary hypertension An “overwedge” pattern suggests eccentric balloon inflation, overdistention, or both. If hemoptysis develops, the catheter should be pulled back, with the balloon deflated. Massive hemoptysis necessitates placement of a double-lumen endotracheal tube and occlusion of the bronchus on the side of the rupture with a Fogarty catheter. Emergency thoracotomy is needed. Looping or knotting of the catheter may occur in the right ventricle during insertion and can be avoided if no more than 10 cm of the catheter are inserted after a ventricular tracing is identified and before a PA tracing appears. Although catheter-related sepsis occurs in only up to 2% of insertions, bacterial colonization takes place in 5%–35% of catheterizations. Infections are more common when the catheter is left in place for more than 72 h or when it is inserted via an antecubital vein.

Answer 11

ANSWER: C COMMENTS: Acute pancreatitis may have a variable presentation dependent on both etiology and severity. If the patient is presenting with signs of shock and organ hypoperfusion, initial interventions must be targeted toward the improvement of oxygen delivery. Additionally, CT is helpful in determining if pancreatic necrosis with or without infection is present. Typically, infected pancreatic necrosis will present with air within the peripancreatic fluid collection, necessitating drainage or debridement. The role of prophylactic antibiotics in severe pancreatitis has been debated without consensus. A small number of randomized trials found benefit with fewer infectious complications when antibiotics are given prophylactically. However, this has not been widely repro- ducible. Cholecystectomy should be performed prior to the patient’s discharge from the hospital, but not in the acute setting. Early enteral feeding, typically beyond the second portion of the duodenum, is preferable over parenteral nutrition and is associated with fewer infectious complications.

Answer 12

ANSWER: D COMMENTS: Many measures are utilized in order to determine the appropriateness for a trial of extubation. The RSBI is RR divided by Vt. A value of more than 105 predicts failure of extuba- tion in over 95% of patients, while an RSBI less than 105 predicts success in over 80% of patients. Other factors can be useful in the decision to extubate; however, they are individually not as reliable as the RSBI. The importance of reliable and objective indicators for successful liberation from the ventilator is tied to the avoidance of complications such as ventilator-associated pneumonia (VAP), along with a decreased requirement for sedative medications.

Answer 13

ANSWER: D COMMENTS: This patient remains in septic shock postoperatively from debridement of an infected wound. We can presume the source to be the wound and therefore source control has been obtained. He should remain on broad-spectrum antibiotics and achieve certain parameters as directed by goal-directed therapy. He is intubated, which mandates a goal CVP of 10 to 12 mmHg. If he were extubated, a lower CVP of 8 to 10 mmHg would be appropriate, given the absence of positive pressure ventilation. This indicates he is volume resuscitated or has an adequate preload. If you are concerned about cardiac function, or need an indicator other than CVP to determine the volume status, echocardiography is indicated. However, this patient remains hypotensive despite norepinephrine, and something must be done in the interim. The first vasopressor used in septic shock should be norepinephrine. If a second vasopressor is required, it is now recommended that epi- nephrine be added to norepinephrine to achieve a MAP greater than 65 mmHg. Vasopressin may be added subsequently, but the dose should not exceed 0.03 units/min.

Answer 14

ANSWER: B COMMENTS: While mild hyperkalemia is well tolerated, severe hyperkalemia results in a predictable progression of cardiac effects. Classically, peaked T waves are the first to appear on ECG, fol- lowed by a widened QRS complex, loss of P wave, appearance of “sine” waves, and eventually ventricular fibrillation. Emergent treatment of hyperkalemia focuses first on the antagonization of the depolarizing effect that a high level of potassium has on the cardiac membranes. Calcium should be administered (1) to any patient with a serum potassium level of 6.5 or greater or (2) to any patient with ECG changes consistent with hyperkalemia regardless of the potas- sium level. Other treatment of acute hyperkalemia includes redistribution of potassium to the intracellular space with insulin or β-agonists (albuterol). Ultimately, the elimination of excess potassium from the body is achieved by administering loop diuretics, sodium bicarbonate, Kayexalate, or hemodialysis.

Answer 15

ANSWER: C COMMENTS: This patient presents with hemorrhagic shock with altered mental status, tachycardia, and hypotension. Driven to maintain adequate oxygen delivery, early changes in vital signs are representative of the body’s attempt to preserve homeostasis after the rapid loss of a significant amount of its circulating volume. Early care is directed toward eliminating ongoing sources of exsanguination, along with restoration of intravascular volume. The degree of derangement is reliably linked to the volume of blood loss and classified according to the following table. This patient’s constellation of findings places him within class III shock, and he has an estimated blood loss of 1.5 to 2 L. This estimate may help in guiding volume resuscitation to give an understanding of how much volume has been lost. The choice of fluid replacement has been the subject of much debate and investigation. Generally, for moderate-to-severe shock, resuscitation is carried out with a com- bination of both crystalloid and colloid solutions. In the acute setting, hemoglobin is an unreliable indicator; rather, therapy should be aimed at restoring adequate intravascular volume and normalized hemodynamics. (See ATLS, Chapter on Shock)

Answer 16

ANSWER: E COMMENTS: Normal ICP ranges from 5 to 15 mmHg. Because of the bony calvarium, any increase in ICP results in an equivalent decrease in cerebral perfusion pressure (CPP), which is the difference between MAP and ICP. Goals for treatment of closed head injuries are to maintain adequate CPP through the use of various maneuvers to lower ICP. This patient has suffered a severe head injury, as evidenced by his Glasgow coma score (GCS) of 8. He has an abnormal head CT with intracranial hemorrhage and has a significant risk (50%–60%) of elevations of ICP. For all patients with head injury, abnormal CT scan, and GCS less than 9, and ICP monitoring should be considered. One should also consider the placement of a monitor if the patient will be unable to be examined for a prolonged period [i.e., in the operating room (OR)]. There are conflicting data regarding the potential mortality benefit of ICP monitors; however, numerous data published since 2012 indicate improved outcomes when they are placed in these patients. Mannitol and hypertonic saline are indicated for the treatment of elevated ICP, indicated by invasive monitoring or a change in physical examination (unilateral blown pupil). Hypothermia was found in a recent study to have no benefit in patients with traumatic brain injury and elevated ICP.

Answer 17

ANSWER: C COMMENTS: The timing of tracheostomy continues to be a debated topic in both the critical care and trauma literature. The general division between early and late tracheostomy creation is at 10 days after endotracheal intubation. For patients predicted to have prolonged ventilator requirements, the optimal timing of tracheostomy remains uncertain. Early trials suggested a mortality benefit; however, this result has not been reproduced in more recently published data. There does however seem to be a decrease in the incidence of VAP, along with decreased sedation requirements, more ventilator-free days, and shorter ICU length of stay. Trials with longer follow-up are still ongoing; however, there is some evidence that there may be a long-term mortality benefit for early tracheostomy, though more data are needed to establish this conclusion. While pulmonary hygiene and ease of care are improved with tracheostomy, there are no definitive data suggesting improved patient satisfaction with early versus late tracheostomy creation.

Answer 18

ANSWER: C COMMENTS: There are many potential causes of pericardial tamponade, with lung cancer, renal failure, tuberculosis, breast carcinoma, and lymphoma and leukemia being among the most common. Hemodynamic monitoring with a PA catheter can help determine the diagnosis by showing equalization of right ventricular diastolic pressure, a PA diastolic pressure, and a PAOP within 2 to 3 mmHg of each other, along with the elevated mean right atrial pressure. With small effusions most patients are asymptomatic, but with fluid in excess of 500 mL, patients can experience the onset of dyspnea, cough, chest pain, tachycardia, and jugular venous distention. Pulsus paradoxus, hypotension, cardiogenic shock, and paradoxical movement of the jugular venous pulse are also signs to be noted. This patient has pericardial tamponade and is unlikely to improve with medical management. Pericardial drainage is recommended in all patients with large effusions because of recurrence rates in the 40%–70% range. Administration of a fluid bolus is an appropriate measure but likely to be temporary. For immediate decompression, one can perform bedside pericardiocentesis. Definitive treatment of persistent symptomatic pericardial effusions is surgical pericardiectomy.

Answer 19

ANSWER: B COMMENTS: Cardiogenic shock most commonly occurs as a consequence of acute left ventricular infarction. However, it may also be due to right ventricular infarction, ruptured papillary muscle, ruptured ventricular wall, acute aortic valvular insufficiency, mitral regurgitation, and a ventricular septal defect. However, before assuming that the hypotension is caused by a cardiogenic mechanism, one must be sure that there is adequate blood volume. Therefore a patient who is hypotensive with low right and left atrial pressure should undergo fluid administration as the initial management. If cardiac performance improves with fluid administration alone, cardiogenic shock is probably not present. If adequate filling pressures are attained and the hypotension persists in the absence of mechanical defects, arrhythmia, and sepsis, a primary pump problem probably exists and should be managed with inotropic agents. One form of cardiogenic shock is cardiac tamponade, which is seen in traumatized patients, postoperative cardiac patients, and those suffering from uremia and certain malignancies. Pericardial tamponade has a trend toward equalization of pressures in the right and left sides of the heart. In a patient who is overdigitalized or hypokalemic, a very low ventricular rate in response to atrial fibrillation or flutter may result in hypotension and should be managed with cardiac pacing. If a patient remains in cardiogenic shock despite adequate blood volume, appropriate HR, absence of a mechanical or valvular defect, appropriate administration of inotropic agents, and restoration of pressure and coronary blood flow, support via IABP counterpulsation may be needed. IABP counterpulsation is most beneficial in patients with severe left ventricular dysfunction. It assists in left ventricular systolic unloading by directly reducing stroke work, which in turn reduces myocardial oxygen consumption during the cardiac cycle, and in diastolic augmentation, which raises arterial BP and provides better coronary arterial perfusion during diastole and improved delivery of oxygen to the myocardium. Patients with hemodynamic compromise secondary to right ventricular MI require fluid resuscitation and inotropic support. Any preload reducers must be avoided. Afterload reducers in the presence of hypotension are not warranted.

Answer 20

ANSWER: D COMMENTS: The most common sustained dysrhythmia is atrial fibrillation, which has a prevalence of 5% in persons older than 65 years. There are numerous causes that may trigger new-onset atrial fibrillation, including ischemia, MI, hypertension, electrolyte imbalance, pulmonary embolism (PE), and digoxin toxicity. Initially, an ECG should be obtained, and if the arrhythmia is symptomatic, it should be treated aggressively. New-onset atrial fibrillation with a duration of less than 48 h is a clear indication to restore sinus rhythm by either electrical or pharmacologic means. This can be performed with IV calcium channel blockers, amioda- rone, or β-blockers, which are usually effective in rapid conversion. Cardioversion should be performed in patients who are hemodynamically instable. Cardioversion in patients with atrial fibrillation for longer than 48 h is contraindicated until they are fully anticoagulated. Acute intervention may not be necessary in patients with a history of well-tolerated arrhythmia.

Answer 21

ANSWER: C COMMENTS: Inotropic agents increase cardiac contractility by increasing the concentration and availability of intracellular calcium. Catecholamines act by binding to adrenergic receptors. Each type of receptor controls a particular cardiovascular function (Table 10.1). Epinephrine, norepinephrine, dopamine, and dobutamine are all catecholamines. The α1-receptor mediates arterial vasoconstriction by causing contraction of the vascular smooth muscle, and the α2-receptor induces constriction of venous capacitance vessels. The β1-receptor stimulates myocardial contractility, and the β2-receptor causes relaxation of bronchial smooth muscle and relaxation of vascular smooth muscle in skeletal muscle beds. The dopamine receptors cause relaxation of the vascular smooth muscle. The dopamine-1 receptor induces relaxation of renal and splanchnic vascular smooth muscle, and the dopamine-2 receptor inhibits the uptake of norepinephrine at the sympathetic nerve terminal, which results in a prolonged action of norepinephrine at the motor end plate. The effects of dopamine are unpredictable, and the side effects might be significant. Thus its use in the ICU has been ebbing. The response to catecholamines in normal individuals is different from that in critically ill patients. Receptor populations change over short periods, and upregulation and downregulation can occur depending on the disease state. It is important that catecholamines be administered for a predetermined effect. If the effect is not attained with the particular catecholamine chosen, the dose should be adjusted or another agent used.

Answer 22

ANSWER: B COMMENTS: Placement of a PEG tube is a viable and safe option for many critically ill patients or those who are unable to maintain adequate PO intake. There are few contraindications and complications when performed on a properly selected patient population. The technique of PEG placement relies on the principles of transillumination of the entry site with a lighted gastroscope and 1:1 palpation. These steps are critical to ensure the stomach and anterior abdominal wall are sufficiently opposed, and there are no other organs (i.e., transverse colon) that may be injured during tube insertion. Contraindications to PEG include irreversible coagulopathy, hemodynamic instability, oropharyngeal or esophageal mass unable to be passed by a gastroscope, a history of total gastrectomy, massive ascites, or portal hypertension with varices. There are reports of successful PEG placement with small-to-moderate ascites and the concurrent use of paracentesis; however, the complication rate in this population is much higher suggesting the risks of the procedure outweigh the benefits.

Answer 23

ANSWER: E COMMENTS: The most common causes of increased dead space in critically ill patients are decreased CO, PE, pulmonary hypertension, acute respiratory distress syndrome (ARDS), and excessive PEEP, all of which directly cause decreased blood flow to the pulmonary vasculature. In dead space ventilation with a high ventilation/perfusion (V/Q) ratio, there is decreased blood flow to ventilated areas, which primarily affects the elimination of carbon dioxide. In ARDS, some areas of the lung are perfused but not ventilated. Alveoli may be filled with secretions, exudate, blood, or edema, thereby increasing the shunt fraction. Other areas of the lung may be ventilated but not perfused, which accounts for the dead space ventilation. PEEP can cause dead space ventilation by decreasing CO and stenting alveoli open, which causes the surrounding capillaries to collapse and thereby decreases alveolar perfusion. Carbon dioxide production and the dead space–tidal volume ratio (Vds/Vt) determine minute ventilation. The anatomic dead space includes the volume of the airways to the level of the bronchiole (150 mL). Dead space can also include alveoli that are well ventilated but poorly perfused. When combined, the anatomic and alveolar dead space constitutes the physiologic dead space, which is essentially the volume of gas moved during each tidal breath that does not participate in gas exchange.

Answer 24

ANSWER: D COMMENTS: Intrinsic PEEP (commonly known as auto-PEEP) is a state at end exhalation in which there is incomplete gas emptying, which can elevate alveolar volume and pressure. It is the threshold pressure needed to be overcome to initiate inspiratory flow. Severe bronchospasm increases the expiratory time needed, and patients in status asthmaticus or severe chronic obstructive pulmonary disease (COPD) are at risk for intrinsic PEEP. If combined with narrowed airways, such as in asthma, and parenchymal noncompliance, the inspiratory work of breathing is increased. Therefore there is an imbalance of respiratory muscle strength and work of breathing leading to respiratory failure. During mechanical ventilation, when the expiratory time is insufficient to allow full exhalation of a ventilator breath, expiratory flow is still occurring when the next ventilator breath is delivered. To best limit intrinsic PEEP, one can decrease the RR, thereby giving the patient more time to exhale between breaths. In addition, decreasing Vt will allow minimal improvement. One should also limit the inspiratory time to leave more time in the respiratory cycle for exhalation. Avoidance of hyperinflation and overdistention at the expense of minute ventilation, otherwise known as permissive hypercapnia, is an important method of ventilatory management in asthmatics.

Answer 25

ANSWER: D COMMENTS: The concept of daily interruption in sedation has been widely adopted by ICUs despite little convincing evidence of its independent efficacy. A number of studies have demonstrated improved time-to-extubation with combined SAT and SBT versus SBT alone. However, SAT has been shown to be equivalent to no SAT in many more recent trials. In these studies, there was no decrease in time-to-extubation, sedation requirement, and ICU stay or mortality. In line with no change in sedation requirements, there also has been no proven improvement in the incidence of ICU delirium with routine SAT. SAT can be associated with adverse events such as patient removal of the endotracheal tube or other lines; however, when performed in an appropriate setting, there was also no significant increase in these adverse events.

Answer 26

ANSWER: B COMMENTS: For patients with COPD, the work of breathing is increased because of increased expiratory work, not inspiratory work. It can be assessed by preoperative pulmonary function testing and optimized by preoperative chest physical therapy, bronchodilators, and antibiotics if infection is present. The work of breathing at rest consumes 2% of the total-body Vo2 and can be markedly increased, up to 50% of total Vo2, in postoperative patients because of increased airway resistance and decreased compliance of the lung, chest wall, and diaphragm. The proper use of volume-cycled ventilators and pressure support (PS) ventilation can take over most of the work of breathing during the postoperative period. Compliance is defined as the change in pressure associated with each milliliter increase in the lung volume. Measuring airway pressure reflects the compliance of the chest wall and diaphragm, as well as that of the lungs. In relaxed patients this is of little importance, but in restless patients, intraesophageal or intrapleural pressure pro- vides a more accurate measure of compliance. In acute respiratory failure, decreased compliance is usually associated with decreased functional residual capacity. Less compliant lungs need ventilatory management that maintains inflation of alveoli by the use of PEEP and recruits closed alveoli by elevating peak inspiratory pressure. However, because positive airway pressure may overdistend already-ventilated alveoli, the peak inspiratory pressure should be kept below 40 cm H2O.

Answer 27

ANSWER: A COMMENTS: Though uncommon, air embolism is a potentially lethal complication of the central line placement. Providers must be familiar with its presentation and immediate, lifesaving treatment maneuvers. Presentation depends upon the exact volume of air that enters the venous system. The lethal dose for humans has been estimated at 3 to 5 mL/kg/min; however, cardiovascular compromise can be seen with rates less than 1.5 mL/kg per min. The incidence of air embolism with central line placement is reported as between 0.2% and 1%. Physical examination for a significant air embolism will demonstrate hemodynamic instability and, often, hypoxia, along with a “mill-wheel” murmur in the precordium. Immediate intervention is Durant’s maneuver—left lateral decubitus and Trendelenburg position in order to entrap air in the apex of the ventricle. Aspiration via central venous catheter may then allow removal of some amount of the air in the system.

Answer 28

ANSWER: A COMMENTS: Many indices have been proposed to predict weaning outcome and success or failure of extubation. Most surgical patients (90%) are weaned from mechanical ventilation in less than 1 week. Conventional weaning criteria include: (1) measurements of oxygenation with a pulse oximeter (best determined by arterial blood gas analysis, with an Sao2 > 90% and any FiO2 usually being adequate for weaning) and (2) measurements of ventilation, such as an RR less than 24 breaths/min, Paco2 less than 50 mmHg, peak inspiratory pressure below 30 cm H2O, Vt of at least 5 to 8 mL/kg, and a vital capacity double the Vt value. Failure to satisfy these conventional criteria is associated with unsuccessful weaning in as many as 63% of patients. The rapid, shallow breathing test (RF/Vt) is performed by having the patient breathe room air for 1 min. When RF/Vt is 105 or less, successful weaning occurs in 78% of patients, and when RF/ Vt is less than 80, the success rate is 95%. Conversely, an RF/Vt value of 105 or higher is accompanied by a failure rate of 95%. Another method often described is the Simple Object Access Protocol (SOAP) assessment: (1) ability to clear secretions, (2) adequate oxygenation (Pao2/FiO2 ratio > 200 mmHg, which requires an FiO2 of 0.4 to 0.5 and PEEP < 8 cm H2O), (3) ability to protect the airway, and (4) adequate pulmonary function. Clinical judgment and correction of underlying pulmonary and nonpulmonary complications continue to be the best guide to successful weaning. In addition, helpful ventilation scores include an FiO2 of less than 40%, continuous positive airway pressure (CPAP) of 3 cm H2O, effective static compliance greater than 50 mL/cm H O, dynamic compliance greater than 40 mL/cm H2O, ventilator minute ventilation of less than 10 L/min, and a triggered ventilatory rate of less than 20 breaths/min. The duration of ventilatory support is not correlated with survival rates at discharge. Forty-one percent of long-term ventilated patients survive. Because muscle atrophy is often present, a progressive ventilatory withdrawal plan designed to restore muscle function should be used. Intermittent mandatory ventilation, PS ventilation, and weaning by T-piece have been used effectively.

Answer 29

ANSWER: D COMMENTS: This patient has an obstruction of the endotracheal tube. The key to identifying this problem is recognizing the components of the patient’s respiratory pressure as shown in Table 10.2, most importantly the peak inspiratory and plateau pressures. The peak inspiratory pressure is the pressure required to overcome the resistance in the endotracheal tube and airways, as well as the compliance of the airways. The inspiratory plateau pressure is the pres- sure generated to overcome the elastance of the lung parenchyma, pleural space, and chest wall. This patient had increasing peak inspiratory pressure, so her problem was related to the tube, not the lung itself. Tension pneumothorax and flash pulmonary edema are associated with increases in both peak inspiratory pressure and inspiratory plateau pressure. PE also does not change the inspiratory pressure.

Answer 30

ANSWER: A COMMENTS: Because the principal physiologic problem in ARDS is hypoxemia refractory to increasing FiO2, therapy is centered on the provision of mechanical ventilation to maximize oxygen delivery while minimizing lung injury. PEEP is used to improve oxygenation and lung compliance and should be optimized with the help of pressure–volume curves to facilitate the maintenance of open alveoli and diffusion of oxygen into the pulmonary capillaries. For a given FiO2, Pao2 usually increases on the administration of PEEP in patients with ARDS. However, excessive PEEP (>15 cm H2O) can be hazardous and lead to pneumothorax from barotrauma and decreased venous return to the heart. Overdistention of alveoli can be prevented by keeping the peak inspiratory pressure below 35 cm H2O. Newer ventilatory methods attempt to enhance alveolar recruitment, maintain alveolar patency throughout the respiratory cycle, maintain an Sao2 of greater than 90%, avoid dynamic hyperinflation (volu-trauma), and reduce the risk for oxygen toxicity. Spontaneous, augmented low-volume ventilation, with PS ventilation being used as a primary ventilatory support mode, directs flow to regions of low ventilation/perfusion. Diuretics in cases of obvious fluid overload and cardiac decompensation and broad-spectrum antibiotics in cases of established pulmonary infection or other sources of sepsis may be useful for patients with ARDS. The consensus conference on ARDS (ARDSnet.org) showed that a volume-restricted ventilation strategy reduced mortality. In this well-accepted study, 861 patients were randomly assigned to either a traditional-volume ventilation strategy (12 mL/kg of ideal body weight with plateau pressures < 50 cm H2O) or low-Vt ventilation (6 mL/kg with plateau pressures < 30 cm H2O). The study was halted early because of significantly reduced overall mortality (31.0% vs. 39.1%, P < .0007). Permissive hypercapnia was allowed, and sodium bicarbonate was given to maintain pH higher than 7.2. The patient developed ARDS, probably because of acute pancreatitis and systemic inflammatory response syndrome (SIRS). Criteria used to define ARDS have been recently revised. The Berlin definition developed in 2013 now stratifies ARDS based upon the degree of hypoxemia. All types of ARDS include an acute onset within 1 week of clinical insult, bilateral pulmonary infiltrates on chest radiographs, and some degree of hypoxemia not fully explained by cardiac failure. There does not have to be an infectious process for a patient to have ARDS, and no longer are patients with cardiac failure excluded from having coexisting ARDS. ARDS and acute lung injury have now been combined and categorized based on the severity of the Pao2/FiO2 ratio: mild (200 to 300), moderate (100 to 200), and severe (<100). The lung response can be divided into an exudative phase (24 to 96 h), with leakage of proteinaceous fluid into the pulmonary interstitium and corresponding damage to the alveolar–capillary interface; an early proliferative phase (3 to 10 days), with proliferation of alveolar type II cells, cellular infiltration of the septum, and organization of hyaline membranes; and a late proliferative phase (7 to 10 days), with fibrosis of the alveolar septum, ducts, and hyaline membranes. Frequently, the radiographic changes can lag behind the clinical picture in ARDS considerably.

Answer 31

ANSWER: E COMMENTS: Acute renal failure is a serious morbidity for post- surgical patients, with mortality rates greater than 50%. Renal failure can be prerenal, renal, or postrenal. The most common cause in surgical patients is hypovolemia, as is the case in this patient from blood loss in the OR. Some indicators for prerenal causes include urine osmolality greater than 500 mOsm/kg, fractional excretion of sodium (FENa) of less than 1%, and urine sodium concentration of less than 20 mEq/L, whereas an FENa greater than 3% and urinary sodium concentration greater than 40 mEq/L are indicative of parenchymal or postrenal causes. Medications, IV contrast material–induced nephropathy, rhabdomyolysis, and transfusion reactions are all options to consider. This patient’s FENa is 0.8%.

Answer 32

ANSWER: D COMMENTS: A creatinine clearance of 125 mL/min represents a normal renal function. ATN is characterized by a rise in plasma creatinine concentration [decrease in creatinine clearance or glomerular filtration rate (GFR)], a urine volume that is reduced (oliguric) or normal, changes in the findings on urinalysis, and a FENa greater than 1%–2%. Oliguria, or urine output less than 500 mL/24 h, is a frequent but not an absolute feature of ATN. Whether oliguria occurs may depend on the severity of the renal injury or the relative reabsorption of filtrate at the tubular level. Even if a patient’s GFR falls to 10 L/day (normal, 180 L/day), a urine output of 1 to 2 L/ day would still be normal as long as 8 to 9 L of filtrate was reabsorbed. In cases of well-preserved tubular function, as in prerenal forms of acute kidney injury (ARF), FENa is low, consistent with the sodium-avid state. As tubular dysfunction progresses, the ability of nephrons to reabsorb sodium is disrupted, and a greater percentage of the filtered sodium is excreted in urine. As a result, FENa will be greater than 1%–2% because of inappropriate sodium wasting by altered tubular function. Loss of urinary concentrating ability is an early feature of ATN. A urine osmolality of less than 350 mOsm/L is consistent with ATN, whereas an osmolality greater than 500 mOsm/L suggests a prerenal cause of ARF. However, lower values can be seen during prerenal ARF thus limiting the value of this test as a sole indicator of tubular function.

Answer 33

ANSWER: C COMMENTS: In most cases, radiocontrast agents can lead to a reversible form of ARF. The pathogenesis is not well established, but two proposed mechanisms of injury are renal vasoconstriction and direct tubular toxic effects. The risk is minimal in patients with normal renal function, including those with diabetes, and the renal failure is nonoliguric and transient in most cases. Severe renal failure requiring short- or long-term dialysis is rare and most likely to occur in patients whose baseline creatinine level is greater than 4 mg/dL. Risk factors for the development of contrast-induced nephropathy include underlying chronic renal failure with a plasma creatinine level greater than 1.5 mg/dL, diabetic nephropathy with renal insufficiency, CHF, multiple myeloma, and a large volume of contrast material. Saline volume expansion in the precontrast and postcontrast periods is the only preventive measure consistently shown to be of benefit. Hydration with furosemide may increase the risk for contrast-induced nephropathy when compared with saline alone. Furthermore, the use of saline solution and mannitol does not have any benefit over the use of saline alone. Calcium channel blockers given to minimize renal vasoconstriction after exposure to contrast media have not been conclusively shown to prevent renal failure. The role of nonionic contrast agents is not clearly defined. Studies seem to support the use of isosmolar non-ionic agents in high-risk patients, especially those with diabetes. There are conflicting data on the role of acetylcysteine and sodium bicarbonate infusions in the prevention of contrast-induced nephropathy, but given its relatively safe side-effect profile and the few series supporting its use, use of both can be justified, particularly in high-risk patients. A rational approach to preventing con- trast-induced nephropathy in high-risk patients, such as the patient in question, would include acetylcysteine (600 mg orally twice daily the day before and on the day of exposure to contrast mate- rial), saline volume expansion before and after the procedure, and an isosmolar nonionic contrast agent. Several recent meta-analyses have shown that sodium bicarbonate infusion can decrease the damage associated with contrast-induced nephropathy if given both before and after the procedure as well. The former may be more important for patients with renal dysfunction and diabetes.

