Anesthetics - Critical Care Flashcards
A 28-year-old woman, gravida 2, para 1, is brought to the emergency department after a motor vehicle collision in which she was a restrained passenger. ATLS evaluation shows that her vital signs are stable, and she is calm and lucid. The patient reports that she is 32 weeks’ pregnant. Repeat blood pressure is 80/60 mmHg, and the patient reports that she feels light-headed; tachycardia is noted. After maintaining cervical spine precautions, which of the following is the most appropriate initial management of this patient?
A) Administer 2 L crystalloid bolus
B) Intubate the patient
C) Logroll the patient onto her left side
D) Place patient in Trendelenburg position
E) Transfuse 2 units of blood
The correct response is Option C.
Pregnancy alters normal physiology as well as anatomy. At 32 weeks’ pregnancy, gravid uterus and fetus is anatomically at the costal margin and can be somewhat protective of bowel injury in a restrained passenger. A hematocrit of 31 to 35% is within normal range; however, the overall volume has increased dramatically and a loss of 1.2 to 1.5 L is well tolerated without symptoms.
Another crucial anatomical difference is the gravid uterus and its ability to compress the vena cava while in the supine position. Thirty percent decreased cardiac output can occur from the uterus occluding venous return from the lower extremity. In order to avoid this, the uterus should be physically displaced to the patient’s left side to allow return from the inferior vena cava. Should there be cervical spine precautions, the board can be rolled to the left 4 to 6 inches, thus alleviating pressure. In general, pregnant patients should be monitored on their left side.
Maternal well-being is the most crucial for fetal well-being, as the number one cause of fetal death is maternal hypotension and maternal death. The second most common cause of fetal death is abruption of the placenta. Fetal monitoring is extremely important, especially after 20 to 24 weeks’ gestation. However, in this case there is no evidence of cramping or tender abdomen.
Advanced Trauma Life Support (ATLS) protocol dictates airway, breathing, and circulation are normal, and, in this case, her airway and breathing are normal. The most appropriate next step is reestablishing this patient’s circulation, which is alleviating the initial possibility of decreased venous return. Should this not occur, then following the protocol for crystalloid resuscitation would be the most appropriate.
A 65-year-old woman undergoes ventral hernia repair with component separation and mesh placement. On postoperative day two, the patient suddenly becomes unresponsive and has no palpable pulse. Cardiopulmonary resuscitation (CPR) is promptly started and a cardiac monitor is attached. Cardiac tracing is consistent with pulseless electrical activity (PEA). Administration of which of the following drugs is most appropriate in this patient?
A) Adenosine
B) Atropine
C) Diltiazem
D) Dopamine
E) Epinephrine
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.
A 57-year-old man has chest pain in the recovery room after undergoing uneventful septorhinoplasty for repair of a deviated septum and collapsed internal nasal valve. Electrocardiography shows changes consistent with acute myocardial ischemia. He has no history of cardiac disease and takes no medications. Weight is 154 lb (70 kg). Intraoperative anesthesia included 1% lidocaine 20 ml with 1:100,000 epinephrine infiltrated into the nasal tissues, followed by intranasal placement of pledgets soaked in 4 ml of 10% cocaine solution. Infraorbital nerve blocks were performed bilaterally using a total of 10 ml of 0.5% bupivacaine. Which of the following is the most likely mechanism of the myocardial ischemia?
(A) Decreased systolic and diastolic left ventricular function
(B) Histamine-induced coronary spasm
(C) Impaired depolarization of the cardiac action potential
(D) Increased peripheral vascular resistance
(E) Vasoconstriction of epicardial coronary arteries
The correct response is Option E.
The most likely cause of change in electrocardiography in the patient described is vasoconstriction of the epicardial coronary arteries caused by a toxic dose of cocaine. The maximum safe dose of cocaine is 1.5 mg/kg, or 100 mg in a 70-kg adult. The patient described received a topical dose of 400 mg. With an average 37% mucosal absorption rate, the absorbed dose is still approximately 150 mg. Cocaine increases myocardial oxygen demands via alpha €‘adrenergic stimulation and decreases myocardial oxygen supply through vasoconstriction of the coronary arteries, resulting in myocardial ischemia. Adverse cardiovascular reactions are possible after the administration of local anesthetics. At toxic levels, lidocaine and bupivacaine block sodium channels in cardiac tissue, resulting in a depressed rate of depolarization during phase 0 of the cardiac action potential. This manifests as prolonged QRS width, depression of left ventricular function, and ventricular arrhythmias from increased activity in reentrant pathways. Hypersensitivity reactions to local anesthetics usually result in a shock-type scenario with hypotension, although histamine can cause coronary artery spasm. High doses of epinephrine can cause hypertension through increased peripheral vascular resistance. The doses of lidocaine, epinephrine, and bupivacaine that were administered to the patient described were within the range of maximum recommended doses.
