Anesthetic Flashcards
A 36-year-old woman undergoes reduction mammaplasty. An intravenous infusion of vancomycin 1.5 g is started preoperatively as antibiotic prophylaxis. Medical history includes allergies to penicillin and clindamycin, but the patient has never received vancomycin. After 5 minutes of continuous infusion, an erythematous rash develops over the patient’s torso, neck, and face, and she reports headache and generalized pruritus. She remains hemodynamically stable and is otherwise asymptomatic. After discontinuing the antibiotic infusion, which of the following is the most appropriate next step in management?
A) Administer epinephrine intramuscularly
B) Administer morphine intravenously
C) Document the patients allergy to vancomycin in the medical record
D) Order a STAT vancomycin serum level
E) Resume the infusion at a slower rate once the patients symptoms improve
The correct response is Option E.
This patient developed a mild form of red man syndrome (RMS), caused by vancomycin administration. The most appropriate next step in management after discontinuing the antibiotic infusion is symptomatic treatment with an antihistamine drug (eg, intravenous or oral administration of diphenhydramine). The vancomycin infusion can be resumed after resolution of the rash and other symptoms, albeit at a slower rate.
Vancomycin can cause a plethora of hypersensitivity reactions, ranging from localized skin reactions to anaphylactic shock. RMS is its most common form and consists of an erythematous rash that involves the face, neck, and upper torso, commonly associated with generalized discomfort and cutaneous pruritus or burning. Patients can experience headache, chills, fever, perioral paresthesia, and/or dizziness. Although rare, chest pain, diffuse muscle spasms, angioedema, and hypotension can also occur. RMS is associated with rapid intravenous infusion of vancomycin, occurring in less than 10% of patients with serious infections who receive 1 g infused over 1 hour. However, healthy patients may have a higher susceptibility. Contrary to true anaphylaxis, RMS is not thought to be mediated by vancomycin-specific antibodies, and can occur even with its first administration.
Intramuscular injection of epinephrine is indicated for anaphylactic reactions. Morphine and other opioids have been shown to increase the rate of RMS in patients receiving vancomycin infusion, and, therefore, should be avoided. A vancomycin serum level at this time would unlikely provide any valuable information. RMS is not considered a patient-specific allergy, but rather an idiosyncratic reaction related to speed of drug infusion.
2018
A 45-year-old man is brought to the emergency department after sustaining a gunshot wound to the chest. He is in respiratory distress and has decreased breath sounds on the right side. Needle decompression is performed in the right chest, and a tube thoracostomy is placed. The patient stabilizes. Which of the following initial findings is most likely in this patient?
A) Cardiac murmur B) Decreased urine output C) Hyperresonance of the left chest D) Hypertension E) Tracheal deviation to the left
The correct response is Option E.
Tension pneumothorax occurs when there is injury to the lung and air leakage into the pleural space that cannot escape. Each subsequent breath increases the volume of air in the pleural space and increases the intrapleural pressure. As pressure builds, structures of the chest are compressed, impairing ventilation and decreasing venous return.
Tension pneumothorax is a clinical diagnosis. Features include tachypnea, dyspnea, jugular venous distention, decreased air entry, hyperresonance on the affected side, tracheal deviation to the opposite side, and hypotension. Treatment is immediate decompression of the pleural space with a long, large-bore needle followed by insertion of a chest tube.
In this patient with a history of penetrating chest trauma, decreased breath sounds, and respiratory distress, tension pneumothorax is diagnosed. The trachea will be deviated to the contralateral side (left) and the patient will be hyperresonant to percussion on the right side. Cardiac murmur and hypertension are not features of tension pneumothorax. Urine output is irrelevant.
2018
A 30-year-old man comes to the emergency department 4 months after undergoing transplantation of the right hand because he has a painful, burning rash on the transplanted hand. Physical examination of the hand shows a maculopapular erythematous rash. Which of the following types of rejection is most likely in this patient?
A) Hyperacute B) Accelerated C) Acute D) Chronic E) Graft-versus-host
The correct response is Option C.
In transplantation, rejection is categorized as hyperacute, accelerated, acute, and chronic.
Hyperacute rejection is a humoral response mediated by antibodies that are already present in the host at the time of transplantation. It starts in the operating room, at the time blood flow to the transplanted organ is reestablished. Exposure to the graft tissue activates preexistent antibodies, which then activate the complement system, causing diffuse thrombosis in the graft’s microcirculation and rapid ischemic failure, usually within the first few minutes to hours of graft reperfusion.
Accelerated rejection is a cellular and humoral response that usually occurs between the second and fifth day after transplantation. Considered a variant of hyperacute rejection, it also results from recipient presensitization to donor tissue antigens, but without the formation of large numbers of preexistent antibodies. Instead, memory cells mediate a rapid immune response against the graft. Complement activation and intravascular thrombosis usually leads to graft loss.
This patient is experiencing acute rejection, which is regulated by the activation of T-cells. It can occur at any time after the fifth postoperative day, although it is more common within the first 4 to 6 months. Clinical presentation depends on the transplanted organ, but is usually characterized by short-term organ dysfunction (eg, liver, kidney) or graft cutaneous/mucosal manifestations. A graft biopsy is usually necessary for diagnosis. The majority of acute rejections respond well to higher levels of immunosuppressive therapy, although recurrent events might be predictive of the development of chronic rejection.