Answer 34

ANSWER: D COMMENTS: Indications for acute dialysis treatment include: (1) persistent hyperkalemia refractory to medical management; (2) pulmonary edema unresponsive to conventional therapy; (3) severe acidemia; (4) symptoms of uremia such as anorexia, nausea, and vomiting; (5) uremic encephalopathy, seizures, asterixis, uremic pericarditis, and uremic bleeding; and (6) overdose with a dialyzable toxin such as lithium or ethylene glycol. Renal replacement therapy is needed in 1%–2% of patients with ARF, and as many as 15% of patients may ultimately require dialysis at some point in their life. It may be indicated for symptomatic fluid overload, sepsis, uremic complications, and severe electrolyte or acid-base disorders. Frequently in the ICU, continuous renal replacement therapy is superior to intermittent hemodialysis or peritoneal dialysis, but in the United States, it is only used in 10%–20% of ICU patients. Proponents of this method over others argue that it allows better hemodynamic stability and prevention of shifts in intracerebral water, minimizes the risk for infection, and provides continuous control of fluid status and acid-base abnormalities. Complications include the need for anticoagulation and a high level of nursing care.

Answer 35

ANSWER: E COMMENTS: Risk factors for stress-related mucosal lesions are mechanical ventilation longer than 48 h, coagulopathy, significant burns, and head injury. These lesions have been found in 25%– 100% of ICU patients within 48 h of admission, but clinically significant bleeding occurs in only 5%–10%. Patients with risk factors should receive prophylaxis until consuming an enteral diet of at least 50% of their caloric intake.

Answer 36

ANSWER: A COMMENTS: The most efficient strategy to wean patients from the ventilator has been studied many times and remains somewhat controversial. It is clear that the most effective way to identify those patients who are ready to have a trial of extubation is the daily SBT. However, those who have failed repeated SBTs may require a more targeted and purposeful weaning technique in order to avoid the complications associated with the long-term mechanical ventilation in the ICU setting. Early tracheostomy, when compared to late tracheostomy, does improve ICU length of stay and number of ventilator days; however, it has not shown direct benefit over other modes of weaning mechanical ventilation and will lead to a higher rate of tracheostomy. When compared directly, SIMV weaning is not as effective as PS weaning, and there is some evidence that PS weaning improves diaphragmatic dysfunction over both AC and pressure-control modes. Regardless of strategy, daily SBT and reassessment of readiness for extubation remain appropriate.

Answer 37

ANSWER: D COMMENTS: Hyponatremia is common in the setting of central nervous system disease. Most often it results from inappropriate SIADH. With SIADH, the hyponatremia initially results from ADH induced water retention. This volume expansion activates natriuretic mechanisms that induce the loss of sodium and water, with the patient typically being restored to a nearly euvolemic state. With chronic SIADH, the loss of sodium (and often potassium) is much more significant than the water retention. CSW is characterized by hyponatremia and loss of extracellular volume from inappropriate sodium wasting in urine. Patients with CSW meet the laboratory criteria for SIADH: hyponatremia, elevated urine osmolality (>100 mOsm/kg), elevated urine sodium concentration (>40 mEq/L), and low serum uric acid concentration. However, they also have clinical evidence of hypovolemia (decreased skin turgor, elevated hematocrit, decreased weight, and hypotension) rather than the nearly euvolemic state seen with SIADH. Furthermore, volume repletion with isotonic saline in patients with CSW will lead to a dilute urine (and eventual correction of the hyponatremia), whereas isotonic saline administration may worsen the hyponatremia of SIADH because the sodium is retained while the water is excreted. SIADH is usually treated by fluid restriction; however, this must be done with caution in patients with SIADH because of the risk of hypotension and cerebral infarction. Iso- tonic saline may be used but requires careful monitoring of the serum sodium concentration; if a further fall in serum sodium occurs, a switch to hypertonic saline may be necessary. CSW generally responds well to volume repletion with isotonic saline. Salt tablets and mineralocorticoids (such as fludrocortisones) may also be useful as adjunctive measures.

Answer 38

ANSWER: D COMMENTS: Arterial blood gas is commonly used to adjust ventilation parameters in order to optimize a patient’s respiratory function and maintain homeostasis. This patient has a respiratory alkalosis with low Paco2 contributing to increased pH. Pao2 is in the normal range and will maintain saturation of hemoglobin with oxygen. Adding PEEP will increase the Pao2 and is unnecessary for this patient. Decreasing the minute ventilation, however, either by changing the RR or Vt, will increase CO2 retention and thereby decrease the pH. This patient’s primary disturbance is respiratory distress, and while the renal system does compensate for prolonged acid-base disturbance, it requires a much longer duration than do our respiratory compensatory mechanisms. Sepsis is generally associated with metabolic or lactic acidosis.

Answer 39

ANSWER: D COMMENTS: In a patient in septic shock who is adequately volume resuscitated (shown by a CVP of 10 mmHg) and is unresponsive to fluid challenges, vasopressor therapy should be started. Administration of vasopressors can quickly restore BP; in the Sur- viving Sepsis Guidelines, norepinephrine administered centrally is the initial vasopressor of choice. Epinephrine, phenylephrine, and vasopressin should not be administered as the initial vasopressor to patients in septic shock. Epinephrine can be used as the first alternative agent in septic shock when BP is poorly responsive to norepinephrine. Dobutamine should be used in patients with myocardial dysfunction as evidenced by elevated cardiac filling pressures and low CO. In general, the rate of fluid administration should be reduced if cardiac filling pressures increase without concurrent hemodynamic improvement.

Answer 40

ANSWER: B COMMENTS: Although there is still much debate in the critical care literature about steroids, IV corticosteroids are recommended in patients with septic shock who despite adequate fluid replace- ment require vasopressor therapy to maintain adequate BP. Random cortisol levels may be helpful in determining a patient’s benefit from steroid therapy, although it is not required. Consideration can be made to discontinue corticosteroid therapy in patients with a random cortisol level of greater than 25 mcg/dL. An ACTH stimulation test is not recommended to identify the subset of patients with septic shock who should receive hydrocortisone.

Answer 41

ANSWER: B COMMENTS: This patient is having a myasthenic crisis, which is a consequence of an autoimmune attack on the acetylcholine receptor complex. There is clinical weakness that is mostly marked after prolonged muscle exertion and should be considered in any patient with respiratory distress and cranial nerve findings. The myasthenic crisis with respiratory failure develops in approximately 20% of patients and necessitates intubation. It can be precipitated by bronchopulmonary infections, sepsis, surgical procedures, tapering of steroid medications, pregnancy, and some drugs. Upper airway muscle weakness can lead to the collapse of the airways and aspiration. Patients with marginal vital capacity (<15 mL/kg), weak cough or voice, and worsening negative inspiratory force should be considered for intubation.

Answer 42

ANSWER: C COMMENTS: Therapeutic anticoagulation is the mainstay of treatment for confirmed or suspected PE. The goal range for partial thromboplastin time (PTT) in the treatment of venous thromboembolism is 60 to 90s, and the drip should be titrated to this value. Massive PE is defined as hypotension with systolic BP < 90 mmHg, while submassive PEs are those with systolic BP > 90 mmHg but with right heart strain or right ventricular dilation on echocardio- gram. Thrombolysis is an option for many nonsurgical patients diagnosed with massive or submassive PE. Contraindications to systemic tPA include recent head trauma, ischemic stroke (within 3 weeks), any prior intracranial hemorrhage, or neoplasm. Relative contraindications include age > 75, recent surgery (within 3 to 4 weeks), pregnancy, or remote ischemic stroke. For patients with massive or submassive PE who do not meet criteria for systemic tPA, a more recent consideration is catheter-directed tPA. While more studies are ongoing, early randomized trials of catheter- directed tPA in postsurgical patients have demonstrated improve- ment in right ventricle (RV) function at 24 h without increase in bleeding complications.

Answer 43

ANSWER: B COMMENTS: Nearly 15% of patients who receive central venous catheters will have an associated complication. While there is an obvious risk associated with their placement, many of these com- plications are related to catheter-associated infection or thrombosis. Experience reduces the likelihood of complications with line placement, and it has been shown that the complication rate after three attempts is nearly six times that of the complication rate after only one attempt by any one proceduralist. Ultrasound does reduce the risk of complication with internal jugular catheter placement but does not reliably improve outcomes with subclavian catheter placement. Regardless of the use of ultrasound guidance, pneumothorax is a potential complication and does not obviate the need for a chest x-ray. A recent meta-analysis demonstrated 4.5 infections per 1000 femoral venous catheter placements versus only 1.2 infections per 1000 subclavian venous catheter placements. Likewise, subclavian catheters were also demonstrated to be associated with fewer bloodstream infections than internal jugular venous catheters.

Answer 44

ANSWER: E COMMENTS: DVT occurs in 30% of ICU patients and is moni- tored by governing bodies in the United States; all ICUs should have a prevention protocol. High-risk factors are thoracic or general procedures requiring general anesthesia for longer than 30 min, active malignancy, neurosurgical procedures, coronary artery bypass grafting (CABG), CHF, and respiratory failure, along with the traumatic injury. ICU patients almost always have at least one risk factor and need prophylaxis. Options include pharmacologic treatment with low-molecular-weight heparin (LMWH), unfractionated heparin, or pneumatic compression devices. In regard to diagnosis, duplex ultrasound has a specificity and sensitivity greater than 95%. Many emboli can be silent, but symptoms of small-to-medium emboli are usually pulmonary (i.e., dyspnea, chest pain, and cough). Tachypnea and tachycardia are present as well. Massive PE often produces cardiovascular findings such as elevated PA pressure and right heart strain. Angiography is the definitive diagnostic technique for this disease, but a helical CT scan of the chest with infusion has shown excellent specificity. Even without pulmonary infarction, radiographic abnormalities appear as diaphragmatic elevation, atelectasis, and effusion. For treatment of DVT, heparin therapy over a period of 5 to 7 days with an overlap with warfarin constitutes the treatment of choice. Warfarin should be continued for 6 to 12 weeks for calf vein and large- vein thrombosis and up to 6 months for PE.

Answer 45

ANSWER: C COMMENTS: A rare genetic syndrome, VHL is associated with numerous benign tumors that have potential malignant transformation or other physiologic consequences. Pheochromocytoma is one of these associated lesions and should be suspected in any young patient with the disorder and hypertension. All patients with pheo- chromocytoma should undergo preoperative α-blockade to negate the activity of the tumor. Typically this is accomplished with twice- daily dosing of phenoxybenzamine or another α-blocking medication. The dose is generally started at a low level and increased until orthostatic hypotension develops. At this point, with the patient sufficiently α-blocked, there is often rebound tachycardia for which a β-blocker is then started. These medications are continued through the perioperative period until the patient has had the pheochromocytoma surgically excised. If the patient is also adrenally insufficient, stress-dose steroid at the time of the operation may be indicated.

Answer 46

ANSWER: E COMMENTS: Anemia is very common in critically ill patients; in the United States, approximately 85% of patients spending more than 1 week in the ICU receive one or more units of PRBCs in their first week. Blood is a scarce and expensive resource and is associated with morbidity, including transfusion reactions, infections, and worse outcomes. Historically, patients received transfusions if their hemoglobin level dropped below 10 g/dL. However, a multicenter prospective randomized clinical trial in 1999 showed that transfu- sion for a hemoglobin level of less than 7 g/dL had the same 30-day mortality rate as transfusion when the hemoglobin level was less than 10 g/dL (except in patients with the significant cardiac disease). This patient had preoperative cardiac clearance and is not presently showing any signs of hemodynamic instability. Patients with anemia of critical illness have been shown to have a blunted response to both endogenous and exogenous erythropoietin. A multicenter trial showed a mild increase in hemoglobin, but it is unclear in the literature whether this improves clinical outcomes.

Answer 47

ANSWER: A COMMENTS: Most of the items are routinely included on “VAP bundles” in ICUs across the country, although not all are aimed at specifically preventing VAP. The use of H2 blockers and DVT prophylaxis are indicated for nearly all mechanically ventilated patients given their increased risk for stress ulcer and thromboembolic disease; however, they play no role in the reduction of pneumonia or liberation from the ventilator. Chlorhexidine oral rinse and head- of-bed elevation are also standard practice for ventilated patients, and while not often harmful, their efficacy has been unable to be proven or widely replicated in randomized trials. It is widely accepted, however, that an established ventilator weaning protocol does reduce overall days of mechanical ventilation, which in turn results in a decreased rate of VAP. Daily SATs do not have a significant effect on ventilator days, ICU length of stay, or rates of VAP. Other considerations include the role of early tracheostomy as well as newer technologies like endotracheal tubes with the aspiration of subglottic secretions and their potential applications going forward.

Answer 48

ANSWER: A COMMENTS: Type II HIT has developed in this patient. Type I HIT occurs in 1%–2% of patients and causes transient sequestration of platelets with a drop in the count to less than the normal range or a 50% fall in the platelet count within the normal range. In general, this is of little consequence. Platelet levels normalize in a few days after heparin is discontinued. Type II is more severe, and antiplatelet antibodies develop in 0.1%–0.2% of patients exposed to heparin. It is associated with thromboticcomplications in more than 30% of cases and should be suspected in a patient in whom resistance to anticoagulation, thromboembolic events, and a fall in the platelet count greater than 30% or a count of less than 100,000/mm3 develop. Once HIT is suspected, all sources of heparin, including LMWH, should be discontinued. Warfarin can worsen the prothrombotic state and should not be used before complete anticoagulation is achieved with argatroban or lepirudin, both antithrombin agents. Lepirudin undergoes renal elimination, which should be noted in situations such as this patient with renal insufficiency. Argatroban is metabolized hepatically and is the best choice in this situation.

Answer 49

ANSWER: A COMMENTS: Hospital-acquired pneumonia (HAP) is the second most common of all nosocomial infections in the United States. The Centers for Disease Control and Prevention’s definition of nosocomial pneumonia is a clinical one that requires pneumonia to occur more than 48 h after hospital admission and excludes any infections that are present or incubating at admission. The other two criteria include appropriate findings on physical examination or an infiltrate on chest radiography plus one of the following: purulent sputum, isolation of the pathogenic organism from blood or the lung, identification of a virus from the lower respiratory tract, or serologic or pathologic evidence of recent infection. Many clinical studies have shown that early, appropriate, and adequate antibiotic therapy can reduce the mortality rate from HAP, currently listed as anywhere from 24% to 76%. T he American Thoracic Society presumes that early-onset pneumonia is due to Haemophilus influenzae, methicillin- susceptible Staphylococcus aureus, Streptococcus pneumoniae, or anaerobes. Late-onset HAP occurs more than 4 days after admission and is usually caused by gram-negative organisms, especially Pseudomonas aeruginosa, Acinetobacter, Enterobacteriaceae (Klebsiella, Enterobacter, Serratia), or methicillin-resistant S. aureus (MRSA). Broad-spectrum antibiotics should be started early and deescalated, not escalated, when culture sensitivities are known. This patient does not require intubation at this time, and low-volume, lung-protective ventilation is best used for ARDS. Patients with HAP do not need bronchoscopy daily. Chest therapy, elevation of the head of the bed, and ambulation are all methods to improve pulmonary toilet.

Answer 50

ANSWER: C COMMENTS: The most likely diagnosis is a catheter-related bloodstream infection. He had a catheter placed on an emergency basis and is now experiencing fevers and malaise, with cellulitis evident in the right side of his neck. His infection can explain the anorexia, ileus, and elevated WBC count. Catheter-related blood- stream infection is seen in approximately 5% of patients with indwelling catheters and should be suspected if any erythema or purulence is identified at the catheter site. The subclavian vein is the preferred site for the reduction of infection, over internal jugular or femoral locations. Once an infection is suspected, blood should be drawn through the line and peripherally for culture, and immediate removal of the catheter is suggested and the tip sent for culture. A catheter–peripheral colony-forming unit (CFU) ratio of 8 signifies line sepsis, and a catheter tip culture with 25 CFUs confirms a catheter-related infection.

Answer 51

ANSWER: B COMMENTS: Critical illness polyneuropathy (CPU) is an axonal motor sensory neuropathy that accompanies sepsis with encephalopathy. It is due to primary axonal degeneration and affects motor fibers more than sensory fibers. Frequently, it is manifested as a failure to wean a patient from the ventilator because of phrenic nerve involvement despite clinical improvement. Symmetrical quadriparesis with facial sparing and depressed deep tendon reflexes is characteristic, and electromyography confirms the diagnosis. Spinal fluid is normal, unlike the case in patients with Guillain-Barré syndrome. Facial involvement and detection of antibodies against acetylcholine are characteristic of myasthenia gravis. Nerve biopsy shows axonal degeneration without demyelination or inflammation. Treatment is supportive, and corticosteroids are contraindicated.

Answer 52

ANSWER: D COMMENTS: VAP has significant costs and a mortality of about 25%. The risk of acquiring VAP is highest in the first week (3% per day), thereafter decreasing to 2% per day in the second week and to 1% per day in the third week. VAP is generally categorized as early (<48 h after intubation) or late (occurring after 5 to 7 days of intubation). Early-onset VAP is associated with bacteria that are normally sensitive to antibiotics (S. aureus, H. influenzae, and S. pneumoniae), whereas late-onset VAP is typically associated with antibiotic-resistant bacteria (MRSA, P. aeruginosa, Acinetobacter, and Enterobacter species). The major risk factors for VAP include trauma, burns, and stay in neurosurgical units as opposed to medical ICUs. Known risk factors include patients older than 60 years who require prolonged (>48 h) mechanical ventilatory support, aspiration, a nasogastric tube, failure to elevate the head of the bed, and endotracheal cuff pressures of less than 20 cm H2O. Orotracheal intubation carries a lower incidence of VAP than nasotracheal intubation. Because contamination of ventilator circuits is universal, the ventilator circuit change interval does not affect the incidence of VAP. Heat and moisture exchangers may be associated with a slightly lower incidence of VAP than heated humidifiers. Drainage of subglottic secretions is associated with a decreased incidence of VAP, especially early-onset VAP. Kinetic beds and positioning of patients at 45 degrees from the horizontal are also associated with a decreased incidence. Previous exposure to antibiotics in a pro- longed preoperative hospitalization exposes patients to health care– related infections. Selective digestive decontamination has been reported to be associated with a decreased incidence of VAP, yet these therapies should be time limited to prevent the growth of resistant organisms. The suspicion for VAP in this patient with a prolonged period of ventilation and new onset of fever, leukocytosis, and purulent sputum should be high, particularly if the chest radiograph shows a new infiltrate. The diagnosis is best established by quantitative culture of secretions obtained from the lower respiratory tract. The two techniques used include protected specimen brush (PSB) sampling and bronchoalveolar lavage (BAL). A threshold of 1000 CFU/mL for PSB and 10,000 CFU/mL for BAL is currently recommended. The presence of less than 50% neutrophils in BAL fluid has also been used to exclude pneumonia. Even though the effect of these techniques on patient outcome is unclear, they have resulted in a significant reduction in the use of antibiotics.

Answer 53

ANSWER: A COMMENTS: Neurogenic shock refers to a condition characterized by hypotension and bradycardia that results from the interruption of the sympathetic nervous system pathways within the spinal cord. Common causes include sensory stimulation, such as severe pain, exposure to unpleasant events or sights, high spinal anesthesia, and traumatic spinal cord injury. Clinical characteristics include a BP that is often low, as in other forms of shock. However, the pulse rate is usually slower than normal, and the skin is flushed, warm, and dry. CO is reduced secondary to decreased blood return to the heart because of the increased capacitance of the arterioles and venules. Since the heart receives sympathetic input, there is a difference between injuries above and below T4. The former depresses cardiac function and decreases venous return. The bradycardia is caused by sympathectomy of the spinal injury above the level of T4 with no capacity for compensatory tachycardia. Treatment of neurogenic shock secondary to spinal cord injury is usually more complicated not only because of more prolonged hypotension but also because of the presence of coin- cident hypovolemic shock resulting from associated injuries. Such patients often require ventilatory support as a result of decreased spontaneous respiration and loss of the accessory muscles for breathing. Aggressive fluid therapy should be instituted early under continuous cardiovascular monitoring. Persistent hypotension necessitates recognition of possible hemorrhagic shock, and a vasopressor such as ephedrine or phenylephrine may be needed. If the injury is below T4, a pure α-agonist may aggravate the reflex bradycardia. Thus a drug with mixed chronotropic and inotropic effects (e.g., norepinephrine or dopamine) is preferred. A nasogastric tube should be inserted because gastric atony, dilation, and hypersecretion develop in these patients. Treatment of milder forms of neurogenic shock consists of removing the nociceptive stimulus. Neurogenic shock resulting from high spinal anesthesia can usually be treated with a vasopressor such as ephedrine or phenylephrine, each of which increases CO by direct effects on the heart and by increasing peripheral vasoconstriction. Although the administration of steroids remains controversial, their useful- ness for blunt spinal cord injury has been suggested when they are given within 8 h of injury and their administration is extended for 48 h.

Answer 54

ANSWER: C COMMENTS: In the newest definitions of sepsis and septic shock, the Society of Critical Care Medicine has identified the utility of the SOFA score and its association with in-hospital mortality. The variables include the Pao2:FiO2 ratio, platelet count, serum creatinine, and bilirubin. Sepsis may now be indicated by an increase in an individual patient’s SOFA score by 2 points, which is associated with a 10% increase in in-hospital mortality. The quick SOFA, or qSOFA, has been advocated for the rapid assessment of patients and consists of three variables: mental status, tachypnea (RR > 22 breaths/min), and hypotension (systolic BP < 100 mmHg). If at least two of these criteria are met, there should be a high index of suspicion for sepsis in these patients and admission to an intensive care setting is appropriate. Lastly, they identified that the combination of hypotension requiring at least one vasopressor along with a serum lactate value of 2 mmol/L or greater in the absence of hypovolemia is associated with a 40% in-hospital mortality rate. These two criteria are now recognized and utilized as the definition of septic shock.

Answer 55

ANSWER: A COMMENTS: Fulminant hepatic failure is classically defined as the development of severe liver injury with impaired synthetic function (INR ≥ 1.5) and new encephalopathy in patients without preexisting liver disease. In the United States, the most common causes of acute liver failure are acetaminophen overdose and viral hepatitis. Acetaminophen toxicity can be difficult to predict, as there are often no early symptoms and the modified Rumack- Matthew nomogram is widely used to predict poisoning severity following acetaminophen overdose. The use of activated charcoal for gastrointestinal decontamination is useful for patients who present within 4 h of acetaminophen ingestion; however, activated charcoal should be used with caution in patients who may not be able to protect their airway. N-acetylcysteine is the most effective antidote for acetaminophen toxicity, and initiation of therapy within 8 h of ingestion is associated with greatly decreased morbidity. The King’s College Criteria is used to identify patient’s with a poor prognosis with acetaminophen-induced fulminant hepatic failure. An arterial pH less than 7.3 or a combination comprising INR greater than 6.5, creatinine greater than 3.4 mg/ dL, and grade III/IV encephalopathy are strong predictors of poor prognosis. Patients who continue to deteriorate despite appropriate medical therapy should be considered for liver transplantation.

Answer 56

ANSWER: D COMMENTS: Massive blood transfusion is classically defined as transfusion of 10 units of red blood cells within 24 h; however, many other definitions have been proposed. There are many physiologic alterations associated with massive blood transfusion that require careful monitoring. Large-volume transfusion of red cells can dilute serum coagulation proteins and platelets leading to a prolongation in PT and activated partial thrombo- plastin time (aPTT). Additionally, transfused blood is anticoagu- lated with sodium citrate and citric acid. Rapid transfusion of red blood cells can overwhelm a patient’s ability to metabolize the excess citrate, which can bind ionized calcium and can lead to clinically significant hypocalcemia. Generally, very rapid transfusion is required to cause significant hypocalcemia; however, those with preexisting liver disease are at a greatly increased risk. Administration of either calcium gluconate or calcium chloride is an acceptable treatment of hypocalcemia following massive transfusion.

Answer 57

ANSWER: A COMMENTS: ACS is defined as an end-organ dysfunction in the setting of intraabdominal hypertension. Intraabdominal hyper- tension refers to sustained intraabdominal pressures ≥ 12 mmHg. Clinically, there is no defined intraabdominal pressure for ACS as end-organ dysfunction can occur at a variety of pressures between different patients; however, intraabdominal pressures ≥ 25 mmHg are frequently associated with ACS. Bladder pressures are widely used as a surrogate measurement for intraabdominal pressure. ACS can occur in a variety of clinical settings, including trauma, burns (>30% of the total body surface area), liver trans- plantation, and postsurgical patients. Additionally, large-volume resuscitation has been associated with increased occurrence of ACS. The diagnosis of ACS is generally made with the triad of a tense abdomen, decreased urine output despite fluid resuscitation, and increased airway pressures, all in the setting of abdominal hypertension. For patients with progressive renal dysfunction or worsening shock, the definitive management of ACS is a decompressive laparotomy. In patients where there is a concern for the impending development of ACS, supportive care measures can be made to decrease intraabdominal pressures. Nasogastric and rectal decompression, deep sedation, chemical paralysis, limited fluid administration, and ventilator support to reduce airway pressures may be used. In the above scenario, the patient is minimally sedated and may have improved intraabdominal pressures with increased sedative dosing.

Answer 58

ANSWER: C COMMENTS: The Advanced Trauma Life Support (ATLS) Program of the American College of Surgeons has put forth a general framework on how to approach and manage an injured patient. To streamline care, the A, B, C, D, E, and F sequence has been endorsed, which represents Airway, Breathing, Circulation, Disability, Exposure, and Focused Assessment with Sonography for Trauma (FAST). This comprises the primary survey with the goal of identifying life-threatening injuries and supporting oxygenation, ventilation, and perfusion. A team leader confirms that each system is intact and then moves to the next step with continued reassessment and interventions as needed. Common interventions include endotracheal intubation or cricothyroidotomy, placement of chest tubes and central venous catheters (CVCs), and, rarely, an emergency department (ED) thoracotomy. This is followed by a secondary survey that allows for a head-to-toe examination and a brief medical history.

Answer 59

ANSWER: A COMMENTS: The most commonly used method for securing a trauma patient’s airway is orotracheal intubation. Rapid-sequence intubation consists of preoxygenating the patient for 3 min with bag-valve-mask ventilation while maintaining in-line cervical stabilization, applying cricoid pressure to limit aspiration, administering an induction agent followed by a paralytic, performing laryngoscopy, and then placing an endotracheal tube. In-line cervical stabilization should be maintained with the help of an assistant, not a rigid cervical spine collar. Common medications used include etomidate, ketamine, and succinylcholine. Etomidate is an induction agent that has a quick onset of action and is indicated for patients with a suspected brain injury or open globe because it does not cause an increase in intracranial pressure (ICP). However, it can cause adrenal insufficiency in rare cases. Ket- amine is a dissociative anesthetic that can cause tachycardia and hypertension as common side effects. Succinylcholine should be avoided in patients with burns or a spinal cord injury because it can cause a rise in the serum potassium concentration and can lead to severe hyperkalemia. Confirmation of tube placement should be completed with a carbon dioxide detector and chest x-ray.