A 16-year-old boy who has asthma is brought to the emergency department 3 hours after accidentally injecting the index finger of the nondominant hand with his epinephrine auto-injector. On examination, the finger is cool, pale, and painful. Which of the following drugs works to competitively antagonize the sympathomimetic effects of epinephrine?
A) Lidocaine
B) Marcaine
C) Nitroglycerin paste
D) Phentolamine
E) Prostacyclin
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.
A 40-year-old woman with a history of severe postoperative nausea and vomiting is scheduled for exchange of bilateral breast tissue expanders for permanent silicone implants. Use of which of the following medications is most likely to decrease the chance of postoperative nausea?
A) Bupivacaine
B) Fentanyl
C) Isoflurane
D) Midazolam
E) Nitrous oxide
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
An otherwise healthy 52-year-old woman with a family history of cardiac disease undergoes suction-assisted lipectomy of the flanks, thighs, and abdomen using a tumescent technique. She returns to the emergency department 6 hours after discharge because of slurred speech and restlessness. Which of the following is the most likely diagnosis?
A) Fat embolism
B) Lidocaine toxicity
C) Parietal stroke
D) Pulmonary embolism
E) Third spacing
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.
A 25-year-old man presents for consultation for surgical resection of a large abdominal pannus. The patient’s mother has a history of malignant hyperthermia. Which of the following best describes the inheritance pattern of this condition?
A) Autosomal dominant
B) Autosomal recessive
C) Mitochondrial
D) X-linked dominant
E) X-linked recessive
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.
A 43-year-old woman is scheduled to undergo bilateral tissue expander-based breast reconstruction. Preoperative pectoral nerve 1 and 2 blocks with liposomal bupivacaine with ultrasound guidance is performed. An image is shown. When performing pectoral nerve 1 block in this patient, which of the following is the most appropriate location for infiltration of the local anesthetic?
A) Between the breast parenchyma and pectoralis major
B) Between the pectoralis major and pectoralis minor
C) Between the pectoralis minor and the serratus anterior
D) Between the serratus anterior and the latissimus dorsi
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.
A 65-year-old man is evaluated for an increased serum potassium concentration of 6 mEq/L. ECG shows peaked T waves, decreased P wave amplitude, and prolonged QRS wave duration. Which of the following is the most appropriate initial step in management?
A) Administration of acetazolamide 250 mg intravenously
B) Administration of metoprolol succinate 20 mg in 4 mL nebulization, inhaled over 10 minutes
C) Administration of spironolactone 100 mg intravenously over 2 to 3 minutes, repeated after 5 minutes if ECG changes persist or recur
D) Administration of succinylcholine 30 g orally, and repeated every 2 hours as indicated
E) Administration of 10 units of regular insulin followed by 50 mL of 50% dextrose intravenously
The correct response is Option E.
Acute hyperkalemia is an electrolyte derangement that can result from a variety of scenarios including supratherapeutic potassium replacement, rhabdomyolysis, hemolysis, tumor lysis syndrome, severe sepsis, acute renal failure, and Addison disease. Among the most serious manifestations are progressive neuromuscular paralysis and progressive volatility in cardiac conduction terminating in cardiac arrest. The spectrum of cardiac collapse is evident on ECG starting with peaked T waves, decreased P wave amplitude, and prolonged QRS wave duration, followed by progressive blending of QRS and T waves into a sinusoidal ventricular fibrillation, followed by asystole.
Because cardiac arrest can occur at any point during ECG progression, hyperkalemia with ECG changes constitutes a medical emergency. Rapidly acting treatments aimed at sequestering or reducing serum potassium include administration of calcium, insulin with glucose, beta-2-adrenergeic agonists (e.g., albuterol, sodium bicarbonate), potassium wasting diuretics (e.g. furosemide), cation exchange resins (e.g., Kayexalate), and dialysis.