Chronic rejection is both an antibody- and cell-mediated immune response that causes indolent, progressive arterial sclerosis and fibrosis of the transplanted organ (eg, coronary atherosclerosis in hearts, bronchiolitis obliterans in lungs, vanishing bile duct syndrome in livers, etc). It usually clinically manifests itself several months to years after transplantation. Initial measurable organ dysfunction usually progresses to failure.
Graft-versus-host disease is a cellular response caused by activation of the transplanted graft’s immune cells by the recipient’s tissues. It most commonly occurs several months after bone marrow or stem cell transplantation. Clinical manifestation varies, but usually involves tissues/organs of the recipient individual.
2018
A 45-year-old man is brought to the emergency department/intensive care unit after sustaining multiple facial fractures and a closed head injury with intraparenchymal hemorrhage in a motor vehicle collision. He is currently intubated and unresponsive. Serum sodium concentration is 140 mEq/L. Which of the following is this patient’s free water deficit?
A) 0 L B) 1 L C) 2 L D) 3 L E) 4 L
The correct response is Option A.
Free water deficit is calculated by the formula: Water deficit = normal body water x (1-(Serum Na/140)). The calculated free water deficit is the amount of free water required to bring the sodium concentration back to normal. Free water deficits and the associated hypernatremia can occur with diabetes insipidus after closed head injuries and need to be corrected if present. Although this patient does have a closed head injury and is unresponsive, his serum sodium concentration is in the normal range, and no calculated free water replacement is necessary.
2018
Temporary paresthesia is most likely in which of the following teeth after an infraorbital nerve block is performed?
A) Both central incisors, ipsilateral lateral incisor and canine
B) Both central incisors, ipsilateral lateral incisor, canine, and first and second molars
C) Ipsilateral central incisor, lateral incisor, canine, and both bicuspids
D) Ipsilateral lateral incisor, canine, both bicuspids, and first and second molars
E) Ipsilateral canine, both bicuspids, and first and second molars
The correct response is Option C.
Anesthetic blocks are routinely performed for office procedures. They are especially useful for facial procedures because of their reliable anatomy. Understanding the anatomy of each of the branches of the trigeminal nerve is important to successfully use this technique. The superior alveolar branch is a branch of the infraorbital nerve that controls sensation to the central and lateral incisor, the canine, and both bicuspid teeth.
The first and second molars are not innervated by branches of the infraorbital nerve. The contralateral central incisor is not innervated by the contralateral infraorbital nerve.
2018
Which of the following patient positioning interventions is most appropriate for prevention of perioperative peripheral neuropathy?
A) Abducting the arms at 100 degrees in supine patients
B) Pronating the forearms in supine patients with arms tucked at side
C) Securing the arms in dorsal extension in supine patients
D) Stabilizing the neck in extended position in prone patients
E) Using leg holders with heel support in lithotomy position
The correct response is Option E.
For patients in lithotomy position, the use of leg holders that incorporate heel support may prevent compression injury to the peroneal nerve. Contrarily, leg holders without heel support or the use of wraps to maintain the leg on leg rests may increase the risk of compression injuries to this nerve. For prevention of brachial plexus perioperative neuropathy in the supine patient, arm abduction should be limited to no greater than 90 degrees. In addition, dorsal extension of the arm (poorly padded or sagging arm boards) should be avoided.
For prevention of ulnar perioperative neuropathy in the supine patient, care should be taken to decrease pressure on the post-condylar (ulnar) groove of the humerus. When the upper extremity is on an arm board, the forearm should be positioned in either supination or neutral positions. When tucked at side, the forearm should be in a neutral position.
When in prone position, the patient’s neck should be well stabilized in neutral, nonextended position. Although neck extension has not been reportedly associated with peripheral neuropathies, authors have reported cases of vertebral artery injury.
2018
A 28-year-old woman, gravida 2, para 1, is brought to the emergency department after a motor vehicle collision in which she was a restrained passenger. ATLS evaluation shows that her vital signs are stable, and she is calm and lucid. The patient reports that she is 32 weeks’ pregnant. Repeat blood pressure is 80/60 mmHg, and the patient reports that she feels light-headed; tachycardia is noted. After maintaining cervical spine precautions, which of the following is the most appropriate initial management of this patient?
A) Administer 2 L crystalloid bolus
B) Intubate the patient
C) Logroll the patient onto her left side
D) Place patient in Trendelenburg position
E) Transfuse 2 units of blood
The correct response is Option C.
Pregnancy alters normal physiology as well as anatomy. At 32 weeks’ pregnancy, gravid uterus and fetus is anatomically at the costal margin and can be somewhat protective of bowel injury in a restrained passenger. A hematocrit of 31 to 35% is within normal range; however, the overall volume has increased dramatically and a loss of 1.2 to 1.5 L is well tolerated without symptoms.
Another crucial anatomical difference is the gravid uterus and its ability to compress the vena cava while in the supine position. Thirty percent decreased cardiac output can occur from the uterus occluding venous return from the lower extremity. In order to avoid this, the uterus should be physically displaced to the patient’s left side to allow return from the inferior vena cava. Should there be cervical spine precautions, the board can be rolled to the left 4 to 6 inches, thus alleviating pressure. In general, pregnant patients should be monitored on their left side.