Answer 60

ANSWER: D COMMENTS: When traditional vascular access methods have not been successful, IO access can provide a means to give resuscitative fluids, medications, blood, and contrast. The IO route has been demonstrated to have a significantly higher first-attempt success rate and can be completed in a much quicker fashion and with fewer complications. Even experienced providers have dif- ficulty placing a CVC using landmarks. CVC in trauma has about a 50% success on the first pass and requires an average of 8 min to place. In contrast, IO placement is over 90% successful and takes approximately 1 min to place. Ultrasound guidance has been shown to improve central line placement. However, it is not always practical in an emergency setting because it may not be readily available, takes time to set up, and space around a patient is limited. Many sites have been utilized for IO access. Although IO use is limited to the anterior tibia in the pediatric population, cadaver studies in adults showed the best flow rates with minimal placement or dislodgement issues in the sternum followed by the humerus. The humerus is now the preferred position.

Answer 61

ANSWER: B COMMENTS: Approximately 1%–3% of trauma patients require a massive transfusion. The US Department of Defense’s Prospec- tive Observational Multicenter Major Trauma Transfusion (PROM- MITT) study demonstrated that early transfusion with higher plasma-to-platelet ratios was associated with decreased mortality. The Pragmatic, Randomized Optimal Platelets and Plasma Ratios (PROPPR) trial demonstrated the optimal ratio of 1 plasma:1 plate- let:1 red blood cell versus 1 plasma:1 platelet:2 red blood cells was associated with more patients achieving hemostasis with fewer hemorrhage-related deaths without increased complications. The overall 24-h and 30-day mortality was equal between groups. Both these studies support the early use of balanced transfusion therapy in an exsanguinating injured patient.

Answer 62

ANSWER: D COMMENTS: As the population grows older and more novel anticoagulants are prescribed, trauma surgeons need to know how to manage and reverse these medications acutely in a bleeding patient. Warfarin, a vitamin K antagonist, has traditionally been managed with fresh-frozen plasma and vitamin K injections. Recombinant factor VII has also been used to treat these patients and cirrhotics with an elevated international normalized ratio (INR). However, there is an increased prothrombotic risk potential with this therapy. Newer therapies include either 3- or 4-factor prothrombin complex concentrates (PCCs) that contain variable amounts of factors II, VII, IX, and X and proteins C and S and rapidly reverse the effects of warfarin within 30 min. Heparin and low-molecular-weight heparin (LMWH) are reversed with variable dosing of protamine sulfate. The effects of platelet inhibitors including aspirin and clopidogrel can be minimized with desmopressin and platelet transfusions. Novel agents including direct thrombin or factor Xa inhibitors can be managed with activated charcoal and PCC. A monoclonal antibody, idarucizumab, specifi- cally adheres to the thrombin-binding site of dabigatran, rendering it inactive within a minute of dosing.

Answer 63

ANSWER: B COMMENTS: This patient has several sources of shock including hemorrhage from his thorax and likely intracranial and spinal injuries. He is too unstable to leave the resuscitation area to go for CT imaging, and an abdominal source of bleeding must be ruled out prior to the definitive management of his injuries. Diagnostic peritoneal tap with lavage is a very sensitive, but nonspecific, test that can be used for either blunt or penetrating trauma. In this situation, diagnos- tic peritoneal lavage (DPL) is used to determine an intraperitoneal injury. However, it will miss retroperitoneal bleeding. DPL is performed by introducing a catheter into the abdomen via the Seldinger technique and then infusing 1 L of 0.9% normal saline. The fluid is then returned by gravity and sent to the laboratory for analysis. A positive DPL is defined as one with greater than 100,000 red blood cells/mm3, 500 white blood cells (WBCs)/mm3, or the presence of bilious/particulate material. A limited version of this procedure is a diagnostic peritoneal tap in which a needle is passed into the peritoneal cavity. If blood or succus is aspirated by a 10-ml syringe, it is deemed positive. If this patient has a positive DPL, the next most appropriate step in management is exploratory laparotomy. Serial abdominal examinations in an unstable patient are not appropriate.

Answer 64

ANSWER: E COMMENTS: Focused assessment for the sonographic examination of trauma patients is performed as part of the ATLS secondary survey. A 3.5-MHz convex-array transducer is used to evaluate for the presence of fluid in the abdomen. Four areas are to be examined. The first is the pericardial window, which is viewed with the transducer placed subxiphoid. The hepatorenal space is evaluated in the right midaxillary line, between the 11th and 12th ribs. The splenorenal space is evaluated in the right posterior axillary line, between the 9th and 11th ribs. The last area examined is the pouch of Douglas in the pelvis. This rectouterine/rectovesical space is evaluated with the transducer placed approximately 3 cm above the pubic symphysis. A full bladder aids in detecting the presence of blood in this space; therefore Foley catheters should be placed after FAST has been performed.

Answer 65

ANSWER: D COMMENTS: An ED thoracotomy is performed for a select group of patients, with the overall survival rate being dependent on the mechanism and ranging from 1.5% to 19%. It is least successful in patients with injuries caused by a blunt mechanism and is therefore usually reserved for those who initially have vital signs present but then lose these signs in the ED. In patients with a penetrating mechanism, a thoracotomy is indicated for those who have lost their pulse and blood pressure either in the ED after initial evalu- ation or during transport to the ED. Thoracotomy is best used when cardiac tamponade or severe thoracic hemorrhage is suspected. The thoracotomy is performed on the left side via an anterolateral approach, regardless of the supposed side of the injury, and allows the release of pericardial tamponade, open cardiopulmonary resus- citation, and aortic cross-clamping. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a newer, less invasive technique that is being utilized to control intraabdominal and pelvic hemorrhage. Outcomes are still inconclusive, and studies are ongoing to establish its routine use as an adjunct or alternative to current therapy.

Answer 66

ANSWER: B COMMENTS: Trauma is the leading cause of death in women of childbearing age and thus understanding the physiologic changes throughout the progression of pregnancy is imperative. However, since approximately 10% of pregnant patients are unaware of their pregnancy, a pregnancy test is recommended for all women of childbearing age early in their resuscitation. The most common cause of fetal death is maternal death. Therefore the focus of all initial resuscitative effort is directed toward the mother. Although the primary and secondary surveys for a pregnant patient are virtu- ally identical to those of a nonpregnant patient, it is important to perform a focused abdominal examination. Normal physiologic changes in pregnancy include an increase in HR by 10 to 15 beats/ min, a 25% increase in cardiac output, mild hypotension with average systolic blood pressures of 100, increased minute ventilation with resulting respiratory alkalosis, relative anemia, and a hypercoagulable state. Blood volume may increase by as much as 50% during pregnancy, which means that a patient may not have the tachycardia and hypotension usually associated with acute blood loss until almost 30% of total blood volume is lost. The pelvis typically protects the uterus until about 12 weeks. At about 20 weeks’ gestation, the fundal height of the uterus approximates the umbilicus, and for every week of gestation past this stage, the height increases roughly by 1 cm. During the advanced stages of pregnancy, the uterus causes compression on the inferior vena cava (IVC), thereby leading to a decreased central venous return. Hypotensive patients should be placed in the left lateral position, which even in patients with a suspected spinal injury can be accomplished by securing the patient firmly to the backboard, which can then be tilted to the left. Evaluation of the fetus is accomplished by fetal heart tone monitoring and pelvic ultrasound. Tachycardia, bradycardia, and decelerations with contractions are all signs of potential fetal distress.

Answer 67

A N S W E R S : C, E, B COMMENTS: The GCS score allows multiple health professionals to follow a patient’s neurologic status. It is based on the evaluation of three examinations—eyes, verbal, and motor—that are independently recorded and added together to obtain an overall score. The best examination from each category is utilized. The motor component is the most important regarding prognosis. As with all trauma patients, repeated examinations with a focus on the fundamentals of airway, breathing, and circulation are key. This patient demonstrates a decline in GCS score, which should prompt an evaluation of his airway and intubation. A GCS score of 8 is often used as a marker for the need for intubation to secure an airway. Any patient with a GCS score ≤ 14 or loss of consciousness should get a CT of the brain without contrast to evaluate for an intracranial injury; however, this is secondary in this patient. The overall goal in treating patients with a traumatic head injury is maintaining adequate cerebral blood flow. An estimate of this flow is obtained by calculating CPP (CPP = mean blood pressure − ICP). The goal CPP in an adult is 60 to 70 mmHg. Therefore patients should be aggressively volume resuscitated or started on vasopressors to maintain adequate mean blood pressure. ICP monitors are indicated in patients with a GCS score of 3 to 8 and either (1) an abnormal finding on CT of the head or (2) any two of the following: (a) age older than 40 years, (b) posturing response to pain, or (c) systolic blood pressure less than 90 mmHg. Overall, there is a 5% infection and 1% hematoma formation rate associated with ICP-monitoring catheters. Treatment measures used to decrease ICP include elevation of the head of the bed to 30 degrees or more, hyperventilation of patients to a PaCO2 of 35 mmHg, barbiturates, and mannitol at a dose of 1 g/kg IV. PaCO2 should not be kept below 30 mmHg to avoid worsening the cerebral ischemia. Steroids do not have a role in the treatment of acute traumatic head injury.

Answer 68

ANSWER: E COMMENTS: Clearance of cervical spine precautions relies on the patient’s ability to participate in the examination. In an awake patient with minimal risk factors, clinical examination alone is appropriate. In an obtunded patient, many accepted algorithms are present to evaluate for injury. According to the Eastern Association for the Surgery of Trauma, obtunded patients should have a CT of the cervical spine. If no focal neurologic deficits are present and the patient is likely to be obtunded for greater than 72 h, the collar can be removed with a negative CT scan only. Alternatively, MRI evaluation can be added to the workup. If both studies are negative, the collar can be removed. If a person is likely to become appropriate within 24 h as determined by an alert mental state without distracting injuries, CT should be completed, and if negative, it should be followed by a clinical examination when the patient is appropriate. Prolonged use of a cervical collar has been linked to pressure ulcers, increased ICP, prolonged ICU stay, and pneumonia and should be avoided. CT allows for evaluation of the bony elements of the spine while MRI is best for soft tissue, the spinal cord, intervertebral disks, and ligaments. Patients with spinal cord injuries, especially in the cervical area, may require early intubation for airway protection and aggressive fluid resuscitation and vasopressors to counter the neurogenic shock due to the loss of autonomic innervation. These patients typically present with hypotension and relative bradycardia. Regardless of suspicion for the neurogenic cause of hypotension, full primary and secondary surveys should be completed to rule out the hemorrhagic shock.

Answer 69

ANSWER: A COMMENTS: The neck is divided into three zones, and management of penetrating injuries is based on the affected area. Zone 1 is most inferior from the base of the neck to the cricoid cartilage and is exposed with an incision along the anterior border of the sternocleidomastoid muscle with possible extension into a median sternotomy. Zone 2 extends from the cricoid cartilage to the angle of the mandible and is best approached with an incision along the anterior border of the sternocleidomastoid muscle. Zone 3 is most superior from the angle of the mandible to the skull base. It is very difficult to approach and may require nasotracheal intubation, division of the digastric muscle, and subluxation of the mandible. Endovascular techniques may be also utilized in this area. The aerodigestive tract, vascular system, and the spine all run through the neck and must be evaluated for injury. This can include a combination of a barium swallow followed by an esophagogastroduodenoscopy (EGD), bronchoscopy, a CT angiogram, or an MRI based on clinical symptoms.

Answer 70

ANSWER: D COMMENTS: The best way to evaluate for a significant BCI is an initial ECG and troponin. If these are both normal, BCI can be ruled out. Patients with significant blunt trauma to the anterior chest with associated injuries, including, but not limited to, rib and sternal fractures, pulmonary contusions, hemothorax, pneumothorax, and polytrauma, should be screened. Within this population, the incidence of BCI is 13%. Patients who have abnormal findings on EKG, an elevated troponin, or hemodynamic instability require telemetry monitoring for 24 h. These patients are at risk for a lethal arrhythmia, which may require immediate defibrillation. A transthoracic or transesophageal echocardiogram is also indicated. Most common findings include myocardial contusion and right ventricle and right atrial injuries. Left-sided, valvular, and coronary artery injuries are rare and may require cardiopulmonary bypass for repair. A subset of patients that will have abnormal ECG and elevated troponin are those who had an acute myocardial infarction immediately prior to or during their trauma. Cardiac CT or MRI can be used to distinguish these patients who may benefit from cardiac catheterization and anticoagulation.

Answer 71

ANSWER: A COMMENTS: Penetrating thoracic trauma is common, and the choice of incision can be critical in exposing and repairing the injury. For an unstable patient in the emergency room (ER), a left anterolateral thoracotomy that can be extended across the sternum onto the right chest can provide maximal exposure to the heart and pericardium, root of the ascending aorta, descending aorta to cross-clamp, and pulmonary hilum. A median sternotomy allows access to the ascending aorta, the innominate artery including the proximal right carotid and subclavian arteries, the left common carotid artery, and the heart. The distal right subclavian artery can be approached via a right supraclavicular incision with resection of the middle part of the clavicle. The proximal descending aorta and left subclavian artery are best exposed via a left posterolateral thoracotomy; however, this is not a favorable position in emergency surgery. Alternatively, a left third intercostal space antero- lateral thoracotomy and a supraclavicular incision with resection of the middle part of the clavicle can be used. A median sternotomy can join these incisions, completing a trapdoor incision; however, this adds significant morbidity to the procedure. Placing a patient on cardiopulmonary bypass can assist with the repair of proximal thoracic vessels; however, this requires additional time and expertise.

Answer 72

ANSWER: D COMMENTS: The reported incidence of a blunt thoracic aortic injury is approximately 0.5%; however, the real incidence is likely much higher due to the vast majority of patients dying prior to arrival to a hospital. The most common aortic injuries include pseudoaneurysms, dissections, intimal flaps, and transections. This occurs most often just distal to the takeoff of the left subclavian artery on the medial wall due to shear forces on a relatively fixed part of the aorta. Characteristic x-ray findings of a widened mediastinum, left apical capping, depression of left mainstem bronchus, and loss of aortic knob may initially be seen, raising suspicion for injury, and diagnosis can be confirmed with a CT angiogram of the chest. Treatment includes strict blood pressure control with restrictive fluid resuscitation and short-acting β-blockers such as esmolol titrated to maintain systolic blood pressures between 90 and 100 mmHg. This has reduced the incidence of rupture to less than 5% of patients who present to the hospital. Repair is now routinely delayed until other life-threatening injuries are definitively managed with minimum risk. Both open and endovascular techniques can be utilized, with recent literature demonstrating reduced morbidity and mortality with endovascular approaches. However, patients may suffer from complications such as endoleaks and access vessel injuries that may require additional procedures.

Answer 73

ANSWER: E COMMENTS: Rib fractures are one of the most common injuries in trauma. Chest x-rays diagnose less than 50% of rib fractures, while CT scan detects nearly 100% of significant fractures. Fractures of ribs 1 to 3 can be associated with major thoracic vascular injuries, while fractures of ribs 9 to 12 can puncture intraabdominal organs such as the liver and spleen. The ideal treatment of rib fractures is centered on pain control and aggressive pulmonary toilet. Pain regimens include scheduled IV and per os (PO) medications, patient-controlled analgesia (PCA), intercostal blocks, and epidurals. Pulmonary toilet includes aggressive suctioning, deep breathing and coughing, incentive spirometer use, and early ambulation to decrease atelectasis. Conservative fluid management is encouraged to decrease pulmonary edema, which can worsen pulmonary contusions that are associated with rib fractures. Rib plating is making a resurgence with many proponents stating that early rib plating within 72 h can decrease many of the complications associated with severely displaced rib fractures, including prolonged need for ventilator support and pneumonia.

Answer 74

ANSWER: D COMMENTS: Many life-threatening injuries to the chest, such as a massive hemothorax, tension pneumothorax, open chest wound, and cardiac tamponade, must be identified on clinical examination and require prompt intervention. The clinical examination requires visual inspection of the chest rise for symmetry, open wound with air bubbles, paradoxical motion, and jugular venous distention. Palpation can detect crepitus and instability of ribs and sternum, while auscultation identifies absent or diminished breath sounds or dullness of heart tones. Extended FAST can also be used as part of the primary survey to detect a pneumothorax or pericardial effusion. Once the diagnosis is determined, immediate intervention must take place. A tension pneumothorax is classically described with absent breath sounds, hypotension, distended neck veins, and tracheal deviation and requires urgent chest tube placement. Many start with needle decompression; however, many times this intervention is done incorrectly, provides a false sense of security, and delays definitive treatment with tube thoracostomy. Cardiac tamponade presents with distended neck veins, muffled heart sounds, and hypotension due to fluid in the pericardial sac, decreased right atrial filling, and decreased venous return. This requires a pericardiocentesis or pericardial window.

Answer 75

ANSWER: C COMMENTS: This patient has a massive hemothorax, which is defined as greater than 1500 mL of blood loss on initial placement of tube thoracostomy, continuing loss greater than 200 mL/h for 4 h, or a total of 2500 mL in 24 h after the initial placement. This is an indication that there is ongoing bleeding that requires surgical intervention. Additional indications for an urgent thoracotomy include tracheal, esophageal, great vessel, or lung injury. Penetrating injury to the lung parenchyma may present with a large and persistent air leak. This may be best managed with a tractotomy, which utilizes a stapler passed into the tract through the lung parenchyma to control the air leak and bleeding.

Answer 76

ANSWER: D COMMENTS: Diaphragmatic injury/rupture occurs in 3%–5% of patients suffering major blunt abdominal trauma. Although this injury is uncommon, it is associated with a high incidence of coexistent injuries, including pelvic fractures (15%), hepatic and splenic injuries (40%), and rupture of the thoracic aorta (5%). The left side is affected three times more often than the right side. The use of CT imaging of these patients has significantly decreased the incidence of missed injury. Once a diagnosis of diaphragmatic rupture has been made, treatment is operative. In this situation, in which large diaphragmatic rupture is strongly suspected, laparoscopy is typically avoided because insufflation of the abdomen may cause a tension pneumothorax. However, laparoscopy may be useful to evaluate for a penetrating diaphragm injury. In the acute setting of a blunt diaphragmatic injury, laparotomy is the preferred operative approach. It allows reduction of any organs back into the abdominal cavity, as well as thorough inspection of all intraperitoneal contents. In the acute setting, even large defects can be closed primarily with a # 0- or # 1-monofilament or braided nonabsorbable suture. Diagnosing small diaphragmatic injuries can be difficult in as much as up to almost half of all patients have normal findings on physical examination at initial evaluation. Missed diaphragmatic injuries tend to enlarge over time, which may lead to herniation and strangulation of abdominal organs. Primary repair is not usually feasible because of the rapid atrophy of diaphragmatic muscle fibers. A thoracotomy is generally performed for a chronic diaphragmatic hernia since it provides better access to the adhesions usually found in the chest.

Answer 77

ANSWER: A COMMENTS: The incidence of a blunt small bowel injury is less than 1% of all traumatic injuries reported; however, it is associated with significant morbidity and mortality. A high index of suspicion must be used when evaluating for a blunt bowel injury. CT findings can be nonspecific with bowel wall thickening, fat stranding, mesenteric edema, and free fluid without solid organ injury. The presence of seatbelt sign or a lumbar vertebral body fracture significantly increases the risk of a small bowel injury. A patient without signs of peritonitis who is alert and appropriate can be monitored with clinical examinations. CT with oral contrast has not been shown to enhance the detection of these injuries and can lead to a delay of treatment and risk aspiration. If the patient has an unreliable examination, DPL may be attempted to look for amylase, bilirubin, particulates, or WBC > 500. Alternatively, a diagnostic laparoscopy or laparotomy may be completed.

Answer 78

ANSWER: C COMMENTS: Blunt cerebrovascular injury (BCVI) refers to inju- ries to the carotid and vertebral arteries. Patients at risk include those with a neck hematoma or arterial bleeding, bruit, neurologic deficit, CT brain with stroke, Lefort II or III fractures, basilar skull fracture involving the carotid canal, cervical spine fracture or ligamentous injury, diffuse axonal injury with GCS ≤ 6, and near- hanging with anoxia. These patients should be screened with a CT angiogram of the neck. Some may require a traditional angiogram if CT images are inadequate. Injuries are graded from I to V. Grade I injury is a dissection with <25% luminal narrowing, while grade II is ≥25% narrowing, a thrombus, or intimal flap. A pseudoaneurysm is a grade III lesion, and total occlusion is grade IV. These are all treated with systemic anticoagulation with heparin, with a partial thromboplastin time (PTT) goal of 40 to 50 and an antiplatelet agent, aspirin or clopidogrel. Anticoagulation has decreased the incidence of stroke in these patients, which most often occurs during the first week after injury. Grade V injuries are transections with free extravasation and require immediate operative or endovascular management. Repeat imaging is completed 7 to 10 days after the initial injury. If no lesion is seen, the injury has healed and antithrombotic therapy is stopped.

Answer 79

ANSWER: A COMMENTS: Blunt injuries to the duodenum can be difficult to diagnose. Duodenal hematomas typically occur up to 3 days after injury with a gastric outlet obstruction type of clinical picture. The duodenal lumen is narrowed because of the hematoma itself and the associated edema. CT with oral contrast enhancement and upper gastrointestinal studies are useful in diagnosing this condition. If no other indication exists for exploration, treatment is conservative and consists of placement of a nasogastric tube for decompression and parenteral nutrition. Typically, these hematomas and their symptoms resolve within 7 to 15 days after injury. Operative exploration is reserved for patients in whom the symptoms do not resolve within this period.

Answer 80

ANSWER: A COMMENTS: Management options for duodenal injuries include repair, reinforcement, intraluminal decompression, and enteric diversion. These can all be used in varying degrees depending on the nature of the injury and surgeon’s preference. Two-layer primary repair may be completed for small injuries; however, with injuries involving the retroperitoneal duodenum or greater than 50% of the lumen, additional steps should be taken to prevent complications. Primary repairs can be reinforced with additional tissue such as a rotational flap of peritoneum from the abdominal wall, omentum, or a piece of small bowel (Thal patch). Internal drainage to reduce intraluminal pressure can be completed by passing a nasogastric tube postpyloric into the proximal duodenum or retrograde from the jejunum into the proximal duodenum. An enteric diversion while maintaining enteral nutrition can be completed with a Billroth II gastrojejunostomy or placement of a nasojejunal tube. A temporary alternative is a pyloric exclusion with a stapler or hand-sewn closure of the pylorus and a distal feeding jejunostomy; however, most open up within 4 weeks. Pancreatico-duodenectomy is only indicated in trauma if the damage to both the duodenum and pancreas is beyond repair and the patient is hemodynamically stable. Assessment of the pancreas and extrahepatic biliary tree is also mandated with duodenal injuries due to their close proximity to the duodenum.

Answer 81

ANSWER: A COMMENTS: Treatment of bowel injuries relies on the amount of damage to the viscera and stability of the patient. Patients who are hemodynamically stable and have injuries that involve less than 50% of the circumferential bowel with no vascular disruption can undergo primary repair without the need for diversion. Resection is indicated for injuries involving greater than 50% of the wall circumference, multiple injuries in a short segment, or both. Anastomosis can be hand-sewn or stapled. However, there may be a slight decrease in the number of complications with a hand-sewn technique. This can be completed with a running absorbable full- thickness suture for the inner layer and an interrupted silk suture for the outer seromuscular layer. Complications occur in approximately 10% of cases and include anastomotic leaks, deep space abscesses, and enterocutaneous fistulas. They are increased in damage control cases and those with other intraabdominal injuries, especially pancreaticoduodenal injuries. Broad-spectrum antibiotics should be given preoperatively and discontinued 24 h postoperatively.

Answer 82

ANSWER: B COMMENTS: Operative management of pancreatic injuries centers on the location of the injury and whether the duct is involved. Approximately 50% of the pancreas is located on either side of the superior mesenteric artery. For pancreatic wounds with an intact duct, drainage of the area with soft closed suction drains suffices. If the main pancreatic duct is injured to the left of the mesenteric vessels, as in this patient, distal pancreatectomy with drainage of the proximal stump is indicated. The proximal pancreatic duct should be individually ligated with nonabsorbable suture, if possible, and the parenchymal tissue oversewn or stapled across with a stapler. The spleen should be preserved if the patient’s hemodynamic status allows. Roux-en-Y pancreaticojejunostomy to the distal end of the pancreas with oversewing of the proximal pancreatic stump carries a high rate of leakage. A pancreaticoduodenectomy and total pancreatectomy would be reserved for injuries that involve extensive devitalization of the duodenum and pancreas. Primary repair is technically difficult and does not address the transected pancreatic tissue. Intraoperative cholangiography and pancreaticogram, or postoperative endoscopic retrograde cholangiopancreatography (ERCP) or magnetic resonance cholangio- pancreatography (MRCP), can aid in defining critical anatomy.

Answer 83

ANSWER: E COMMENTS: With regard to hepatic injuries, there are three overall goals of treatment: (1) control of hemorrhage, (2) debridement of nonviable tissue, and (3) adequate drainage. Multiple operative techniques can be used to establish control of bleeding, and often a combination of these techniques is used. The Pringle maneuver is direct compression of the portal triad, either manually or with a vascular clamp. This is helpful in identifying whether the bleeding source is from the hepatic artery or portal vein versus hepatic veins or retrohepatic vena cava. The clamping time should be minimized as much as possible with 5 min of flow for every 15 min clamped. These patients tend to be hypovolemic and, as a rule, do not tolerate hepatic ischemia well. Omental packing is performed by first creating a pedicle of omentum and then placing it across or in the defect. This creates a well-vascularized “packing” of the liver that also has its own natural hemostatic properties. Large mattress sutures using a 0-chromic on a blunt tipped needle work by compressing the bullet track with the surrounding liver parenchyma. A tractotomy is the act of opening the already present wound to fully examine the track and identify the bleeding vessels. This then allows directed individual vessel ligation. Historically, selective hepatic artery ligation has been used and involves ligation of the hepatic artery branch to the involved lobe. Although this is still a viable option, it is associated with a fairly high rate of abscess formation and hepatic necrosis.

Answer 84

ANSWER: E COMMENTS: The overall success rate for nonoperative management of blunt hepatic injuries is about 90%. Patients with grade IV and V injuries are able to be treated without surgery between 75% and 80% of the time. Requirements for nonoperative therapy include hemodynamic stability, no signs or symptoms of peritonitis, and a transfusion requirement of no more than two to four units of packed red blood cells. This patient is hemodynamically stable, and therefore further imaging with CT is warranted. The initial CT can not only localize the injury but, in the case of solid organ injuries, also provide information regarding active hemorrhage. The patient should be closely monitored in an intensive care setting with serial abdominal examinations and hemoglobin determinations. Angiography is a helpful adjunct to nonoperative treatment, but it is usually reserved for situations in which active extravasation or a “blush” is seen on CT. Repeated CT is advised for patients who do experience a decrease in their hemoglobin to reevaluate the liver damage and to look for any active extravasation that would be amenable to angiographic embolization.

Answer 85

ANSWER: C COMMENTS: Because of the increasing number of patients with significant liver lacerations being treated nonoperatively, posttreatment complications are being encountered more often. Such complications include hemobilia, biloma, hepatic necrosis, and abscess. Hemobilia occurs when a connection exists between the biliary and arterial systems, and it is typically manifested as RUQ pain, melena, and jaundice. Hemobilia can be diagnosed by CT with IV contrast enhancement or upper endoscopy and is usually treated by angiography with embolization. Patients with hepatic necrosis or abscess (or both) typically have RUQ pain, fever, leukocytosis, and, at times, localized peritonitis. It can be appreciated on CT with IV contrast enhancement as nonperfused liver parenchyma sometimes associated with a heterogeneous fluid collection. This condition warrants laparotomy with debridement. Bilomas occur as a result of leakage of bile and typically close spontaneously over time. The fluid collections themselves are best treated with image-guided percutaneous drainage when localized, as in this patient. If the fluid collection is not amenable to percutaneous drainage, ERCP is recommended because biliary stents and sphincterotomy can reduce intrahepatic biliary pressure and increase healing.

