Local Anesthetics Flashcards

Question

A healthy 154-lb (70-kg), 30-year-old woman is undergoing liposuction of multiple sites. Five minutes after the local anesthetic infusion, she sustains a cardiac arrest. Local anesthetic systemic toxicity is diagnosed. After CPR is initiated, administration of which of the following is the most appropriate next step in management? A) Adenosine B) Intralipid C) Propranolol D) Vasopressin E) Verapamil

Answer 1

The correct response is Option B. This patient has sustained a cardiovascular collapse secondary to local anesthetic systemic toxicity (LAST). The maximum safe dose of lidocaine with epinephrine in this patient is 35 to 55 mg/kg. Lipid Rescue protocol recommends an initial intralipid 20% bolus of 1.5 mL/kg over 1 minute. This should be followed immediately with a continuous infusion at 0.25 mL/kg/min. A single bolus is typical, but should be repeated or the infusion increased if spontaneous circulation fails to return or blood pressure declines. Cardiovascular collapse from LAST differs from that secondary to myocardial ischemia. In LAST, raising the peripheral vascular resistance with vasopressors like vasopressin, can impair cardiac output and impede resuscitation. Epinephrine should be given in small doses (\<1 mcg/kg). Pharmacologic agents that reduce contractility (beta blockers {propranolol}, calcium channel blockers {verapamil}, or propofol) should be avoided when there is evidence of cardiovascular instability. Adenosine is not useful in the management of LAST patients. It is typically used to treat supraventricular tachycardia. 2016

Answer 2

The correct response is Option E. No further preoperative cardiac testing is needed for this patient being considered for an elective, greater-than-low-risk procedure, without any evidence of active cardiac conditions or clinical risk factors, and with moderate functional capacity (metabolic equivalents, or METs, \>= 4). Assessment of left ventricular function at rest, whether by echocardiogram, radionuclide angiogram, or contrast ventriculography, has not been shown to be a consistent predictor of perioperative ischemic events. Cardiac stress testing, including by exercise or drug induced, is not indicated in this patient. In 2007, the American College of Cardiology and the American Heart Association published updated guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery (NCS), suggesting a stepwise algorithmic approach to perioperative cardiac risk assessment: Is there need for emergency NCS? If yes, proceed with surgery. Are there active cardiac conditions (unstable coronary syndromes, decompensated heart failure, significant arrhythmias, severe valvular disease)? If yes, evaluate and treat per specific guidelines before considering NCS. Is the NCS considered low risk (e.g., superficial and ophthalmologic procedures)? If yes, proceed with low-risk NCS. Does the patient have good functional capacity (METs \>= 4) without symptoms? If yes, proceed with NCS. Is there need for emergency NCS? If yes, proceed with surgery. Three or more clinical risk factors undergoing vascular surgery: consider testing if it will change management One or two clinical risk factors undergoing vascular surgery or one or more clinical risk factors undergoing intermediate-risk surgery: either proceed with surgery with heart rate control (beta blockade) or consider noninvasive testing if it will change management Preoperative cardiac assessment should include an estimation of the patient’s functional capacity, based on his/her ability to perform a spectrum of common daily tasks. This has been shown to correlate well with maximum oxygen uptake by treadmill testing. Four METs is a common threshold used in many decision-making points in the perioperative cardiac evaluation. 2016

Answer 3

The correct response is Option A. A patient who underwent placement of a drug-eluting stent 4 months ago should continue on aspirin and clopidogrel for at least 6 months, except in cases with high risk of bleeding (intracranial or spine surgery). The combination of aspirin and clopidogrel appears to reduce the rates of cardiovascular ischemic events. Patients with coronary stents have an 8 to 10% risk of developing major adverse cardiovascular events and stent thrombosis after elective noncardiac surgery, which exceeds the 1 to 5% risk of major adverse cardiovascular events in non-stented patients having noncardiac surgery. 2016

Answer 4

The correct response is Option C. Immediate cardioversion is recommended for patients with atrial fibrillation (AF) or atrial flutter with rapid ventricular response associated with hemodynamic instability such as hypotension, ongoing myocardial ischemia, or decompensated heart failure. Both chemical and electrical cardioversion can be attempted according to established protocols until sinus rhythm is restored with a goal of optimizing hemodynamic parameters. If initial cardioversion is unsuccessful, repeated attempts at cardioversion may be made after adjusting the location of the electrodes, applying pressure over the electrodes, or following administration of an antiarrhythmic medication according to Advanced Cardiac Life Support (ACLS) algorithms. A trial of medical management for rate control is appropriate in the absence of hemodynamic instability. In general, beta blockers are the most common agents used for rate control, followed by nondihydropyridine calcium channel blockers such as diltiazem, as well as other agents such as digoxin and amiodarone. Patient comorbidities influence the choice of medical therapy to minimize risk of adverse events such as heart failure decompensation, exacerbation of chronic obstructive pulmonary disease, or acceleration of conduction in patients with preexcitation physiology. Appropriate anticoagulation management around the time of elective cardioversion is essential for reducing thromboembolic risk. When AF has clearly existed at \< 48 hours’ duration, it is common practice to perform cardioversion without transesophageal echocardiography (TEE) or antecedent anticoagulation. When AF has existed at \>48 hours’ duration or duration is unknown, then anticoagulation for ? 3 weeks before and continuing for ? 4 weeks after cardioversion is recommended unless otherwise contraindicated. In case of relative contraindications to anticoagulation, TEE can be performed to help guide relative risk assessment related to thromboembolism of preexisting cardiac thrombi arising in the setting of prolonged atrial dysfunction. Importantly, when emergent cardioversion is indicated because of hemodynamic instability, initiation of anticoagulation and TEE should not delay acute interventions to stabilize the patient's condition. AV nodal ablation with permanent ventricular pacing can be considered to improve rate control when other attempts at maintaining rate control through medical management are unsuccessful. This intervention is usually reserved for elderly patients, because it leads to pacemaker dependency. However, patients with symptoms refractory to medical therapy who are treated with AV nodal ablation and permanent pacemaker implantation have demonstrated an improvement in cardiac symptoms, quality of life, and health care utilization. 2016

Answer 5

The correct response is Option D. In surgical patients with von Willebrand disease (vWD) receiving desmopressin (DDAVP) for bleeding prophylaxis, total preoperative dose should be determined by preoperative measurement of activity levels of von Willebrand factor ristocetin cofactor (vWF:RCoF) and coagulation factor VIII. The other listed coagulation factors are not associated with isolated vWD. vWD is the most common congenital bleeding disorder, with estimated prevalence as high as 1.3%. It is caused by deficiency (types I and III) or dysfunction (type II) of von Willebrand factor (vWF), leading to impaired platelet adhesion and possibly lower levels of coagulation factor VIII. In its normal state, vWF is a plasma protein that mediates the initial adhesion of platelets at sites of vascular injury and also binds and stabilizes coagulation factor VIII in the circulation. Both vascular endothelial cells and platelets synthesize and store vWF. DDAVP is a synthetic derivative of ADH (vasopressin, antidiuretic hormone) that is used for treatment and prophylaxis of bleeding in patients with vWD. It promotes release of stored vWF from endothelial cells into the plasma, being particularly effective in patients with partial quantitative deficiency of vWF, or type I (about 75% of cases of vWD). Patients who do not appropriately respond to DDAVP administration should receive vWF concentrate. For bleeding prophylaxis for minor surgery, the preoperative goal should be to achieve vFW:RCoF and factor VIII activity levels of at least 30 IU/dL (preferably \>50 IU/dL). Such levels should be maintained for 1 to 5 days postoperatively. For prophylaxis for major surgery, preoperative activity levels should be at least 100 IU/dL and maintained above 50 IU/dL for at least 7 to 10 days. To decrease risk of perioperative thromboembolism, vWF:RCoF levels should not exceed 200 IU/dL and factor VIII activity should not exceed 250 IU/dL. Fluid restriction is advised for patients receiving DDAVP perioperatively, to avoid hyponatremia and seizures. 2016

Answer 6

The correct response is Option C. This patient is presenting with anaphylaxis. The first and most crucial step in managing acute anaphylaxis is the administration of epinephrine. Anaphylaxis is a serious and life-threatening hypersensitivity reaction. Medications and insect stings are the most common triggers in adults, with beta-lactam antibiotic exposure among the most implicated medications. In this setting, anaphylaxis is diagnosed when two or more of the following are observed minutes to hours after exposure: Skin-mucosal tissue reactions (such as generalized urticaria, swollen lip, pruritus, and flushing) Respiratory compromise (such as dyspnea, wheeze, bronchospasm, stridor, and hypoxemia) Hypotension or associated findings (such as syncope, confusion, collapse, and incontinence) Persistent gastrointestinal reactions (such as crampy abdominal pain and vomiting) Intramuscular epinephrine can be repeated every 5 to 15 minutes as needed. If given promptly, most patients respond to one or two doses. Simultaneous with this treatment, an emergency team can be summoned. The patient should be placed in a recumbent position with legs elevated and supplemental oxygen administered. Volume resuscitation can be initiated to compensate for severe loss of intravascular volume that can accompany fluid shifts of untreated anaphylaxis and to support blood pressure not responsive to epinephrine. Bronchodilators, H1 and H2 antihistamines such as diphenhydramine and ranitidine, and glucocorticoids such as methylprednisolone are all reasonable but second-line treatments for acute anaphylaxis. Intubation should be performed immediately in the setting of progressive upper airway closure such as stridor and tongue edema, or if respiratory arrest is present. However, first-dose epinephrine administration should not be delayed for intubation. Epinephrine works rapidly to reduce airway edema that might otherwise prevent successful intubation, if not completely reverse the underlying etiology of cardiopulmonary collapse in anaphylaxis. While cardiovascular disease is a risk factor for poor outcome from anaphylaxis, it is not a contraindication for epinephrine administration. It is generally accepted that the risk of death or brain damage from prolonged or undertreated anaphylaxis outweighs the risk of appropriately administered epinephrine. If there is inadequate response to initial intramuscular epinephrine and volume resuscitation, then intravenous epinephrine can be introduced in an intensive care setting by slow infusion at 2 to 10 mcg per minute and titrated to effect. 2016

Answer 7

The correct response is Option C. Hypotension is most likely to alter pulse oximetry values by reducing peripheral arterial blood flow. Pulse oximetry measures the relative transmission of light at two wavelengths that differ significantly when passed through loaded versus non-loaded hemoglobin (e.g., oxyhemoglobin versus deoxyhemoglobin). In order to provide values that correlate with arterial oxygen saturation levels as opposed to tissue bed or venous saturation levels, standard pulse oximeters require pulsatile blood to distinguish transmission at the peak of arterial pulsation relative to baseline transmission levels. Thus, pulse oximetry measurements will change both with changes in hemoglobin oxygen saturation and with conditions that interfere with the device's ability to detect pulsatile blood flow. Other conditions that alter pulse oximetry measurements by reducing the detection of fluctuations from arterial blood flow include peripheral vasoconstriction from hypothermia and vasopressor and interference from motion, such as tremors or shivering. Incorrect sensor application, highly calloused skin, and nail polish can also affect measurements by interfering with transmission readings. Because standard pulse oximetry only measures the relative difference in transmission between oxygenated and deoxygenated hemoglobin and not the absolute value of oxygenated hemoglobin, anemia does not significantly affect pulse oximetry values within physiologic ranges. Tachycardia, tachypnea, and fever do not directly affect pulse oximetry values. 2016

Answer 8

The correct response is Option A. The patient has a presumed diagnosis of deep vein thrombosis (DVT) and pulmonary embolism (PE). Enoxaparin and rivaroxaban are contraindicated in patients with renal failure. Warfarin is used for long-term treatment of established DVT. Clopidogrel is an antiplatelet inhibitor that inhibits blood clots in coronary artery disease, peripheral vascular disease, cerebrovascular disease, and prevents myocardial infarction. Heparin is safe in renal failure patients and is indicated for treatment in acute DVT/PE. 2016

Answer 9

The correct response is Option D. In this patient with septic shock, once airway and breathing are secured, the next most appropriate step in management is to restore effective circulation and perfusion to peripheral tissues starting with a trial of volume resuscitation with crystalloid. Signs of impaired end organ perfusion in septic shock include hypotension (e.g., mean arterial pressure \<70 mmHg), tachycardia (e.g., heart rate \>100 bpm), warm flushed skin giving way to cool clammy skin as blood flow is redirected to core organs, obtundation, and an elevated serum lactate concentration (e.g., \>1 mmol/L). First-line therapy for restoration of tissue perfusion is volume resuscitation using intravenous crystalloid targeted to physiologic end points while monitoring for clinical or radiographic evidence of either cardiogenic or non-cardiogenic pulmonary edema (ie, ARDS). The addition of pulmonary artery catheters has not been shown to improve outcomes in the routine management of septic shock and is associated with increased complications. As in the given scenario, evidence and expert opinion do not support the transfusion of blood products greater than a hemoglobin concentration of 7 g/dL in the absence of concurrent hemorrhagic shock, cardiac history, or active myocardial ischemia. For example, a recent multicenter randomized study involving 998 patients with septic shock reported no significant difference in mortality or rate of ischemic events between patients transfused when hemoglobin concentration was \<7 g/dL compared with patients transfused when hemoglobin was \<9 g/dL. Their former (more restrictive) transfusion trigger resulted in 50% fewer red blood cell transfusions compared with the more liberal strategy. Vasopressors (e.g., norepinephrine) are second-line agents in the treatment of septic shock refractory to trial of volume resuscitation as long as intravenous fluids successfully improve perfusion without impairing gas exchange. Inotropic agents (e.g., dobutamine) are also second-line agents to initial volume resuscitation in this scenario. They may be useful with refractory shock in the setting of diminished cardiac output. 2016