Maternal well-being is the most crucial for fetal well-being, as the number one cause of fetal death is maternal hypotension and maternal death. The second most common cause of fetal death is abruption of the placenta. Fetal monitoring is extremely important, especially after 20 to 24 weeks’ gestation. However, in this case there is no evidence of cramping or tender abdomen.
Advanced Trauma Life Support (ATLS) protocol dictates airway, breathing, and circulation are normal, and, in this case, her airway and breathing are normal. The most appropriate next step is reestablishing this patient’s circulation, which is alleviating the initial possibility of decreased venous return. Should this not occur, then following the protocol for crystalloid resuscitation would be the most appropriate.
2018
A 42-year-old woman who is BRCA2-positive undergoes delayed reconstruction of both breasts with deep inferior epigastric artery perforator (DIEP) flaps. Medical history includes prophylactic mastectomy and failed implant reconstruction 3 months ago. After closure of the fascia of the rectus abdominis muscles, the triangle bounded by the latissimus dorsi, external oblique, and iliac crest is identified on each side. Infiltration of bupivacaine into which of the following planes is most likely to provide postoperative pain control of the abdominal flap donor site in this patient?
A) Between the external oblique and the internal oblique
B) Between the internal oblique and the transversus abdominis
C) Between the transversalis fascia and the peritoneum
D) Between the transversus abdominis and the transversalis fascia
E) In the deep subcutaneous tissues, superficial to the external oblique
The correct response is Option B.
The peripheral nerve block described is a transversus abdominis plane, or TAP, block. The lumbar (Petit) triangle, which is located at the lateral extent of the abdomen, is formed by the borders of the latissimus dorsi muscle posteriorly, the external oblique anteriorly, and the iliac crest inferiorly. Furthermore, the location can be estimated by the intersection of a horizontal line through the umbilicus and the vertical anterior axillary line. The intercostal nerves providing sensation to the anterior abdominal wall from T6 to L1 are located in the plane between the internal oblique and the transversus abdominis muscles. Long-acting local anesthetic infiltration in this plane is generally approached through the lumbar triangle. Multiple techniques have been described. These include visualized injection with the assistance of ultrasound guidance, catheter insertion under direct vision with surgical cutdown to the appropriate plane, and blind injection using a blunt needle, feeling for the two punctures of the external and internal obliques, respectively. Multiple studies have shown improved postoperative pain control in the abdominal donor site with this technique in breast reconstruction, and patients have demonstrated marked decreases in opioid consumption as well. The other options would be inappropriate for nerve block as the intercostal nerves are not found in those tissue planes.
2018
A 32-year-old man, who is a football player, is brought to the emergency department after being found unconscious and facedown in his home. It is estimated that he was in that position for 6 hours. Physical examination shows swelling of the right forearm and hand. Which of the following physiologic abnormalities is most likely in this patient?
A) Hyperkalemia, hypercalcemia, metabolic acidosis
B) Hyperkalemia, hypocalcemia, metabolic acidosis
C) Hypokalemia, hypercalcemia, metabolic alkalosis
D) Hypokalemia, hypocalcemia, metabolic acidosis
E) Hypokalemia, hypocalcemia, metabolic alkalosis
The correct response is Option B.
The physiological abnormalities that result from rhabdomyolysis are caused because of crush injury to the muscle. The crush injury causes pressure or stretching of the muscle and sarcolemmal membrane. As the sarcolemmal membrane is stretched, sodium, calcium (hypocalcemia), and water leak into the sarcoplasm, trapping extracellular fluid inside muscle cells. In addition to the influx of these elements into the cell, the cell releases potassium (hyperkalemia) and other toxic substances such as myoglobin, phosphate, and urate into the circulatory system (metabolic acidosis). The end result of these events is shock, hyperkalemia, hypocalcemia, metabolic acidosis, compartment syndrome, and acute renal failure. Acute renal failure results because of a combination of hypovolemia with subsequent renal vasoconstriction, metabolic acidosis and the influx of nephrotoxic substances such as myoglobin, urate, and phosphate.
2018
A 56-year-old woman has been in the intensive care unit since she was struck by a car 2 weeks ago. She sustained multiple facial fractures, severe closed head injury with cerebral contusion, pelvic fractures, and multiple lower extremity fractures. The patient required emergent intubation and has been in a coma since the injury. The patient’s current serum sodium concentration is 148 mEq/L, and urinalysis demonstrates dilute urine with low osmolality. Neurogenic diabetes insipidus is suspected. A deficiency in which of the following hormones is most likely the principal cause of this electrolyte imbalance?
A) Aldosterone B) Angiotensin C) Cortisol D) Renin E) Vasopressin
The correct response is Option E.
Neurogenic or central diabetes insipidus is often caused by head trauma resulting in a lack of vasopressin production. Vasopressin is released by the posterior pituitary gland but, unlike other pituitary hormones, is produced in the hypothalamus. Because of this unique relationship, traumatically induced neurogenic diabetes insipidus may occur due to damage to the hypothalamus, pituitary stalk, or posterior pituitary. Vasopressin, also known as antidiuretic hormone (ADH), plays a key role in fluid homeostasis by affecting water retention in the kidneys at the collecting ducts and distal convoluted tubule.