Answer 86

ANSWER: C COMMENTS: The annual incidence of a blunt splenic injury is 40,000 patients, of which over 90% are managed without surgery. Nonoperative management, including observation, serial hemoglobins and abdominal examinations, limited blood transfusions, and angiography with possible embolization, is utilized for the remaining majority of patients. Although controversy exists regarding who should undergo angiography, the literature suggests that those with contrast blush or extravasation on initial CT or American Association for the Surgery of Trauma (AAST) grade III to V splenic injuries may benefit the most from intervention, reducing the need for delayed splenectomy. This strategy is limited to hemodynamically stable patients with reliable examinations. Complications associated with angiography and embolization include splenic abscesses, acute kidney injury, hematomas, and coil migration. Patients should be observed in the hospital or can be discharged home after 24 to 72 h of monitoring, with strict instructions to return to the hospital for any signs of bleeding. Most patients who fail nonoperative management require a splenectomy within 5 days of the injury. Transfusions of greater than two to four units of packed red blood cells, hypotension, tachycardia, or peritonitis are triggers to convert to operative management.

Answer 87

ANSWER: B COMMENTS: Patients with hypotension, tachycardia, or other injuries that limit reliable serial examinations should undergo urgent splenectomy. In this case scenario, the patient initially was appropriate for embolization but deteriorated despite intervention and became unstable, necessitating a trip to the operating room for a splenectomy. Although giving a transfusion is warranted, due to the significant drop in hemoglobin, tachycardia, and hypotension, surgical intervention is indicated. Patients who respond to resuscitation and become relatively stable in the operating room with a limited splenic injury may benefit from splenorrhaphy or partial splenectomy. This can be completed by ligating the blood supply to the damaged part of the spleen, letting the tissue demarcate, and debriding nonviable tissue. The remaining spleen can be wrapped in an absorbable mesh or primarily repaired by approximating the splenic capsule with a pledgeted mattress suture. Patients who undergo splenectomy should be vaccinated against encapsulated organisms, specifically pneumococcus, meningococcus, and Haemophilus influenzae, prior to discharge. Immune function remains preserved after embolization.

Answer 88

ANSWER: D COMMENTS: The major abdominal vasculature is located in the retroperitoneum, which is divided into three zones. Management of injuries is based on the mechanism, blunt versus penetrating, if there is a concern for ongoing bleeding, and which zone is involved. Zone I is the central retroperitoneum and contains the aorta and its branches, the vena cava, and the proximal renal vessels. The lateral areas are zone II and contain the kidney, proximal collecting system, and distal renal vessels. Zone III is the pelvis and its con- tents including the iliac vessels. Most hematomas resulting from blunt trauma should not be explored other than zone 1 injuries or pulsatile expanding hematomas. All penetrating injuries must be explored due to the risk of injury to other retroperitoneal organs such as the duodenum, pancreas, colon, rectum, and bladder. The only exception is a stable retrohepatic hematoma. Obtaining proximal and distal control prior to exploration of a hematoma is ideal but not always possible. With blunt trauma, angiography with embolization may be used as an adjunct in nonexpanding hematomas.

Answer 89

ANSWER: B COMMENTS: Rapid exposure and control of abdominal vessels are critical in patients with life-threatening hemorrhage. The principles of proximal and distal control should always be attempted prior to entering a contained hematoma. However, once bleeding has started and the injury is identified, direct pressure with a finger may allow for temporary control. Left medial visceral rotation, which requires the division of the lateral attachments of the colon and spleen allowing for mobilization to the right toward midline, exposes the aorta and the left renal hilum. The distal aorta and iliac arteries can be exposed by lifting up the transverse colon and dissecting at the base of the mesocolon. The IVC and right renal hilum are best approached with right medial visceral rotation, which divides the colon and duodenum’s lateral peritoneal attachments allowing for mobilization of the ascending and transverse colon, duodenum, and pancreas cephalad and to the left toward the midline. Suprahepatic IVC may require the division of the diaphragm or even a sternotomy for control within the pericardial sac. Supraceliac control of the aorta at the diaphragm can temporarily curb the bleeding when the patient is in extremis and can be used while attempting definitive vascular control. The vena cava can be controlled with sponge sticks placed proximal and distal to the injury. There are a few special maneuvers that can be utilized for repair of intraabdominal vascular injuries. Exposure of the back wall of the vena cava can be done through an anterior venotomy, allowing for repair. Superior mesenteric artery injuries may require transection of the pancreas for exposure, and the right iliac vein may require transection and subsequent repair of the right iliac artery for exposure.

Answer 90

ANSWER: B COMMENTS: Damage control surgery is a staged resuscitation strategy with three phases that include the initial operation, resuscitation in the ICU, and return to the operating room for definitive treatment. Goals for the initial procedure include control of hemorrhage with sutures and packing, limiting fecal contamination and restoring critical blood flow. In the ICU, the patient is aggressively resuscitated with blood products, fluids, and vasopressors with the goal of obtaining a normal physiologic state. Once the patient is stable, a plan can be made to return to the operating room for definitive surgical management and evaluation for missed injuries. The trigger to employ a damage control strategy is metabolic failure defined by hypothermia, metabolic acidosis, and coagulopathy despite hemorrhage control. Published guidelines include an arterial pH of ≤7.2, lactic acid > 5 mmol/L, base deficit < −15 in a patient younger than 55 years or 50% normal.

Answer 91

ANSWER: B COMMENTS: The patient in the above scenario is in extremis and requires a quick establishment of distal perfusion. Although ligation is an option, it puts the lower extremity at risk of ischemia and amputation. Placement of vascular shunts require proximal and distal control, debridement to clean edges, thrombectomy with a Fogarty catheter, regional heparinization, proper shunt selection, securing the distal end first with a 0 silk tie to allow for back bleed- ing, and then securing the proximal end to allow reestablishment of flow. Fasciotomy should be considered based on ischemia time. This will allow perfusion and an increased chance for limb salvage while other life-threating injuries are being managed. Dwell times have ranged from 3 to 36 h and do not require systemic anticoagulation. They are routinely used for peripheral arterial injuries but have also been selectively used for extremity venous and truncal vascular injuries. Definitive repair can be completed during the next trip to the operating room with the best choice being a reversed saphenous vein interposition graft from the contralateral leg.

Answer 92

ANSWER: E COMMENTS: Pelvic injuries are present in approximately 10% of blunt trauma patients. Pelvic fractures can be classified accord- ing to the force vector that caused the injury: anteroposterior compression, lateral compression, or vertical shear fractures. The overall mortality in these patients is 6%. However, it increases to greater than 30% when patients present with hemorrhagic shock. Bleeding is usually from branches of the internal iliac artery or the extensive venous plexus surrounding the sacrum. Early control of pelvic hemorrhage is critical. Placement of a pelvic binder or external fixator works by decreasing the volume of the pelvis and temporarily stabilizes the fractured bones, preventing additional injury. Preperitoneal packing completed through a low midline or supra- pubic incision carried through the fascia allows for three rolled lap pads to be placed into the preperitoneal space on each side of the bladder, resulting in volume reduction and tamponade of bleeding. This can be done in the operating room in conjunction with a laparotomy being completed for other injuries through a separate incision. Bilateral internal iliac artery embolization with a temporary agent, such as gelatin material, is the preferred angiographic treatment in unstable patients. This provides quick control by limiting flow through the large number of collaterals feeding the pelvis and allowing time for a clot to form. REBOA is now being used in a limited number of centers as an adjunct for early control of pelvic bleeding and increasing mean arterial pressure in patients presenting in hemorrhagic shock with isolated pelvic trauma.

Answer 93

ANSWER: C COMMENTS: Approximately 5% of pelvic fractures will have an associated bladder injury. The majority of these will present with hematuria and can be diagnosed with a CT or traditional cystogram. Contrast extravasation into the retroperitoneum is seen as flame- shaped densities surrounding the bladder, which is characteristic of an extraperitoneal injury. With an intraperitoneal injury, contrast leaks into the abdomen, outlining loops of bowel. Approximately 80% of injuries are extraperitoneal and can be treated with a Foley catheter for 10 to 14 days. An intraperitoneal bladder injury requires operative exploration of the bladder, identification of ureteral ori- fices and bladder neck, and a two-layer repair with absorbable suture. A closed suction drain is left next to the repair, and the Foley catheter remains in place for 10 to 14 days. A repeat cystogram is completed at 10 days to evaluate the healing process. The Foley catheter can be removed at that time if no extravasation is noted.

Answer 94

ANSWER: C COMMENTS: Repair of rectal injury largely depends on location, intraperitoneal versus extraperitoneal. The posterior rectum and distal third of the anterior rectum are not serosalized, and an injury in these regions is considered extraperitoneal. Extraperitoneal rectal injuries should be treated chiefly by fecal diversion. Nondestructive intraperitoneal lacerations that are less than 50% of the circumference of the rectal wall should be repaired primarily after debridement of any devitalized tissue in the absence of peritonitis. Presacral drainage, which historically had been used rather rou-tinely, has been decreasing in use and has not been shown to decrease the complication rate.

Answer 95

ANSWER: E COMMENTS: When a trauma patient is unstable on the operating room table and damage control has been initiated, time should not be spent on primary repair of a ureteral injury. Surgical options for this type of situation consist of simple ligation of the ureter, placing a percutaneous nephrostomy through the renal parenchyma into the renal pelvis, inserting a catheter into the proximal end of the damaged ureter and bringing it out through the wound, or placing a catheter or stent in the proximal and distal ends of a small-segment ureteral injury. These methods will allow for urinary diversion until the patient is stable.

Answer 96

ANSWER: C COMMENTS: Approximately 10% of all patients with a pelvic fracture have a concomitant urethral injury. Findings on physical examination, such as blood at the meatus, perineal ecchymosis or hematoma, or inability to void, should raise suspicion for a urethral injury. If any of these signs or symptoms is present, or there is a significant anterior pelvic fracture, a urethrogram should be obtained to exclude an injury before transurethral catheterization is attempted. Bladder decompression and drainage are the mainstays of treatment of urethral injuries, either via suprapubic cystostomy for complete disruption or with a bridging transurethral catheter for partial tears.

Answer 97

ANSWER: D COMMENTS: A significant injury to a limb requires assessment of multiple factors including bone, soft tissue, nerve function, vasculature, and overall hemodynamic status to assist with the decision for limb salvage versus amputation. Although multiple scoring systems, including the mangled extremity severity score (MESS) and the Ganga Hospital Score, have been created to help evaluate and manage mangled extremities, none have been predictive to determine which limb can be salvaged versus amputated. Despite these findings, experts recommend considering primary amputation with a MESS ≥ 7, delay of greater than 6 h to treatment, and in hemodynamically unstable patients. Imaging with CT angiogram or formal angiography may assist the surgeon. However, in the setting of “hard signs,” including ongoing hemorrhage, expanding hematoma, a bruit or thrill, signs of ischemia, or absent pulses, patients should be taken directly to the operating room for exploration. Orthopedic injuries are reduced first and temporarily stabilized, which may unkink vessels and allow for reperfusion and better evaluation of a soft tissue injury.

Answer 98

ANSWER: A COMMENTS: Rhabdomyolysis is the breakdown of muscles that causes a release of myoglobin. Myoglobin causes tubular obstruction and vasoconstriction, which leads to acute tubular necrosis and acute kidney injury. There are a variety of causes of rhabdomyolysis including crush injury, multiple trauma, seizures, illicit drugs, and several medications, including many antibiotics and antipsychotics. Creatine kinase is the most specific marker for diagnosis, and higher levels correlate with a greater injury. Additional tests show the described characteristic urinalysis, hyperkalemia, hypocalcemia, and elevated creatinine. Treatment includes preventing additional muscle breakdown, aggressive IV fluid resuscitation, and managing complications including electrolyte imbalances and renal failure, which may require renal replacement therapy. Indications for dialysis include hyperkalemia, metabolic acidosis, and hypervolemia. Treatment with bicarbonate infusion has been used to alkalinize urine to a pH of 6 to theoretically prevent myoglobin precipitation in the tubules; however, there are minimal data to support this practice. Overall prognosis with early and aggressive volume resuscitation is good, with most patients recovering to baseline renal function within 2 weeks to 3 months.

Answer 99

ANSWER: E COMMENTS: Compartment syndrome of the extremity is an extremely important diagnosis to make as early as possible because of the significant risk for permanent limb dysfunction and potential loss. Causes of compartment syndrome include crush injury, reperfusion after a time of ischemia, and fractures, which account for 50% of cases. The anterior compartment of the lower part of the leg contains mostly type I (slow twitch) muscle fibers and is encased by dense fascia, thus making it most vulnerable to the development of ischemia. The diagnosis is largely clinical, with pain out of proportion to the findings on examination, pallor, paresthesias, paralysis, poikilothermia, pulselessness, and tense compartments being the hallmark symp- toms. Because of the fact that even after an hour of ischemia, impulses can still be conducted through peripheral nerves, par- esthesias are a late sign of compartment syndrome. In addition, even though compartment pressures of 30 mmHg or higher are classically quoted, lesser pressures do not prove that there is adequate tissue perfusion, and if other signs or symptoms of compartment syndrome are present, fasciotomies should still be performed.

Answer 100

ANSWER: E COMMENTS: Trauma patients, especially those with multiple injuries, including intracranial hemorrhage, pelvic and extremity fractures, and spinal injuries, are at significant risk of having a DVT. This is also a population that has an increased risk of bleeding, and standard prophylaxis protocols have been modified to account for this. All patients should have sequential compression devices upon admission, and chemical prophylaxis with either heparin 5000 U three times per day or enoxaparin 30 U twice a day should be started as early as possible. LMWH has been shown to be superior in this patient population. Patients with truncal hemorrhage with stable hemoglobin values for 24 h are at minimal risk of bleeding with the initiation of chemical prophylaxis. Controversy has been placed around patients with traumatic brain injuries. Many recent studies have shown that it is safe to start chemical prophylaxis as early as 24 h after a stable brain CT without increased risk of progression of hematoma. Few patients will have contraindications to pharmacologic prophylaxis and should be considered for weekly extremity surveillance duplex ultrasound or placement of a retrievable IVC filter. Risks of placing an IVC filter include dislodgement, perforation, and thrombosis. These should be removed at the earliest occasion when pharmacologic prophylaxis becomes appropriate and the risk of bleeding is minimized.

Answer 101

ANSWER: B COMMENTS: The reported incidence of TRALI varies from 1% to 15% of patients receiving transfusions with a mortality rate of 5%–10%. It occurs 50 to 100 times more often in critically ill patients. It can occur after transfusion of any component of blood but is most associated with fresh-frozen plasma and red blood cells. Several hypotheses exist regarding its pathogenesis, including human leukocyte antigen–specific antibody in the donor directed against an antigen in the recipient, resulting in an inflammatory response causing damage to the endothelial lining of the lungs. Criteria for diagnosis include acute onset, usually within 6 h of transfusion, hypoxemia with a PaO2/FiO2 ratio less than 300, and bilateral infiltrates on chest x-ray in a patient with no alternative risk for lung injury. Symptoms include dyspnea, tachypnea, tachycardia, hypotension, and fever. Treatment is supportive, with approximately 70%–90% of patients requiring ventilator support. Being diagnosed with TRALI does not affect the ability to receive blood transfusions in the future. However, risk reduction maneuvers including restrictive transfusion policies and washing of stored blood products should be employed with future transfusions.

Answer 102

ANSWER: B COMMENTS: A mass casualty incident involves an influx of hundreds of casualties that overwhelms the capacity and resources of a hospital, resulting in suboptimal and delayed care. Field triage is defined as sorting casualties according to their needs, considering their chance of survival, and is key in providing the greatest benefit to the maximum number of patients in these emergencies. Sort, Assess, Lifesaving Interventions, Treatment/Transport (SALT) triage allows for quick determination of which patients will benefit the most from immediate hospital transfer. Approximately 15% of patients will be critically injured in any event, and limited resources such as ICU beds, ventilators, and operating rooms need to be directed toward these critical patients with a high likelihood of survival with intervention. Causalities defined as expectant will vary depending on casualty numbers, type and severity of injuries, and resource availability. To minimize a large resource expenditure on a patient with a low likelihood of survival, these patients are kept out of the hospital until the immediate surge subsides.

Answer 103

C. Traditional teaching of advanced cardiac life support (ACLS) and advanced trauma life support (ALLS) concepts stress the "ABCDE" mantra (airway, breathing, circulation, disability, and exposure), in which airway control is paramount. However, in the setting of combat injuries and civilian catastrophes such as blast injuries, immediate control of life-threatening hemorrhage takes precedence as fatal hemorrhage can rapidly occur while addressing other elements of the primary survey. Hemorrhage remains the leading cause of potentially preventable morbidity and mortality in both military and civilian trauma, reinforcing the importance of pre-hospital efforts to control bleeding and prevent exsanguination after severe injury. The experiences gained during combat operations in Iraq and Afghanistan have led to a change in the priorities of treatment that are taught to combat medics and first-responders. As the most likely cause of potentially preventable death in these scenarios is hemorrhage, the standard ATLS approach of focusing first on the airway has been changed to a primary focus on C, or the control of hemorrhage, as the first priority. T e next priorities would be on assessing the airway and breathing for life-threatening issues such as airway obstruction, tension pneumothorax, or an open pneumothorax (“sucking chest wound”).

Answer 104

C Major extremity hemorrhage can be effectively controlled in both the pre-hospital and hospital setting using an effective proximal tourniquet. Application of tourniquets to control major hemorrhage should be placed as distal as possible yet proximal to the site of injury, to control hemorrhage and limit the extent of tissue ischemia. Hasty tourniquets applied in combat under lire or prior to moving a patient to a safer location may be placed expediently anywhere proximal on the injured extremity and later moved distally. Approximately one-third of bleeding deaths after explosive events arc due to extremity hemorrhage, with the remaining two-thirds attributed to junctional bleeding or non-compressible truncal hemorrhage (Figure 67-2). “Junctional” injuries are defined as injuries to the groin, axilla, neck, or perineum. These injuries present major challenges to hemorrhage control as damaged deep vascular structures transition from the extremities to major cavities beyond the effective reach of a proximal tourniquet. Direct pressure and topical hemostatic adjuncts are often the only currently available treatments of potential benefit before proximal surgical control can be achieved. Non-compressible truncal hemorrhage is the most feared and fatal type of bleeding as it is not amenable to pre-hospital hemorrhage control measures, and requires higher-level interventions such as surgery or angioembolization. Significant pelvic hemorrhage may result from complex bony injuries and damage to the pelvic vasculature. Treatment of pelvic fractures may include pelvic sheeting, commercial or improvised binders, and forms of external fixation, that aim to stabilize the pelvic ring. Surgical control of pelvic hemorrhage includes open and catheter based therapies as well as pre-peritoneal pelvic packing to tamponade hemorrhage. Permissive hypotension is the concept that avoiding normal or elevated blood pressure in a bleeding patient prior to surgical hemorrhage control limits blood loss. The goal is to maintain an adequate arterial pressure for critical organ perfusion while limiting overpressurization from vigorous fuid resuscitation that may exacerbate hemorrhage. Although there was initial interest in the use of activated recombinant factor VII (rFactor Vila) as an adjunctive therapy for bleeding, subsequent studies have found little to no benefit and it also would not be used as a prehospital therapy for pelvic bleeding. The treatment of traumatic intracranial hemorrhage begins with reversal of any identified coagulopathy, not hypercoagulable state, treatment of associated cerebral edema, and possible neurosurgical interventions. Distribution of preventable bleeding deaths from battlefield wounds by site of hemorrhage: Torso 48% Extremity 31% Axilla/Groin 21%

Answer 105

C. Damage control surgery (DCS) is a concept that includes the principles of limiting further physiologic insult to a severely injured patient through therapid surgical control of life-threatening hemorrhage and enteric spillage, to minimize further bleeding, restore tissue perfusion, and prevent sepsis. The goal is to avoid prolonged, initial operative procedures that may further exacerbate hypothermia, coagulopathy, and/or acidosis. Temporary closures of the abdomen and thorax may be employed to shorten the procedure length and allow for urgent or planned re-operation in this population. Once bleeding and gastrointestinal spillage arc controlled, there are no further attempts to address other non-life-threatening abdominal injuries at the initial surgery. The operation is terminated and the patient is returned to the ICU for resuscitation and restoration of normal physiology and coagulation. Following physiologic restoration these patients arc taken back to the operating room for definitive treatments and closure. In mass casualty situations and resource-constrained environments, DCS allows limited surgical personnel to provide critical surgical procedures to severely injured patients rapidly, and then either evacuate them to higher levels of care or clear the operating room for additional patients.

Answer 106

D. Damage control resuscitation (DCR) or hemostatic resuscitation is the concept of limiting further blood loss before surgical hemorrhage control is obtained, as well as replacing shed-blood volume with a balanced blood product based resuscitation that restores the capacity to carry and deliver oxygen and addresses derangements ol the coagulation system. DCR research has focused upon improved morbidity and mortality with limitation of crystalloid infusion to prevent hemodilution (colloid solutions are, in general, not advocated for trauma resuscitations), acidosis and worsening of coagulopathy, in favor of transfusion ratios approaching 1:1:1 of packed red blood to fresh frozen plasma and platelets. Additional targeted treatment of specific coagulation abnormalities based upon traditional studies (PT/INR, PTT, fibrinogen) and point of care testiing such as thromboelastography is recommended, to avoid unnecessary transfusion and appropriate resource utilization. Permissive hypotension is the concept that avoiding normal or elevated blood pressure in a bleeding patient prior to surgical hemorrhage control limits blood loss. The goal is to maintain an adequate arterial pressure for critical organ perfusion while limiting over-pressurization from vigorous fuid resuscitation that may exacerbate hemorrhage. Previous studies in civilian trauma patients have confirmed a favorable survival advantage by limiting pre-hospital resuscitation but heterogeneity in clinical trials such as optimal blood pressure target and f uid resuscitation type have yet to yield definitive conclusions. Current research has identified early derangements of the coagulation system that appear to confer an increased risk of morbidity and mortality after trauma, termed the acute coagulopathy of trauma. Hyperfibrinolysis is a key component of this condition. and targeted pharmacologic intervention with the antifibrinolytic agent, tranexamic acid (TXA), has been linked to a survival advantage in several studies of bleeding trauma patients. The use of TXA in the setting of major hemorrhage and massive transfusion situations is now recommended in the early treatment (< 3 hours from injury) in civilian and combat injuries.

Answer 107

A. Blast injuries are traditionally classified based upon the discrete mechanism of injury involved. Primary blast injuries involve damage to gas-filled organs such as the intestine, lungs, and middle ear as well as the brain. These injuries result from overpressurization due to the blast force. Rupture of the tympanic membrane is a frequently encountered primary blast injury, but the absence does not rule out other types of blast injury. Secondary blast injuries result from injury due to flying debris and fragments that are propelled by the blast. These are the most frequently sustained type of blast injuries. Tertiary injuries occur when a person is thrown through the air by the blast, while Quaternary injuries include other blast effects such as burn injury, inhalation of toxic gases, or injury due to collapse of structures around the person. Lastly, quinary injuries are the result of contamination by chemical, radiologic, or biologic materials from the blast itself or other injured persons. In addition to the injury classification described above, the severity of injury sustained after a blast mechanism depends upon the patient’s proximity to the blast, the energy of the blast itself, and whether or not the blast occurred in a closed space. Persons injured by a blast in an enclosed space such as a vehicle or building frequently sustain a higher rate of lethal primary blast injury as well as increased frequency ot secondary penetrating injuries.

Answer 108

B. In any trauma patient, the first priority is to ensure stable A,B,C’s, airway, breathing, and circulation, which may include emergent interventions (e.g.,tube thoracostomy). In this patient with stable vital signs, the initial step is to perform a primary and secondary survey—a brief head to toe physical exam. A common mistake in the setting of penetrating trauma is failure to identity multiple injuries. Common locations for missed penetrating injuries can be in the back, axilla, or perineum, so a complete head to toe survey is critical. Most patients can be stabilized enough to undergo a secondary survey, but any problems identified on the primary survey should be immediately addressed. Once all injuries arc identified, they can be prioritized for diagnostic imaging or operative repair. Both chest X-ray and FAST scan can be used as adjuncts to the secondary survey, but they do not replace the need lor a head-to-toe assessment of the patient. In the initial evaluation of a trauma patient, priorities are: 1. identifying all wounds, 2. determining if urgent lifesaving intervention is indicated, and 3. determining if additional testing is needed.

Answer 109

B. In the setting of penetrating trauma to the chest, the differential diagnosis for hypotension includes tension pneumothorax, cardiac tamponade, and hemothorax. Classically, a tension pneumothorax will present with deviation of the trachea away from the injury, increased percussion and decreased breath sounds with distended neck veins. However, these can be late findings and may be difficult to appreciate in a busy and noisy trauma bay. If a tension pneumothorax is suspected, the first step would be placing an large bore (14 or 18 gauge) angiocath to needle decompress the thoracic cavity. The diagnosis would be confirmed by a rush of air from the needle, and a chest tube should then be placed. In this patient, the absence of tracheal deviation along with dullness to percussion makes a hemothorax the more likely diagnosis, and a chest tube the appropriate next step. The preferred method for tube thoracostomy is to enter the “safe triangle” bounded by the anterior border of the latissimus, the lateral border of the pectoralis major, and a horizontal line at the level of the nipple (males) or infra-mammary crease (females). This positioning minimizes the likelihood of entering the abdominal cavity, injuring muscle or breast tissue, or underlying structures such as the internal mammary artery, and avoids the major chest wall musculature that can cause significant pain with chest tube insertion.

Answer 110

B. Accepted indications for emergency department thoracotomy in the setting of penetrating thoracic trauma are loss of pulses with previously witnessed cardiac activity and unresponsive, persistent, hypo¬ tension. In blunt trauma, indications are rapid exsanguination from the chest tube (> 1500 cc on initial placement with unresponsive hypotension. Survival rates after emergency thoracotomy are up to 30% for penetrating trauma, but closer to 1% for blunt trauma patients. The goals of an emergency department thoracotomy are to control hemorrhage (which may require cross-clamping the descending thoracic aorta), allow access for internal cardiac massage, and treat potential cardiac tamponade. Access to the heart, descending aorta, and mediastinum requires a left thoracotomy incision. Regardless of the side of injury, traumatic arrest warrants a left thoracotomy for access to the mediastinal structures. If necessary, the incision can be extended to the right chest (clamshell thoracotomy) for access to the right thoracic cavity. Stable patients with penetrating trauma may stillrequire exploration in the operating room. Traditionally, anterior abdominal stab wounds warranted mandatory laparotomy to rule out intraabdominal injury, although recent evidence has raised the possibility of expectant management for the stable patient with penetrating injuries. Thoracic injury to “the box,” the area defined by nipples, sternal notch, and xiphoid process generally warrants operative exploration as well. In a stable patient, however, it is reasonable to proceed with additional diagnostic studies. Although some have advocated an extensive workup including esophagoscopy, bronchoscopy, and a pericardial window, more recent data indicates that a high-quality CT scan provides excellent imaging of the thorax and mediastinum, and additional studies can be performed based on the clinical exam and CT findings. In a patient who undergoes tube thoracostomy, indications to proceed to the operating room are: > 1500 cc on initial placement, > 150-200 cc/hr for > 3 hours, or hemodynamic instability requiring persistent blood transfusions.