Answer 10

The correct response is Option E. Accidental self-injection of epinephrine with an EpiPen occurs in 1 in 50,000 syringes. There have been no documented cases of digital necrosis following injection, and observation is indicated in this case. The effect of epinephrine’s vasoconstriction lasts for approximately 90 minutes and will likely resolve on its own. Phentolamine has been described as a reversal agent for epinephrine and has shown clinical efficacy, but there has been no study to show that there are better outcomes with phentolamine injection compared with observation. Also, the added volume of injection with phentolamine could cause pressure necrosis and the timing between EpiPen injection and definitive treatment would usually be outside of the 90 minutes it would take for the epinephrine to wear off on its own. Topical nitroglycerin paste and subcutaneous injection of calcium channel blockers such as nifedipine have not shown to be viable treatment modalities. Application of a hot pack can lead to increased tissue damage and burns and is not indicated. Emergent exploration is indicated for compartment syndrome and is not indicated in this case where the finger is soft. 2015

Answer 11

The correct response is Option D. Risk factors for postoperative nausea and vomiting include: female gender, nonsmoking status, prior history of postoperative nausea/vomiting/motion sickness, use of volatile anesthetics/general anesthesia, opioid/narcotic use, facial rejuvenation procedures, and long duration of surgery. Several measures can be taken to decrease postoperative nausea and vomiting. A thorough history with identification of risk factors can aid stratification of patients preoperatively. Use of long-acting local anesthetic agents, nonsteroidal anti-inflammatory drugs (NSAIDs), and cyclooxygenase-2 selective inhibitors can decrease the need for postoperative opioid use. Avoidance of nitrous oxide, especially in combination with fentanyl and volatile inhalational gases, and multimodal use of serotonin antagonists combined with other antiemetic agents can also decrease postoperative nausea and vomiting. 2015

Answer 12

The correct response is Option B. Higher American Society of Anesthesiologists (ASA) class has been identified as a risk factor for postoperative complications in HIV-positive patients in multiple studies. A patient who is ASA Class 2 has only mild systemic disease. Increasing class number indicates increasing severity of disease (Class 3 – severe systemic disease, Class 4 – severe systemic disease that is a constant threat to life). Acquired immunodeficiency syndrome (AIDS) is diagnosed when the CD4 count is \<200 cells/mm3 or with acquisition of an AIDS-defining illness. An absolute CD4 count of \<200 cells/mm3 has been associated with increased risk of complications including wound infections. HIV seropositivity alone has been found not to be an independent risk factor for postoperative complications. Percutaneous surgery, such as fat grafting, has not been associated with increased risk of infection in HIV patients, nor has skin incisional surgery. Transoral mucosal incisional surgery has been found to be associated with a significantly greater risk of wound infection in HIV patients. A viral load greater than 10,000 copies/mL suggests that antiretroviral therapy is no longer effective and has been identified as an independent risk factor for complications. 2015

Answer 13

The correct response is Option D. Propofol can be safely used in patients with a suspected diagnosis of malignant hyperthermia. Malignant hyperthermia is a rare, life-threatening inherited skeletal muscle disorder that shows symptoms of hypermetabolic reaction to volatile anesthetic gases and depolarizing muscle relaxants. The incidence is between 1 in 5000 to 1 in 100,000 anesthetic encounters. Mortality rates have decreased from 70% to less than 5% as awareness of this condition has led to accurate diagnosis and treatment. Malignant hyperthermia is genetically transmitted through an autosomal dominant inheritance pattern with variable penetrance. In obtaining a medical history, it is important to document family history of adverse outcomes to general anesthesia. If it is reported that a first-degree relative has had a malignant hyperthermia crisis or susceptibility, then the patient should not be exposed to triggering agents. Anesthetic agents that trigger malignant hyperthermia include: halothane, enflurane, isoflurane, desflurane, sevoflurane, and succinylcholine. Nitric oxide can be used if the anesthesia machine is “vapor-free” and contains no traces of volatile gas. Other safe agents include nondepolarizing muscle relaxants (such as vecuronium, rocuronium, and pancuronium), all ester and amide local anesthetics, ketamine, propofol, etomidate, barbiturates, opiates, and benzodiazepines. Although it is safe to undergo minor procedures with administration of a topical or local anesthetic agent, patients undergoing complex procedures with intravenous sedation, general anesthesia, or major conduction blockade should be referred to an accredited ambulatory surgical center or hospital. If symptoms are recognized in the operating room (high temperature, increased end-tidal CO2, muscle rigidity), rapid treatment with dantrolene sodium is the highest priority. Acute episodes may require stopping the procedure and transfer to an intensive care unit. 2015

Answer 14

The correct response is Option E. True allergic reactions to local anesthetics are rare. Type I hypersensitivity reactions may include anaphylaxis, and are modulated by immunoglobulin E. Both ester-based local anesthetics, such as procaine, and amide-based local anesthetics may induce an allergic response. The most likely allergen is para-aminobenzoic acid (PABA). This compound consists of a benzene ring substituted with an amino group at the 4-position (leading to the analogous label of 4-aminobenzoic acid) as well as a carboxyl group. Preservatives such as methylparaben have also been shown to cause allergic reactions to local anesthetics, but are less likely than allergic reactions caused by PABA. Epinephrine can induce vasoconstriction and increase the safe dosage of administered local anesthetic, though it would not be expected to cause an allergic response itself. Iodine and acetaldehyde should not be found in local anesthetic mixtures. 2015

Answer 15

The correct response is Option B. Because lidocaine absorbs slowly from fat, infiltrate solutions that contain up to 35 mg/kg of lidocaine are generally considered safe. Nonetheless, lidocaine toxicity is still a risk of the procedure. In tumescent solution with epinephrine, peak plasma lidocaine levels occur approximately 10 to 14 hours after infiltration, and thus, the presentation 6 hours after discharge is consistent with peak plasma concentration. Lidocaine toxicity has symptoms of neurologic or cardiac toxicity. In the early stages, the complications are primarily neurologic and can include slurred speech, restlessness, tinnitus, and a metallic taste, as well as numbness of the mouth. As the concentrations increase, the neurologic concentrations become more severe, and can progress to muscle twitching, seizures, and cardiac arrest. Treatment of lidocaine toxicity is supportive. Fat embolism presents as a petechial rash, respiratory dysfunction, and cerebral dysfunction, and the symptoms usually appear 24 to 48 hours after surgery. Pulmonary embolism presents as leg pain and edema, tachycardia, and low-grade fevers. Parietal strokes usually cause sensory symptoms, self-perception anomalies, and left-right agnosia. Third spacing refers to fluid shifts into interstitial spaces and can cause edema, hypotension, and decreased cardiac output. 2015

Answer 16

The correct response is Option A. Addition of local anesthetics during general anesthesia, whether by subcutaneous, tumescent, or regional block infiltration, can result in decreased dosage requirements of the common sedatives and analgesics that can result in nausea and emesis. Common anesthetic agents that promote nausea and emesis include opioids (fentanyl, hydromorphone, morphine) and inhalationals (halothane, isoflurane, nitrous oxide). Propofol is currently the most commonly used intravenous agent. It does not appear to directly result in nausea, but it has limited analgesic effects. Therefore, effective anesthesia with propofol requires addition of opioid narcotics (which cause nausea) and/or local anesthetics such as lidocaine and bupivacaine (which may decrease the narcotic requirement). Midazolam is a sedative-hypnotic that has anxiolytic and amnesic effects, both of which are helpful adjuncts to the surgical patient experience. Nausea is possible with midazolam, but less commonly reported than with narcotic and inhalational agents. The cause of postoperative nausea and vomiting is multifactorial and not fully understood. Strategies for prevention include: Recognition of high-risk patients (females, nonsmokers, history of motion sickness, previous postoperative nausea, general anesthesia) Pre- and postoperative treatment with multiple modalities (such as scopolamine, ondansetron, aprepitant, corticosteroids) Supplemental intraoperative oxygen and hydration 2014

Answer 17

The correct response is Option D. The most appropriate management of acute bupivacaine toxicity is a bolus and infusion of 20% lipid emulsion. Every facility where local anesthetic is used in large doses should have a lipid rescue kit clearly labeled and available should the need arise. Although lipid rescue mechanism of action is not completely understood, it may be that the added lipid in the bloodstream acts as a “sink,” allowing for the removal of lipophilic toxins from affected tissues. Major local anesthetic toxicity can have such symptoms as sudden loss of consciousness, tonic-clonic seizures, hypertension followed by progressive hypotension, tachycardia, ventricular fibrillation, bradycardia, asystole, and cardiac arrest. Arrhythmias may be refractory to treatment, and resuscitation may be prolonged, sometimes requiring more than 1 hour. In the event of a local anesthetic toxicity event, airway management, seizure suppression, and, if needed, cardiopulmonary resuscitation should be performed. Alert the nearest facility having cardiopulmonary bypass capability and administer 20% lipid emulsion (values in parentheses are for 70 kg) as follows: Bolus 1.5 mL/kg intravenously over 1 minute (~100 mL) Continuous infusion 0.25 mL/kg/min (~500 mL over 30 minutes) Repeat bolus every 5 minutes for persistent cardiovascular collapse Double infusion rate if blood pressure returns but remains decreased Continue infusion for a minimum of 30 minutes Although beta-adrenergic blockers may be useful in treating the excitatory cardiovascular phase of local anesthetic toxicity, the potential to progress to more advanced phases with myocardial depression and collapse preclude their routine use. In addition to lipid emulsion, the treatment for local anesthetic–induced cardiac toxicity is generally supportive, and may include amrinone, closed-chest cardiac massage, and cardiopulmonary bypass. Flumazenil is used to reverse the effects of benzodiazepine toxicity. Dantrolene is administered in the acute treatment of malignant hyperthermia. Atropine and dopamine are administered as part of the Advanced Cardiac Life Support protocol for bradycardia or asystole and would not be used in the scenario described. 2014

Answer 18

The correct response is Option D. Epinephrine use in hand surgery is becoming more common as is the inadvertent self-injection by people who carry epinephrine injectors (EpiPens). Typically, there is little treatment needed other than supportive care. However, when concern for tissue viability is raised or there is marked pain, subcutaneous phentolamine is the drug of choice to reverse the sympathomimetic effects of epinephrine. Plain lidocaine (typically 2% or more) will cause vasodilation but by a different mechanism than the reversal of the epinephrine. Topical nitroglycerin paste has been used for reversal of vasospasm, but again, a different mechanism is used. Marcaine is an amide anesthetic that inhibits sodium ion channels. It is not an antagonist of epinephrine. 2014

Answer 19

The correct response is Option D. Signs and symptoms of lidocaine toxicity include dizziness, agitation, lethargy, tinnitus, metallic taste, perioral paresthesia, slurred speech, euphoria, hypotension, and bradycardia. Tachycardia is not a sign of lidocaine toxicity. Bradycardia is more common. Bronchospasm and urticaria are not signs of lidocaine toxicity. 2014

Answer 20

The correct response is Option E. Pregabalin (Lyrica) has been shown to decrease narcotic needs after breast surgery. It is a gamma-aminobutyric acid (GABA) analogue and decreases GABA in the brain and acts primarily as an anticonvulsant. It is more potent than gabapentin as an analgesic. Compression garments would be useful for post-mastectomy lymphedema but would not decrease narcotic needs. Hypnosis might decrease narcotic use slightly, but the effects are negligible. Oxycodone is a narcotic which does not decrease narcotic needs. The use of ondansetron (Zofran) has not been shown to reduce post-operative narcotic requirements. 2019

Answer 21

The correct response is Option E. The primary mechanism of action for the increased bleeding time associated with the use of ketorolac is the inhibition of thromboxane A2. Ketorolac is a non-steroidal anti-inflammatory drug (NSAID). Most NSAIDs inhibit the activity of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), and thereby the synthesis of thromboxane A2. This produces a systemic bleeding tendency by impairing thromboxane-dependent platelet aggregation and consequently prolonging the bleeding time. It is thought that inhibition of COX-2 leads to the anti-inflammatory, analgesic, and antipyretic effects through the inhibition of formation of prostaglandins and prostacyclin. Inhibition of lipoxygenase and nitric oxide are not the primary mechanisms associated with NSAID-related platelet inhibition. 2019

Answer 22

The correct response is Option C. The patient shows all the signs of tension pneumothorax, and although the precise etiology is unclear, the patient requires decompression. Intubation will not help relieve the tension and pressure, with decreased venous return jeopardizing hemodynamic stability. Immediate chest x-ray is inappropriate because of the time required. Opening the chest incision is not a good option because it requires surgical equipment, general anesthesia, and cannot be completed in a timely fashion. Needle decompression at the second intercostal is the standard of care to decompress a tension pneumothorax. After oxygen saturation and hemodynamics are stabilized, definitive treatment of pneumothorax can be pursued. This would include placement of chest tube to low suction and serial chest x-ray to monitor the progress of the lung inflation. Arterial blood gas will not help make the diagnosis and potentially will delay the appropriate intervention. 2019

Answer 23

The correct response is Option C. It is recommended that follow-up retesting be done at 6 weeks, 3 months, and 6 months in known HCV exposure cases. Tests at 1 or 3 weeks would possibly lead to false negative results. There is no advantage in waiting beyond 6 weeks. 2019

Answer 24

The correct response is Option B. Postoperative delirium is an acute brain dysfunction that is characterized by changes in levels of consciousness, inattention, and disorganized thinking. There are two types of delirium. Delirium can manifest with hyperactive signs (agitation, restlessness), or hypoactive signs (lethargy, inattentiveness). It is very common in hospitalized patients, with 60 to 80% of mechanically ventilated patients and 20 to 50% of patients with a lower severity of illness developing delirium at some point during their hospitalization. For patients at risk of postoperative delirium, benzodiazepines and antihistamines should be avoided, as these medications could exacerbate the symptoms. 2019