Cortisol is a hormone secreted by the adrenal glands that plays a role in numerous functions including maintaining normal metabolism and regulation of fluid balance. Angiotensin and aldosterone are key hormones of the renin-angiotensin system that is involved in the regulation of plasma sodium concentration and arterial blood pressure. Renin (also known as angiotensinogenase) is an enzyme that converts angiotensinogen to angiotensin. Angiotensin is a peptide hormone that causes vasoconstriction. It is formed by the action of renin on the liver-derived precursor, angiotensinogen, followed by the action of angiotensin-converting enzyme (ACE) to convert angiotensin I to the active form angiotensin II. Aldosterone is a steroid hormone produced by the adrenal glands and released in response to increased angiotensin. It plays a central role in regulation of plasma sodium, extracellular potassium, and arterial blood pressure. Cortisol, renin, angiotensin, and aldosterone deficiencies are not created by neurogenic diabetes insipidus related to head trauma.
2018
An otherwise healthy 154-lb (70-kg) woman undergoes a planned facial aesthetic procedure using conscious sedation. The anesthetic plan includes a combination of intravenous 0.25 mg/kg midazolam and 12.5 mg/kg fentanyl. Midway through the procedure, two consecutive noninvasive blood pressure readings taken 5 minutes apart demonstrate a systolic blood pressure of 85 mmHg. Which of the following is the most appropriate next step in management of this patient’s hypotension?
A) Administer flumazenil B) Administer naloxone C) Administer a vasopressor intravenous bolus (ephedrine or phenylephrine) D) Begin cardiopulmonary resuscitation E) Increase intravenous fluids
The correct response is Option E.
Conscious sedation is a common anesthetic technique used routinely by plastic surgeons for cosmetic procedures. The patient described is healthy and of average size. The two drugs used in this study are the most commonly used agents for this scenario. The dose chosen is on the low end of normal for both drugs. Increasing the amount of intravenous fluids is the correct answer because in the Marcus et al paper, 20% of the patients who underwent a similar conscious sedation procedure experienced this scenario. One hundred percent of these patients responded appropriately to increased intravenous fluid.
Administration of flumazenil to reverse midazolam toxicity is unnecessary as the patient is not experiencing midazolam toxicity. The dosage of midazolam is within the normal range. The patient is not demonstrating any additional signs or symptoms of narcotic (fentanyl) toxicity. The dose is on the low side of normal. Reversal of fentanyl is not indicated. The patient’s systolic blood pressure is only mildly low with no other symptoms in an otherwise healthy adult woman. Vasopressors would only be indicated if a fluid challenge was unsuccessful.
2018
A 60-year-old man is transferred to the surgical intensive care unit (SICU) following ventral hernia repair. Medical history includes coronary artery disease. Shortly after arrival in the SICU, the 12-lead ECG shown is obtained. This finding is most consistent with which of the following cardiac dysrhythmias?
A) Atrial fibrillation B) Atrial flutter C) First-degree AV block D) Multifocal atrial tachycardia E) Second-degree AV block
The correct response is Option E.
Cardiac dysrhythmias in the postoperative setting are extremely common, occurring 9% of the time in non-cardiac surgery patients without a history of cardiac disease to over 40% in cardiac surgery patients. In the surgical intensive care unit (SICU) setting, cardiac dysrhythmias may have several causes including hypoxia, cardiac ischemia, catecholamine excess, routine medications, and electrolyte abnormalities. It is important to be able to identify the characteristic electrocardiographic features of common dysrhythmias.
The PR interval is a measure of the conduction time through the AV node and bundle of His. When the PR interval is prolonged, the patient has a first-degree AV block. Second degree AV block occurs with intermittent failure of the conduction of the impulse to the ventricles. Progressive prolongation of the PR interval until a failure of conduction (“dropped” QRS complex) occurs is second degree AV block (Wenckebach block).
Multifocal atrial tachycardia is thought to be caused by abnormal automaticity. It demonstrates an irregular rate and rhythm, characterized by the presence of three or more morphologically different P waves on EKG with increased rates of 110 to 140 beats per minute.
Atrial fibrillation is one of the most common dysrhythmias encountered in an ICU setting. It is associated with dilation of the left atrium due to fluid shifts or structural heart disease. Echocardiographically, it is characterized by normal complex tachycardia without P waves.
Atrial flutter is associated with atrial enlargement and is caused by a reentrant circuit within atrial tissue. Increased atrial rates of 250 to 350 beats per minute are common, and not all of the atrial beats pass to the ventricle, typically in a 2:1 ratio. The EKG has a characteristic “sawtooth” flutter wave.
2018
Compared with the code team, which of the following is a typical criterion for calling the Rapid Response Team (RRT)?
A) Absence of respiratory effort B) No recordable blood pressure C) No recordable pulse D) Rapid heart rate E) Unresponsiveness
The correct response is Option D.
The Rapid Response Team (RRT) was conceptualized to intervene in the care of a greater number of hospitalized patients at an earlier stage of clinical deterioration. The goal of the RRT is to act acutely to prevent catastrophic adverse events.