Answer 111

B. Zone I of the neck extends from the clavicles to the cricoid cartilage. Zone II is from the cricoid cartilage to the angle of the mandible, and Zone III is from the angle of the mandible to the skull base. The majority of penetrating injuries, as with the patient in this case, occur in Zone II. For unstable patients with signs of major vascular or airway injury, management of penetrating neck trauma involves securing an airway and proceeding directly to the operating room for neck exploration. These signs include stridor, massive subcutaneous air, gurgling or bubbling through the wound, hemoptysis/hematemesis, and pulsatile bleeding or rapidly expanding hematoma. Historically, all Zone II injuries that breached the platysma mandated operative exploration. This is no longer widely practiced, and stable patients with no hard signs of vascular or airway imaging can be managed expectantly with appropriate diagnostic tests. CTA has similar sensitivity to operative exploration for identifying vascular and soft tissue injuries. CT imaging can also provide valuable information about potential injuries to the esophagus or trachea that can guide the selective use of additional studies to evaluate these structures. Esophageal injuries are frequently asymptomatic, and morbidity significantly increases if repair is delayed beyond 24 hours. Contrast esophagography or esophagoscopy is recommended for all Zone II injuries that breach the platysma and have cither physical exam or CT scan findings concerning for an esophageal injury. Similarly, flexible bronchoscopy can be used selectively based on any exam or CT imaging findings concerning for airway injury.

Answer 112

A. Retained hemothorax is a relatively commonproblem among patients who present with a moderate or large volume hemothorax with either blunt or penetrating trauma. Although observation only is an option, this carries the risk of developing an infected hematoma (empyema) or fibrothorax. If there is still a significant amount of clotted blood in the thoracic cavity that is not adequately drained by the initial chest tube, then there are several options for management. These include placement of a second chest tube (or removal and replacement of the initial chest tube) in a better position to evacuate the fluid collection or administration of local lytic therapy (TPA or urokinase administered through the chest tube) to attempt to break up the clot and allow drainage through the chest tube. Although these can be effective in select cases, they have been associated with relatively high failure rates. Since the retained hemothorax likely consists of clotted blood, a small-bore pigtail catheter is unlikely to achieve adequate drainage. There has been a trend toward the increased use of early VATS to evacuate the hematoma and place a well-positioned chest tube under direct visualization. This approach can also be useful if there is suspicion for an associated diaphragm injury that can be repaired simultaneously. Median sternotomy would not be indicated for evacuation of a retained hemothorax.

Answer 113

Gunshot wounds fall under the broad classification of penetrating trauma and comprise up to 10% of all major trauma in the United States. The energy imparted to tissue can be calculated using the kinetic energy equation: Ke= ½m(∆v)2, where m is the mass of the projectile and ∆v, is the change in velocity before and after contact. Simplistically, it can be inferred that higher caliber firearms and those projecting higher velocities will cause more grievous injury. This assumes, of course, that the entirety of the projectile’s kinetic energy is imparted to the tissue. Those bullets that enter and exit do not expend all of their kinetic energy on the body. Furthermore, the projectile’s behavior in the body is a function of its relative density. Lower density projectiles (e.g., lead or so-called “hollow-point” bullets) will tend to expand, creating a progressively enlarging wound tract with a comparatively small entrance wound and a large exit wound. High density and/or high velocity projectiles tend to pass directly through tissue but can cause significant indirect injury via cavitation. Even further, high density tissue like bone can dramatically alter the initial trajectory, deflecting the projectile in nearly any direction. It is imperative that patients who have sustained gunshot wounds undergo a systematic evaluation with complete anatomic exposure and physical examination. 1. A. The primary survey on trauma patients follows an algorithmic approach to prevent overlooking potentially life-threatening pathology. Patients with gunshot wounds arc no exception. Evaluation and stabilization of the patient^ airway to ensure adequate oxygenation and ventilation represents the first step in resuscitation. This sort of vignette is ubiquitous on board examinations and the admonition is to "Keep it Simple,” by following the algorithm delineated by Advanced Trauma Life Support. ``` Remember the acronym ‘ABCDE’ for the primary survey. This involves assessing the patient^ airway and maintaining in-line cervical spine immobilization, ensuring adequacy of the patient^ breathing by assessing both oxygenation (via pulse oximetry) and ventilation (evaluating respiratory rate and effort), circulation (pulse examination, addressing life-threatening bleeding), disability (neurologic examination), and exposure (strip patient and perform rapid scan for injuries). It is important to be mindful that with a team approach in a working trauma, much of the above can be performed simultaneously. ``` For our patient, his unresponsiveness, agonal breathing, and oxygen desaturation are concerning and a definitive airway is indicated. While a chest X-ray will be performed and the left-sided needle decompression will need to be supplanted by a tube thoracostomy, these are of subsidiary importance to securing the patientk airway. A central venous catheter is not necessary at this time given the presence of two large bore peripheral IVs. While it will be important to take down the patient’s tourniquet to perform a detailed extremity evaluation, the report of pulsatile bleeding in the field is suggestive of vascular injury and given present hemostasis, this can be deferred until the initial resuscitation has been performed. E. Knowing the indications for operative intervention is essential to caring for patients having sustained traumatic injuries. For penetrating thoracic trauma, immediate resuscitative thoracotomy (the so-called “Emergency Department T oracotomy”) is indicated for witnessed pulseless electrical activity (overall survival 4% to 5% for gunshot wounds vs. 18% to 24% for stab wounds). Urgent thoracotomy (within 1 to 4 hours of admission) is indicated for: initial chest tube output > 1500 mL, evidence of ongoing bleeding at a rate of 200-300 mL/h, massive air leak, or cardiac tamponade. For abdominal trauma, indications for laparotomy include hemodynamic instability, peritonitis on examination, or evisceration. Strong consideration should also be given to exploration for those patients with an abdomen that cannot be evaluated clinically (e.g., due to altered mental status, distracting injury, paralytic/sedative administration, etc.). Hard signs of arterial injury include pulsatile hemorrhage, cxpanding/pulsatile hematoma, bruit or thrill over wound, absent distal pulses, or evidence to suggest extremity ischemia (pallor, poikilothermia, pain, paralysis). So-called ‘soft signs” include non-expanding hematoma, peripheral nerve deficit, history of pulsatile hemorrhage at the time of injury, and unexplained hypotension. Any patient presenting with hard signs of vascular injury should undergo prompt exploration as the positive predictive value of physical examination for arterial injury approaches 100%. In the absence of hard signs, an alternate means of performing a bedside evaluation is with the injured extremity index (analogous to an ankle-brachial index, also known as an arterial pressure index) with a normal value of > 0.9 having a reported sensitivity/specificity of 95/97% respectively for major vascular injury. A normal physical examination and injured extremity index virtually exclude major arterial injury.

Answer 114

B. Most thoracic injuries can be managed with tube thoracostomy; only 10% to 15% of thoracic trauma requires operative intervention. Tamponade physiology classically only requires 50cc of blood in the pericardial space and is characterized clinically by Beck’s Triad (jugular venous distention, muffled heart sounds, hypotension), occasionally with a narrowed pulse pressure, and the presence of an effusion on FAST examination. Patients with tamponade physiology should receive aggressive volume administration because they will be dependent on their preload to generate cardiac output. Decompressive pericardiocentesis may be performed though in the setting of trauma, but this is often a temporizing measure. Definitive surgical management in this setting of trauma involves the creation of a pericardial window. The reported incidence of great vessel injury in penetrating chest trauma is only 4%, as the majority of these patients exsanguinate prior to presentation. Gunshot wounds to the mediastinum should raise suspicion and the diagnosis can be confirmed with CT angiography. If present, urgent exploration is warranted. Lung injury that requires surgical intervention is more commonly encountered with penetrating trauma. T c majority oi these injuries can be man¬ aged with pulmonary tractotomy (for penetrating non-hilar injuries) or nonanatomic stapled resec¬ tions. Inadequately evacuated hemothorax can result in secondary in lection (post-traumatic empyema) or fibrothorax (entrapped lung). Unfortunately, prophylactic antibiotics do not appear to prevent the secondary development of infection in this set¬ ting. Chest tubes arc often unsuccessful in remov¬ ing clotted blood and consideration should be given to operative exploration for patients with retained hemothorax.

Answer 115

C. While a FAST examination is a useful bedside adjunct to detect the presence of free intra-abdominal or pericardial fluid, it is operator dependent and has a poor sensitivity with respect to hollow viscous, retroperitoneal, and diaphragmatic injuries. A negative FAST examination docs not rule out intra-peritoneal injury. There is evidence to suggest that hemodynamically stable patients with abdominal gunshot wounds and no evidence of peritonitis on exam may undergo evaluation via computerized tomography of the abdomen to determine whether further operative intervention is required. Even if the posterior fascia is violated, elective non-operative management with observation and serial examinations is a safe alternative to reflex operative exploration in a major trauma center with in-hospital surgical support. In general, primary repairs can be done on both small and large bowel if 50% or less of the circumference is damaged. The most commonly injured abdominal organ with penetrating trauma is the small bowel. For unstable patients with penetrating abdominal injuries, a full laparotomy incision should be made so that all of the injuries can be identified quickly.

Answer 116

D. Spinal cord injury following a traumatic cervical spine injury typically results from blunt compression injury to the cord itself. Typically the central grey matter is affected first while the peripherally located white matter fiber tracts may be relatively spared. If the spinal cord injury is severe enough, neurogenic or spinal shock may occur. The most basic definition of this is inadequate tissue perfusion due to paralysis of vasomotor input, most commonly due to loss of sympathetic tone and significant disruption of the vasodilator and vasoconstrictor balance. It is commonly characterized by bradycardia, hypotension, decreased peripheral vascular resistance, and decreased cardiac output. Common physical examination findings demonstrate flaccid paralysis of the extremities with no sensory function, lack of rectal tone, lack of foley catheter sensation, and priapism in males. If the spinal cord injury occurs at C5 or above then respiratory depression may occur. As this patient demonstrates some deltoid function, this indicates a lower cervical cord injury. Presence of a shoulder shrug should not fool the examiner. T is motor function is provided by the 11th cranial nerve. The most common classification of spinal cord injuries occurs via the ASIA system: A = Complete (No motor or sensory function is preserved in the sacral segments S4-S5) B = Incomplete (Sensory but no motor function is preserved below the neurological level and includes the sacral segments S4-S5) C = Incomplete (Motor function is preserved below the neurological level, and more than half of key muscles below the neurological level have a muscle grade less than 3) ``` D = Incomplete (Motor function is preserved below the neurological level, and at least half of key muscles below the neurological level have a muscle grade of 3 or more E = Normal ```

Answer 117

E. Any patient suspected of a cervical spine injury and therefore potentially unstable cervical spine should be placed in cervical immobilization with a rigid collar. Maintenance of in-line cervical alignment during intubation as well as log-roll precautions must be upheld during transfers. Per the NEXUS criteria, a patient can be cleared with a 99.8% negative predictive value for cervical spine injury if the following criteria are met: Meets all low-risk criteria? 1. No posterior midline cervical-spine tenderness 2. No evidence of intoxication 3. Anormal level of alertness 4. No focal neurologic deficit 5. No painful distracting injuries ``` YES = No Radiography NO = Radiography ```

Answer 118

C. Current treatment protocols for spinal shock involve the mainstays of aggressive fluid resuscitation and vasopressors. Vasopressor choice is left to the discretion of the treating physician based on the patient’s co-morbid factors. A goal MAP of > 85 sustained for 7 days has demonstrated some promise for improving a patient’s outcome. Usage of high dose steroids in acute spinal cord injury is a controversial topic and has been for quite some time. Various large trials (NASCIS I, II, III) have demonstrated mild benefits with the administration of methylprednisolone bolus of 30 mg/kg followed by 23 hours or continuous infusion at 5.4 mg/kg/hour. However, these studies have also demonstrated significant deleterious side effects with high dose steroids leading to the Congress of Neurosurgeons to declare that high dose steroids’ risks outweigh their benefits, and are thus not recommended.

Answer 119

A. Blunt carotid or vertebral artery injuries can be a potentially lethal injury if missed upon initial trauma evaluation. Level II evidence exists neck CTA screening in trauma patients with an exam out of proportion to their cranial imaging (i.e., a comatose patient with minimal traumatic intracranial damage). Level III evidence exists for such screening in trauma patients with GCS 8 or below, petrous bone fractures, diffuse axonal injury, C1-3 fractures, any cervical spine fracture with subluxation, cervical spine fracture through the foramen transversarium, or Le Fort II/III injuries. Surprisingly, despite its widely believed association with cervical vascular injuries, presence of an isolated “seat belt sign” with no other above listed injuries is only associated with a 1% yield for blunt cervical vascular injuries. Treatment of such blunt injuries attempt to prevent intracranial ischemic injuries. Previously aggressive treatment with open surgical or endovascular repair, often in the form of stenting or coiling, provided the mainstay of treatment. However, current emerging evidence suggests these lesions, if diagnosed prior to evidence of ischemia, can be quite benign if treated with antithrombotic medications. Currently, either anticoagulation via heparin/Coumadin or anti-platelet medications via aspirin 325 mg daily are widely used.

Answer 120

C. The Glasgow Coma Scale (GCS) is the most basic method of quickly communicating a patient’s neurologic examination. It is comprised of three components. Thus, a non-responsive comatose patient has a GCS of 3 while an awake, oriented patient would demonstrate a GCS of 15. Intubated patients automatically receive just 1 point for verbal response. If a patient’s motor exam is asymmetric, the best response is used for grading. Thus this patient’s exam is E1, V1, M5 for a total GCS of 7. For intubated patients, many providers use the convention of adding a "T” following the GCS score, so this patient would be described as a "GCS 7T"!

Answer 121

D. Insertion of an intracranial pressure monitor can be used to evaluate and treat elevated ICP or as a surrogate for a neurologic examination in those who require sedation or chemical paralysis for other injuries (such as a trauma patient with an open abdomen on paralytics). The most common indication for an ICP monitor is a patient with a traumatic intracranial injury on imaging and a GCS of 8 or less. These patients will have an elevated ICP 60% of the time. Patients with a normal head CT scan will only demonstrate elevated ICP 13% of the time. This occurs most commonly in patients over 40 years of age who demonstrate posturing on examination and hypotension.

Answer 122

C The Monro-Kellie doctrine states that the skull is a fixed compartment with 3 basic components: brain (80%), cerebrospinal fluid (10%), and blood (10%). An increase in any one of these components requires an equal decrease in one or both of the other two to prevent an increase in intracranial pressure. Typical cerebral blood flow compromises 15-20% of the cardiac output; a decrease in this may result in unmet cerebral metabolic demands. The primary goal of treatment of severe brain injury is to maintain adequate cerebral blood flow and oxygen delivery, but it is dif cult to readily measure these parameters. However, cerebral blood flow can be roughly estimated by cerebral perfusion pressure (CPP = MAP - ICP), and is commonly used to guide therapy. In uninjured patients, the brain will maintain cerebral perfusion via autoregulation over estimated CPP ranges of 50 to 150. However, patients with severe brain injury will commonly exhibit loss of autoregulation, which means that their cerebral blood flow will be directly dependent on an adequate mean arterial pressure (MAP) and a normal intracranial pressure (ICP). This is why there is so much attention paid to maintaining a normal to slightly elevated blood pressure and aggressive measures to avoid ICP elevations in patients with severe brain injury. All attempts at treating elevated intracranial pressure keep this Monro-Kellie hypothesis and its relationship with cerebral perfusion pressure in mind. The first steps toward the treatment of a patient with elevated intracranial pressure begin with many simple bedside maneuvers. Initial steps should include elevation of the head of bed to aid cerebral venous outflow, seizure prophylaxis, maintenance of hemoglobin of at least 7 g/dL or above, avoidance of elevated intra-adominal pressure, and adequate pulmonary support. Pulmonary support should focus on avoidance of hypoxia, hypercapnia, and excessive PEEP. Elevated levels of PaCO2 lead to intracranial vasodilation and cerebral blood volume, thus elevated ICP. Excessive PEEP may lead to increased intra-thoracic pressure and thus impaired cerebral venous outflow. However, patients with severe brain injury will commonly exhibit loss o autoregulation, which means that their cerebral blood ow will be directly dependent on an adequate mean arterial pressure (MAP) and a normal intracranial pressure (ICP). T is is why there is so much attention paid to maintaining a normal to slightly elevated blood pressure and aggressive measures to avoid ICP elevations in patients with severe brain injury.

Answer 123

B. If elevated ICP occurs, more aggressive methods of treatment include increased sedation (via propofol or barbituates to decreased cerebral metabolic demands), paralytics, mannitol or both rheologic and osmotic effects, and hypertonic saline. Steroids should be avoided in intracranial trauma. Despite the usage of dexamethasone with other causes of cerebral edema, steroids are associated with elevated mortality in trauma patients with severe brain injury due to the myriad of side effects. Hypotension should be avoided to help maintain the CPP.

Answer 124

D. Hemodynamic instability after blunt trauma is due to ongoing hemorrhage until proven otherwise, with the common locations being the chest, abdomen, pelvis, or extremity/cxtcrnal bleeding. The normal chest X-ray and abdominal ultrasound in conjunction with the abnormal pelvis X-ray make the pelvis the most likely source of bleeding in this patient. Although arterial injuries in association with major pelvic trauma can occur, the majority of bleeding occurs at the venous plexus located on the anterior aspect of the sacrum and sacroiliac joints. This historically has responded best to pelvic packing orfracture reduction, rather than immediate angiography. Injuries to the superior gluteal arteries posteriorly and the Corona Mortis anteriorly have been reported and can be devastating, but they are far outnumbered by the venous lacerations of the presacral venous plexus. Morel-Lavallee lesions are common after blunt force trauma, but do not typically lead to hemodynamic instability seen from the deep pelvic venous lacerations.

Answer 125

B. The current management of pelvic fracture patients who are hemodynamically unstable consists of aggressive resuscitation, mechanical stabilization, and angioembolization. Despite this multidisciplinary approach, mortality rates of these high-risk patients can exceed 40%. Initial maneuvers to reduce the pelvic fracture and decrease the pelvic volume include placement of a pelvic binder, wrapping the pelvis with a sheet, or application of an external fixation device. Preperitoneal pelvic packing (PPP) via laparotomy can directly address the venous bleeding that compromises 85% of pelvic fracture hemorrhage and docs not respond to the initial maneuvers listed above. The remaining 15% of vascular injuries are arterial and may best be addressed via angiography in the event of continued hemodynamic instability following pelvic packing.

Answer 126

A. In an antero-posterior compression fracture (APC), the fracture propagates from anterior to posterior. This widens the symphasis pubis and depending on the level of force, can widen the anterior sacroiliac joint or disrupt it entirely. In an APC III injury, the pelvic floor ligaments (sacrospinous and sacrotuberous) are disrupted and can leading to instability and increased volume in the pelvic cavity. Disruption and displacement of the sacroiliac joint has the potential to lead to massive hemorrhage from the anterior sacral venous plexus that is closely approximated to the joint. Major hemorrhage in patients with pelvic fractures can reliably be predicted based on a pulse greater than 130, a hematocrit of 30 or less, and wide diastasis of the pubic symphisis. Although pelvic binders are now routinely applied for suspected or proven pelvic fractures, they may have no benefit or may even cause additional harm in select types of fractures. The AP pelvic radiograph will identify injuries that may benefit from provisional stabilization with external compression with a sheet or pelvic binder. In general, LC injuries will not respond to binder placement, whereas APC and VS injuries will. Compression of an LC injury is potentially damaging as it may induce additional lateral compression and fracture dislocation or bleeding. Occasionally, an LC injury in an elderly patient may have a hemorrhage associated with vascular or visceral disruption; these patients will not benefit from wrapping or binding, but may be candidates for angiography.

Answer 127

E. Open pelvic fractures are potentially lethal injuries with a reported mortality rate of 30% to 50%. Open fractures of the pelvis by definition communicate with the rectum, the vagina, or the outside environment by disruption of the skin. They are often associated with disruption of the pelvic floor, leading to loss of tamponade and persistent bleeding. An additional concern is pelvic infection and sepsis due to the open communication with the rectum, vagina, or skin. Clinical suspicion of an open fracture and any rectal or vaginal bleeding mandates a thorough examination of the pelvis, perineum, rectum/anal complex, and vagina in females. In addition to visual inspection and digital examination, full evaluation should include rigid proctoscopy or flexible sigmoidoscopy, and speculum examination in females. Management of major open pelvic fractures includes administration of intravenous antibiotics, washout and debridement of open wounds, and consideration for a possible diverting colostomy to prevent fecal contamination of the open fracture.

Answer 128

B. Early diagnosis of an open pelvic fracture is essential and a thorough examination must be done so that no such injuries are missed. While it is not difficult to diagnose an open fracture when massive wounds of the skin and perineum arc present, a small vaginal or rectal tear that communicates with and contaminates the fracture may be missed unless it is sought specifically. Rectal injuries must be sought, particularly in patients with a sacral fracture, because the fragments of bone frequently traverse the rectal wall. Classically, an open pelvic fracture prompts recommendations for colostomy to prevent soft-tissue sepsis in an expanded perineum. It has recently been suggested that fecal diversion in an open pelvic fractures can be applied selectively, according to the actual location, nature, and size of the cutaneous wound. For open fractures with an associated rectal injury, immediate diverting colostomy and repair of the rectal laceration (if possible) arc indicated. Anterior wounds of the groin, anterior thigh, iliac crest, or pubis do not require diversion.

Answer 129

1. D. Image 73-1 is an axial cut of CT head (bone window) showing a left parietal compound depressed bone fracture. This is a case of an open skull fracture or compound depressed skull fracture. It is recommended to manage patients with skull fractures overlying a dural venous sinuses conservatively provided that there is no neurological deficit or CSF leak. The high probability of vessel wall laceration with subsequent profuse bleeding during surgery is the main cause of perioperative mortality. Meier and his colleagues reported 100% mortality rate of cases with skull fractures lacerating the posterior third of the superior sagittal sinus and a 50% mortality rate in cases in which the middle third was afflicted. The study showed an overall mortality rate of 41% for cases with major dural sinus injury. In a retrospective review of 27 patients with depressed compound skull fractures overlying but not disrupting a venous sinus, a management recommendation was made that wound washout with antibiotics is an adequate treatment as long as there is no mass effect or contamination deep to bone. A depressed skull fracture greater than the thickness of the calvarium, an intracranial hematoma with mass effect are considered possible indications of surgery. 2. B. There is no evidence that bone elevation following open skull fractures necessarily decreases the incidence of post-traumatic seizures which probably do occur as a direct result of the initial brain injury. Early surgery has been recommended to reduce the risk of infection but it does not effect the extent of a traumatic brain injury. Antibiotics are part of the management strategics of compound depressed fractures. Same session cranioplasty or repair of autologous bone is accepted only if there is no evidence of infection. Marked cosmetic deformity may warrant elective but not urgent surgical skull reconstruction.

Answer 130

A. Image 73-2 is an axial cut of CT head (soft tissue) shows a case of "Tension Pneumocephalus” with ‘"Mount Fuji sign" due to collection of bifrontal subdural air compressing the brain. This image depicts a case of tension pneumoccphalus. Pneumocephalus is defined as the presence of air within the intracranial cavity and may include one or more of the following compartments: (a) epidural, (b) subdural. (c) subarachnoid, (d) intraparenchymal. and/or (c) intraventricular. Tension pncumocephalus is a term used when a considerable amount of air or gas is detected on a CT scan of the head with rapid clinical deterioration. This scenario usually warrants immediate surgical intervention in order to avoid fatal brain herniation. The CT here shows accumulation ot trapped air in subdural and interhemispheric space with some resulting compressing of the brain. This radiological linding is called “Mount Fuji sign". The air usually appears black on CT scans with a density measuring - 1000 Hounsfield units. No hydrocephalus is seen as there is no ventricular enlargement. The latter usually occurs due to obstruction of the CSF-flow resulting in CSF accumulation and subsequent ventriculomegaly from obstructive hydrocephalus. Hydrocephalus ex vacuo is a term that falsely describes relative ventricular enlargement that may occur in elderly patients secondary to brain parenchymal atrophy from the natural aging process. The presence of a subdural hygroma is a post-traumatic condition that develops due to a separation of the dura-arachnoid interface followed by a passive fluid accumulation secondary to decreased ICP or from excessive dehydration. Such a fluid collection overlying the brain convexity rarely shows any mass effect which makes surgery usually unnecessary. The dynamics of alternating absorption and expansion is thought to be responsible for the occasional transformation of some SDHG cases into chronic subdural hematomas.

Answer 131

E. Most post-traumatic CSF leaks subside within 72 hours to 1 week without any need tor surgical intervention. Daele and colleagues recommended surgery tor spontaneous CSF fistula cases since they are more likely to persist. Post-traumatic CSF otorrhea on the other hand usually stops within 5 to 10 days. Detection of ßj-transferrin in rhinorrhea-fluid corroborates the presence of a CSF fistula. Tahir and colleagues reported that CT-cisternography has the highest sensitivity and specificity when compared to CT- and MR-scanning to detect the site oi a CSF leak. Pneumococci arc the most common causative organisms in eases of meningitis following a CSF fistula. Glucose urine strips could help in identifying CSR due to its high glucose concentration (> 40 mg/dl) when compared to low glucose levels (< 5 mg/dl) found in mucus secretions.

Answer 132

A. Tearing or avulsion of the bridging cortical veins is one of the causes of aSDH. Hemorrhagic brain contusions or lacerations might be another source of aSDH. EDH is commonly caused by an arterial injury of the middle meningeal artery which may progressively strip the dura from the inner table of the skull. EDH is sometimes caused by bleeding from dural veins, venous sinus or diploic channel injury following skull fractures. In a case series of 40 infants with EDH, Leggate and colleagues could identify the bleeding source in 31 cases. In 42.5% of those cases it was from the middle meningeal artery. Skull fractures were seen in 45% of cases in another series of 210 traumatic EDH cases.

Answer 133

E. The false localizing sign, or Kernohan’s notch phenomenon, is a compression of the contralateral cerebral peduncle against the edge of tentorial incisura which can lead paradoxically to an ipsilateral hemiparesis. It is an important motor localizing sign that appears raise in topography, but may occur with any supratentorial mass during uncal herniation. Yoo and colleagues explored this state of the corticospinal tract in a patient with chronic SDH and ipsilateral hemiparesis by using diffusion tensor imaging (DTl) and transcranial magnetic stimulation (TMS). EDH occurs less frequently in children and elderly patients likely due to adherence of the dura to the inner table of the skull, thus sealing firmly the epidural space. In an epidemiological analysis of 210 cases of traumatic EDH 59.2% of cases were in males and the observed presenting GCS was between 13 and 15. Therefore, it is not uncommon for patients with EDH to be fully conscious at the time of clinical assessment. A classic lucid interval is seen in only 21% of traumatic EDH cases. Ipsilateral pupillary dilation mostly occurs following oculomotor nerve compression by the medially displaced uncus and hippocampal gyrus (called: uncal herniation). In 27 posterior fossa EDU cases reported in a study by Su and colleagues, headache and vomiting the most frequently seen symptoms. Rapid brainstem compression with respiratory depression and death may occur in posterior fossa EDU eases if not treated promptly.

Answer 134

A. CT scanning of the head usually shows a classic appearance of EDH which is a homogeneous hyperdense extra-axial lenticular mass with convex borders. IV post-contrast CT is very rarely needed in cases of isodense EDH. EDH is usually localized to a limited part ot the calvarium since it is confined by the skull sutures (not the falx). On the other hand, a SDH is characterized on head CT as a crescentic mass with biconcave shape, diffusely spann mg a large area of the brain convexity and is not limited by the sutures. This is illustrated in Figure 73-6. A “Swirl sign" is a distinct radiographic sign of active bleeding which may occur in different types of intracranial hemorrhage. It presents as an area of irregular density in the hyperdense clot and is typically of low attenuation (radiolucency). Its occurrence is associated with worse clinical outcomes and bigger sizes of intracerebral hematomas as reported by Sclariu et al., as it represents an area of active ongoing bleeding.