Answer 25

The correct response is Option E. This patient has acute kidney injury (AKI) after a surgical procedure. International practice guidelines recommend insulin therapy for targeted glucose control in critically ill patients. Although the Kidney Disease – Improving Global Outcomes (KDIGO) task force recommended a plasma glucose target of 110 to 149 mg/dL, the latest recommendation by the Surviving Sepsis Campaign is for an upper blood glucose level not higher than 180 mg/dL. Other recommendations for prevention and treatment of AKI by the 2012 KDIGO Clinical Practice Guideline included: Isotonic crystalloids rather than colloids (albumin or starches) as initial management for expansion of intravascular volume in patients at risk for or with AKI; Avoding restriction of protein intake with the aim of preventing or delaying initiation of renal replacement therapy (RRT); Administration of 0.8 to 1.0 g/kg/d of protein in non-catabolic AKI patients without need for dialysis; 1.0 to 1.5 g/kg/d in patients with AKI on RRT; and up to a maximum of 1.7 g/kg/d in patients on continuous renal replacement therapy (CRRT) and in hypercatabolic patients; Providing nutrition preferentially via the enteral route in patients with AKI; Not using diuretics to prevent AKI; Not using diuretics to treat AKI, except in the management of volume overload; Not using low-dose dopamine to prevent or treat AKI 2019

Answer 26

The correct response is Option C. Obtaining a serum lactate level is the most appropriate next step for the diagnosis of septic shock in this scenario. Patients with septic shock can be clinically identified by having both of two criteria: Vasopressor requirement to maintain a mean arterial pressure of 65 mmHg or greater and Serum lactate level greater than 2 mmol/L (\>18 mg/dL) in the absence of hypovolemia. In 1991, a consensus task force developed initial definitions that focused on the prevailing view at the time that sepsis resulted from a host’s systemic inflammatory response syndrome (SIRS) to infection. SIRS was defined by the presence of two or more of four criteria, including body temperature, heart rate, respiratory rate, and white blood cell count. Despite their known limitations, these definitions remained mainly unchanged for almost three decades. In 2016, the Society of Critical Care Medicine and the European Society of Intensive Care Medicine sponsored a task force to review the definition of sepsis and its management guidelines (Sepsis-3). Sepsis is now defined as a life-threatening organ dysfunction caused by a dysregulated host response to infection. This organ dysfunction can be represented by an increase in the Sequential [Sepsis-related] Organ Failure Assessment (SOFA) score of two points or more. Another measure called quick SOFA (qSOFA), although less robust, may be more practical for providers diagnosing sepsis in the non-ICU setting. qSOFA incorporates altered mentation (GCS \<15), systolic blood pressure of 100 mmHg or less, and respiratory rate of 22/min or greater. Septic shock is a subset of sepsis with profound circulatory and cellular/metabolic dysfunction, associated with a higher risk of hospital mortality than with sepsis alone (40% versus 10%, respectively). The term "severe sepsis," previously defined as sepsis complicated by organ dysfunction, has been incorporated into the current definition of sepsis and abandoned. 2019

Answer 27

The correct response is Option A. Minors are neither eligible for nor able to receive organ donation without the consent of a parent or guardian. Creutzfeldt-Jakob disease or any other prion disease is a contraindication for organ donation of any kind. Metastatic cancer is a contraindication for organ donation. HIV status is no longer a contraindication to donate or receive an organ, provided the donor and recipient are both HIV positive. 2019

Answer 28

The correct response is Option B. According to current Advanced Cardiac Life Support (ACLS) guidelines, CPR should be resumed immediately after shock delivery, without pausing for a rhythm or pulse check. It should begin with chest compressions and continue for 2 minutes, after which the rhythm should be checked and the cycle (shock/CPR 2 min/check) repeated if there is no return of spontaneous circulation (ROSC). Increasing emphasis has been placed on the importance of continuous “high-quality” chest compression (5 cm sternal depression, 100 to 120/min), to maximize tissue perfusion and probability of ROSC. A 30:2 compression:ventilation rate is recommended in the absence of an endotracheal or supraglottic airway. Otherwise, 10 breaths per minute should be delivered with continuous chest compressions. There are no studies directly addressing the timing of advanced airway placement and outcome during resuscitation from cardiac arrest. Although insertion of an endotracheal tube during ongoing chest compressions is possible, in most instances intubation is associated with interruption of compressions for many seconds. Particularly, patients with witnessed cardiac arrest from ventricular fibrillation or pulseless ventricular tachycardia may benefit from a few uninterrupted cycles of CPR prior to placement of an advanced airway. Adenosine is not indicated in the treatment of adult cardiac arrest. Capnometry/capnography requires placement of an endotracheal tube. 2019

Answer 29

The correct response is Option A. Malignant hyperthermia is an inherited myopathy that is autosomal dominant with variable penetrance. Anesthetic agents that trigger malignant hyperthermia include halothane, enflurane, isoflurane, desflurane, sevoflurane, and succinylcholine. These agents trigger an earlier calcium release into the skeletal muscle, resulting in an abnormal buildup of calcium in the myoplasm. This flood of calcium causes the muscle to remain in a contracted state, producing high levels of lactic acid, carbon dioxide, phosphate, and heat. The resulting physiologic changes are metabolic acidosis, hypercapnia, hyperphosphatemia, and fever in a patient experiencing malignant hyperthermia. The treatment of malignant hyperthermia is discontinuation of volatile agents and succinylcholine, dantrolene, treatment of hyperkalemia and metabolic acidosis, and transfer to an acute care hospital. 2019

Answer 30

The correct response is Option D. The ASPS recently published the first consensus statement/guidelines for antibiotic prophylaxis in plastic surgery which is based on comprehensive systematic review of the available evidence. Systemic antibiotic prophylaxis is recommended for clean-contaminated, contaminated, or dirty plastic surgery of the head and neck, orthognathic/mandibular, septoplasty/rhinoplasty, hand and upper limb, and skin. Antibiotic prophylaxis is also recommended to reduce surgical-site infection for clean plastic surgery of the breast. Antibiotic prophylaxis is not recommended to reduce surgical-site infection in clean surgical cases of the head and neck, orthognathic/mandibular area, hand and upper limb, skin, and abdominoplasty. With the exception of cosmetic breast surgery, clean operations have not been shown to benefit from routine antibiotic prophylaxis. Clean-contaminated and contaminated plastic surgical procedures do benefit from the use of antibiotic prophylaxis. The duration of antibiotic use should generally be limited to a single preoperative dose because studies have generally showed no benefit for longer term antibiotic prophylaxis. As far as choosing the antibiotic, it should have activity against the most frequently encountered microorganisms in postoperative surgical-site infections. Cefazolin as a single dose preoperatively is the most commonly recommended agent and would be considered appropriate in most cases. In the event of allergy or intolerance, clindamycin or vancomycin may be appropriate alternatives. 2019

Answer 31

The correct response is Option C. Minute ventilation is calculated by multiplying respiratory rate and tidal volume. Tidal volume is the amount of air/gas displaced during each quiet breath, using no extra inspiratory (“deep breath”) or expiratory effort. Minute ventilation is an important concept in mechanical ventilation because of its inverse relationship with blood carbon dioxide levels. The caveat of this relationship is that not all inhaled air/gas takes part in gas exchange, whether because it remains in the conductive airways (ventilator tubing, endotracheal tube, trachea, etc) or it reaches alveoli that are not adequately perfused. The volume of air/gas that does not take part in gas exchange is called dead space. Residual volume is the volume of air still remaining in the lungs after the most forcible expiration possible. Inspiratory capacity is the volume of air that enters the lungs during the most forcible inspiration possible, starting at rest. Inspiratory reserve volume equals inspiratory capacity minus tidal volume, or the difference between the deepest breath and a quiet breath. Expiratory reserve volume is the amount of air that can still be expired after a quiet expiration ends. It requires contraction of expiratory chest wall muscles, as opposed to quiet expiration, which is passive. Vital capacity is the total amount of air that can be forcefully expired from the lungs after the most forcible inspiration possible. It represents the addition of inspiratory reserve, tidal, and expiratory reserve volumes. Total lung capacity is the combination of vital capacity and residual volume. 2019

Answer 32

The correct response is Option B. This patient is experiencing symptoms of lidocaine toxicity. Lidocaine toxicity occurs within a few minutes after injection but can occur up to 60 minutes after injection. The maximum dose of lidocaine without epinephrine is 4.5 mg/kg and with epinephrine is 7 mg/kg. Symptoms of lidocaine toxicity can range from central nervous system (CNS) excitement (circumoral/tongue numbness, metallic taste, light-headedness, dizziness, visual and auditory disturbances, disorientation, drowsiness), and at higher doses CNS depression (muscle twitching, convulsions, unconsciousness, coma, respiratory depression and arrest, cardiovascular depression and collapse). Cardiovascular manifestations include chest pain, shortness of breath, palpitations, hypotension, and syncope. Of the options presented, fat emulsion (Intralipid) is the treatment of choice. Flumazenil is the treatment for benzodiazepine overdose, naloxone is for opioid overdose, dantrolene is for malignant hyperthermia, and propofol is used for induction and maintenance of general anesthesia. 2019

Answer 33

The correct response is Option C. Superficial incisional surgical-site infection is defined by the following criteria: Date of event for infection occurs within 30 days of a procedure AND involves only skin and subcutaneous tissue of the incision AND the patient has at least one of the following: A. purulent drainage at incision site B. positive cultures from the incisions or underlying tissue C. superficial incision that is deliberately opened by a surgeon or other designee with the following signs or symptoms: pain or tenderness; localized swelling; erythema; or heat D. diagnosis by the surgeon or attending physician designee 2019

Answer 34

The correct response is Option E. Early administration of antibiotics (less than 3 hours after injury) has been shown to be the most important determinant of infection prevention after traumatic open fractures of the lower extremity; this is more influential than other factors including time to initial washout, seniority of surgeon involved, as well as severity of the extremity trauma. Guidelines differ by institution but at least a cephalosporin is advocated with consideration given to additional gram-negative plus or minus anaerobic coverage in grossly contaminated wounds. In a large multi-institutional study of open fractures, Pollak et al, showed a significant decrease in infection rate with either early direct admission (\<2 hours) or transfer (\<11 hours) to a level I trauma center, though this was only true for the Gustilo Type III open tibial fracture subgroup and not all open fractures. The authors hypothesized that early transfer resulted in earlier administration of antibiotics, though this was not directly compared. While prompt debridement is important in obtaining wound control in traumatic lower-extremity open fractures, no clear advantage has been shown to debridement within 6 hours versus 24 hours, with the accepted standard that this can typically wait until daylight hours in the setting of timely prophylactic antibiotic administration. Intramedullary reaming has not been shown to decrease infection risk in open tibial fractures, although early skeletal reduction and stability will minimize ongoing soft tissue damage. 2019

Answer 35

The correct response is Option B. Epinephrine is the first line of treatment for patients with anaphylaxis and should be administered intramuscularly (anterolateral thigh) as soon as the diagnosis is made. In a setting where an exact dose can be drawn up, the recommended dosage is 0.01 mg/kg (maximum dose of 0.5 mg), administered intramuscularly every 5 to 15 minutes as necessary to control symptoms. It can also be administered more frequently than every 5 minutes if needed. Greater emphasis has been placed on early administration of epinephrine in the management of anaphylaxis. The mean time to cardiac or respiratory arrest from medication-induced anaphylaxis in a hospital setting has been shown in one study to be only 5 minutes, with only 14% of patients receiving epinephrine prior to arrest. Besides intramuscular epinephrine, recommended immediate interventions for anaphylaxis include an assessment of airway, breathing, and circulation; intravenous access; supplemental oxygen; monitoring; and placing the patient in supine position. Depending on the initial response, other interventions include establishing an airway, rapid intravenous fluid infusion, intravenous epinephrine infusion, bronchodilators, steroids, H1/H2 antihistamines, and glucagon. Ketamine and midazolam (versed) are not indicated for the treatment of anaphylaxis. Diphenhydramine (Benadryl) and other antihistamine drugs are recommended as a second line of therapy for anaphylaxis. The same applies to systemic corticosteroids. 2019

Answer 36

The correct response is Option C. Brain death is a permanent and irreversible state. There will be no return of cerebral or cortical function. Hypothermia is not required for brain death examination; it needs to be reversed for at least 4 hours (up to 24 hours) to establish brain death. Neuromuscular blockade must be reversed and patient must have normal peripheral muscle response to peripheral nerve stimulus in order to undergo brain death examination. Brain death examination includes elicitation of brain reflexes, which can be muted by neuromuscular blockade. Anoxic brain injury must be observed for at least 24 hours prior to beginning brain death examination. Cause or reason for brain death must be established prior to beginning brain death examination. Absence of deep tendon reflexes is not required to initiate the examination. 2019

Answer 37

The correct response is Option C. Risk factors for postoperative nausea and vomiting fall into four categories: patient-related, anesthesia-related, surgery-related, and other factors. Patient-related predictors are: female sex, non-smoking status, history of postoperative nausea and vomiting/motion sickness, genetics, age of 50 years or younger, and obesity (BMI greater than 30 kg/m2). Anesthesia-related predictors are: postoperative opioids, inhalational anesthetics, and nitrous oxide. Surgery-related predictors are: surgery duration and surgery type. Other factors including high patient anxiety and postoperative pain. 2019

Answer 38

The correct response is Option B. Enhanced recovery after surgery (ERAS) protocols are multimodal, multidisciplinary perioperative care pathways designed to achieve rapid recovery after surgery. These pathways include consensus recommendation for postoperative analgesia. In addition, improved postoperative pain control can be obtained with emphasis on the use of procedure-specific pain management. Some procedures have a higher propensity for persistent postoperative pain which generally are neuropathic in origin, ie: mastectomy, thoracotomy, hernia repair, abdominal wall surgeries. The primary goal of an optimal pain therapy is to provide “dynamic” pain relief (pain relief during movement) that would allow early ambulation while reducing opioid consumption. The ideal multimodal analgesic technique would include a local/regional analgesic (wound infiltration or peripheral nerve block) as the principal component because they provide excellent dynamic pain relief. Liposomal bupivacaine (Exparel) allows delivery of bupivacaine for 96 hours with a single local administration. There can be significant pain relief with the combination of wound infiltration with liposomal bupivacaine acetaminophen and NSAIDs or COX2 inhibitors as multimodal analgesic regimens. Epidural analgesia, dexamethasone, lidocaine and ketamine infusions all have demonstrated postoperative pain relief and reduction in opioid requirements to varying degrees. But local/regional analgesia (wound infiltration) should be used as the first-line analgesic therapy, which should be combined with acetaminophen, NSAIDs or COX1 inhibitors. 2020