The RRT would typically be called for hypotension, rapid heart rate, respiratory distress, and altered consciousness. While the traditional code team would treat cardiac arrest, respiratory arrest, and airway obstruction, the RRT would assess and manage sepsis, pulmonary edema, arrhythmia and respiratory failure.
Typically, hospital mortality in patients treated is 70 to 90% for the traditional code team, while it is 0 to 20% for the RRT.
2018
A 35-year-old woman is scheduled for abdominoplasty with flank liposuction. Regional anesthetic block is planned. The most appropriate location for placement of the anesthetic is between which of the following?
A) External oblique muscle and internal oblique muscle
B) Internal oblique muscle and transversus abdominis muscle
C) Skin and external oblique muscle
D) Transversalis fascia and peritoneum
E) Transversus abdominis muscle and transversalis fascia
The correct response is Option B.
The transversus abdominis plane (TAP) block is a regional anesthetic that blocks sensory afferent nerve fibers that supply the anterior/lateral abdominal wall dermatomes of T6-L1. These sensory nerves travel below the internal oblique muscle in the plane above the transversus abdominis muscle. Traditionally, the technique is performed blindly by placing a needle through the triangle of Petit posteriorly until the needle reaches the TAP. Once the needle is in the appropriate plane, 20 mL of a long-acting local anesthetic, such as bupivacaine, is injected. More recent modifications include the use of ultrasound guidance to optimize precise placement and the use of diluted long-acting multivesicular liposomal bupivacaine (Exparel). Several studies have demonstrated the benefits of a TAP block during abdominal surgery. These benefits include decreased pain, opioid use, and nausea/vomiting, as well as faster return of bowel function. Complications include potential systemic toxicity due to dose of anesthetic delivered/inadvertent intravascular injection and intraperitoneal injection with possible injury to intraabdominal organs such as, the liver or spleen.
2017
A 42-year-old woman presents for fat grafting from the abdomen to the upper breast poles under intravenous sedation. Patient history includes implant-based breast reconstruction. She receives 1 g of intravenous cefazolin in the preoperative holding area. Ten minutes later, she has onset of generalized hives, flushing, and swelling of the lips. She reports dyspnea and has audible wheezing. The most appropriate next step is administration of epinephrine by which of the following routes?
A) Intradermal injection B) Intramuscular injection C) Intravenous bolus D) Intravenous infusion E) Subcutaneous injection
The correct response is Option B.
This patient meets the diagnostic criteria for anaphylaxis, manifested by acute onset of generalized hives and swelling along with either respiratory compromise or hypotension. Intramuscular injection of epinephrine, 0.3 to 0.5 mg, preferably in the mid-outer thigh, is the initial treatment in adults. Other treatments include administration of supplemental oxygen and rapid normal saline infusion. Absorption of epinephrine after subcutaneous injection may be too slow to reverse anaphylaxis. Bolus injections of epinephrine should be avoided because of the risks of dosing errors and overdose. Epinephrine infusion can be considered for anaphylaxis that is refractory to intramuscular injections, but it is not a first-line choice. Subcutaneous or intradermal injection would result in delayed absorption.
2017
A 154-lb (70-kg), 42-year-old woman undergoes wide-awake flexor tendon repair during local anesthesia. The surgical area is infiltrated with a total of 20 mL of 1% lidocaine with epinephrine. To minimize bleeding, which of the following is the optimal timing between injection of the anesthetic and initiation of the incision?
A) 5 minutes B) 10 minutes C) 15 minutes D) 25 minutes E) 45 minutes
The correct response is Option D.
Wide-awake hand surgery has been successfully performed for a number of procedures including nerve decompression, excision of soft-tissue tumors, fracture repair, arthrodesis, tendon repair, and fasciectomy for Dupuytren disease. The wide-awake technique allows the surgeon to perform the procedure without general anesthetic or sedation and often without the use of a tourniquet to minimize tourniquet pain. In order to successfully use this technique, a bloodless field is paramount, and allowing the epinephrine to achieve maximal vasoconstrictive effect is essential.
A prospective, randomized, triple-blind study was performed comparing the subcutaneous hemoglobin level at various times in patients after undergoing local anesthetic infiltration of lidocaine with epinephrine in one arm and plain lidocaine in the contralateral arm as the control. This study demonstrated that the lowest cutaneous hemoglobin level in the epinephrine group was obtained 25.9 minutes after injection. This is considerably longer than the 7 to 10 minutes often cited in the literature. The authors recommend waiting 25 minutes after injection if optimal visualization is desired.
2017
A 65-year-old woman is brought to the recovery room after undergoing brow lift surgery. Postoperatively, acute ST-elevation myocardial infarction is noted. Aspirin is administered. Frequent ventricular premature beats and occasional short runs of nonsustained ventricular tachycardia are noted on cardiac monitoring. Current blood pressure is 115/75 mmHg, heart rate is 65 bpm, and respiratory rate is 12/min. Oxygen saturation is 100%. Which of the following is the most appropriate next step in management?