Answer 135

B. An EDH measuring more than 30 cm in volume must be surgically evacuated regardless of the GCS. A midline shift of more than 5 mm is also a critical radiological sign of brain compression which usually indicates the need tor surgical intervention. A patient with a GCS of more than 8 and a hematoma less than 30 cm, less than 15 mm in thickness, with less than 0.5 cm midiinc shift, and without local deficit can be managed by close observation with serial scans and placement in a monitored neurosurgical unit. Acute intracranial hematomas are evacuated by cranitomics or craniectomies as the fresh blood is almost clotted. On the other hand, chronic SDH are usually liquified and can be surgically drained by one or two burr holes. Dural tenting/tack-up/hitching stitches (that holds the dura to bone) are advocated by many surgeons at the end of the surgical procedure as a routine to close the epidural space in order to prevent EDH reaccumulation. However, hemostasis is still the most relevant aspect to prevent rebleeding and there is no compelling evidence to support the role of dural tenting for all intracranial operations. Lumbar puncture may lead to life threatening central or tonsillar herniation in eases in which there is high ICP and a pressure gradient between the intracranial and intraspinal compartments.

Answer 136

E. Uncal herniation usually occurs with middle cranial fossa masses where the uncus herniates medially compressing the occulomotor nerve, cerebral peduncles of mid brain, and posterior cerebral arteries which may cause unilateral ptosis with mydriasis, hemiparesis, and hemianopia, respectively. In a case series of 161 consecutive patients operated on for post-traumatic EDH, the overall mortality was 12%, which could be further lowered by early diagnosis and proactive management. The overall mortality in another study of aSDH was 66%. The Cushing triad is a reflex triggered by markedly elevated ICP causing hypertension, bradycardia, and respiratory irregularities. Delayed EDH is defined as a radiologically evolving EDH during sequential neuroradiologic examination and which was not present initially. Detection of a skull fracture is an indication for hospital admission under neurologic observation for early detection ol possible delayed EDH.

Answer 137

D. Image 73-3 is an axial cut of CT head shows multiple hemorrhagic brain contusions (left frontal and bitemporal). This is a case showing a right temporal hemorrhagic brain contusion. It is also called diffuse post-traumatic intracerebral hemorrhage and usually appear on CT during the post-traumatic phase as an intra-axial hyperdensity indicating Iresh blood within the brain parenchyma.

Answer 138

D. The degree of temporal involvement often plays a critical role due to its proximity to the brain stem, whereas mass effect is better tolerated in affected supratentorial brain areas. Therefore, the development of temporal hematomas carries a lower threshold for surgical intervention. The indications for surgery in cases of traumatic brain contusions include hematoma causing progressive neurological deterioration; signs of significant mass effect on CT; medically refractory intracranial hypertension; patients with GCS scores of 6 to 8 with a frontal or temporal contusion greater than 20 cm in volume and with a midline shift of at least 5 mm and/or cisternal compression on CT scan, and patients with any lesion greater than 50cm in volume. Patients with such features should be treated operatively with decompression and possible resection of the affected area. Cerebral contusions most frequently develop after a mechanical impact of distinct skull areas onto the rather soft brain substance in moments in which the brain bounces. Frontal and temporal lobe tips arc most commonly aficctcd by such local hemor¬ rhagic contusions following translational accel¬ eration. Glucocorticoids are not recommended to improve the outcome or lower the ICP in patients with severe traumatic brain injury.

Answer 139

C ICP is one of the most powerful predictors of neurological outcome in patients with traumatic brain injury. Normal values are variable among different age groups and are shown in the following table (p.273): Age group & Normal Range (mmHg): Adults <10-15 Children 3-7 Term infants 1.5-6 Variable thresholds have been suggested for the initiation of treatment for raised ICP in patients with head injury. Most neurosurgical centers use a sustained ICP >20-25 mm Hg. An intraventricular catheter is the most accurate way of monitoring. The goal of ICP management is to keep it below 20 mm Hg provided that the CPP is not lowered below 50 mm Hg (not 70 mm Hg) to guard against cerebral ischemia. ``` CBF = CPP/CVR- (MAP- ICP)/CVR CBF is the cerebral Blood Flow CVR is the Cerebrovascular Resistance MAP is the Mean Arterial Pressure CPP is the Cerebral Perfusion Pressure ICP is the Intracranial Pressure ``` The average cerebral blood flow usually ranges from 50 to 60 mLmin/100 g of brain tissue during resting state. Normal white matter receives 18-25 mL/min/100 g, while normal gray matter receives 67-80mL/min/100g.

Answer 140

D. Hyperglycemia aggravates cerebral edema. Brain cell swelling is increased by hyperglycemia and ketosis especially during hypocapnia. Therefore, Dextrose 10% is not considered appropriate in cases of head trauma as it will further increase the ICP impeding both the CPP and CBF. Osmotic medical therapy includes mannitol and/or hypertonic saline (used to control the ICP in traumatic brain injury). Furosemide is a loop diuretic that can result in greater reduction of brain water content if administered in combination with mannitol as it enhances its effect on plasma osmolality.

Answer 141

B. It is not recommended to use hyperventilation vigorously to lower PaCO2 to less than 25 mm Hg as a PaCO; of less than 30 mm Hg may lower the CBF or distort cerebral autoregulation without consistently lowering ICP. The goal is to keep PaCO2 at the lower end of eucapnia (35 mmHg). The other options that arc considered routine measures to control ICP are head of bed elevation to 30°, light sedation, intubation for a GCS< 8.

Answer 142

A. Image 73-4 is an axial cut of CT head shows diffuse post-traumatic subarachnoid hemorrhage. This is a case of subarachnoid hemorrhage (SAH) shown in the CT in the form of a hyperdense blood film in the subarachnoid cisterns. Trauma is still the most common cause of SAH. Aneurysmal rupture is the most common cause of spontaneous SAH. Ruptured AVM usually presents in the form of intracerebral hemorrhage or intraventricular hemorrhage. SAH occurs in about 5% of AVM cases. Other causes may include pituitary apoplexy, coagulopathy, and cocaine abuse.

Answer 143

E. Nuchal rigidity may occur in some eases of SAH due to meningeal irritation but it is not a must for diagnosis— Patients with SAH may present with increased ICP symptoms, seizures and/or neurological deficit. Unilateral ptosis with pupillary dilation may indicate oceulomotor nerve compression secondary to a posterior communicating artery (P-comm) aneurysm. Nine percent of P-comm aneurysms present with unilateral occulomotor nerve palsy, which may indicate impending rupture and prompt intervention by a specialized neurovascular team. Cytotoxic brain edema is usually seen in head trauma patients (vs. vasogenic brain edema in brain tumor cases).

Answer 144

D. Lumbar puncture always carries the risk of rebleeding in ease of aneurysmal SAH. Therefore, LP is only needed to confirm the diagnosis of clinically suspicious cases of SAH with negative or equivocal CT scans. Sidman et al. reported that CT scans of the head had 100% sensitivity in detecting SAH within the first 12 hours. Morgenstern and his colleagues stated that 97.5% of patients with SAH presenting to the emergency room with "worst headache” symptoms were adequately diagnosed by CT imaging alone. MR1 is valuable in demonstrating subacute and chronic hemorrhages due to Methemoglobin formation which may determine the source of bleeding in patients with multiple cerebral aneurysms. The FLAIR sequence has the highest sensitivity in detecting the cases with low-grade SAH. T2/ Gradient echo sequence or Susceptibility Weighted Image (SWI) may be done as a complementary sequence. Post-contrast CT of the head may be misdiagnosed as SAH especially if the contrast is injected intrathecal.

Answer 145

C. The four-vessel cerebral angiogram or catheter cerebral angiography is the gold standard study for the evaluation of cerebral aneurysms. CT angiography (CTA) with 3 -dimensional reconstruction imaging may be used instead of catheter angiography in some centers as the sole imaging diagnostic study before major surgical intervention. CTA is a non-invasive tool that may provide prompt, accurate, and versatile diagnostic and anatomical information on which clipping can be based. However, unnecessary craniotomies based exclusively on CTA findings were also reported. MRA can also detect cerebral aneurysms, but it has lower sensitivity and specificity compared to the catheter cerebral angiogram especially for aneurysms less than 3 mm diameter. MRA is also useful in screening high-risk patients. ``` MRI Diffusion (DW1) is the best imaging study for detection of acute brain ischemia within the first hours especially when it involves the brain stem or cerebellum. ``` CT perfusion identifies the area surrounding the infarction called potentially salvageable penumbra that allows for better outcomes it interventional treatment modalities are available. Transcranial doppler (TCD) is a non-invasive semi-quantitative technique of ultrasound derived blood velocity measurements within major cerebral vessels (eg., MCA) through thin regions of skull bones providing a window. TCD is usually used in SAH to detect cerebral vasospasm early prior to the clinical delayed ischemic neurological deficit. Theoretically, the higher the velocity of blood flow, the narrower the lumen of the cerebral blood vessel.

Answer 146

F. SAH has numerous possible complications that may cause neurological deterioration. It is believed that proteinaceous blood products may occlude the arachnoid granulations causing secondary communicating hydrocephalus in 20% of SAH survivors. Angiographic cerebral vasospasm is a contributing factor of delayed neurological deficit in patients with SAH. Broderick and his colleagues reported on the causes of morbidity and mortality following aneurysmal SAH. In their study, re-bleeding was the most important preventable cause of death. It is also well-known that seizures may occur early following SAH mostly due to the presence of blood in the cisterns which may irritate the cerebral cortex, but the explanation of late onset seizures remains unclear. The prevalence rate of hyponatremia following SAH is about 30% to 55%. Hyponatremia may lead to seizures, vasospasm, altered mental status, or death. It may occur due to syndrome of inappropriate ADH (SIADH) secretion or glucocorticoid deficiency. However, correction of hyponatremia should always be gradual and monitored, as rapid corrections may cause central pontine myelinolysis (osmotic demyelinating syndrome).

Answer 147

B. Image 73-5 is an Axial cut of CT head shows right frontoparietal chronic subdural hematoma. Patients with chronic anticoagulation/ antiplatelet therapies are considered to be at high risk for chronic subdural hematoma from trivial traumas. Those patients are prone to develop subdural bleeding within days or weeks after small head trauma. The mechanism is not yet very well understood, although alteration in the blood hematoma components was found in most anticoagulation treated patients. For answer A, although patients with uncontrolled seizure episodes are more prone to frequent head traumas from potential recurrent seizure episodes, those patients don't have higher incidence of subdural hematomas after trivial trauma compared to patients with chronic anticoagulation therapy. For answer C, there is higher incidence of chronic subdural hematoma in male compared to female, but gender does not seem to influence the development of CSDH after slight head trauma. In answer D, history of alcohol abuse associated with coordination and motor problems, consequently more falls, that put the patient at risk for recurrent head trauma. But history of alcohol abuse does not show a strict correlation with CSDH after trauma as coagulation therapies do. For answer E, although old people (e.g. age >65 years) have a higher incidence of CSDH compared to those with age <65, age is not considered a risk factor for the development CSDH after head trauma.

Answer 148

C. Conservative treatment including bed-rest and corticosteroids have been shown to be very efficient in the treatment of patients with hematoma less than 1 cm without focal neurologic deficit or mental status changes. Corticosteroids have been posited as both an anti-inflammatory and anti-angiogenic agents. Answer B, Burrhole drainage with the placement of subdural drain, was shown to decrease significantly the recurrence rate of CSDH after treatment. . Answer C, Craniotomy with excision of subdural membranes, is indicated when the hematoma persistently recurs despite the treatment with twist-drill craniostomy or burrhole drainage. It has been shown to be safe and valid technique. Answer D. Percutaneous twist-drill bedside drainage, is the least invasive technique over the above mentioned techniques. It requires a 0.5 cm incision in the scalp and has been shown to be a safe technique. Operating room twist drill craniostomy, answer E, is a valid option for the management of CSDH, although, it does not offer any advantage over the percutaneous twist-drill drainage in terms of recurrence. However, given that CSDH is more frequent among the elderly, the treatments diverge regarding the perioperative risks related to general anesthesia; burrholes are frequently performed under general sedation, whereas a local anesthetic is usually sufficient with percutaneous drainage, so patients' comorbidities have to be taken into consideration.

Answer 149

A. Brain atrophy, hydrocephalus, midline shift, and hematoma density on CT (c.g.. high, iso, or low) all influence the outcome of CSDHs. Traumatic causes, sex, hematoma location and age have never been shown to correlate with CSDHs outcome.

Answer 150

A. The presence of bilateral effusion and poor re-expansion is associated with high rate of recurrence. For answers B, C, D. E, etiology (e.g., alcoholism, head injury, neurosurgery, anticoagulant, coagulopathy, subarachnoid cyst), interval from trauma to first operation, CT-findings (e.g,. high, iso, or low density), and age are not associated with higher recurrence of rate of CSDH after surgery.

Answer 151

A. The diagnosis for the cause of hyponatremia is generally reached in an algorithmic fashion. After a lab measurement shows serum sodium less than 135 mEq/L, you must determine the effective serum osmolality. This rules out hyperglycemia, hypertriglyceridemia, and hyperproteinemia (so called pseudohyponatremia). The next step is to evaluate urine osmolality to ensure that the patient is not suffering from water intoxication. After these three steps are complete, the patient's volumes status must be ascertained. This is extremely important in a neurologic patient as it will help differentiate the most common neurologic causes of hyponatremia: syndrome of inappropriate antidiuretic hormone secretion (SIADH) and cerebral salt wasting (CSW). -------------------------- C. As with the diagnosis, the treatment for SIADH also runs as an algorithm. Again, the patient must be confirmed to be euvolemic as the treatment for CSW involves fluid resuscitation and for SIADH often involves fluid restriction. In the case of a patient with mild hyponatremia (125 135 mEg/L) with no symptoms, treatment should involve fluid restriction. If there are symptoms, patients should receive saline infusion with 0.9% saline and Lasix. Finally, in cases with Na levels less than 125 mEq/L and symptoms, patients are treated 3%saline and Lasix. Newer medications such as the vaptan class, which act as a vasopressin antagonist, can be used in refractory cases.

Answer 152

E This question relates to the symptoms and general treatment options of hyponatremia. The neurologic symptoms of mild hyponatremia or chronic hyponatremia involve headache, poor concentration, anorexia, and muscle weakness. The more acute and severe hyponatremia cases can lead to cerebral edema, nausea, seizures, respiratory arrest, coma, and death from transtentorial herniation. Symptoms generally are easily diagnosed below 125 mEq/L. Symptoms are more apparent with acute onset (< 48 hours in duration) as there is less time for mechanisms of the brain to compensate. For that reason, chronic hyponatremia (> 48 hours) can be relatively asymptomatic even at low Na levels. The rate of correction even in symptomatic and acute cases should not exceed 1 to 2 mEq/L/hr and 8-10 mEq/L in 24 hours to avoid central pontine myelinolysis.

Answer 153

C Hypernatremia is defined as a serum sodium >150mEq/L. In patients with neurologic injuries, this is commonly due to diabetes insipidus (DI). DI is due to low levels of ADH or renal insensitivity to ADH. The diagnosis can be reached by high output of inappropriately dilute urine with high serum osmolality and high serum sodium. The two major etiologies are neurogenic DI and nephrogenic DI. The primary causes of nephrogenic DI are medications, renal disease, hypokalemia, and hypercalcemia. Neurogenic DI can be idiopathic, posttraumatic, tumors, infections, vascular, and autoimmune. In a posttraumatic patient who has worsening mental status, the cause is most likely due to herniation from pituitary stalk injury or hypothalamic injury from impending brain death.

Answer 154

B. After arriving at the diagnosis of central diabetes insipidus, it is essential to begin treatment of the patient. The treatment of DI is based around antidiuretic hormone (ADH) analogues. These include Pitressin® and the longer acting, more potent form, DDAVP. In a conscious and ambulatory patient, often their thirst mechanisms will compensate for the hypernatremia. However, the patient in this scenario is unable to drink or compensate with his thirst mechanism, so D is clearly incorrect. If the patient is not able to drink, they should be monitored for I and O q1 with serum sodium draws every 6 hours. To deal with the fluid loss, the patient should be placed on a basal fluid rate with D51/2 NS with replacement for urine output above the base rate. If the fluid replacement continues to fall behind and the hypernatremia worsens, Pitressin or DDAVP may be given. Though all the possible answers are treatments for DI, only the first three could be utilized for this patient.

Answer 155

A. Although the majority of thoracic gunshot wounds will be localized to one side of the thoracic cavity, it is critical to identify the smaller subgroup of patients with a trans-mediastinal trajectory. Trans-mediastinal gunshot wounds carry a significantly higher mortality and morbidity, and can present a diagnostic and management dilemma due to the number of critical structures at risk of injury. Unstable patients require immediate intervention and surgical exploration based on the initial examination and imaging findings. Stable patients require further radiologic workup, with the goal of excluding injury to the heart, lungs, great vessels, esophagus, and tracheobronchial tree. Historically this mandated an exhaustive series of imaging studies including chest X-ray or CT scan, echocardiogram, esophagoscopy and esophagography, thoracic angiography, and bronchoscopy. With the improved availability and image quality obtained with modern CT scanners, this exhaustive workup has largely been replaced by a single high-quality CT scan of the chest with intravenous contrast in most trauma centers. In addition to imaging the critical mediastinal structures of interest, the CT scan can be used to re-create the missile tract and assess the proximity to these structures and to identify any secondary signs of injury (Figure 76-1). Patients with a negative CT scan can be safely observe, while those with any concern for a potential injury can then undergo additional focused evaluation based on the CT scan results. This patient has a left pneumothorax and thus a left tube thoracostomy should be placed prior to obtaining the CT scan. Immediate operative exploration is not indicated in the stable patient with no other obvious signs of injury to a mediastinal organ or structure.

Answer 156

C This patient presents with mild symptoms after motor vehicle collision. Cardiac contusion should be suspected but unlikely given clinical presentation and normal electrocardiogram. Serial cardiac panel could yield mildly elevated enzymes but not clinically relevant data. Echocardiogram would not be indicated either given normal electrocardiogram. Cardiology consult is not necessary since the patient's symptoms are not related to myocardial ischemia. A repeat CT scan of the chest will likely show no changes. This patient can be safely discharged home.

Answer 157

A. This patient has a retained hemothorax. There is a significant risk for this patient to develop a complicated fluid collection, fibrothorax, or empyema if the hemothorax is not evacuated in a timely manner. The instillation of thrombolytic agents into the chest cavity or CT scan guided aspiration of hemothorax may not result in complete evacuation of the hematoma since much of the hemotoma is probably solidified clot at this point. Patients who received early VATS (within 5 days) had lower incidence of developing empyema in several studies. Thoracotomy would not be warranted at this time since the hemothorax can be evacuated less invasively with VATS. CT guided drainage is an option but a significant portion of the hematoma has clotted; therefore, this will not likely be an effective therapy.

Answer 158

C The patient has sustained significant chest trauma but tracheobronchial injury must be ruled out given persistent pneumothorax. This is particularly true in the presence of a large and persistent air leak and inability to re-expand the lung despite adequate mechanical ventilation and chest tube drainage. An urgent bronchoscopy will be needed to evaluate for a tracheobronchial injury that may require intervention or surgical repair. It would not be wise to perform a blind thoracotomy until bronchoscopy is performed first to identify and localize the injury. Observation is particularly dangerous in this situation since even a brief period of hypoxia is not tolerated well in a patient with traumatic brain injury. 100% oxygen therapy is usually reserved for non-traumatic pneumothoraces.

Answer 159

C The patient is an elderly male who sustained chest trauma resulting in multiple rib fractures and pulmonary contusion. This patient is at a high risk for pulmonary complications, pneumonia, and death if not managed appropriately and aggressively. The patient should be admitted to the intensive care unit for close monitoring and pain management. Elderly patients often have limited physiologic reserve and unrecognized decompensation on a medical-surgical ward could have tragic implications. Pain control with either a thoracic epidural infusion or intravenous/oral narcotics supplemented with a non-steroidal anti-inflammatory agent such as ketorolac should be initiated, and titrated to allow full inspiratory effort without pain. Intubation should not be done until the patient has failed conservative management (including in selected cases a trial of non-invasive ventilator support). Operative fixation of rib fractures is usually reserved for patients who are difficult to wean from mechanical ventilation, and would not be indicated this early after the initial injury.

Answer 160

b. Alveolar flooding and collapse leading to decreased lung compliance

Answer 161

d. daily sodium replacement

Answer 162

c. Increase the positive end expiratory pressure

Answer 163

c. 30 - 40%

Answer 164

d. Flail chest

Answer 165

D. The initial draining of 1,000mL of blood after chest tube insertion requires immediate thoracotomy.

Answer 166

D. Should be performed after a FAST scan. Dx: Aortic rupture/tear Transient responder FAST -- Pericardium

Answer 167

A. Reexamine the chest ?CPS: Blunting - 250-300

Answer 168

C. Administer supplemental oxygen

Answer 169

B. A long spine board

Answer 170

C. Is consistent with blood loss from bilateral femoral fractures. Long bones: 1.5-2L of blood

Answer 171

A. Adequate urine output

Answer 172

D. Evidence of inadequate perfusion of the body's organs

Answer 173

B. Direct pressure on the wound

Answer 174

C. Cerebral vasodilatation

Answer 175

B. Thoracotomy

Answer 176

D. Posterior displacement of tongue

Answer 177

D. Resource limitations as determined by the referring physician.

Answer 178

A. Vasoactive medications have no role in early management. After the airway is secured and ventilation is ade- quate, fluid resuscitation and restoration of intravascular volume often will improve perfusion in neurogenic shock. Most patients with neurogenic shock will respond to restoration of intravascular volume alone, with satisfactory improvement in perfusion and resolution of hypotension. Administration of vasoconstrictors will improve peripheral vascular tone, decrease vascular capacitance, and increase venous return, but should only be considered once hypovolemia is excluded as the cause of the hypotension and the diagnosis of neurogenic shock is established. If the patient’s blood pressure has not responded to what is felt to be adequate volume resuscitation, dopamine may be used first. A pure α-agonist, such as phenylephrine, may be used primarily or in patients unresponsive to dopamine. Specific treatment for the hypotension is often of brief duration, as the need to administer vasoconstrictors typically lasts 24 to 48 hours. On the other hand, life-threatening cardiac dysrhythmias and hypotension may occur up to 14 days after spinal cord injury. The duration of the need for vasopressor support for neurogenic shock may correlate with the overall prognosis or chances of improvement in neurologic function. Appropriate rapid restoration of blood pressure and circulatory perfusion may improve perfusion to the spinal cord, prevent progressive spinal cord ischemia, and minimize secondary cord injury. Restoration of normal blood pressure and adequate tissue perfusion should precede any operative attempts to stabilize the vertebral fracture.

Answer 179

C. Be treated for hypovolemic shock

Answer 180

D. Performing lower extremity fasciotomies

Answer 181

B. Aspiration of bone marrow confirms the appropriate positioning of the needle IO: Indicated for <6 years - proximal tibia

Answer 182

D. Complete spine x-ray series Dx: Compression fx

Answer 183

A. Permissive hypotension and early plasma infusion

Answer 184

A. Secure the airway.

Answer 185

D. His systolic blood pressure will be decreased with a narrowed pulse pressure.

Answer 186

D. Increasing the volume of blood loss to produce shock.

Answer 187

D. Respiratory rate of 32 breaths per minute

Answer 188

D. A spinal fracture has been excluded clinically or by roentgenograms.

Answer 189

D. Placement of an occlusive dressing that is open on one side over the wound.

Answer 190

B. Chest and pelvis

Answer 191

C. Breath sounds

Answer 192

C. Add positive end-expiratory pressure (PEEP)

Answer 193

B. Leakage of amniotic fluid is an indication for hospital admission.

Answer 194

B. Undergo prompt laparotomy

Answer 195

E. Duodenal rupture Retroperitoneal (CT scan)

Answer 196

C. Exploratory laparotomy

Answer 197

D. Increasing the volume of blood loss to produce maternal hypotension.

Answer 198

D. Free intraperitoneal air demonstrated on follow-up CT

Answer 199

A. Placement of a pelvic binder

Answer 200

C. A syndrome of rapidly appearing septic shock unresponsive to antibiotic therapy, with an average mortality of 50%

Answer 201

D. Delayed splenic rupture is seen in splenic injuries due to liquefaction of haematoma

Answer 202

A. Abdominal exam is not included in the primary survey.

Answer 203

GCS = E + DVS + M DVS: Derived Verbal Score = E(0.4) + M (0.5)

Answer 204

Developed to improve ability to predict patient prognosis. Pupil Reactivity Score: # of non-reactive pupils - both pupils unreactive = 2 (59% mortality) - only one pupil unreactive = 1 (38% mortality) - both pupils reactive = 0 (16% mortality) GCS-P score = GCS - P (range = 1 to 15)

Answer 205

High-risk factors (for neurological intervention) - GCS <15 at 2h post injury - Suspected open skull fracture - Signs of basal skull fracture - >2 episodes of vomiting - Age >65 years old Medium-risk factors (for brain injury on CT) - amnesia before impact >30mins - dangerous mechanism of injury