Answer 39

The correct response is Option E. Postoperative nausea and vomiting remains a significant problem after cosmetic and reconstructive plastic surgery. Reported studies on the condition list incidences as high as 56%, whereas a meta-analysis found that the overall incidence was 28.3%. For many plastic surgery procedures, general inhalational anesthesia and narcotic pain control are required and may predispose patients to postoperative nausea and vomiting (PONV).The effects can be disastrous including hematoma, incisional dehiscence, respiratory compromise, pain, longer hospital stay, slower recuperation, and patient dissatisfaction. A number of risk factors have been associated with a positive overall incidence of PONV. Patient-specific risk factors for PONV in adults include female sex, a history of PONV, non-smoking status, young age, general versus regional anesthesia, postoperative opioids, and type of surgery. Other factors have been disproven including placement of a nasogastric tube, peri-operative fasting, obesity, and supplemental oxygen. 2020

Answer 40

The correct response is Option D. This patient is experiencing nephrotoxicity and chronic kidney disease (CKD) from tacrolimus. Calcineurin inhibitor nephrotoxicity is a well-known phenomenon posttransplantation, and close monitoring of kidney function is essential. There are multiple described pathways of kidney damage secondary to calcineurin inhibitors including irreversible damage to all compartments of the kidney (glomeruli, arterioles, and tubule-interstitium). Krezdorn et al. evaluated 99 recipients of facial or extremity transplantation and concluded that kidney dysfunction represents a major complication posttransplantation in vascularized composite allografts and recommends pretransplant, peritransplant, and posttransplant strategies to reduce kidney damage. These include identifying patients at risk for CKD. Pretransplantation recommendations include treating existing renal conditions, avoiding hypotension and hypertension, limiting nephrotoxic drugs, limiting intravenous contrast, and avoiding hypovolemia. Peritransplantation recommendations include minimizing use of nephrotoxic agents, avoiding hypovolemia, and limiting ischemia time. Postoperative recommendations include minimizing tacrolimus exposure including reduction of trough levels, treating hypertension, treating hyperglycemia, treating dyslipidemia avoiding intravenous contrast, and limiting potentially nephrotoxic drugs such as nonsteroidal anti-inflammatory drugs. Therefore, in this patient, tacrolimus troughs should be reduced. Initiation of oral corticosteroids is not appropriate. The patient should remain on antihypertensive and dyslipidemia drugs. 2020

Answer 41

The correct response is Option D. Virchow recognized a triad of factors that predispose to intravascular thrombosis. These are stasis in blood flow, endothelial (intimal) damage, and intrinsic hypercoagulability. One recent review identifies a personal history of prior thrombotic event as perhaps the single greatest risk factor of a hypercoagulable state. Other known hypercoagulable disorders that can be identified by specific blood test include Factor V Leiden mutation, prothrombin gene (20210A) mutation, protein C deficiency, protein S deficiency, antithrombin III (AT3) deficiency, lupus anticoagulant, anticardiolipin antibodies, and anti-beta-2 glycoprotein 1 antibodies. These appear to increase the risk of microsurgical thrombotic complications as well. However, the severity of the increased risk for each remains to be fully elucidated. Another published series of 41 patients showed an 80% free flap success rate in patients with identified hypercoagulable states. Therefore, a thorough preoperative evaluation of patients for microvascular procedures may help to identify those at increased risk for thrombotic complications, guiding patient selection and perioperative anticoagulation therapy. The Caprini Risk Assessment Model (RAM) is used to assess venous thromboembolism (VTE) risk, and its use has been validated in plastic and reconstructive surgery patients. The Caprini RAM score for the patient in this question is 5 (2 risk factor points for major surgery over 45 minutes, 2 points for presence of malignancy, and 1 point for ages 41 to 60). According to the recommendations of the American Society of Plastic Surgeons VTE Task Force Report, one should consider postoperative chemoprophylaxis for VTE for this patient who is at intermediate risk. However, data are lacking, which would support the use of the Caprini Risk Assessment Model as a tool to stratify risk of microvascular thrombotic complications. This examination contains test materials that are owned and copyrighted by the American Society of Plastic Surgeons. Any reproduction of these materials or any part of them, through any means, including but not limited to, copying or printing electronic files, reconstruction through memorization or dictation, and/or dissemination of these materials or any part of them is strictly prohibited. Keep printed materials in a secure location when you are not reviewing them and discard them in a secure manner, such as shredding, when you have completed the examination. BRCA-2 genetic mutation is a heritable condition that significantly increases lifetime risk for breast and ovarian cancer. However, it has not been shown to play any role in risk for thrombotic events. Similarly, sickle cell trait (heterozygous carrier of the sickle cell mutation in the hemoglobin-beta gene) has not been shown to increase risk for microsurgical thrombotic complications. While chest wall irradiation might negatively impact the recipient chest wall vessels for deep inferior epigastric perforator (DIEP) flaps, the impact of radiation following a lumpectomy is very unlikely to be as significant as that of a prior personal thrombotic event. 2020

Answer 42

The correct response is Option A. Malignant hyperthermia is an autosomal dominant trait, thus, based on Mendelian Genetics, if one parent has a confirmed diagnosis, their biological children will have a 50% chance of inheritance of the affected gene. Malignant hyperthermia is a potentially life-threatening condition. Individuals with this inherited myopathy present with a hypermetabolic reaction to potent volatile anesthetic gases, such as halothane, enflurane, isoflurane, sevoflurane, and desflurane. Individuals are also susceptible to the depolarizing muscle relaxant succinylcholine. The preoperative workup for an individual with suspected malignant hyperthermia is the Caffeine-Halothane Contracture Test. In this test, a piece of skeletal muscle is excised, and its contractile properties are determined when exposed to the ryanodine receptor agonist halothane and/or caffeine. Abnormal contractile activity is indicative of susceptibility. Based on basic Mendelian Genetics, the risk of inheritance is 50%. Given this pattern of inheritance, x-linked, autosomal recessive and mitochondrial inheritance are incorrect answers. 2020

Answer 43

The correct response is Option B. The direct anticoagulation agent rivaroxaban (Xarelto) is a direct anticoagulant, which acts within the clotting cascade by blocking Factor Xa, which, along with Factor Va, helps convert prothrombin to thrombin. This step in the cascade is where the intrinsic and extrinsic pathways intersect and the common pathway that leads to fibrinogen being cleaved to fibrin and stabilized by factor XIIIa as a cross-linked clot. Aspirin is a drug that interferes with platelet function. Coumadin affects the vitamin K dependent factors II (prothombin), VII, IX and X. Heparin prevents clot propagation by blocking thrombin-mediated activation of fibrinogen to fibrin. The primary benefits of the direct anticoagulation agents over coumadin include no need for monitoring and equivalence in efficacy across many clinical situations. It is excreted by the kidney, so dosages must be altered or the drug avoided in renal failure. A U.S. Food & Drug Administration–approved reversal agent, recombinant coagulation factor Xa (Andexxa), is now available on the market for life-threatening or uncontrolled bleeding in patients using direct anticoagulants affecting factor Xa, like rivaroxaban. Prior to this, administration of fresh frozen plasma (FFP) was the antidote of choice. 2020

Answer 44

The correct response is Option E. Systematic review drawing from 30 studies and more than 14,000 patients undergoing minor cutaneous surgery firmly supports continuation of aspirin therapy in all minor cutaneous surgery, as patients on aspirin monotherapy are at no greater risk of hemorrhagic complications than those on no agents. While a case-by-case risk profiling in all patients on aspirin therapy is prudent, the preponderance of evidence favors meticulous hemostasis over aspirin cessation in prevention of bleeding complications in minor cutaneous surgery. There is no reported association between aspirin utilization and increased risk of wound dehiscence, wound infection, or cosmetic outcome. 2020

Answer 45

The correct response is Option B. The patient is showing signs of symptomatic progressive intracranial pressure following head trauma. Hypertonic infusion therapy can be used in this scenario to decrease intracranial pressure and curtail progressive cerebral edema. Hypertonic (3%) saline fits into conventional algorithms for treatment of symptomatic acute intracranial hypertension along with hyperventilation, mannitol, diuretics, and surgical decompression. Hypertonic solutions have been shown to decrease intracranial pressure with greater efficiency than mannitol in early stages of trauma for patients with evolving brain injury. Ringer’s lactate and physiologic (0.9%) saline solution would not prevent or counteract progressive cerebral edema following head trauma. Hypotonic solutions (such as dextrose 5% in water and 0.45% saline solutions) are broadly contraindicated in patients who suffer severe traumatic brain injury, because they may lower serum osmolarity and exacerbate cerebral edema. 2020

Answer 46

The correct response is Option A. The 2016 Surviving Sepsis Campaign guidelines strongly recommend that administration of intravenous antibiotics be initiated as soon as possible after recognition and within 1 hour for both sepsis and septic shock. In the presence of sepsis or septic shock, increasing delays in administration of appropriate antibiotics are associated with increasing mortality and detrimental effects on secondary endpoints, such as length of hospital stay, acute kidney injury, acute lung injury, and the Sepsis-Related Organ Assessment score. Although data suggest that optimal outcomes are achieved by the earliest possible administration of appropriate antibiotics following recognition of sepsis, 1 hour was recommended as a reasonable minimal target, considering multiple patient and organizational factors that may cause delay. 2020

Answer 47

The correct response is Option A. Traumatic placental injury can cause maternal-fetal hemorrhage in 10 to 30% of pregnant trauma patients. The majority of these are subclinical, without measurable effects to the fetus. However, as little as 0.001 milliliter of Rh-positive fetal blood can cause alloimmunization of an Rh-negative mother. Therefore, determination of Rh status is mandatory for all pregnant trauma patients and all Rh-negative of these should be given anti-D immune globulin (IgG). A single dose administered within 72 hours from injury may provide protection against sensitization in up to 90% of the cases. Higher doses may be necessary if it is determined that transplacental hemorrhage was in excess of 30 milliliters. Simply discharging the patient for a future obstetric follow up is not acceptable. At least 4 hours of electronic fetal monitoring should be provided to all pregnant trauma patients with \>= 23 weeks gestation. Internal electronic fetal heart rate monitoring (with an electrode in the scalp) is not indicated at this time. Instead, external monitoring could be done using a dedicated Doppler ultrasound device. MRI of the abdomen/pelvis and diagnostic peritoneal lavage are not indicated in the scenario described. Radiographic imaging generally indicated for trauma evaluation, including abdominal computed tomography, should not be deferred or delayed due to concerns of fetal exposure to radiation. Ultrasonography (FAST) should be part of the secondary survey in all pregnant trauma patients. 2020

Answer 48

The correct response is Option E. Epinephrine is the initial drug of choice in the acute management of this patient with pulseless electrical activity (PEA). Desirable effects of epinephrine in the treatment of cardiac arrest include vasoconstriction (alpha-1 adrenergic) and increase in cardiac output (beta-1 adrenergic). According to current Advanced Cardiac Life Support guidelines, epinephrine should be administered to a patient in cardiac arrest as soon as the electrocardiographic diagnosis of either PEA or asystole is made. The intravenous dose is 1 mg every 3 to 5 minutes, always followed by a 20 mL normal saline flush. Cardiopulmonary resuscitation should not be halted for drug administration. The drug can also be administered via intraosseous access or through the endotracheal tube. The other drugs listed are not indicated in the initial treatment of PEA. 2020

Answer 49

The correct response is Option D. Brain death is a criterion for nonliving organ donation. Absence of all brain stem reflexes needs to be present for brain death to occur. Absence of corneal reflex demonstrates an absence of brain stem reflexes. Presence of pupillary reflex and nystagmus during caloric test demonstrates a positive finding and presence of brain stem reflex. Mild cough or gag during tracheal manipulation demonstrates presence of brain stem reflex. Any respiratory rate during apnea test is seen as a sign of brain stem function. Evaluation of deep tendon reflexes is not part of assessing brain death. 2020

Answer 50

The correct response is Option E. Acute blood loss and the need for autologous blood transfusions are common in infants undergoing craniofacial procedures. Techniques to limit blood loss and transfusions have been studied extensively in craniosynostosis surgery. Tranexamic acid (TXA) is a synthetic analog of the amino acid lysine, which inhibits the conversion of plasminogen to plasmin when intravenously administered. TXA inhibits the proteolytic action of plasmin, thus inhibiting fibrinolysis. It has been shown in multiple studies to reduce both intraoperative and postoperative blood loss. Aprotinin is a small protein bovine pancreatic trypsin inhibitor with anti-thrombolytic potential. It was taken off the market in the United States in 2007 as its use was associated with increased complications and death. It has since been reapproved in Canada and Europe but remains banned in the United States. Protamine is a drug used to reduce the effects of heparin toxicity and of no benefit in this clinical scenario. Erythropoietin is a recombinant glycoprotein cytokine that stimulates red cell production. When given preoperatively, it has been shown to reduce the need for blood transfusion (not necessarily acute blood loss) in craniosynostosis surgery. Fibrinogen is not administered intravenously. Fibrin glue does reduce blood loss in craniosynostosis procedures, but it is administered topically, not intravenously. 2020