A) Intravenous administration of amiodarone 150 mg over 10 minutes
B) Intravenous administration of flecainide 2 mg/kg body weight
C) Intravenous administration of lidocaine bolus 1 mg/kg body weight followed by continuous infusion at 1 mg/min
D) Replenishment of serum potassium to > 4.0 mEq/L and magnesium to > 2.0 mg/dL
E) Withhold administration of metoprolol
The correct response is Option D.
Asymptomatic ventricular premature beats (VPBs) and nonsustained ventricular tachycardia (NSVT) are not uncommon following myocardial infarction (MI), with reported incidences as high as 93% and 7%, respectively. These arrhythmias are thought to arise from transient abnormalities of cardiac automaticity or triggered activity in the region of ischemia or infarction. Routine suppression in the absence of hemodynamic compromise does not improve overall mortality, and because treatment may be associated with numerous potential adverse effects, antiarrhythmic medications are not recommended in this setting. Maintaining serum potassium concentration above 4.0 mEq/L and serum magnesium concentration above 2 mg/dL to normal ranges per general ACC/AHA guidelines followed by expectant management is the most reasonable option in this scenario.
In stark contrast, ventricular fibrillation (VF) and other symptomatic sustained ventricular tachyarrhythmias are thought to be indicators, if not potentiators, of ongoing myocardial ischemia and sudden cardiac death following acute MI. Consequently, rapid identification and treatment of these arrhythmias using defibrillation with or without antiarrhythmic medications, according to ACLS protocols, can be lifesaving. When indicated, amiodarone would be the recommended antiarrhythmic in this setting because it has not been associated with increased mortality. Both flecainide and lidocaine have been associated with increased mortality in the post-MI period and are therefore not recommended in the scenario described.
Intravenous administration of beta-adrenergic blockers has demonstrated numerous positive effects post MI including a reduced risk of VF. In the absence of other contraindications such as reactive airway disease and hypoperfusion, its ongoing administration in order to maintain a resting heart rate below 70 bpm is generally supported by the ACC/AHA guidelines for management of patients with STEMI.
Hypokalemia during an acute MI is a risk factor for VF, while hypomagnesemia can interfere with correction of hypokalemia, which is why ACC/AHA guidelines generally recommend maintaining normal concentrations in patients with an acute MI.
2017
During surgical procedures that do not involve the airway, which of the following oxygen delivery methods is most likely to increase the risk of fire in the operating room?
A) Endobronchial tube B) Endotracheal tube C) Laryngeal mask D) Nasal cannula E) Tracheostomy tube with cuff
The correct response is Option D.
For surgical procedures not involving the airway, open oxygen sources such as masks or nasal cannulae are most likely to increase the risk of fire in the operating room, as they may allow for trapping or pooling of an oxidizer-enriched atmosphere (oxygen with or without nitrous oxide).
The incidence of operating room fires in the United States is estimated to be around 600 cases per year. Fire requires the presence of three components: fuel, an oxidizer, and an ignition source. Common fuels in the operating room include alcohol-containing prepping agents, drapes and bandages, gowns and other personal protection equipment, petroleum jelly, etc. Ignition sources include electrocautery, lasers, fiberoptic light sources, and defibrillators. The two most common oxidizing agents in the operating room are oxygen and nitrous oxide.
Most protocols for assessment of risk of fire in the operating room take into account the presence of an open oxygen source, surgical site or incision above the xiphoid, and an available ignition source (such as electrocautery, laser, fiberoptic light source, etc).
For surgical procedures not involving the airway, closed-system oxygen sources using endotracheal/endobronchial tubes, tracheostomy cuffed tubes, or laryngeal masks convey less risk of fire, when compared with open oxygen sources.
2017
A 51-year-old woman undergoes bilateral breast reconstruction with free deep inferior epigastric artery perforator (DIEP) flaps. She is concerned about postoperative pain control. To achieve anesthetic effect, an infusion of 10 mL of 0.25% bupivacaine is administered bilaterally into the transversus abdominis plane (TAP) block space. Which of the following are the most appropriate anatomical landmarks to use when performing this technique?
A) Latissimus dorsi, external oblique, and iliac crest
B) Linea semilunaris, inferior epigastric vessels, and inguinal ligament
C) Quadratus lumborum, internal oblique, and 12th rib
D) Teres major, teres minor, and long head of the triceps
The correct response is Option A.
The transverse abdominis plane (TAP) block is a peripheral nerve block designed to anesthetize the nerves supplying the anterior abdominal wall (T6 to L1). Local anesthetic is injected between the internal oblique and the transverse abdominis muscles in the plane through which the sensory nerves pass. Use of this technique provides a suitable block to the multiple nerves supplying the abdominal wall with a single needle stick. The technique was first described in 2001 by Rafi using the anatomical landmarks of the inferior lumbar triangle (triangle of Petit): the anterior border of the latissimus dorsi muscle posteriorly, the posterior edge of the external oblique muscle anteriorly, and the superior edge of the iliac crest inferiorly.
The effectiveness of this technique has been demonstrated in the general surgery and OB-GYN literature with recent studies also being performed specifically in the harvest of abdominal free flaps for breast reconstruction. In a recent meta-analysis of this technique, the TAP block decreased narcotic use, provided more effective pain relief, and decreased opioid-related side effects including sedation and postoperative nausea and vomiting.