Answer 206

``` Acute hemorrhage Signs of cerebral edema Attenuation of gray-white junction Midline shift Obliteration of cisterns Tonsillar hernia roon Intraventricular hemorrhage with acute hydrocephalus ```

Answer 207

Affected spinal tracts: Incomplete cervical white matter injury Bilateral central CST Lateral STT Etiology: Hyperextension injury (eg, car crash) associated with chronic cervical spondylosis Spinal cord compression Clinical: Bilateral paresis (Upper > lower extremities)

Answer 208

Affected spinal tracts: Anterior gray matter Descending CST and STT with preservation of posterior columns (DCP) Etiology: Trauma (eg penetrating injury, burst fracture of vertebra) Occlusion of anterior spinal artery Clinical: Bilateral motor paralysis Loss of pain and temperature sensation Autonomic dysfunction below level of lesion

Answer 209

Affected spinal tracts: Bilateral posterior columns (DCP) Etiology: Trauma (penetrating injury) Occlusion of posterior spinal artery Multiple sclerosis Clinical: Ipsilateral loss of proprioception, vibration, and touch sensation below the level of the lesion

Answer 210

Affected spinal tracts: Hemisection of the cord Etiology: Trauma (penetrating injury) Spinal cord compression Clinical: Ipsilateral Loss of proprioception, vibration, tactile discrimination below level of lesion Segmental flaccid paresis at the level of the lesion Spastic paralysis below the level of the lesion Ipsilateral Babinski sign Contralateral Loss of pain and temperature sensation one or two levels below the lesion

Answer 211

Affected spinal tracts: Results In a LMNL Etiology: Injuries below the L1 vertebral level Usually incomplete, but can be complete ``` Clinical features: Flaccidity Areflexia Impairment of bowel and bladder function Regeneration of peripheral nerves is possible ```

Answer 212

1) Polyvalent pneumococccal 0. 5mL SC deltoid or upper thigh, q6 years 2) Quadravalent meningococcal or diphtheria conjugate 0. 5mL IM upper deltoid q3-5years 3) Quadravalent meningoccocal polysaccharide 0.5mL SC deltoid or upper thigh q3-5years 4) Haemophilus B conjugate 0. 5mL IM (single dose)

Answer 213

Grade I: 12-5mmHg Grade II: 16-20mmHg Grade III: 21-25mHg Grade IV: 25mmHg onwards

Answer 214

1) Nonoperative - Simple bleeding lacerations 2) Direct suture - Shallow slowly oozing injuries 3) Hepatotomy/Tractotomy - Tracing and unroofing of the wound and bleeding sites directly ligated 4) Pringle maneuver - Intermittent clamping of the hepatoduodenal ligament at the epiploic foramen in cycles (up to 10-15 minutes) 5) Selective hepatic artery ligation - Either left or right hepatic artery may be ligated following a positive Pringle's maneuver (bleeding stops while the hepatoduodenal ligament is clamped and resumes when released) 6) Resection or debridement - For extensive injury and devitalized tissues 7) Atriocaval shunt - For significant hemorrhage likely due to major hepatic venous or retrohepatic vena caval injury (ie, does not stop with Pringle technique) 8) Perihepatic packing - Performed as damage control (coagulopathic, acidotic and hypothermic)

Answer 215

1) Splenorrhaphy - For stable patients without associated multiple injuries 2) Splenectomy - Hemodynamic instability, multiple associated injuries, completely shattered parenchyma 3) Nonoperative - Patients remaining hemodynamically stable 4) Postsplenectomy measures - Giving vaccines 2 weeks post-splenectomy

Answer 216

1) Simple repair and drainage - Minor pancreatic lacerations or contusions 2) Pyloric exclusion or diverticularization - Repair of the duodenum, drainage, and closure of the pylorus with diversion of gastric contents through a gastrojejunostomy 3) Pancreaticoduodenal resection - indicated only for severe injuries to the head of the pancreas and the duodenum (rare occurrence) 4) Distal pancreatectomy - For distal pancreatic injuries with major ductal involvement 5) Damage control surgery and postoperative ERCP - For highly unstable patients

Answer 217

- Involves initial hemostasis, and subsequent repair or resection - Assume even number of wounds (each entry wound has an associated exit wound) - Mesenteric border of the bowel, the retroperitoneal duodenum and colon, the cardia, posterior wall, and greater and lesser curvature of the stomach are areas that might be missed Stomach: 1) Primary repair for small perforations 2) Proximal or distal gastrectomy for extensive injuries Small bowel 1) Primary repair for perforations <50% of bowel circumference 2) Segmental resection and primary anastomosis for perforation >50% of the bowel circumference, multiple injuries in close proximity

Answer 218

1) Primary suture repair without colostomy - For nondestructive injuries (<50% of bowel wall without devascularization) 2) Segmental resection and primary anastomosis - For destructive injuries (>50% of bowel wall or with devascularization) 3) Alternatives for destructive injuries: - Debridement - Primary repair and exteriorization - Proximal colostomy with or without repair 4) Classic Criteria for Colostomy (Stone and Fabian, 1979): - Shock: BP <90/60 - Hemorrhage: intraperitoneal blood loss >1L - Multiple injuries: >2 other intraabdominal injuries - Contamination: significant fecal spill - Time: >8h after injury - Colon wound: So destructive as to require resection - Abdominal wall: Major loss of substance or requiring mesh replacement 5) Timing of colostomy closure after trauma - Within 2 weeks after colostomy creation provided all wounds have completely healed and nutritional state is optimal

Answer 219

1) Intraperitoneal injuries - Manage as colonic injuries 2) Extraperitoneal injuries - 4 D's: - - Debridement (of devitalized tissues) - - Diversion (select cases when satisfactory repair cannot be performed because of anatomic location or extent of injury) - - Drainage (presacral-- not supported by current literature) - - Distal rectal washout (no evidence for reducing morbidity)

Answer 220

Intraabdominal pressure (IAP) - Steady-state pressure concealed within the abdominal cavity - mmHg, measured at end-expiration in supine position after ensuring that abdominal muscle contractions are absent, and with transducer zeroed at the level of the MAL - IAP: ~5-7mmHg in critically ill adults - Reference standard for intermittent IAP measurements is via the bladder (maximal instillation of 25mL sterile saline) ``` Intraabdominal hypertension ( IAH) - Sustained or repeated pathological elevation in IAP greater than or equal to 12mmHg ``` Abdominal perfusion pressure (APP) - Difference between mean arterial pressure (MAP) and intraabdominal pressure (IAP) - AFP = MAP - IAP Abdominal compartment syndrome (ACS) - Sustained IAP >20mmHg with or without APP <60mmHg that is associated with new organ dysfunction or failure.

Answer 221

- Blunt/penetrating trauma with hemorrhage - Abdominopelvic trauma or injury and retroperitoneal hemorrhage - Ruptured aortic aneurysm - Ascites due to liver cirrhosis - Other conditions that require early surgical or angioradiologic intervention (secondary peritonitis)

Answer 222

- Extensive fluid resuscitation following major trauma - Forced abdominal wall closure following peritonitis, ileum or abscess - Laparoscopy and pneumoperitoneum - Abdominal packing following hemorrhage - Other conditions not originating from an abdominal disease (eg sepsis, major burns)

Answer 223

- Recurrent or persistent ACS following prophylactic or therapeutic surgical or medical treatment of ACS (eg, persistence after decompressive laparotomy, new ACS after definite abdominal wall closure)

Answer 224

Conservative - Paracentesis - NGT - Gastric prokinetics - Rectal enemas and suctioning - Colonic pro kinetics (prostigmine) - Furosemide either alone or with human albumin 20% - Continuous venovenous hemofiltration or ultrafiltration - Continuous negative abdominal pressure - Sedation and muscle relaxation - Upright (sitting) body positioning (pilot seat)

Answer 225

Decompressive laparotomy | - Perform or revise abdominal decompression with temporary abdominal closure.

Answer 226

``` Inability to void Blood on urethral meatus Perineal or scrotal hematoma High riding or boggy prostate on DRE Voided specimen with hematuria ``` *Blind urethral catheterization is contraindicated unless urethral injury is ruled out by a urethrogram.

Answer 227

1) Nonoperative - Bed rest, hemodynamic monitoring, serial hematocrit 2) Embolization - For persistent bleeding from a segmental renal artery, unstable patients with complex renal injury, pseudo aneurysm or AVM, persistent gross hematuria, rapidly declining hematocrit. 3) Absolute indications for renal exploration for primary repair, or possible total or partial nephrectomies - Expanding, pulsatile, uncontained retroperitoneal hematomas - Renal pedicle avulsion - Persistent, life-threatening hemorrhage or shock - Ureteropelvic junction disruption

Answer 228

1) Proximal and mid injuries - Ureteroureterostomy (primary anastomotic repair) over a double-J stent 2) Distal injuries - Ureteroneocystostomy (reimplantation of the ureter to adjacent bladder) - Psoas hitch - Boari flap: For bridging wide gaps in ureteral length

Answer 229

1) Intraperitoneal bladder perforations - Primary water tight absorbable suture repair in 2-3 layers and suprapubic cystostomy 2) Extraperitoneal bladder perforations - Transurethral catheter drainage alone for 7-10 days

Answer 230

1) Retrograde urethrogram - Done to rule out urinary extravasation 2) Best managed by suprapubic cystotomy and delayed urethral repair

Answer 231

``` Pulsatile bleeding Expanding hematoma Palpable thrill Audible bruit Acute limb ischemia (pallor, paresthesia, paralysis, pain, pulselessness, poikilothermia) ```

Answer 232

History of moderate hemorrhage Injury (fracture, dislocation, penetrating wound) Diminished but palpable pulse (A-A index of <0.9) Peripheral nerve deficit * Diagnostics: - Doppler assessment of pulsatile flow - Angiography

Answer 233

- Preoperative antibiotics - Adequate surgical exposure with initial proximal and distal vascular control - Systemic heparin (5,000-10,000 units IV) unless contraindicated - Primary repair: if vessels can be repaired without tension or narrowing - Vein patch or autogenous interposition graft (rather than prosthetic graft) - Use of temporary shunts for prolonged procedures - Completion arteriograms to confirm adequacy of the repair and distal flow

Answer 234

``` ARTERIES Aorta Carotid Brachiocephalic Brachial Superior mesenteric Proper hepatic Renal Iliac Femoral Popliteal ``` VEINS Superior vena cava Suprarenal inferior vena cava Portal vein

Answer 235

1) Salvageable postinjury cardiac arrest - Patients sustaining witnessed penetrating trauma with <15mins of prehospital CPR - Patients sustaining witnessed blunt trauma with <10mins of prehospital CPR - Patients sustaining witnessed penetrating trauma to the neck or extremities with <5mins of prehospital CPR. 2) Persistent severe post injury hypotension (SBP less than or equal to 60mmHg) - Cardiac tamponade - Hemorrhage (intrathoracic, intraabdominal, extremity, cervical) - Air embolism

Answer 236

1) Penetrating trauma: CPR> 15mins and no signs of life (pupillary response, respiratory effort, motor activity) 2) Blunt trauma: CPR> 10mins and no signs of life or asystole

Answer 237

(C) High-output renal failure should be suspected if the BUN continues to rise with urine output >1000–1500 mL/d. It is associated with mild-to-moderate renal insufficiency; in comparison, severe renal injury results in oliguric renal failure. The kidneys do not tolerate ischemia for more than 30–90 minutes. Hypothermia is protective. There is a decrease in creatinine clearance. Vasopressors aggravate the deleterious effects of shock.

Answer 238

(B) Hyperkalemia can manifest by GI or cardiovascular signs. GI symptoms include nausea, vomiting, intestinal colic, and diarrhea. Abdominal distension as a result of paralytic ileus is due to hypokalemia. An ECG is useful to monitor potassium levels. Hyperkalemia is characterized by peaked T waves. ECG changes also include ST-segment depression, widened QRS complex, and heart block. Cardiac arrest occurs in diastole with increasing levels of potassium. Osborne (J) wave is seen in hypothermia.

Answer 239

(C) In hyperkalemia, all oral and intravenous potassium must be withheld. Sodium chloride worsens the metabolic acidosis. Sodium bicar- bonate intravenously is given to divert potassium intracellularly by causing alkalosis. Calcium gluconate (1 g [10 mL of 10% solu- tion]) is given to counteract the effect of potassium on the myocardium. The hypertonic glucose solution stimulates the synthesis of glycogen, which causes cellular uptake of potassium. Small amounts of insulin (1 U/5 g of glucose) is helpful. The usual recommen- ded dose is 100 mL of 50% glucose with 10 U of insulin. Calcitonin is used for treating hypercalcemia. Serum magnesium is also ele- vated in renal failure.

Answer 240

(D) This patient has metabolic acidosis with normal anion gap. The normal value of anion gap is 10–15. Loss of bicarbonate (e.g., small- bowel fistula, pancreatic fistula, or diarrhea) and gain of chloride (e.g., administration of ammo- nium chloride or HCl and decreased excretion as in distal renal tubular acidosis) result in meta- bolic acidosis with normal anion gap. In con- trast, in acidosis due to increased production of an organic acid (e.g., ketoacids in diabetes, sulfur and phosphoric acid in renal failure, and lactic acid in shock), the anion gap is increased.

Answer 241

(B) The patient has acute respiratory distress syndrome (ARDS). Measurement of ABGs pro- vides initial evaluation of pulmonary function in terms of oxygenation and ventilation. ECG is valuable for diagnosing myocardial ischemia or cardiac arrhythmias. Ventilation perfusion scanning is used for diagnosing pulmonary embolism. A central venous line provides infor- mation regarding the volume status of the patient, which may be low to normal in ARDS.

Answer 242

(C) Increased airway resistance (stiff lung) may be noted early in shock lung. The alveo- lar capillary membrane becomes more per- meable. There is a leak of a high-protein fluid from the capillary to the interstitial tissues and then into the alveoli. This is commonly called ARDS. Sepsis syndrome is the most frequent cause of ARDS (39%), followed by aspiration, multiple transfusion, massive soft- tissue injury, multiple trauma, near drown- ing, fat embolism, DIC, and pancreatitis. ARDS is associated with ventilation–perfusion imbalance. In some areas of lung, there is ven- tilation with no perfusion, whereas, in other areas, nonventilated alveoli are being per- fused. The net result is decrease in functional residual capacity, shunting, and increased dead space ventilation. Chest x-ray reveals diffuse alveolar infiltration, and findings are normal in the initial stage.

Answer 243

(B) A history of bleeding should alert the clini- cian to evaluate the underlying cause. The bleed- ing time is influenced by those factors affecting platelet and capillary integrity. Prolongation of the PT may be attributed to decreased absorption of fat-soluble vitamin K, liver impairment, or decrease in the blood components because of consumption.

Answer 244

(B) Possible causes of this syndrome include head injury, central nervous system (CNS) dis- orders, neoplastic diseases, pulmonary dis- eases, drugs, and idiopathic. It results in impaired water excretion characterized by olig- uria, hyponatremia, significantly decreased serum osmolality, and increased urinary osmo- lality. Administration of a hypotonic solu- tion(D5/0.33 NS) would not result in decreased urine output. Decreased ADH secretion would result in an increased urine output as opposed to a decreased urine output. Naso-gastric suc- tion while it can result in a hypo-kalemia, hyponatremia is less likely. Renal insufficiency would likely result in a decreased urine osmolality.

Answer 245

(B) Hyponatremia occurs because of overhydra- tion and/or inadequate sodium replacement. When serum sodium is <130 mEq/L, acute symptomatic hyponatremia is manifested by CNS symptoms due to increased intracranial pressure. Muscle twitching and increased tendon reflexes seen in moderate hyponatremia progress to convulsions, loss of reflexes, and hyperten- sion with severe hyponatremia. Oliguric renal failure may become irreversible if not immedi- ately treated. Mild asymptomatic hyponatremia is treated with fluid restrictions. In the presence of CNS symptoms, the patient should be given hypertonic saline.

Answer 246

(D) Sodium deficit is estimated by multiplying the decrease in serum sodium times the total body water, which is 60% of body weight: (normal serum sodium − observed serum sodium) × 0.6 × (total body weight) = (140 − 120) × 0.6 × 60 = 720 mEq Half of this amount should be administered over 12–18 hours.

Answer 247

(B) Oliguria may be prerenal or renal. The fol- lowing table characterizes findings in prerenal failure versus those observed in intrinsic renal failure (acute tubular necrosis). TABLE 1–1. PRERENAL VS. INTRINSIC RENAL FAILURE (Lange Q&A Surgery)

Answer 248

(C) The composition of various GI secretions is different. They are as follows: A, saliva; B, gas- tric; C, ileal; D, pancreatic; and E, colonic. The composition of intestinal fluid is the closest to that of plasma.

Answer 249

(A) The composition of small intestinal fluid is sodium, 140 mEq/L; potassium, 5 mEq/L; chlo- ride, 104 mEq/L; and bicarbonate, 30 mEq/L. Daily losses are best replaced by administra- tion of balanced salt solution (Ringer’s lactate) whose composition is depicted in A. B repre- sents normal saline (0.9%), C is half normal saline (0.45%), D is M/6 sodium lactate, and E is 3% sodium chloride.

Answer 250

(B) A decrease in pH below 7.4 indicates acido- sis. PCO2 is increased over 40 mm Hg, suggest- ing respiratory acidosis. To differentiate pure from combined acidosis, pH is calculated based on changes in CO2. A change of 10 mm Hg from 40 mm Hg changes pH by 0.08 from 7.4. In this case, there is a 20 mm Hg increase in PCO2, which would decrease pH by 2 × 0.08 = 0.16 from 7.4 or 7.24. The measured pH is 7.24. Therefore, the patient has pure respiratory acidosis.

Answer 251

(D) Respiratory acidosis in the immediate post- operative period is due to inadequate ventila- tion. Adequate ventilation needs to be restored by prompt intubation and ventilatory support. Use of morphine will further depress the respiration.

Answer 252

(B) Villous adenoma of colon can result in watery diarrhea and hypokalemia. Massive tissue injury producing myoglobinemia is associated with significant release of intracellular potassium. Massive blood transfusion results in release of large amounts of potassium. The ability to excrete potassium is impaired in high-output renal failure. Spironolactone is a potassium- sparing diuretic.

Answer 253

(E) A change in PCO2 of 10 mm Hg from the normal value of 40 mm Hg produces a 0.08 change in pH (from 7.4). A PCO2 of 30 mm Hg, representing a decrease of 10 mm Hg, can account for an increase in pH by 0.08 (i.e., 7.4–7.48). The patient’s measured pH is 7.54. The additional increase in pH is due to meta- bolic alkalosis.

Answer 254

(A) Alkalosis is associated with hypokalemia. Hypokalemia can be sudden and severe. It is related to (a) intracellular shift of potassium in exchange for hydrogen and (b) excessive uri- nary potassium loss. The oxyhemoglobin dis- sociation curve is shifted to left, and a decrease in levels of ionized calcium can result in tetany and convulsions.

Answer 255

(E) Zinc is one of the metalloenzymes involved in lipid, carbohydrate, protein, and nucleic acid metabolism. Skin lesions similar to enterohep- atic acrodermatitis are the most common sign seen in zinc deficiency. Other manifestations include hypogonadism, diminished wound healing, and immunodeficiencies. Copper defi- ciency is characterized by microcytic hypo- chromic anemia.

Answer 256

(E) The fall in pressure will signal changes via baroreceptors located in the arch of the aorta and carotid sinus and will cause sympathetic stimulation with tachycardia, peripheral vaso- constriction, and hypothermia. Eosinopenia rather than eosinophilia is more likely to be present. There is a switch from aerobic to anaer- obic metabolism. Lactic acid accumulation indi- cates an adverse prognosis in shock. There is a progressive deterioration in prognosis as the blood lactate level increases from 1 to above 3 mm/L.

Answer 257

(C) The fall in cardiac output results in a rela- tively larger proportion of blood to be distrib- uted to the heart. The changes are mediated mainly by sympathetic stimulation. There is increased arteriolar and precapillary sphincter tone in the skin and in the renal and splanchnic circulation. In the heart, coronary artery vasodi- lation occurs, which is brought about partly by local release of vasodilator substances (due to hypoxemia and acidosis).

Answer 258

(C) Initial resuscitation of a trauma patient is best done by administering Ringer’s lactate, because it is isotonic, and it is similar to plasma in electrolyte composition. There is no conclu- sive evidence that colloid solutions (albumin, plasma protein solution, or hydroxyethyl starch solution) improve the rate of resuscitation or eventual outcome. D5W and D5W and 0.45% normal saline are hypotonic. Use of crystalloid solutions also aids in the resuscitation of the interstitial compartment.

Answer 259

(C) Neurogenic shock (not to be confused with spinal shock, which is defined by loss of reflexes below the area of spinal cord injury, a neurologic phenomena) is secondary to high spinal cord injury as evidenced by inability to move all four extremities. Neurogenic shock is clinically man- ifested by warm skin, bradycardia, and hypoten- sion. In septic shock, while the skin is warm, the patient usually has tachycardia. In all other types of shock, the skin is cold. Treatment consists of volume replacement with balanced salt solution (lactated Ringer’s solution). On rare occasions, some patients may need vasoconstrictors (e.g., phenylephrine hydrochloride).

Answer 260

(D) Succussion splash is elicited by placing one hand behind and the other in front of the left abdomen and rib cage and rocking the patient gently between the two hands. In pyloric obstruction, one can feel the fluid hitting the fingers (succussion). Peristalsis is likely to be observed in infants with congenital pyloric stenosis.

Answer 261

25. (B) Duodenal ulcer and gastric carcinoma are the most likely causes of pyloric obstruction in adults. Metabolic alkalosis results from loss of fixed acids from the stomach. The bicarbonate content of the blood accompanies the elevation in pH. In severe metabolic alkalosis, paradoxical loss of acid (hydrogen) in the urine occurs in an attempt to conserve potassium. Hypokalemia worsens the metabolic consequences of meta- bolic alkalosis.

Answer 262

26. (D) Potassium should not be given initially until moderate hydration has been achieved, and urine flow is adequate. Normal saline is required initially to correct the hypochloremia.

Answer 263

27. (D) Initial management of hypochloremic meta- bolic alkalosis includes administration of isotonic sodium chloride solution with replacement of potassium chloride. In patients refractory to stan- dard therapy use of O.1 N and 0.2 N hydrochlo- ric acid has been shown to be safe and effective therapy. Ammonium chloride solution has also been used, but this can lead to ammonia toxicity, especially in patients with hepatic insufficiency.

Answer 264

28. (B) The actual surgical treatment for obstruc- tion caused by peptic ulcer is controversial. Appropriate gastric surgery with drainage usu- ally is required if pyloric stenosis is severe. Drainage procedures include pyloroplasty, gas- trojejunostomy, or antrectomy. An alternative to vagotomy and drainage would be vagotomy, antrectomy with gastrojejunostomy, or a Billroth II subtotal gastrectomy with gastrojejunal anas- tomosis. It is important to be certain that a gas- tric carcinoma is not the cause of the pyloric outlet obstruction.

Answer 265

(B) The presence of an adequate urine output does not preclude a diagnosis of high-output renal failure. The mechanism is based in part on prior ischemia to the nephron structure of the kidneys. There may be an initial period of olig- uria. Urea, potassium, and acids are still partly excreted in the urine, and lactate or bicarbonate is given to avoid development of acidosis.

Answer 266

30. (A) Potassium should not be given, and potas- sium levels must be monitored carefully to avoid hyperkalemia. Phosphorous and mag- nesium levels may be increased, and hyperna- tremia is likely to occur when fluid is restricted and a solute-poor urine is excreted. Autopsy in patients dying early shows that the distal nephron is affected more than the proximal nephron. Although mortality figures are high, if the patient survives the postoperative period, satisfactory renal function can be anticipated.

Answer 267

31. (C) Marked fluid restriction may result in hypernatremia. If the condition is treated appro- priately, urea nitrogen usually falls after 1 or 2 weeks. In elderly and cardiac patients, pul- monary edema occurs more readily, and diuret- ics may be contraindicated because azotemia may be made more severe. Ammonium chlo- ride would make the acidosis worse. Potassium has to be monitored carefully, because severe hyperkalemia is readily induced.

Answer 268

32. (D) Hemophilia (factor VIII deficiency) usually occurs during infancy. It is sex-linked, recessive, and affects males almost exclusively. DES administered during the mother’s pregnancy has not been incriminated in coagulation disor- ders but is associated with vaginal carcinoma in adolescent girls. Henoch-Schönlein purpura usually occurs about 3 weeks after a streptococ- cal infection and includes joint pain, purpura, and nephritis. Wilson’s disease is associated with a disturbance in copper metabolism.

Answer 269

33. (B) Spontaneous bleeding occurs when factor VIII is reduced below 2–3%. Once serious bleeding occurs, a higher factor VIII activity— probably approaching 30%—is required for adequate hemostasis. The half-life of factor VIII is 8–12 hours. In minor lesions, 10 U/kg body weight of factor VIII is administered. For severe lesions, the dosage is 40–50 U/kg body weight of factor VIII. After major surgical procedures, factor VIII must be given daily for 7–10 days. Penicillamine is used to inhibit excess copper deposition (e.g., in Wilson’s disease).

Answer 270

34. (D) The clinical picture is suggestive of hemo- philia. The normal bleeding time excludes cap- illary fragility or platelet deficiency. If fibrinolysis was evident, the fibrinogen level would be reduced. In the presence of a normal PT, a pro- longed PTT indicates a deficiency of factor VIII, IX, XI, or XII. The PT evaluates the extrinsic coagulation pathway. The normal PT excludes factor VII deficiency. The thrombin time eval- uates fibrinogen to fibrin conversion with an external source of thrombin and will be normal as fibrinogen levels are normal.

Answer 271

35. (C) Thrombocytopenia is the major hemostatic disorder in massive blood transfusion. Platelet transfusion usually is indicated when more than 6–8 U of blood is transfused rapidly. There is the risk of causing hepatitis. Stored blood is defi- cient in factors V and VIII; as such, PT and PTT may be slightly prolonged after massive blood transfusion. Fresh-frozen plasma is the source of factors V and VII, which would be deficient in banked blood. Unless there is previous liver cir- rhosis, the procedures enumerated are unlikely to lead to liver failure. Hypersplenism occurs in patients with enlarged spleens.

Answer 272

36. (A) Platelet deficiency is likely to be evident, but tests to exclude other causes of bleeding are indicated. The possibility of defibrinogenation, intravascular coagulopathy, or fibrinolysis must be excluded by appropriate coagulation studies. Bleeding from a vein or artery, incom- patible blood transfusion, DIC, acidosis, and hypothermia are other considerations to explain any unusual bleeding after a major surgical procedure.

Answer 273

37. (B) In desperate cases where bleeding persists despite all other measures, packing the abdomen with laparotomy packs may offer temporary control. The patient is taken to the OR 24–48 hours later for removal of packing after stabi- lization of hemodynamic status and correction of coagulopathy.

Answer 274

38. (D) Symptoms are due to magnesium deficiency. Magnesium is mainly intracellular. Magnesium deficiency occurs in the presence of starvation, malabsorption syndrome, acute pancreatitis, and chronic alcoholism. Symptoms are charac- terized by neuromuscular and CNS hyperactiv- ity, such as muscle tremors, hyperactive tendon reflexes, and tetany with a positive Chvostek sign. The syndrome of magnesium deficiency can exist in the presence of normal serum mag- nesium levels. Magnesium deficiency is treated with parenteral magnesium sulfate or magne- sium chloride.

Answer 275

39. (C) Symptomatic hypermagnesemia is seen after early thermal injury, massive trauma, surgical stress, and in the presence of severe renal insufficiency. ECG changes resemble those seen with hyperkalemia. Hypokalemia and hypophosphatemia can cause symptoms of generalized weakness, but potassium and phosphorus are increased in renal failure. Hypokalemia is characterized by flattening of T waves and U waves. Hypocalcemia is characterized by hyperactive tendon reflexes. Hyponatremia is characterized by nervous irri- tation as restlessness and convulsions with no specific ECG changes.

Answer 276

40. (B) Administer calcium chloride. Management of hypermagnesemia involves correction of extracellular volume deficit and acidosis and withholding exogenous magnesium. Calcium chloride should be administered to reverse the ECG changes temporarily. Peritoneal dialysis or hemodialysis is necessary for persistent symptoms or toxicity. Calcium chloride stabi- lizes the cardiac cell membrane and thereby reduces the risk of dysrhythmias.

Answer 277

41. (D) Determination of serum albumin or protein level is necessary for proper determination of serum calcium level. For every 1 g decrease of serum albumin, the serum calcium level is cor- rected by 0.8. Intravenous administration of calcium chloride is indicated in the presence of symptoms. Approximately 45% of serum cal- cium is ionized and responsible for neuromus- cular stability. Half of the calcium in the blood is bound to protein, and an additional 5% is attached to substances other than protein. Alkalosis decreases the ionized component. Hypercalcemia causes polydypsia and polyuria.

Answer 278

42. (C) Serum osmolality is calculated from serum values of sodium, potassium, glucose, and BUN by using the formula 2 (Na + K) + BUN/2.8 + glucose/18.

Answer 279

43. (C) Injury to the pituitary stalk in major skull fractures involving the base of the skull can result in decreased secretion of vasopressin (ADH). There is increased urine output that is diluted (osmolality <270 mOsm/kg). The extracellular fluid volume is contracted, resulting in high serum osmolality (>300 mOsm/kg) and increased serum sodium.

Answer 280

44. (D) Hypophosphatemia results in decreased syn- thesis of phosphorylated intermediate metabo- lites such as adenosine triphosphate (ATP), 2, 3-DPG, and cyclic adenosine monophosphate (cAMP). Deficiency can result in erythrocyte membrane instability, WBC dysfunction, platelet dysfunction, congestive heart failure, arrhyth- mias, weakening of respiration muscles, hemol- ysis, and rhabdomyolysis.