Answer 51

The correct response is Option D. Indirect calorimetry measurements, or a metabolic cart, are used to help calculate the resting energy expenditure (REE) and respiratory quotient (RQ) as a means to help determine the caloric needs of a patient as well as optimize the patient’s nutrition. Indirect calorimetry measures the amount of oxygen consumed (VO2) and the amount of carbon dioxide produced (VCO2) by the patient. REE is calculated by the Weir equation [REE = (3.94 x VO2) + (1.1 x VCO2)] while the RQ is calculated as VCO2 / VO2. The calculated values of the respiratory quotient are reflections of what fuels are being oxidized by the patient with typical values as follows: Optimal values of RQ for nutrition assessment are between 0.8 and 0.9, representing a balance between lipid and glucose oxidation. Values below 0.8 suggest underfeeding, while values greater than 1.0 suggest overfeeding. A value of 1.3 in this patient suggests significant overfeeding and lipogenesis and the enteral nutrition should be adjusted based on the current energy expenditure obtained from indirect calorimetry. Ketosis is not measured by RQ. 2020

Answer 52

The correct response is Option C. This patient has breast implant–associated anaplastic large cell lymphoma (BIA-ALCL) which is a distinct form of CD30-positive T-cell, non-Hodgkin’s lymphoma that arises in association with a breast implant after either reconstructive or cosmetic surgery. The disease is typically contained within the capsule and fluid immediately adjacent to the implant. Patients commonly present with delayed seroma, but can also present with pain, capsular contracture, and/or a palpable mass. BIA-ALCL risk is higher with textured devices and these concerns led to the 2019 FDA recall of Allergan Biocell devices. The recall includes older McGhan and Inamed implants and current Natrelle implants. When patients with suspicious history or symptoms are evaluated, pre-operative imaging (e.g., mammography, ultrasound, and/or MRI) is recommended with aspiration of identifiable fluid or biopsy of mass. Ultrasound is considered the diagnostic modality of choice. Diagnostic evaluation should indicate concern for BIA-ALCL to the pathologist to include cytological evaluation of seroma fluid or mass with Wright-Giemsa stained smears and cell block immunohistochemistry/flow cytometry testing for cluster of differentiation (CD30) and anaplastic lymphoma kinase (ALK) markers. Wright-Giemsa staining shows pleomorphic cells with horseshoe shaped nuclei, nuclear folding and abundant vacuolated cytoplasm. All known cases of BIA-ALCL are CD30-positive and -negative for ALK, distinct from systemic ALCL which is ALK-positive. 2021

Answer 53

The correct response is Option C. Anterior thoracic hypoplasia is characterized by hypoplasia of the breast in the context of normal sternum and normal pectoralis major muscle. It is on the differential diagnosis of congenital breast deformities, and is distinguished from Poland syndrome by the normal pectoralis major muscle. Pectus excavatum is another condition of the chest wall; it is characterized by abnormal development of the sternum and ribs, and does not affect breast growth, although it can cause medial displacement of the breasts. Pectus excavatum is more common in males than females. Treatment of the breast in Poland syndrome and anterior thoracic hypoplasia depends on the degree of deformity and the goals of the patient; both implant-based reconstruction and fat grafting have been used. Amazia is an absence of the mammary gland with a present nipple areolar complex, and amastia is complete absence of the mammary gland and nipple areolar complex. Athelia is an absence of the nipple. 2021

Answer 54

The correct response is Option C. In utero, the breasts develop from paired mammary ridges of thickened ectoderm which extend from the axillae to the inguinal regions. The ectoderm will give rise to the nipple and ductal elements, while the mesoderm will eventually give rise to the connective tissue and vascular structures of the breast. Polythelia, or supernumerary nipples, occur as a result of incomplete involution of one of the many epithelial buds along the mammary ridge. 2021

Answer 55

The correct response is Option B. The patient description is consistent with tuberous breast deformity. Surgical intervention usually includes reduction of the periareolar herniation with periareolar incisions and radial release of parenchymal bands. Reduction would not address the issues associated with a tuberous breast. Vertical mastopexy alone through standard approaches would potentially further constrict the lower pole. Skin grafting of the nipple-areola complex would not address the tissue herniation. Elevation of the inframammary fold would not address the tuberous deformity and might exacerbate it. 2021

Answer 56

The correct response is Option D. The presence of a supernumerary nipple occurs in 2-6% of females. Polythelia is the presence of two or more supernumerary nipples. A correlation exists between renal disease and polythelia. It is associated with 19% of patients with renal adenocarcinoma and 16.5% of patients with end-stage renal disease. Regular physical examination and urinalysis should be performed in patients with polythelia and any noted abnormality should alert the physician to the need for a renal ultrasound. 2021

Answer 57

The correct response is Option E. Tubular breasts are caused by connective tissue malformations and occur in puberty. Clinical characteristics include breast asymmetry, dense fibrous rings around the areola, hernia bulging of the areola due to hypoplastic fascial support, hypoplasia of one, two or more quadrants, narrowing of the breast base, and a high location of submammary folds. 2021

Answer 58

The correct response is Option E. Breast implant illness (BII) is a term used to describe a multitude of symptoms seen in patients with breast implants. These symptoms may include the following (as well as others): fatigue, anxiety, headaches, brain fog, anxiety, photosensitivity, hormonal issues, rash, and hair loss. There is no definitive link between these symptoms and breast implants. Research is ongoing. It is important that all patients with these symptoms are evaluated. BII has been self reported by patients with all types of implant characteristics including silicone, saline, textured surfaces, and smooth-walled implants. Before undergoing surgery, evaluation of these patients is important. Many of these symptoms can be associated with known autoimmune diseases and should be evaluated for this possibility, either by a rheumatologist or other medical professional. If a known autoimmune disease is diagnosed, then traditional treatment for this known disease should be tried before explantation surgery. Women who underwent explantation for possible BII had varying degrees of improvement including no improvement, temporary improvement, and permanent resolution of symptoms. In one study, patients with documented autoimmune disease showed no improvement following explantation. MRI would not initially be needed with a normal physical examination and saline implants. Stereotactic biopsy would be indicated for palpable masses or breast mass evaluation, not symptoms of BII. 2021

Answer 59

The correct response is Option D. In the realm of upper extremity surgery, younger age, bone procedures, mental health disorders, history of substance abuse, and pain disorders have consistently been found to be risk factors for prolonged opioid use. A specific gender has not been consistently shown to be a risk factor of opioid abuse following upper extremity surgery, with some studies pointing to female gender, while others point to male gender. Other factors that have been identified in specific studies include elective versus traumatic hand surgeries, lower versus higher income, and comprehensive insurance coverage versus medicare insurance. Aside from identifying risk factors, the majority of recent studies regarding prolonged opioid use after either upper extremity surgery or plastic surgery point to overprescription of opioids as a common problem. Recent reports demonstrate that narcotics are overprescribed by 40 to 60% after upper extremity surgery. 2021

Answer 60

The correct response is Option D. Isosulfan blue has many uses. It is used to identify sentinel nodes in melanoma and Merkel cell skin cancer as well as in breast cancer. It is used in reverse axillary mapping in order to preserve extremity lymph nodes while harvesting those that drain the breast. Allergic reactions to this dye occur in up to 1.6% of patients. These adverse events are unexpected and occur with unpredictable severity. There is no current validated method to detect or decrease the risk of allergic reaction. It is important for the plastic surgeon to be able to quickly recognize and treat complications. The most common allergic reactions are urticaria, blue hives, and skin rash. Anaphylaxis has been reported, but much less commonly. In this scenario, the first sign of anaphylactic reaction is the sudden and severe drop in blood pressure. This can occur immediately or unexpectedly later during the surgical procedure. After halting the operation and starting a fluid bolus, a vasopressor should be administered to counteract the hypotension. Once this is done, both a corticosteroid (dexamethasone) and an antihistamine (diphenhydramine) should be given to counteract the allergic reaction. Changing the fraction of inspired oxygen will not help the allergic reaction. A needle thoracostomy would be indicated if dissection high in the axilla resulted in a tension pneumothorax, but that is not the case here. Administration of lipid emulsion is appropriate for local anesthetic toxicity. A commonly suggested alternative to isosulfan blue, without the risk of anaphylaxis, is methylene blue. However, there is a significantly higher rate of wound healing complications with the use of methylene blue, which is why isosulfan blue is preferred in plastic surgical procedures, specifically skin grafting. 2021

Answer 61

The correct response is Option C. The pectoral nerve (PECS) 1 and PECS 2 anesthetic blocks have become increasingly common methods for regional anesthesia to decrease postoperative pain in many early recovery after surgery (ERAS) protocols. The PECS blocks are thoracic regional fascial plane blocks that typically require ultrasound guidance for proper infiltration of the anesthetic between the muscles of the thoracic wall. A PECS 1 block is performed between the pectoralis major and pectoralis minor muscles and anesthetizes the lateral and medial pectoral nerves. A PECS 2 block, in addition to the PECS 1 block, involves an additional injection of anesthetic between the pectoralis minor and serratus anterior muscles and blocks the intercostal and intercostobrachial nerves. The serratus plane block is another thoracic regional fascial plane block requiring injection of local anesthetic between the serratus anterior and latissimus dorsi muscles in order to block the long thoracic and thoracodorsal nerves. 2021

Answer 62

The correct response is Option A. This patient has a very high thromboembolic risk and a high bleeding risk. Recommended heparin bridging is 3 days before a planned procedure (ie, two days after discontinuing warfarin), when the prothrombin time and international normalized ratio (PT/INR) has started to drop below the therapeutic range. Atrial fibrillation accounts for the highest percentage of patients for whom perioperative anticoagulation questions arise. Importantly, patients with atrial fibrillation are a heterogeneous group; risk can be further classified according to clinical variables such as age, hypertension, congestive heart failure, diabetes, prior stroke, and other vascular disease. Bridging anticoagulation may be appropriate in patients who will have a very high thromboembolic risk with prolonged interruption of their anticoagulant (generally a vitamin K antagonist). Individual patient comorbidities that increase bleeding risk may also need to be considered because an increased postoperative bleeding risk may be a reason to avoid bridging. Suggested use of bridging in individuals taking warfarin includes: Embolic stroke or systemic embolic event within the previous three months Mechanical mitral valve Mechanical aortic valve and additional stroke risk factors Atrial fibrillation and very high risk of stroke (eg, systemic embolism within the previous 12 weeks, concomitant rheumatic valvular heart disease with mitral stenosis) Venous thromboembolism (VTE) within the previous three months (preoperative and postoperative bridging) Recent coronary stenting (e.g. within the previous 12 weeks) Previous thromboembolism during interruption of chronic anticoagulation The other answer choices are not appropriate strategies for this patient. 2021

Answer 63

The correct response is Option D. Atrial fibrillation manifests as irregularly irregular QRS complexes without P waves on ECG. Postoperative atrial fibrillation (POAF) is multifactorial in origin, and occurs in 5 to 10% of patients undergoing non-cardiothoracic surgery. In the largest trial to date comparing rate versus rhythm control (Atrial Fibrillation Follow-Up Investigation of Rhythm Management [AFFIRM]), rhythm control was associated with a greater number of hospitalizations, torsades de pointes, pulmonary events, gastrointestinal events, bradycardia, and QT prolongation events. Rate control is the treatment strategy of choice, with the goal of 80 to 100 bpm. Metoprolol is the preferred beta blocking agent due to its efficient conversion between IV and oral routes, low cost, and clinician familiarity. Diltiazem (non-dihydropyridine calcium channel blocker) is a second-line therapy, and is intended for use if first-line therapy is ineffective at rate control at maximum doses or the first-line therapy is contraindicated. Digoxin is considered when other options are ineffective or contraindicated because of its narrow therapeutic window. Amiodarone has both beta-blocking and calcium channel blocking properties in addition to its antiarrythmic effects. Amiodarone can be used in patients with decreased ejection fractions. It is associated with acute pulmonary toxicity. 2021

Answer 64

The correct response is Option B. Intravenous calcium gluconate should be given to this patient with severe hyperkalemia and associated electrocardiographic changes. Hyperkalemia causes a decrease in the resting membrane potential, leading to increased myocardial excitability and cardiac arrhythmias, including ventricular fibrillation and asystole. Electrocardiographic changes associated with progressive hyperkalemia include peaked T waves, prolonged P-R segment, flattening/loss of P waves, widening of QRS complex, ectopic beats, ventricular fibrillation, conduction blocks, and asystole. Neither a specific serum potassium level threshold nor an electrocardiographic pattern that predisposes patients to life-threatening cardiac arrhythmias has been well established. However, the initial therapy for patients presenting with a serum potassium level greater than 6 mEq/L and hyperkalemia-related electrocardiographic changes should focus on stabilizing the myocardium to prevent or reverse cardiac arrhythmias by intravenous administration of a calcium salt (gluconate or chloride). The onset of action is nearly immediate, but the duration of the protective effect is only 30 to 60 minutes. Therefore, repeat administration may be required. Interventions to shift potassium intracellularly (intravenous dextrose and insulin, with or without nebulized albuterol/beta-2 agonist; intravenous sodium bicarbonate) or eliminate it from the body (intravenous furosemide, rectal or oral potassium-binding agents, hemodialysis) should be carried out as soon as possible after intravenous administration of calcium. 2021

Answer 65

The correct response is Option A. The pH is low, indicating an acidosis, while the bicarbonate is high, indicating that a respiratory acidosis with metabolic compensation is present. The pH is low so the primary problem is an acidosis and is likely to be respiratory in nature. The PaCO2 is very high and indicates a respiratory acidosis is present. The very high PaCO2 level seen here is typical of a person with respiratory disease that results in retention of CO2, (ie, the primary clinical problem is respiratory failure due to chronic obstructive pulmonary disease).The most likely cause for this acid-base abnormality is an acute exacerbation of chronic obstructive pulmonary disease. 2021