The teres major, teres minor, and long head of the triceps muscles form the borders of the triangular space through which the circumflex scapular artery can be found when harvesting the scapular flap.
Hesselbach triangle is bounded by the lateral border of the rectus muscle (linea semilunaris), the inferior epigastric vessels, and the inguinal ligament and is the space through which direct inguinal hernias pass.
The quadratus lumborum, internal oblique, and 12th rib are the anatomical landmarks of the superior lumbar triangle (Grynfeltt triangle) and a site of lumbar herniation.
2017
A 65-year-old man is evaluated for an increased serum potassium concentration of 6 mEq/L. ECG shows peaked T waves, decreased P wave amplitude, and prolonged QRS wave duration. Which of the following is the most appropriate initial step in management?
A) Administration of acetazolamide 250 mg intravenously
B) Administration of metoprolol succinate 20 mg in 4 mL nebulization, inhaled over 10 minutes
C) Administration of spironolactone 100 mg intravenously over 2 to 3 minutes, repeated after 5 minutes if ECG changes persist or recur
D) Administration of succinylcholine 30 g orally, and repeated every 2 hours as indicated
E) Administration of 10 units of regular insulin followed by 50 mL of 50% dextrose intravenously
The correct response is Option E.
Acute hyperkalemia is an electrolyte derangement that can result from a variety of scenarios including supratherapeutic potassium replacement, rhabdomyolysis, hemolysis, tumor lysis syndrome, severe sepsis, acute renal failure, and Addison disease. Among the most serious manifestations are progressive neuromuscular paralysis and progressive volatility in cardiac conduction terminating in cardiac arrest. The spectrum of cardiac collapse is evident on ECG starting with peaked T waves, decreased P wave amplitude, and prolonged QRS wave duration, followed by progressive blending of QRS and T waves into a sinusoidal ventricular fibrillation, followed by asystole.
Because cardiac arrest can occur at any point during ECG progression, hyperkalemia with ECG changes constitutes a medical emergency. Rapidly acting treatments aimed at sequestering or reducing serum potassium include administration of calcium, insulin with glucose, beta-2-adrenergeic agonists (e.g., albuterol, sodium bicarbonate), potassium wasting diuretics (e.g. furosemide), cation exchange resins (e.g., Kayexalate), and dialysis.
Of the options listed, only insulin with glucose is an accepted rapidly acting treatment for hyperkalemia. It works primarily by driving via the activity of the Na-K-ATPase pump in skeletal muscle. The effect begins in 10 to 20 minutes, peaks at 30 to 60 minutes, and lasts for four to six hours. Insulin can be given alone if serum glucose is > 250 mg/dL, and treatment can be repeated as needed. In all cases, serum glucose should be monitored to avoid acute hypoglycemia.
2017
An otherwise healthy 28-year-old woman undergoes emergency splenectomy because of isolated splenic rupture after sustaining blunt trauma. Examination shows hemodynamic instability. Postoperatively, the patient continues to experience hypotensive episodes that are difficult to manage. Total urine output is 200 mL over 12 hours. Tertiary survey identifies no ongoing hemorrhage or other injuries. Laboratory studies show:
Blood
- Na 145 mEq/L
- Cl 96 mEq/L
- K 4.1 mEq/L
- HCO3 21 mEq/L
- BUN 60 mg/dL
- Cr 4.5 mg/dL
- Osmol 350 mOsm/kg
Urine 700 mg/dL
- Na 35 mEq/L
- Cl 59 mEq/L
- BUN 450 mg/dL
- Cr 35 mg/dL
- Osmol 270 mOsm/kg
Which of the following most closely represents the fractional excretion of sodium (FENa) in this patient?
A) 0.3% B) 1.2% C) 2.3% D) 3.1% E) 4.1%
The correct response is Option D.
Acute kidney injury (AKI, formerly called acute renal failure) is characterized by an abrupt decrease in renal function. The differential diagnosis can be categorized into prerenal, intrinsic renal, and postrenal causes. Of these, decreased renal perfusion (prerenal disease) and acute tubular necrosis (ATN) represent the two most common causes, accounting for 65 to 75% of all cases. The fractional excretion of sodium (FENa) has been shown in a variety of studies to more clearly differentiate between prerenal disease and ATN than other laboratory tests and guide patient management when taken in the context of history and physical examination. FENa measures the percent of filtered sodium and is calculated as:
FENa = [ (UNa * PCr) / (PNa * UCr) ]* 100%
where UNa and PNa represent urine and plasma concentrations of sodium, and UCr and PCr represent and urine and plasma concentrations of creatinine, respectively.
In general, a FENa below 1% suggests prerenal disease, where there is appropriate reabsorption of the majority of all filtered sodium in response to decreased renal perfusion. FENa above 2% reflects inappropriate salt wasting indicative of ATN. Of note, important limitations of the predictive value of a high FENa include diuretic therapy and chronic renal failure, by altering normal salt handling.
In the example given above, FENa = [ (35 * 4.5) / (145 * 35) ] * 100% = 3.1%
2017
A 28-year-old woman is scheduled to undergo office-based outpatient augmentation mammaplasty during general anesthesia. Medical history includes postoperative nausea and vomiting, and motion sickness. In addition to ondansetron 4 mg intravenously, preinduction administration of which of the following drugs is likely to be most effective in this patient?