Answer 281

45. (D) The symptoms are suggestive of hypercal- cemia. Major causes of hypercalcemia are cancer with bony metastasis and hyperparathyroidism. Symptoms involve the GI, renal, musculoskele- tal, and CNS.

Answer 282

46. (B) Patients with hypercalcemia have decreased extracellular fluid volume due to vomiting and polyuria. Vigorous resuscitation with salt solu- tion will lower the serum calcium by dilution and increased renal excretion. Furosemide and not thiazides increase renal excretion of calcium. Additional therapy includes administration of oral or intravenous inorganic phosphates, corti- costeroid, mithramycin, and calcitonin.

Answer 283

47. (B) Methanol ingestion results in increased pro- duction of lactic acid causing an increased anion gap. The other conditions listed are associated with normal anion gap. Diarrhea, proximal renal tubular acidosis, and ureterosigmoidostomy result in loss of bicarbonate, while distal renal tubular acidosis is associated with decreased acid excretion.

Answer 284

48. (C) The boy has hemophilia. Management con- sists of infusion of factor VIII concentrate. Bed rest and local cold packs are helpful. Aspiration of the knee to remove blood and passive exer- cise are not recommended for fear of recurrent bleeding. In contrast, active exercise is benefi- cial because movement beyond the point when bleeding can recur is limited owing to pain. Fresh-frozen plasma has a low level of factor VIII (0.6 U/mL) and is not useful because the required volume is excessive. Patients can use long leg splint.

Answer 285

49. (E) Obtaining a detailed history is the most important preoperative information that pre- dicts the risk of unexpected intraoperative bleeding complication. It is even more reliable than laboratory tests.

Answer 286

50. (C) von Willebrand disease is characterized by decreased level of factor VIIIc (procoagulant). It has autosomal-dominant inheritance. These patients have prolonged bleeding times and PTT, with normal PTs. In contrast to platelets of normal patients that aggregate when resto- cetin is added, in von Willebrand’s resease, platelets fail to aggregate in presence of restocetin.

Answer 287

51. (B) von Willebrand disease is the most common hemostatic disorder transmitted by autosomal- dominant mode. Other disorders transmitted by this mode are hereditary hemorrhagic telangiectasia and factor XI deficiency. Diseases transmitted by an autosomal-recessive mode are factor X, factor V, factor VII, and factor I deficiencies. Factor VIII (true hemophilia) and factor IX (Christmas disease) deficiencies are sex-liked recessive.

Answer 288

52. (D) ADP, serotonin, and thromboxane A2 are important mediators of platelet aggregation. In the presence of calcium, magnesium, and platelet factor 4, they cause release of platelet content and their granules resulting in the for- mation of a platelet plug. This process is inhib- ited by aspirin.

Answer 289

53. (E) Requires cessation of Coumadin and infu- sion of heparin. Warfarin (Coumadin)-induced skin necrosis is a rare complication with high morbidity and mortality. It usually occurs 3–10 days after initiation of therapy, affects women more commonly than men, and most often involves the skin of thighs, buttocks, abdomen, and breast. The exact mechanism is unknown but may be related to depression of protein C levels in some patients. Management involves immediate cessation of Coumadin and admin- istration of heparin IV.

Answer 290

54. (D) Patients receiving barbiturates, oral contra- ceptive agents, and corticosteroids often require larger amounts of Coumadin to maintain ade- quate anticoagulation. In patients with vitamin K deficiency or impaired liver function and in those with thyrotoxicosis, there is increased effect of Coumadin. Also, the cholesterol-lowering agent clofibrate, D-thyroxine, and certain antibiotics given concomitantly with Coumadin enhance its anticoagulant effect. It is important to adjust the dose of Coumadin when initiating anticoag- ulation therapy in such patients.

Answer 291

55. (D) Fibrinolysis may be primary or acquired. Primary fibrinolysis is seen after fibrinolytic ther- apy with streptokinase or urokinase; surgical procedures on the prostate gland (which is rich in urokinase) and severe liver failure. Secondary fibrinolysis is most commonly seen in DIC. If the PT, PTT, and platelet count are normal, DIC is unlikely to be present. Aminocaproic acid inhibits plasminogen activation to plasmin and can be used if there is excessive fibrinolysis. It must not be given in DIC, because serious intravascular clotting may occur.

Answer 292

56. (E) In the anesthetized patient, the classic signs of transfusion reaction are masked. The sudden unexplained onset of bleeding and hypoten- sion should include transfusion reaction in the differential diagnosis. In the conscious patient, chills, fever, pain in the lumbar region, a tight sensation over the chest, flushing of the face, and dark-colored urine may be evident.

Answer 293

57. (E) Acute hemolytic transfusion reaction due to transfusion of incompatible blood in a patient under general anesthesia usually presents as gen- eralized bleeding due to DIC. PT, PTT, and bleed- ing time will be abnormally high, and platelets may be decreased because of DIC. The most spe- cific tests to determine hemolysis are free plasma hemoglobin and hemoglobinuria. The labora- tory criteria are hemoglobinuria with a concentration of free hemoglobin over 5 mg/dL, a serum hepatoglobin level below 50 mg/dL, and serological criteria to show antigen incompati- bility of the donor and recipient blood.

Answer 294

58. (C) Patients with polycythemia vera do poorly in general surgery if they have not had appro- priate treatment to reduce the RBC and platelet count. With chlorambucil treatment, elective cholecystectomy should be performed to avoid the possible need to perform the operation on an emergency basis when the patient is not fully prepared.

Answer 295

59. (D) Cross-matching should be done before dex- tran administration. Group O is the universal donor, and if there is insufficient time to do appropriate cross-matching of blood, this type of blood should be used. Serum of the recipient should be <24 hours old, because antigenicity may be altered in blood stored for a longer time. Before hypothermia is undertaken, the patient’s (recipient’s) blood should be tested for cold agglutinin titer. Cryoglobulin may be present in patients with lymphoma or leukemia. Blood must be given at room temperature to such patients.

Answer 296

60. (D) In general, total caloric needs for the majority of patients ranges between 25 and 35 kcal/kg/d. An alternative formula for calcu- lating daily caloric requirements is the Harris- Benedict equation, which is based on sex, age, weight, and height. The caloric requirements of humans also varies by amount of activity, degree of stress of surgery, trauma, sepsis, or burns.

Answer 297

61. (D) The baseline protein requirements are cal- culated as 1 g/kg/d. Following stress, there is an increased protein requirement, and protein intake should be 1.5 g/kg/d after surgery, 2 g/kg/d after polytrauma, and after sepsis. Glucose and amino acids must be infused simultaneously to appropriately utilize nitrogen. The ideal ratio is 100 nonprotein kcal/g of nitrogen. In starvation, the nonprotein calorie- to-nitrogen ratio of 150 kcal/g is adequate.

Answer 298

62. (D) Lipid emulsions derived from soybean or safflower oils are widely used. One of the real advantages of lipid emulsion is that a large amount of calories can be provided through a peripheral vein. The 10% solution provides 4.62 kJ/mL and the 20% solution, 9.24 kJ/mL. Dextrose concentration in peripheral route is 10%. Concentrations >10% require administra- tion into a central vein to prevent phlebitis owing to hypertonicity of the solutions. Lactulose is used to treat hepatic encephalopathy.

Answer 299

63. (C) Essential fatty acid deficiency usually occurs if hyperalimentation is extended for more than 1 month and when soybean oil is not administered at least twice a week. There is a decrease in linolenic, linoleic, and arachidonic acids and an increase in oleic and palmitoleic acid. In addition to the skin changes, there may be poor wound healing, increased susceptibil- ity to infection, lethargy, and thrombocytope- nia. It is characterized by a triene-to-tetraene ratio >0.4.

Answer 300

64. (D) In metabolic alkalosis, there may be a loss of fixed acids or excess of base. It is associated with hypokalemia because of renal conser- vation of H+ ions and urinary potassium loss. Loss of hydrochloric acid as seen in vomiting in patients with pyloric obstruction results in hypochloremic, hypokalemic, metabolic alkalosis.

Answer 301

65. (B) Many of the adverse changes can be accounted for by endotoxin release. Escherichia coli is the most common organism involved in gram-negative septicemia, followed by Klebsiella, Aerobacter, Proteus, and Pseudomonas. The car- diac index is high, peripheral resistance is decreased, and CVP is low to normal. The most common conditions leading to gram-negative sepsis are those of the urinary tract, followed by respiratory and biliary tract and abdominal visceral infections. Endotoxins are lipopolysac- charide complexes. The lipid A portion is prob- ably responsible for the toxicity.

Answer 302

66. (C) Most patients are elderly. The underlying conditions leading to septic shock occur more commonly in elderly patients. The mortality is higher in this patient population. The overall mortality rate exceeds 40–50%. Gram-positive organisms, parasites, or fungi also may be responsible. The genitourinary and respiratory tracts are more common sources for initiating sepsis. Two or more organisms are found in 10–20% of cases.

Answer 303

67. (C) The patient’s clinical picture is suggestive of cardiogenic shock. However, he may still be hypovolemic, because distension of neck veins does not accurately reflect the filling pressures of the heart. A Swan-Ganz catheter should be inserted for appropriate assessment of hemody- namic status and institution of appropriate ther- apy. Fluid therapy will worsen cardiogenic shock, and Lasix will make the patient hypov- olemic. Dopamine will increase BP but is delete- rious to the heart. The patient should not be extubated until he is stable.

Answer 304

68. (C) Low cardiac output in the presence of ele- vated filling pressures is characteristic of cardio- genic shock. PCWP is decreased in all the other types of shock.

Answer 305

69. (D) Thrombocytopenia is a common complica- tion of heparin therapy. The most common form, type I (seen in up to 30% of patients), is a milder form that occurs after 2–3 days of heparin therapy. The platelet count remains over 50,000/mm3 and has no clinical significance. Type II, seen in 1–2%, usually occurs 7–10 days after heparin treatment. It is immune mediated and can be caused by heparin therapy in any form, in any dose, including heparin flushes and heparin-bonded intravenous catheters. Treat- ment consists of immediate cessation of heparin administration in any form.

Answer 306

70. (B) The patient has tension pneumothorax, as evidenced by distended neck veins and absent breath sounds. Increased intrathoracic pressure interferes with venous return to the heart, resulting in shock. Immediate management should be insertion of a large-bore needle in the left second intercostal space, followed by insertion of a chest tube. In a trauma patient, venous access should be achieved by inserting two large-bore (16-gauge) angiocatheters in the cubital veins. Insertion of a central venous line on the right side should not be done, because it carries the risk of producing pneumothorax in the opposite side.

Answer 307

71. (D) Institute positive end-expiratory pressure (PEEP). This patient has developed ARDS, which is associated with a significant decrease in functional residual capacity (FCR) of the lungs from collapse of alveoli and increased shunt from perfusion of unventilated alveoli. The most appropriate way to improve his oxy- genation is by instituting PEEP.

Answer 308

72. (B) Administration of a depolarizing anesthetic agent such as succinylcholine in quadriplegics, in paraplegics, or after burns and severe trauma can result in life-threatening hyperkalemia from release of intracellular potassium.

Answer 309

73. (C) Dobutamine is the drug of choice for improving cardiac function. It is a b -receptor 1 agonist and increases myocardial contractibil- ity and also reduces afterload by b2 effect. Dopamine at low doses (1–3 mg/kg/min) stim- ulates dopaminergic receptors and increases renal blood flow. At moderate doses (3–10 mg/kg/min), it stimulates b-receptors, resulting in a positive inotropic and chronotropic effect. Systolic and mean BP are increased; whereas, diastolic BP is usually unchanged. At higher doses (10–20 mg/kg/min), stimulation of a- receptors occurs and it significantly increases systemic vascular resistance. Norepinephrine, epinephrine, and phe-nylephrine are powerful vasoconstrictors.

Answer 310

74. (C) The criteria for need for ventilatory support are apnea, respiratory rate >30 breaths/min, PaO2 <60 mm Hg on room air, and PaCO2 >55 mm Hg (except in patients with chronic obstructive pulmonary disease [COPD]).

Answer 311

75. (C) Vital capacity (VC) of 5 mL/kg body weight. See Answer 76.

Answer 312

76. (D) Successful weaning from the ventilator is suggested by the presence of (a) PaO2 of 70 mm Hg or more with an FiO2 of 0.35 or less (b) An alveolar arterial gradient of <350 mm Hg (c) A PaO -to-FiO ratio of >200 22 (d) A PaCO2 of over 30 mm Hg and <55 mm Hg (e) A VC of more than 10–15 mL/kg (f) A maximum negative inspiratory force of more than -25 cm H2O (g) A minute ventilation of <10 L/min (h) A tidal volume of over 5 mL/kg (i) A respiratory rate of <30 breaths/min

Answer 313

77. (B) Patients with SIADH have low urinary output with hyponatremia. Urine-specific grav- ity or osmolality is increased, urinary excretion of sodium is increased (>20 mEq/L), and TBW is increased as manifested by low serum osmo- lality. SIADH is seen after various CNS disor- ders, in neoplastic disease, pulmonary diseases, and with some drugs and may be idiopathic.

Answer 314

78. (D) The metabolic response to stress is different to that seen following starvation, as illustrated in Table 1–2.

Answer 315

79. (D) Resting energy expenditure is decreased fol- lowing starvation (e.g., in the patient with pyloric obstruction) and increased after the stress of sur- gery, trauma, or sepsis. The increase in energy expenditure correlates with the severity of insult being 1.2 times greater after minor operation (e.g., right inguinal herniorrhaphy), 1.35 times greater after skeletal trauma (e.g., fractured femur), 1.6 times greater after major sepsis (e.g., perforated diverticulitis), and 2 times greater after severe thermal burns.

Answer 316

80. (D) It is easy to start and administer nutrient requirements rapidly. Parenteral nutrition should be administered when enteral access cannot be obtained, when enteral nutrition support fails to meet nutritional requirements, or when feeding into the GI tract is contraindicated. Current evi- dence suggests that in addition to safety, con- venience, and cost, enteral feeding is well tolerated, preserves gut mucosal mass and normal gut flora, prevents increased gut per- meability to bacteria and other toxins, main- tains mucosal immunity, and attenuates the hypermetabolic response to surgery. As com- pared to parenteral nutrition, enteral nutri- tion is also associated with significantly reduced septic complications. Therefore, enteral feeding is preferred over TPN when feasible.

Answer 317

81. (C) It is a major fuel for the gut. It is readily syn- thesized de novo in skeletal muscle, lung, and liver. Glutamine is a nonessential amino acid. It is not a component of presently available TPN solutions because of its lack of stability. Glutamine is a major fuel for the small intes- tinal mucosa and other replicating cells such as lymphocytes, macrophages, fibroblasts, and endothelial cells. Glucose is the primary source of fuel for the brain.

Answer 318

82. (B) Patients on TPN with hypertonic glucose solutions have elevated islet-cell production of insulin. Sudden cessation of TPN can lead to rebound hypoglycemia, because pancreatic islet-cell insulin secretion is not immediately downregulated. Symptoms are attrbutable to high catecholamine release secondary to hypo- glycemia. In general, the TPN rate should be reduced to 50 mL/h during surgery. This pre- vents both hypoglycemia and the hyper- glycemia seen with higher infusion rates. Weaning from TPN should be done gradually over 24–48 hours. In instances where TPN is discontinued suddenly, a solution of D10W should be administered in the interim.

Answer 319

83. (C) Hyperosmolar-nonketotic coma is a seri- ous complication seen when an excessive amount of glucose is given, especially in the presence of sepsis, steroids, or inadequate insulin. Furthermore, the combination of sur- gery and sepsis results in an increased insulin- resistant state. The increased urine output is secondary to osmolar load from blood glu- cose. Low CVP, hypernatremia, and BUN-to- creatinine ratio over 20 suggest hypovolemia and not fluid overload. Normal creatinine level and BUN-to-creatinine ratio over 20 rules out high-output renal failure. The stress of surgery is characterized by water retention and not diuresis. Management consists of aggressive hydration, discontinuation of TPN, and insulin drip. Insulin drives the potassium intracellu- larly and potassium must be replaced.

Answer 320

84. (C) Glucose infusion should not exceed 4–5 mg/kg/min, equivalent to 365–432 g for this patient. The patient is receiving 750 g of glucose. Glucose has a respiratory quotient of 1. Excess glucose results in increased produc- tion of CO2, making it difficult to wean the patient off ventilator. Treatment consists of reducing glucose load and providing fat calo- ries (up to 40% of total calories). Fat has a res- piratory quotient of 0.7, resulting in decreased production of CO2.

Answer 321

85. (C) Systemic vascular resistance (an approxi- mation of afterload) is a calculated value. All the other choices are directly measured.

Answer 322

86. (A) The oxyhemoglobin dissociation curve is a convenient method to study the affinity of hemoglobin for oxygen. It is S-shaped, which provides an efficient method of uptake and release of oxygen. It holds on to the oxygen at high concentrations and as the blood enters the lower pressures encountered in the capillaries, it releases the oxygen. Hemoglobin is 75% satu- rated at a PO2 of 40 mm Hg and 50% saturated at a PO2 of 27 mm Hg. At the peripheral tissues, a right or left shift does have a real impact on the affinity of hemoglobin for oxygen. If the S-curve is shifted to the right, there is a decreased affin- ity of hemoglobin for oxygen (more oxygen is released). A right shift occurs with increase in 2,3-DPG, acidosis, increase in temperature, and increase in hormones (cortisol, thyroid, or aldos- terone). A left shift occurs with a decrease in temperature, alkalosis, low DPG, carboxyhemo- globinemia, and old age.

Answer 323

87. (D) Intravenous protamine sulfate. The cause of bleeding is circulating heparin. The antico- agulative effect of heparin can be immediately neutralized by intravenous protamine sulfate. One milligram of protamine sulfate usually neutralizes 100 U of heparin. Fresh-frozen plasma is given to counteract the effect of war- farin (Coumadin). Cryoprecipitate is useful in treating patients with hemophilia. Intravenous sodium bicarbonate is indicated after mis- matched blood transfusion to alkalinize the urine. Platelet transfusions are necessary to cor- rect dilutional thrombocytopenia seen after massive blood transfusion.

Answer 324

88. (D) Transient arrhythmias and right bundle branch block are seen during the insertion of the PA catheter as it may hit the wall of the right ventricle causing these electrical distur- bances. Pneumothorax is a risk associated with the insertion of the introducer for the PA catheter. Cardiac perforation is certainly a risk anytime a catheter is being placed through the heart. Mural thrombus is not a known complication.

Answer 325

89. (A) Rapid correction of hyponatremia >1–2 mEq/L/h can lead to central pontine myeli- nolysis. Serum sodium level should not be raised >25 mEq/L within 48 hours of starting therapy. Only symptomatic hyponatremia requires treatment with hypertonic saline, oth- erwise fluid restriction is sufficient.

Answer 326

90. (D) Abnormal hemostasis, common in chronic renal failure, is characterized by prolonga- tion of bleeding time, decreased activity of platelet factor 3, abnormal platelet aggrega- tion, and adhesiveness. The prolonged bleeding time is related to failure of platelet interaction with von Willibrand’s factor (factor 8-VWF) This interaction can be corrected by using desmopressin or by transfusing cryoprecipitate.

Answer 327

91. (D) The coagulation changes can be reversed with desmopressin or cryoprecipitate.

Answer 328

92. (C) Daily maintenance fluid requirements are calculated on the basis of 100 mL/kg for the first 10 kg of body weight, 50 mL/kg for the second 10 kg of body weight, and 20 mL/kg for each additional kg of body weight (i.e., 100 × 10 + 50 × 10 + 20 × 50 = 2500 mL). Hourly fluid requirement can be calculated using the 4, 2, 1 rule as follows: 4 mL/kg, for the first 10 kg, 2 mL/kg for second 10 kg, and 1 mL/kg for each additional kg of body weight (i.e., 4 × 10 + 2 × 10 + 1 ( 50 = 110 mL/h).

Answer 329

93. (B) Low molecular weight heparins (LMWH) are fragments of unfractionated standard heparin with mean molecular weights between 4000 and 64,000 d. They bind to and accelerate the activity of antithrombin III. LMWH has greater bioavailability, more effective antico- agulant effect, lower incidence of heparin- associated thrombocytopenia, and can be administered once daily.

Answer 330

94. (C, E, I) Zinc deficiency, vitamin A deficiency, and vitamin C deficiency. Zinc is a metalloen- zyme involved in protein and nucleic acid metabolism. Deficiency results in diminished wound strength and healing rates. Vitamin A deficiency results in delayed wound healing, specifically epithelization. Vitamin C deficiency results in defective sulfonated mucopolysac- charides and chondroitin sulfate with retarded wound healing.

Answer 331

95. (B, D) Chromium is an insulin cofactor. Defi- ciency state results in hyperglycemia. Manganese is a cofactor of enzyme of energy and protein metabolism and also of fat synthesis. Besides causing glucose intolerance, manganese defi- ciency also causes hypocholesterolemia.

Answer 332

96. (C) Zinc is one of the metalloenzymes involved in lipid, carbohydrate, protein, and nucleic acid metabolism. Skin lesions similar to enterohepatic acrodermatitis are the most common signs seen in zinc deficiency. Other manifestations include hypogonadism, diminished wound healing, and immunodeficiencies. Copper deficiency is characterized by microcytic hypochromic anemia.

Answer 333

97. (B, D) Factor V and VIII are deficient in stored plasma. In contrast, fresh-frozen plasma con- tains all the coagulation factors. The major dis- advantage of plasma administration, however, is the risk of hepatitis.

Answer 334

98. (C) There are two coagulation pathways— extrinsic and intrinsic. In the extrinsic system, tissue thromboplastin (a lipoprotein) interacts with factor VII. The intrinsic pathway requires factors XII, XI, IX, and VIII. Factor XII is the ini- tial step in the coagulation cascade. Factor XII, activated by contact with a nonendothelial sub- stance, will activate factor XI (plasma throm- boplastin antecedent). However, factor XI can be activated even when factor XII is deficient. Calcium is required for nearly all of the enzyme reactions in both the intrinsic and extrinsic sys- tems. The amount of ionized calcium required for these reactions is extremely small, and clin- ical hypocalcemia itself is not a cause of abnor- mal bleeding. Fibrin split products are not part of the normal pathway in either the intrinsic or extrinsic system. The excessive breakdown of fibrinogen results in measurable amounts of the breakdown products of fibrinogen in the blood. Their presence may signal DIC if the PT and platelet count are deranged. In pure fibri- nolysis, fibrinogen breakdown product levels also may be increased.

Answer 335

99. (D, H) All the coagulation factors except throm- boplastin, calcium, and factor VIII are synthe- sized in the liver. Factors II, VII, IX, and X are vitamin K dependent.

Answer 336

100. (B) Disseminated intravascular coagulation is characterized by diffuse intravascular coagu- lation, thrombosis, and fibrinolysis. It results in thrombocytopenia, hypofibrinogenemia, pro- longation of PT and PTT, and increased con- centration of fibrin degradation products in plasma. Sepsis is a major factor that can trigger DIC.

Answer 337

101. (D) Dopamine activates b -receptors and this 1 was probably the reason for the arrhythmia. Amrinone will inhibit phosphodiesterase and result in an increased cyclic AMP level, pro- ducing the same result as b-receptor stimu- lation. Dobutamine and epinephrine also stimulate the b- receptors. The only choice which stimulates only a-adrenergic receptors is phenylephrine. Intra-aortic balloon pump is invasive¯, therefore, less appropriate as a choice.

Answer 338

102. (E) Hetastarch is a synthetic colloid that is metabolically inert and can be infused IV. A 6% solution of hetastarch has the same osmotic properties as 5% albumin. Relatively few com- plications are associated with hetastarch. Large volumes do cause dilution of plasma proteins as well as coagulation and platelet function disorders. Hetastarch binds to amylase and impairs renal excretion of amylase causing hyperamylasemia.

Answer 339

103. (D) In anaphylactic shock, which this patient is showing, the HR would reflexively increase due to the drop in BP. The intravascular hypovolemia and decreased preload are clearly present along with the vasodilation; however, the cardiac output is initially decreased not increased.

Answer 340

104. (B) The only ECG rhythm, which can obscure ST-segment changes seen in acute myocardial infarction, is left bundle branch block. All the other rhythms would allow visualization of the ST-segment changes.

Answer 341

105. (B) The Glasgow Coma Score scale is made up of eye opening, verbal response, and motor response.

Answer 342

106. (E) The patient is suffering from anaphylaxis, and the treatment of choice is epinephrine. Epinephrine IM has been shown to be more effective than SC for the treatment of anaphy- laxis.

Answer 343

107. (D) The prone positioning reduces the dispar- ity in mechanics between the dependent and nondependent regions of the lungs. This reduces the collapsing of the alveoli in the dependent portions of the lungs and overdis- tention in the nondependent portions of the lungs. The prone position also has other effects—it allows a more normal curvature of the diaphragm and allows better function. It also stiffens the chest wall allowing a more even distribution of ventilation and reduction in overventilation of nondependent alveoli.

Answer 344

108. (C) The patient has a diagnosis of dissecting aortic aneurysm. This requires emergent med- ical as well as surgical intervention. The BP needs to be lowered by using nitroprusside as well as a b-blocker to reduce dp/dt (the force with which the heart is pumping). Once BP is controlled the surgical intervention is needed to correct the problem.

Answer 345

BALANCED RESUSCITATION - Initial bolus of 1L may be required. - Fluids are administered judiciously, as aggressive resuscitation before control of bleeding has been demonstrated to increase mortality. MINIMAL RESUSCITATION - Minimum 18gauge peripheral access x 2. PICC - Choice of site for alternate access based on clinician experience and skill. ``` EARLY BT - Early resuscitation with blood and blood products must be considered in patients with evidence of class III and IV hemorrhage. ``` MTP - Coagulopathy associated with severe trauma can be fueled by resuscitative measures. - Use of massive transfusion protocols with blood components administered at predefined low ratios may mitigate this. - 1:1:1 PRBC:Plasma:Plt EARLY TXA - Administer tranexamic acid in prehospital setting to severely injured patients within 3h of injury. - The first dose (1g) is usually given over 10 minutes and is administered in the field; the follow up dose of 1g is given over 8h.

Answer 346

1) HYPOVOLEMIC - Decreased MAP, CO, PAOP - Increased SVR 2) CARDIOGENIC - Decreased MAP, CO - Increased PAOP, SVR ``` 3) OBSTRUCTIVE (Tension pneumothorax, ACS, PE, Pericardial tamponade, auto-PEEP, severe aortic stenosis, dissecting AA, severe aortic coarctation) - Decreased MAP, CO - Unchanged/increased PAOP - Increased SVR ``` ``` 4) DISTRIBUTIVE (Sepsis) - Decreased SVR - Unchanged/increased CO - Unchanged/decreased PAOP ``` Hypotension leads to: 1) Low CO - > a. Low stroke volume - --> i. Decreased venous return - --> ii. Ventricular dysfunction - > b. Low heart rate 2) Low vascular tone

Answer 347

≥60mmHg Higher MAP may be necessary in select cases: - Intracranial HTN (hemorrhage, cerebral edema, closed head trauma, large strokes) - Chronic HTN MAP = (CO x SVR) = ((HR x SV) x SVR)

Answer 348

DYSFUNCTION The organ is incapable of maintaining homeostasis. - GI: Ileus, intolerance of enteral feeds - HPB: High serum bilirubin, liver function tests that are twice normal values FAILURE The organ cannot meet minimal demands, and is not considered viable. - GI: Stress ulcers, acalculous cholecystitis - HPB: Clinical jaundice, TB >8-10mg/dL