Answer 66

The correct response is Option C. All the medications listed are safe for use the night before surgery with the exception of an ACE inhibitor. While there have been some questions in the past regarding the safety of selective serotonin reuptake inhibitors (SSRIs) like sertraline due to bleeding concern, the current consensus is that it is safe to take.1 Beta blockers can have a beneficial effect for the cardiovascular system before surgery and thus, patients may take them even the morning of surgery.2 Lisinopril, however, can lead to hypotension during surgery and anesthetic management, and should be stopped the night before surgery. As an ACE inhibitor, it may counter the medications the anesthesiologist uses for blood pressure control. 2021

Answer 67

The correct response is Option E. Several studies have shown that timing of antibiotic delivery does impact the rate of surgical site infection (SSI). Current recommendations suggest that, when indicated, antibiotics should be given between 1 and 2 hours before surgery. There are no data to support a reduction in SSI risk when antibiotics are given within 30 minutes of surgery. In the retrospective review by Bykowski et al, authors reported the SSI rates in patients undergoing elective soft-tissue surgery. Rates of SSI did not differ between patients who received preoperative antibiotics and those who did not (0.54% versus 0.26%, p less than 0.05). When a subgroup analysis was performed, SSI infection rates for patients who were active smokers, diabetics, and with procedure length greater than 60 minutes showed no difference with or without antibiotic administration. Traditionally, patients with rheumatoid arthritis are viewed to be at higher risk for infection following surgery. There are no data to suggest that there is a risk reduction with the use of preoperative and/or postoperative antibiotics. Also, methotrexate does not increase one’s SSI risk and is therefore not an indication for perioperative antibiotic therapy. 2021

Answer 68

The correct response is Option D. The advantage of using this combination is that midazolam has excellent anxiolytic and amnestic effects, whereas fentanyl is an excellent short-acting analgesic. A recent multicenter, randomized study demonstrated that the combination of fentanyl and midazolam is superior to midazolam alone in decreasing the patient’s subjective report of pain and anxiety. The main drawback of fentanyl is respiratory depression; however, it does have a very short half-life. Midazolam, in contrast, has minimal effects on the respiratory system except in some older patients, in whom lower doses must be used. Continuous oxygen saturation monitoring and checking the patient's respiratory status and other vital signs every 5 minutes are important for patient safety. Medications are only administered in small doses at each 5-minute interval (no more than 50 mg of fentanyl and 2 mg of midazolam at a time). This helps achieve a steady-state effect. Both of these medications have antagonists that are able to reverse their effects. Flumazenil and naloxone, the antagonists of midazolam and fentanyl, respectively, should be readily available in the operating room. The surgeon should be familiar with their dosage and administration. Ketamine would not resolve anxiety in this patient. Use of propofol in combination with an opiate and benzodiazepine can be used for conscious sedation; however, the disadvantage of this combination is the higher risk of respiratory depression and the lack of a reversing agent for propofol. Because a deeper level of sedation can be maintained, this technique is preferable for selected patients who are very anxious. A recently published series of abdominoplasty with sedation using propofol used monitored anesthesia care by an anesthesiologist or nurse anesthetist. Propofol and benzodiazepines have no significant analgesic effect. 2021

Answer 69

The correct response is Option C. This patient is suffering from a bleeding disorder called von Willebrand disease (VWD), which occurs when the von Willebrand factor (VWF) is deficient or qualitatively abnormal. Von Willebrand factor (VWF) works by mediating the adherence of platelets to one another and to sites of vascular damage. It also binds to Factor VIII, keeping it inactive while in circulation since Factor VIII rapidly degrades when not bound to VWF. VWD is the most common of the inherited bleeding disorders, with an estimated prevalence in the general population of 1 percent by laboratory testing. Patients will often present with signs of easy bruising, extensive bleeding after dental work, heavy or long menstrual periods, and prolonged nose bleeds. Patients with a history of abnormal bleeding should always be properly worked up prior to surgery. There has been an extensive discussion over the years about the treatment of patients suffering from von Willebrand’s disease and rhinoplasty procedure. The recommended treatment of patients suffering from VWD undergoing rhinoplasty procedure is 0.3 ?g/kg of 1-deamino-8-D-arginine-vasopressin (Desmopressin). Desmopressin is an analogue of vasopressin that exerts a substantial hemostatic effect, by inducing the release of von Willebrand factor from its storage sites in endothelial cells. Patients with the mild form of VWD have lower than normal levels of VWF, and the release of the additional proteins from the endothelial cells aids with clotting. Factor V Leiden is a mutated form of human Factor V, which condition that result in a hypercoagulable state. Due to this mutation, Protein C, an anticoagulant protein which normally inhibits the pro-clotting activity of factor V, is not able to bind normally to Factor V, leading to a hypercoagulable state. Desmopressin does not have a direct interaction on this molecule. Thrombin is an enzyme that converts fibrinogen to fibrin, and a reaction that leads to the formation of a fibrin clot. There are several thrombin products commercially available. Hemophilia is a condition that is deficient in Factor VII. Recombinant activated factor VII. Aspirin irreversibly blocks the formation of thromboxane A2 in platelets, producing an inhibitory effect on platelet aggregation. 2021

Answer 70

The correct response is Option B. Malignant hyperthermia is an anesthetic crisis that is potentially fatal if not appropriately managed. The mechanism of malignant hyperthermia is an accelerated release of calcium from the sarcoplasmic reticulum. The increasing release of calcium surpasses uptake and leads to an inability to control the intracellular calcium level. The symptoms of malignant hyperthermia include unexplained high end-tidal CO2 levels, tachycardia, increasing body temperature, masseter muscle rigidity, and skeletal muscle rigidity. The first step in the management of malignant hyperthermia is discontinuing the volatile anesthesia. The subsequent steps in management include administering dantrolene, switching to IV anesthesia, and treatment of arrhythmia. Depolarizing muscle relaxants can cause malignant hyperthermia and these drugs should be immediately discontinued and not administered. Infusion of lipid emulsion is done for lidocaine toxicity. 2021

Answer 71

The correct response is Option B. Gabapentin is a structural analogue of the neurotransmitter gamma-aminobutyric acid and high affinity to voltage-gated calcium channels at presynaptic terminals of hyperexcited neurons through reduction in depolarization-influx of calcium required for release of excitatory neurotransmitters, including glutamate, noradrenaline, dopamine, and serotonin. The exact nature of its analgesic effect is incompletely understood. Contemporary evidence demonstrates that perioperative administration in conjunction with an ERAS protocol is associated with a significant reduction in postoperative opioid use. Lidocaine is an amide local anesthetic that decreases the excitation threshold of nociceptive afferent neurons by decreasing neuronal membrane permeability through voltage-gated sodium channels. The inhibition of neuronal depolarization results in blockade of pain transmission. Oxycodone is a semi-synthetic opioid that is primarily the mu-opioid receptor agonist that opens calcium-dependent inward-rectifying potassium channels, which causes hyperpolarization and reduced excitability of neuronal ascending pain pathways. Acetaminophen was previously believed to exert its analgesic effect by inhibiting cyclooxygenase enzymes 1 and 2. Recent investigations demonstrated that the main analgesic mechanism is the metabolite p-aminophenol, which crosses the blood-brain barrier and is converted to N-acylphenolamine (AM404). AM404 then acts on the transient receptor potential vanilloid subtype 1 (TRPV1) and cannabinoid 1 receptors in the brain and terminals of C-fibers in the spinal dorsal horn. Both the brain and spinal dorsal horn are critical to pain pathways and modulate nociceptive transmission. Therefore, acetaminophen induces analgesia by acting on the brain and spinal cord. Ketamine is a noncompetitive antagonist to the N-methyl-d-aspartate (NMDA) receptors. The NMDA receptor is involved in the amplification of pain signals, central sensitization, and opioid tolerance. The ketamine molecule is hydrophilic and lipophilic, allowing it to cross the blood-brain barrier to exert its NMDA antagonist effects in the brain and spinal cord. 2022

Answer 72

The correct response is Option C. This patient is classified as ASA III, on the basis of a BMI greater than 40 kg/m2. Thus, she may not be a candidate for surgical facilities that are restricted to ASA I or II cases, like many office-based surgical facilities. Other examples of health factors that potentially classify a patient as ASA III (or higher) include: history of transient ischemic attack, stroke, poorly controlled diabetes mellitus or hypertension, chronic obstructive pulmonary disease, active hepatitis, alcohol dependence or abuse, implanted pacemaker, moderate decrease of ejection fraction, end-stage kidney disease undergoing regularly scheduled dialysis, percutaneous coronary angioplasty within 60 weeks, and history of myocardial infarction or stents for coronary artery disease more than 3 months ago. 2022

Answer 73

The correct response is Option B. Wait at least 20 minutes before injecting liposomal bupivacaine. Liposomal bupivacaine (Exparel), is a long-acting (approximately 72 hours) local anesthetic that is an extended-release multivesicular liposomal version of bupivacaine. It has been shown that this drug can decrease the need for opiates in the postoperative period. Nonbupivacaine anesthetics, including lidocaine, when mixed with liposomal bupivacaine may cause an immediate release of bupivacaine, potentially causing an overdose. For this reason, lidocaine and liposomal bupivacaine should not be mixed together. Administration of liposomal bupivacaine may follow the administration of lidocaine after a delay of 20 minutes or more. Administration of liposomal bupivacaine results in systemic plasma concentrations that can persist for 96 hours after local infiltration. That said, it is recommended that the use of local anesthetics be avoided within 96 hours following administration of liposomal bupivacaine. The other choices are incorrect because they do not conform to the recommendations and pharmacology of the involved medication. 2022

Answer 74

The correct response is Option E. Malignant hyperthermia (MH) is a disturbance of calcium channel homeostasis, causing unregulated calcium release from sarcoplasmic reticulum. The coadministration of dantrolene used during resuscitation and an intravenous calcium channel blocker is contraindicated, since both verapamil and diltiazem have been associated with life-threatening hyperkalemia in this setting. The other agents listed (metoprolol, lidocaine, epinephrine, and dextrose 50%) may be used as needed during advanced cardiovascular life support protocols or for the treatment of hyperkalemia. MH is a pharmacogenetic disorder triggered in genetically susceptible individuals by volatile anesthetic gases and succinylcholine. It has autosomal dominant inheritance. Dantrolene is the only treatment for a MH crisis, and a newer formulation has faster administration than traditional preparations. The resuscitation poster for MH should be in every operating room facility and is mandated by the American Association for Accreditation of Ambulatory Surgical Facilities (AAAASF) standards. Their phone number is 1-800-MH-HYPER. 2022

Answer 75

The correct response is Option D. The ASPS Venous Thromboembolism Task Force Report includes recommendations for risk stratification based on the Caprini Risk Assessment Model (RAM), which has been widely validated in the scientific literature for evaluation of surgical patients. The 2005 model in particular is most applicable to plastic surgery. This model awards a score based on various weighted patient risk factors, with venous thromboembolism (VTE) risk increasing as the score increases. The literature suggests that patients with a Caprini RAM score less than 8, who were not provided chemoprophylaxis, experienced VTE at a rate of 11.3%. The Caprini RAM score for this patient is 12. Age 41 to 60 years is 1 point. BMI greater than 25 kg/m2 is 1 point. Major surgery (longer than 45 minutes) is 2 points. Positive factor V Leiden, an inheritable mutation in factor V protein, which is involved in the blood clotting cascade, is 3 points. Hip, pelvis, or leg fracture within the past month is 5 points. Based on this risk stratification tool, the surgeon "should strongly consider the option to use extended low molecular weight heparin postoperative prophylaxis" in this patient. 2022

Answer 76

The correct response is Option C. Lidocaine and all other local anesthetics are considered safe to be used in patients who are susceptible to malignant hyperthermia. Volatile anesthetic agents (halothane, sevoflurane, ether) and depolarizing muscle relaxants (succinylcholine) are considered potential triggers of malignant hyperthermia and, therefore, should be avoided in susceptible individuals. Other anesthetic agents that are considered safe to be used in patients susceptible to malignant hyperthermia include: * nonvolatile general anesthetics: nitrous oxide * opioids: morphine, fentanyl, alfentanil, hydromorphone, meperidine, naloxone * barbiturates and intravenous anesthetics: thiopental, propofol, etomidate * nondepolarizing muscle relaxants: pancuronium, atracurium, rocuronium * benzodiazepines: lorazepam (Ativan), midazolam (Versed), klonopin Dozens of genetic mutations have been associated with susceptibility to malignant hyperthermia, which is generally inherited in an autosomal dominant pattern. 2022

Answer 77

The correct response is Option C. Obtaining a frailty score would help providers assess the perioperative risk for this elderly patient with limited ambulation and possible cognitive impairment who is about to undergo a significant colorectal and reconstructive operation. Frailty is a state of functional compromise in an elderly patient, which may include declined ability to maintain homeostasis, loss of physiological reserve, and increased vulnerability to adverse outcomes in the perioperative period. Chronological age alone has been found to be a poor predictor of cancer and/or surgery tolerance by elderly patients. This subgroup of surgical patients has been rapidly increasing in number due to overall aging of the US population and can be quite heterogeneous when it comes to individual health status. Therefore, preoperative evaluation of elderly patients should include medical comorbidities and baseline functional status. Several frailty scoring systems have been described, including the Phenotype Model, Cumulative Deficit Model, Comprehensive Geriatric Assessment, Risk Analysis Index, Charlson Comorbidity Index, Hopkins Score, and Frailty Index, along with its 11- and 5-item modified/simplified versions. Scored variables include physical characteristics (unintentional weight loss, slow gait, weak grip strength, etc.), medical history (stroke with deficit, myocardial infarction, congestive heart failure, etc.), and laboratory results (kidney function, nutrition, etc.). Higher frailty scores have been associated with higher risk for in-hospital complications, longer hospital stay, discharge disposition to a skilled nursing facility, increased postoperative complications, and decreased postoperative survival at 30, 180, and 365 days. Liver function may not be indicated in this patient without any history of abnormal bleeding or jaundice or signs of liver disease. FEV1 (forced expiratory volume) to FVC (forced vital capacity) ratio is used to monitor airway flow and assess response to therapy in patients with asthma. APACHE (Acute Physiology and Chronic Health Evaluation) II and SOFA (Sequential Organ Failure Assessment) are used to grade severity of illness in critically ill patients and predict clinical outcomes in the ICU setting. 2022