A) Aprepitant 40 mg orally B) Diphenhydramine 25 mg intravenously C) Droperidol 1.25 mg intravenously D) Metoclopramide 25 mg intravenously E) Promethazine 25 mg orally
The correct response is Option A.
Aprepitant 40 mg should be administered orally 1 to 3 hours before induction of anesthesia.
Postoperative nausea and vomiting is a common complication after receiving general anesthesia. The overall incidence of this complication for all operations and patient populations is approximately 30% and increases to nearly 40% in patients treated at outpatient surgery centers. In patients who are at increased risk, the incidence of postoperative nausea and vomiting can be as high as 70 to 80%. Approximately 65% of all surgical procedures are now done on an outpatient basis and, if untreated, one third of these patients will have this complication. No antiemetic is universally effective in the prevention and treatment of postoperative nausea and vomiting. Each additional prophylactic antiemetic will decrease its incidence by approximately 25%.
Aprepitant is a highly selective, brain-penetrant, neurokinin-1 receptor antagonist with a long half-life and clinical efficacy against opioid-induced vomiting. It is the first in its class to be approved for this indication. Neurokinin-1 receptor antagonists act by blocking the binding of substance P at the neurokinin-1 receptor in the brain stem emetic center and gastrointestinal tract. Because of its mechanism of action and long half-life, it is most effective when administered as prophylaxis before surgery in patients who are at high risk for postoperative nausea and vomiting.
The remaining drugs all have short durations of action and are most effective when administered postoperatively. Ondansetron is a serotonin (5-HT3) receptor antagonist that exerts its effect on the chemoreceptor trigger zone and vagal afferents in the gastrointestinal tract. Droperidol blocks dopamine receptors and has an efficacy equivalent to that of ondansetron. Promethazine is a phenothiazine that acts primarily via central antidopaminergic mechanism. Metoclopramide blocks dopamine receptors in the central vomiting center and can block serotonin receptors at high doses.
2017
A 42-lb (19-kg), 5-year-old girl is brought to the emergency department because of multiple lacerations of the face after being bitten by a dog. Intravenous sedation is administered by the emergency room physician. The plastic surgeon initiates repair of the lacerations by infiltrating an infusion of 60 mL of 0.5% lidocaine with 1:200,000 epinephrine. Ten minutes after the procedure begins, the patient begins to have a seizure. Pulse oximetry and vital signs are within normal range. Which of the following is the most appropriate next step in management?
A) Administer epinephrine B) Administer propofol C) Initiate lipid emulsion therapy D) Secure the airway and ventilate with oxygen E) Transfer the patient to the PICU
The correct response is Option D.
The seizure in this scenario is related to lidocaine toxicity. A seizure in this scenario can be related to head trauma, but the mechanism of injury is not likely to have caused an intracranial injury. Hypoxia can also cause a seizure but is unlikely with a functioning pulse oximeter showing good oxygen saturation and normal vital signs. Lidocaine toxicity is the most likely cause. The safe limit of lidocaine dosage is 7 mg/kg when given with epinephrine. This patient received 60 mL of 0.5% lidocaine, or 300 mg (0.5% solution contains 5 mg/cc). The safe limit for this patient is 133 mg (19 x 7). The first signs of lidocaine toxicity in an awake and conscious patient is tinnitus. Seizures and cardiac arrhythmias follow. Treatment is supportive with establishment of an airway and vascular access. Lipid emulsion is provided intravenously due to the lipophilic nature of the local anesthetic and therefore hastens elimination. Epinephrine toxicity causes tachyarrhythmias and hypertension. Lidocaine is an amide anesthetic.
Administration of epinephrine would be appropriate if anaphylaxis from the preservative in the local anesthesia were suspected. This would present with hypotension and tachycardia. Propofol would stop the seizures, but is contraindicated due to its confounding effects on cardiac arrhythmias in the face of lidocaine toxicity. Lipid emulsion therapy will hasten the clearance of the excess of lidocaine, however, it is first most important to secure the airway and ventilate.
2017
A 50-year-old woman is scheduled to undergo bilateral deep inferior epigastric artery perforator (DIEP) flap breast reconstruction. A donor site regional block with liposomal bupivacaine is planned for analgesia. Which of the following injection locations is most likely to improve pain control and decrease narcotic use in this patient?
A) Between external oblique and internal oblique fascias
B) Between internal oblique and transversus abdominis fascias
C) Deep to rectus abdominis fascia
D) Deep to transversus abdominis fascia
E) Subcutaneous plane
The correct response is Option B.
The patient is undergoing a transversus abdominis plane (TAP) block. TAP blocks have become popular adjunctive pain control measures for a variety of abdominal surgeries. They can either be performed transcutaneously with ultrasound guidance or under direct visualization in the operating room prior to closure of the abdominal donor site in deep inferior epigastric artery perforator (DIEP) or transverse rectus abdominis musculocutaneous (TRAM) flap surgeries. The segmental innervation to be blocked in the TAP block is located between the internal oblique and transversus abdominis muscles. Either infiltration of liposomal bupivacaine or placement of epidural catheters in the TAP space has been described.
2016