Answer 78

The correct response is Option B. In infants, the formula used for estimated circulating blood volume is 75 to 80 mL per kg of body weight. This infant’s estimated circulating volume is 750 mL total. When performing surgery with blood loss that is large relative to circulating volume, blood loss control and blood replacement need to be watched carefully. Estimated circulating blood volume in a 154-lb (70-kg) adult is 5.5 L. For neonates, the formula is increased to 85 to 90 mL/kg, and for children, the formula is decreased to 70 to 75 mL/kg. The surgeon should be aware when working on infants of the changing estimate of circulating blood volume based on weight. A reference for a recent nomogram for prediction of hemoglobin and hematocrit shifts after blood loss and resuscitation is included in the resources, as well as classic papers on fluids in pediatric patients and estimations of estimated circulating volume. 2022

Answer 79

The correct response is Option D. Liposomal bupivacaine is frequently used to manage postoperative pain. The mechanism of action is bupivacaine loads into multivesicular liposomes, thus allowing for slow release of bupivacaine. The potential efficacy of liposomal bupivacaine can last between 72 to 96 hours. Thus, studies have shown that administration of liposomal bupivacaine can decrease postoperative pain and also decrease the usage of opioids. The administration of liposomal bupivacaine is not weight-dependent, and the maximum dose recommended is a single administration of 266 mg or 20 mL. To cover a larger area, volume expansion with saline or bupivacaine can be used by dilution of the 266 mg; however, it is not recommended to exceed this dose. 2022

Answer 80

The correct response is Option C. The most appropriate next step in managing this patient with otherwise unexplainable refractory hypotension and a recent history of long-term steroid use is intravenous administration of hydrocortisone, with the presumptive diagnosis of adrenal crisis. The first case reports of surgery-induced acute adrenal insufficiency in patients on long-term steroid therapy were published in the early 1950s, just a few years after the release of oral cortisone in 1949. Today, over 6 decades later, significant controversy remains in the prevention, diagnosis, and treatment of this disease, despite its fatality if not appropriately prevented or managed. Clinical signs of acute adrenal insufficiency, or adrenal crisis, include hypotension, hypoglycemia, dehydration, altered mental status, and hyponatremia, which can quickly progress to fatal hemodynamic collapse. Prescribed steroid therapy (PST) can cause suppression of the hypothalamo–pituitary–adrenal (HPA) axis, placing these patients at risk for acute adrenal insufficiency as a consequence of surgical stress. Prednisone doses ? 5 mg/day (or hydrocortisone-equivalent dose) in adults via any route of administration (oral, inhaled, topical, intranasal, intra-articular) are sufficient to raise concern. There is no consensus on the minimal duration of PST to place patients at risk for an adrenal crisis, but 3 weeks is commonly cited. The risk may remain for up to 1 year after discontinuation of PST. There seems to exist no consensus on the preoperative evaluation of patients at risk. Laboratory evaluation of their HPA axis is possible (e.g., ACTH challenge), but results correlate poorly with actual incidence of adrenal crisis. There is also no consensus on a prophylactic steroid regimen for patients at risk, although a recent trend away from the perioperative administration of high-dose steroids purely as prophylaxis can be observed, particularly in the inflammatory bowel disease literature. Apart from all the controversy, at least a couple of principles related to this disease seem to be universally accepted: 1) a high degree of suspicion should be exercised when encountering unexplained refractory hemodynamic instability in a patient on PST subjected to stress by surgery or illness; 2) in such a case, preference should be given to prompt administration of rescue steroids, considering the expected mortality of untreated crises and the lack of evidence of long-term adverse consequences from short-term steroid administration. None of the other drugs listed are directly pertinent to the management of the adrenal crisis in this patient. Desmopressin (DDAVP) causes the release of von Willebrand factor from platelets and endothelial cells. It is used in cases of factor VIII or von Willebrand factor deficiency. Insulin and dextrose solutions are used to shift potassium intracellularly in the treatment of hyperkalemia. Dantrolene is used in the treatment of malignant hyperthermia. Labetalol, a beta-adrenergic blocker, would probably worsen the patient’s hypotension. 2022

Answer 81

The correct response is Option D. Tranexamic acid (TXA) has seen an expanding role in plastic surgery in recent years to decrease blood loss. Its mechanism of action is to inhibit the conversion of plasminogen to plasmin, which in turn inhibits the fibrinolytic pathway (clot degradation). All of the other options are steps involved in the clotting cascade, which are required for hemostasis (clot formation). TXA does not have an effect on any of those steps. 2022

Answer 82

The correct response is Option A. Due to growing concern over antibiotic misuse, patterns of antibiotic prescribing and adherence to guidelines must be surveyed. In 2003, Lyle et al. examined the prescribing practices of plastic surgeons with respect to different surgical procedures and compared with previous surveys. Authors found that surgeons were prescribing prophylactic antibiotics in more than 70% of cases for all procedures with the exception of blepharoplasty and chemical peel. Though the evidence supports judicious antibiotic prescribing and consistently denounces long-term antibiotic therapy, surgeons often fail to adhere to these guidelines, in favor of longer duration antibiotic prophylaxis. Ariyan et al. published an evidence-based consensus statement in 2015, detailing antibiotic prophylaxis to prevent surgical site infections (SSI) in plastic surgery. They performed a meta-analysis of the best available evidence across common plastic surgery procedures. With respect to cosmetic breast and body surgery, authors analyzed data from 12 breast studies (three RCTs, nine non-RCTs) and 1 abdominal study (non-RCT). They concluded that the meta-analysis of the RCTs in clean breast surgery showed a significant reduction in risk for SSI with antibiotic prophylaxis versus control (2.5 vs 11.4%; OR, 0.16; 95% CT, 0.04 to 0.061; p = 0.01). When combined with non-RCTs, there was still a significant risk reduction (3.8 vs 6.7%; OR, 0.50; 95% CI, 0.26 to 0.94; p = 0.03). With respect to abdominoplasty, the authors of the consensus statement reported the results of a pseudorandomized study in which antibiotic prophylaxis did not result in a significant reduction in SSI (6.5 vs 13.0%; OR 0.47; 95% CI, 0.18 to 1.23; p = 0.12). Assuming that there is no contraindication, Cefazolin is generally recommended as a first-line, prophylactic antibiotic for clean plastic surgery procedures. CDC guidelines recommend antibiotic administration between 30 to 60 minutes from the initial incision. Two grams of cefazolin is indicated for patients less than 120 kg, and 3 grams is recommended for those over 120 kg. Current data do not support prescribing additional antibiotics beyond a single preoperative dose. 2022

Answer 83

The correct response is Option B. Postoperative urinary retention (POUR) is a common postoperative complication that most often arises secondary to the general anesthesia given during surgery. The prevalence of POUR has been cited as up to 70% in the literature. The anesthetic medications used during the procedure can suppress micturition control and reflexes at the level of the central nervous system and peripheral nervous system while also acting as a smooth muscle relaxant that decreases bladder contractility. Management of POUR can be conservative, including ambulation and cessation of systemic analgesics, or invasive with either intermittent or indwelling catheter placement. Correction of poor pain control with additional narcotic medications would likely worsen POUR. Urinary tract infection, while a possibility, would be associated with pain and burning during urination as opposed to pubic fullness and discomfort. Inadequate resuscitation would present with a lack of bladder fullness associated with oliguria. Acute tubular necrosis is associated with renal failure which this patient is unlikely to have. 2022

Answer 84

The correct response is Option E. The patient most likely has a pulmonary embolism. Pulmonary embolisms are rare but deadly complications following microsurgical breast reconstruction, and they often present with tachycardia alone (with or without hypoxia). The patient is receiving 6 L nasal cannula oxygen supplementation, so hypoxia is difficult to assess. Anxiety would commonly present as tachycardia with hypertension. Hypovolemia and active bleeding would commonly present with tachycardia with hypotension and decreased urine output. Caffeine withdrawal would commonly present with a headache. 2022

Answer 85

The correct response is Option D. Managing anticoagulation in the perioperative period is challenging. The risk for thromboembolic phenomenon is transiently increased with any cessation in anticoagulation therapy. At the same time, this risk needs to be weighed against the risk for bleeding. For the patient described, who is high-risk for recurrent embolus (recent PE) and bleeding (due to the nature of the proposed procedure), these opposing risks need to be weighed carefully. They may be mitigated by a "bridging" strategy where short-acting agents provide prophylactic anticoagulation around the time of surgery while long-acting agents are held. While the decision to adjust anticoagulation therapy in the perioperative period is controversial, the mechanism of bridging therapies is based on the known pharmacokinetic behaviors of anticoagulation agents. The half-life of warfarin is approximately 36 hours, so stopping warfarin prior to surgery will allow the therapeutic INR to return to normal levels by the day of surgery. To maintain therapeutic anticoagulation, low-molecular weight heparin (LMWH) may be initiated 3 days prior to surgery as the INR decreases. In the absence of other factors that predispose the patient to bleeding events, warfarin may be safely resumed 1 to 2 days after surgery. Stopping warfarin 1 to 2 weeks prior to is unnecessary. Furthermore, a longer interval between cessation of warfarin and initiation of LMWH treatment may create a longer window where the patient is at risk for thromboembolic events. Stopping warfarin the day of surgery and initiating LMWH the same day will place the patient at an increased risk for bleeding. 2022

Answer 86

The correct response is Option C. Transversus abdominis plane regional anesthetic blocks have been shown to decrease narcotic consumption and abdominal pain following abdominal-based microsurgical breast reconstruction. The sensory nerves to the anterior abdominal wall run in the interfascial plane between the internal oblique and transversus abdominis muscles. A successful regional block depends on precise identification of the proper plane for the injection. The arrow indicated by letter C represents the transversus abdominis plane. The arrow indicated by letter A indicates the interfascial plane between the internal and external oblique muscles. The arrow indicated by letter B indicates the body of the internal oblique muscle. The arrow indicated by letter D indicates the peritoneum. The arrow indicated by letter E indicates the contents of the abdominal cavity. 2022

Answer 87

The correct response is Option C. Measuring lactate level is the most appropriate next step in management of this patient who is developing sepsis/septic shock in the postoperative period. In the 2018 update of the 2016 Surviving Sepsis Campaign guidelines, an Hour-1 Bundle was modified to reflect the need to begin resuscitation and management of patients with sepsis and septic shock immediately upon presentation. The Hour-1 bundle includes: * Measuring lactate level. To be re-measured in 2 to 4 hours if initial lactate is \> 2 mmol/L * Obtaining blood cultures prior to administration of antibiotics * Administering broad-spectrum antibiotics * Rapidly administering 30 mL/kg crystalloid for hypotension or lactate ≥ 4 mmol/L * Initiating vasopressors if patient is hypotensive during or after fluid resuscitation to maintain MAP ≥ 65 mmHg Serum lactate levels, although not a direct measure, can serve as a surrogate of tissue hypoperfusion. Randomized controlled trials have demonstrated a significant reduction in mortality when lactate-guided resuscitation is employed. The 2016 Surviving Sepsis Campaign recommended against using low-dose dopamine for renal protection (lack of evidence supporting its efficacy), against providing fluid resuscitation with hydroxyethyl starch (higher risk for death compared with other fluids), and against routine use of pulmonary artery catheters (lack of evidence in improving septic patient outcomes). It does recommend narrowing of antimicrobial therapy based on culture results, but these would not be available in this patient’s early phase of management. 2022

Answer 88

The correct response is Option B. The pectoral nerve (PECS) 1 and 2 anesthetic blocks have become increasingly common methods for regional anesthesia to decrease postoperative pain in many early recovery after surgery (ERAS) protocols. The PECS blocks are thoracic regional fascial plane blocks that typically require ultrasound guidance for proper infiltration of the anesthetic between the muscles of the thoracic wall. A PECS 1 block is performed between the pectoralis major and pectoralis minor muscles and anesthetizes the lateral and medial pectoral nerves. A PECS 2 block, in addition to the PECS 1 block, involves an additional injection of anesthetic between the pectoralis minor and serratus anterior muscles and blocks the intercostal and intercostobrachial nerves. The serratus plane block is another thoracic regional fascial plane block requiring injection of local anesthetic between the serratus anterior and latissimus dorsi muscles in order to block the long thoracic and thoracodorsal nerves. 2022

Answer 89

The correct response is Option E. Tranexamic acid is a synthetic reversible competitive inhibitor to the lysine receptor found on plasminogen. The binding of this receptor prevents plasmin (the activated form of plasminogen) from binding to and ultimately stabilizing the fibrin matrix. Heparin inhibits antithrombin. Aprotinin is a competitive inhibitor of several serine proteases, specifically trypsin, chymotrypsin, and plasmin, by inhibiting proteolysis of protease-activated receptor-1. Inhibition of platelet aggregation and activation of protein C and S are antithrombotic mechanisms. 2023

Answer 90

The correct response is Option E. Local anesthetic systemic toxicity can result in serious patient harm, including seizure, cardiac compromise, and fatality. Local anesthetics act on all parts of the nervous system and all nerve types. The primary therapeutic effect of local anesthetics is to block the action potential generated and propagated in peripheral nerves. Ester local anesthetics are metabolized in the circulation by plasma esterases, whereas amide local anesthetics (ie, lidocaine, mepivacaine, bupivacaine, ropivacaine) are processed in the liver by cytochrome P450-linked enzymes. The canonical molecular structure of local anesthetics contains a lipophilic aromatic ring system attached by an ester or amide intermediate chain to a hydrophilic tertiary amine. At physiological pH, local anesthetics exist as a mixture of a protonated acid and neutral base because of their tertiary amine. However, only the uncharged form can cross the membrane, and once intracellular, the ionized cationic form binds to a site on the inner pore of the sodium channel. Lowering the arterial pH may create intracellular ion trapping, thereby modifying cellular effects and potentially worsening toxicity. Local anesthetic systemic toxicity can result from either inadvertent intravascular injection or delayed absorption into circulation from the site of injection or application. Large volumes of local anesthetics are used for cosmetic procedures, including tumescent liposuction. Klein and Jeske have been leaders in the study of safe tumescent anesthesia and suggested that infiltration of lidocaine doses up to 45 mL/kg is safe. However, individual patient sensitivities, comorbidities, and physician or practice deficiencies may predispose to catastrophic outcomes. Furthermore, there are no universal mandated or regulatory reporting requirements that would reliably capture all catastrophic local anesthetic systemic toxicity events. Reporting of fatalities attributable to lidocaine toxicity in otherwise healthy patients following tumescent liposuction has occurred. Cardiac arrest and death caused by local anesthetic systemic toxicity have occurred at outpatient plastic surgery centers, possibly related to large volumes or improper administration. Management of serious local anesthetic systemic toxicity is different from other cardiac arrest scenarios. For local anesthetic systemic toxicity, airway maintenance and oxygenation are the priority in treatment, because both hypoxia and acidosis exacerbate clinical local anesthetic systemic toxicity. Drug administration in response to cardiac arrest caused by local anesthetic systemic toxicity is also different because the standard adult dose of epinephrine (1 mg) can impair resuscitation from local anesthetic systemic toxicity. Therefore, in this scenario, the individual doses of epinephrine should be decreased to less than 1 μg/kg. Pharmacologic management of local anesthetic systemic toxicity should avoid use of vasopressin, calcium channel blockers, beta-adrenergic blockers, or other local anesthetics. A practitioner who suspects local anesthetic systemic toxicity should immediately stop the procedure and call for assistance. In a local anesthetic toxicity event, a summary of the critical steps required to manage the event after stopping the procedure includes: airway management (oxygenate and ventilate), secure intravenous access, seizure suppression, and, if needed, cardiopulmonary resuscitation. Alert the nearest facility that has a cardiopulmonary bypass capability, and administer 20% lipid emulsion. Flumazenil is used to reverse the effects of benzodiazepine toxicity. Naloxone hydrochloride is used to reverse the effect of opiates. 2023

Answer 91

The correct response is Option B. While advanced age has been historically considered a risk factor for increased postoperative complications, this idea has been challenged in the literature, particularly in plastic surgery where many procedures are elective and patients can be functionally optimized for surgery. More recently, the concept of frailty has been suggested as an alternative and better predictor for poor surgical outcomes. While the original Canadian Study of Health and Aging Frailty Index consisted of 70 items, the modified 5-Item Frailty Index has shown similar predictive value with increased simplicity. The components of the modified 5-Item Frailty Index include the following: * Functional status before surgery * Diabetes mellitus * Chronic obstructive pulmonary disease * Congestive heart failure * Hypertension requiring medication 2023

Answer 92

The correct response is Option C. Vitamin B12 (cobalamin) deficiency may cause megaloblastic anemia, a type of macrocytic anemia. The process of vitamin B12 absorption is started by gastric acidity, which separates this vitamin from the food proteins it is attached to. Next, before it can be absorbed in the terminal ileum, vitamin B12 needs to be combined with a protein secreted by the stomach, called the intrinsic factor. Bariatric procedures that include partial gastrectomy can substantially decrease the production of hydrochloric acid and intrinsic factor by the stomach, disrupting the absorption of vitamin B12 from one's diet. Thus, at least annual screening is recommended for patients who have undergone Roux-en-Y gastric bypass. Prevalence of vitamin B12 deficiency in the postbariatric population is thought to be as high as 18%. Interestingly, serum measurement alone may not be adequate to identify vitamin B12 deficiency. It is recommended to include the serum concentration of methylmalonic acid (MMA) with or without homocysteine to identify metabolic deficiency of B12 in symptomatic and asymptomatic patients, in patients with history of B12 deficiency, or in patients with preexisting neuropathy. Megaloblastic anemia is characterized by ineffective erythropoiesis resulting from disrupted DNA synthesis, most commonly caused by deficiency of vitamin B12 or folic acid (folate). An incidental finding in routine laboratory testing is the most common presentation, since anemia usually develops gradually and symptoms are present only in severely anemic patients. When caused by vitamin B12 deficiency, neurologic symptoms can be observed, including balance disorder, paresthesias, and lower extremity pain. Diagnostic suspicion should be raised when a complete blood count shows anemia and high mean corpuscular volume or high mean corpuscular hemoglobin. The other vitamins listed are not associated with macrocytic anemias. Iron deficiency anemia may be common in patients with massive weight loss, but it causes a microcytic anemia. 2023

Answer 93

The correct response is Option B. Absolute stability is achieved by interfragmentary compression, which allows for direct bone healing without the formation of a callus. Forms of this osteosynthesis include lag screws, compression plates, and tension banding. Relative stability does not have interfragmentary compression at the fracture site, and healing is achieved through callus formation. Types of relative stability include intramedullary nailing, bridge plating, external fixation, and splinting/casting. 2023

Answer 94

The correct response is Option A. Use of the terms "whole brain death" and "brainstem death" is no longer recommended. Currently, the term brain death/death by neurologic criteria should be used. According to Greer et al, brain death/death by neurologic criteria can be defined as "the complete and permanent loss of brain function as defined by an unresponsive coma with loss of capacity of consciousness, brainstem reflex, and the ability to breathe independently." In this scenario, the patient is not conscious and is in a coma, in addition to being unable to breathe independently. Of the listed responses, the pupillary reflex is the only brainstem reflex. 2023

Answer 95

The correct response is Option B. Phentermine is a sympathomimetic amine that is prescribed for weight loss. Phentermine is a centrally acting sympathomimetic that is structurally related to amphetamines. It stimulates the hypothalamus to release norepinephrine, causing appetite suppression. Historically, formulations of the drug included a combination treatment with fenfluramine known as "fen-phen," which was discontinued in the late 1990s after several patient deaths stemming from cardiorespiratory complications. Over the last decade, however, stand-alone treatment with phentermine has been demonstrated to be safe and effective, and it remains the most prescribed anti-obesity weight loss drug in the country. Perioperatively, phentermine is associated with refractory hypotension on the induction of general anesthesia, hypothetically stemming from catecholamine depletion and subsequent autonomic dysfunction. In this situation, hypotension may not respond to vasopressors that stimulate catecholamine release (eg, ephedrine), and direct sympathetic agonists (eg, phenylephrine) may be needed. Other complications described in the literature include hypertension and hyperthermia, but these are much less common. Cardiac dysrhythmia, metabolic acidosis, and metabolic alkalosis are not described complications associated with phentermine use, and neither are seizures in the perioperative period. 2023

Answer 96

The correct response is Option B. Aspirin causes an increase in bleeding time through the inhibition of prostaglandin biosynthesis and platelet secretion reaction. Platelet function is altered, but not the platelet count. Prothrombin time/International Normalized Ratio, activated partial thromboplastin time, and D-dimer concentration are unaffected by routine aspirin use. 2023

Answer 97

The correct response is Option B. This patient is showing signs of lidocaine toxicity. Blood lidocaine concentration peaks approximately 12 hours after tumescent infiltration. Many authors have reported safe use of lidocaine in tumescent liposuction at doses of 35 mg/kg or higher. Toxic effects are generally considered to occur at blood concentrations of 6.0 mg/L (μg/mL) and greater; however, signs of toxicity may occur at lower plasma concentrations. These include gastrointestinal effects (commonly nausea and vomiting), central nervous system effects (such as anxiety, confusion, or light-headedness), and more severe and life-threatening effects (such as respiratory depression, seizures, and cardiovascular collapse). Selective serotonin reuptake inhibitors (such as sertraline) are competitive inhibitors of CYP3A4, which is the same enzyme that metabolizes lidocaine. A patient showing systemic effects of lidocaine toxicity should be treated with oxygen administration, and their plasma lidocaine concentration should be checked. If increased, then overnight observation in the hospital is warranted. Benzodiazepine treatment is not indicated for anxiety, and in fact, could further depress the respiratory system. It would only be indicated for treatment of lidocaine-induced seizures. Electrocardiography is not the study of choice for evaluating lidocaine toxicity. Obtaining blood cultures and complete blood count and administering broad-spectrum antibiotics are the first-line treatment of sepsis, but they are not indicated in this patient. Ultrasonography of the lower extremities can evaluate for deep venous thrombosis, but it is not indicated in this patient. 2023

Answer 98

The correct response is Option D. Replantation of composite tissues with high metabolic tissues such as muscle can result in an inflammatory reperfusion syndrome marked by acidosis, myoglobinuria, and hyperkalemia as the by-products of cellular breakdown are released into the circulatory system. In this scenario, myoglobinuria is suggested by the color of the urine and hyperkalemia becomes suspect with the peaked T waves. Calcium and magnesium can be used as cell membrane stabilizers to mitigate the effect of the potassium on the cardiac muscle. Glucose and insulin are used to move potassium intracellularly. Sodium balance is not directly affected in reperfusion. Phosphate plays a role in bone physiology. 2023

Answer 99

The correct response is Option C. This patient with an established diagnosis of obstructive sleep apnea (OSA) should continue to use a continuous positive airway pressure (CPAP) device at night throughout her stay in the hospital, both preoperatively and immediately postoperatively. Patients with OSA should be considered at an increased risk for perioperative complications, with studies reporting a two- to three-fold increase in adverse cardiopulmonary events. Sudden discontinuation of CPAP use by patients previously adherent to treatment has been shown to result in recurrence of OSA-related symptoms within 1 to 3 days and physiologic derangements within 2 weeks. An increasing number of studies suggest that CPAP therapy may play a role in mitigating the increased risk for perioperative complications in patients with OSA. Therefore, continued use of CPAP therapy is recommended during periods of sleep while hospitalized, including before and as soon as feasible after surgery. Adjustments may need to be made to the patient’s baseline CPAP device settings to account for perioperative changes, such as facial swelling, upper airway edema, fluid shifts, pharmacotherapy, and respiratory function. 2023

Answer 100

The correct response is Option A. Anaphylaxis to isosulfan blue dye is a well-documented risk with an incidence of 1 to 3%. This patient's symptoms are not consistent with malignant hyperthermia. Additionally, local anesthesia was used during the punch biopsy, so anaphylaxis to lidocaine is also unlikely. A skin preparation agent anaphylaxis is improbable with the severity of the symptoms. Lastly, a depolarizing agent like succinylcholine can cause histamine release, but the effects are usually transient. 2023

Answer 101

The correct response is Option D. Conventional local anesthetics provide effective postoperative analgesia but are limited by relatively short durations. Even longer-acting local anesthetics, such as bupivacaine hydrochloride, only last about 8 hours. Liposomal bupivacaine (Exparel) is a novel formulation designed for a rapid absorption and prolonged release of bupivacaine that maintains analgesia for up to 96 hours after surgery. Liposomal bupivacaine is available in two doses, 266 mg (20 mL) and 133 mg (10 mL). Dosing is not weight-based. The recommended dose is based on the surgical area that requires analgesic coverage. Large areas, such as the abdominal wall in an abdominoplasty, use the larger volume (266 mg), while the lower volume is used for smaller surgical fields, such as the hand, foot, and brachial plexus for regional nerve blocks. The volume of both doses may be safely expanded with saline or bupivacaine hydrochloride. Twenty mL of liposomal bupivacaine may be expanded with up to 280 mL of normal saline or Ringer's lactate, or up to 60 mL of 0.25% bupivacaine hydrochloride. However, while bupivacaine hydrochloride or saline/Ringer's lactate may be used for volume expansion, the addition of other local anesthetic solutions can alter the release rate of thebupivacaine. Therefore, liposomal bupivacaine and lidocaine should not be mixed together or injected into the same area at the same time. In this patient, injecting liposomal bupivacaine into the abdominal wall plication and lidocaine hydrochloride along the vertical component of a fleur-de-lis incision may cause rapid release of the active medication and alter the safety and efficacy of liposomal bupivacaine. Consequences of bupivacaine toxicity include methemoglobinemia, central nervous system reactions (eg, seizures, respiratory arrest), and cardiovascular dysfunction (eg, hypotension, heart block, dysrhythmias, cardiac arrest). 2023

Answer 102

The correct response is Option D. All of the deficiencies listed are common in massive weight loss patients who present for plastic surgery. It is critical to identify that this woman is exhibiting signs of Wernicke encephalopathy (WE). It is characterized by the classic triad of ataxia, eye movement disorders, and mental status change. This acute neuropsychiatric syndrome results from a deficiency of thiamine. The total number of reported post-bariatric WE cases is growing, and it is important to keep this in the differential for plastic surgery patients. Vomiting is the most frequently described presenting symptom. However, the most profound characteristic of WE identified is ataxia, which often presents itself as gait abnormalities up to the full inability to walk or move. Altered mental status manifests as delirium, confusion, and problems in alertness or cognition. Lastly, eye movement disorders, including nystagmus and ophthalmoplegia, resulting from extraocular muscle weakness, are seen in the majority of cases as well. Adequate and timely thiamine treatment in patients who have undergone bariatric surgery is required to prevent the development of WE, which is a rare but severe complication. Calcium deficiency presents more slowly, due to decreased absorption, and results in bone density loss, causing an increased risk for fracture. Folate deficiency also presents slowly secondary to decreased absorption. It results in anemia and can cause abnormal embryogenesis in pregnant women. Iron deficiency also presents slowly from a lack of adequate absorption and clinically causes anemia. Vitamin B12 requires stomach acid for it to be released from dietary protein. With a paucity of gastric tissue to produce that acid, this vitamin is also frequently deficient, resulting in a microcytic anemia. 2023