Of the options listed, only insulin with glucose is an accepted rapidly acting treatment for hyperkalemia. It works primarily by driving via the activity of the Na-K-ATPase pump in skeletal muscle. The effect begins in 10 to 20 minutes, peaks at 30 to 60 minutes, and lasts for four to six hours. Insulin can be given alone if serum glucose is > 250 mg/dL, and treatment can be repeated as needed. In all cases, serum glucose should be monitored to avoid acute hypoglycemia.
Temporary paresthesia is most likely in which of the following teeth after an infraorbital nerve block is performed?
A) Both central incisors, ipsilateral lateral incisor and canine
B) Both central incisors, ipsilateral lateral incisor, canine, and first and second molars
C) Ipsilateral central incisor, lateral incisor, canine, and both bicuspids
D) Ipsilateral lateral incisor, canine, both bicuspids, and first and second molars
E) Ipsilateral canine, both bicuspids, and first and second molars
The correct response is Option C.
Anesthetic blocks are routinely performed for office procedures. They are especially useful for facial procedures because of their reliable anatomy. Understanding the anatomy of each of the branches of the trigeminal nerve is important to successfully use this technique. The superior alveolar branch is a branch of the infraorbital nerve that controls sensation to the central and lateral incisor, the canine, and both bicuspid teeth.
The first and second molars are not innervated by branches of the infraorbital nerve. The contralateral central incisor is not innervated by the contralateral infraorbital nerve.
A 5-year-old girl undergoes repair of a forehead laceration in the emergency department. Administration of ketamine is used for sedation. Which of the following best describes intravenous administration of ketamine when compared with intramuscular administration in this patient?
A)Higher rate of laryngospasm
B)Longer duration of effect
C)Longer time to clinical onset
D)Lower rate of vomiting
The correct response is Option D.
Ketamine can be administered intravenously or intramuscularly. Intravenous injection is generally safer, and has a lower rate of laryngospasm, shorter duration of clinical onset and effect, and lower rate of vomiting. It can be titrated with a continuous infusion or repeated boluses to effect.
A 56-year-old woman has been in the intensive care unit since she was struck by a car 2 weeks ago. She sustained multiple facial fractures, severe closed head injury with cerebral contusion, pelvic fractures, and multiple lower extremity fractures. The patient required emergent intubation and has been in a coma since the injury. The patient’s current serum sodium concentration is 148 mEq/L, and urinalysis demonstrates dilute urine with low osmolality. Neurogenic diabetes insipidus is suspected. A deficiency in which of the following hormones is most likely the principal cause of this electrolyte imbalance?
A) Aldosterone
B) Angiotensin
C) Cortisol
D) Renin
E) Vasopressin
The correct response is Option E.
Neurogenic or central diabetes insipidus is often caused by head trauma resulting in a lack of vasopressin production. Vasopressin is released by the posterior pituitary gland but, unlike other pituitary hormones, is produced in the hypothalamus. Because of this unique relationship, traumatically induced neurogenic diabetes insipidus may occur due to damage to the hypothalamus, pituitary stalk, or posterior pituitary. Vasopressin, also known as antidiuretic hormone (ADH), plays a key role in fluid homeostasis by affecting water retention in the kidneys at the collecting ducts and distal convoluted tubule.
Cortisol is a hormone secreted by the adrenal glands that plays a role in numerous functions including maintaining normal metabolism and regulation of fluid balance. Angiotensin and aldosterone are key hormones of the renin-angiotensin system that is involved in the regulation of plasma sodium concentration and arterial blood pressure. Renin (also known as angiotensinogenase) is an enzyme that converts angiotensinogen to angiotensin. Angiotensin is a peptide hormone that causes vasoconstriction. It is formed by the action of renin on the liver-derived precursor, angiotensinogen, followed by the action of angiotensin-converting enzyme (ACE) to convert angiotensin I to the active form angiotensin II. Aldosterone is a steroid hormone produced by the adrenal glands and released in response to increased angiotensin. It plays a central role in regulation of plasma sodium, extracellular potassium, and arterial blood pressure. Cortisol, renin, angiotensin, and aldosterone deficiencies are not created by neurogenic diabetes insipidus related to head trauma.
A 59-year-old woman is scheduled to undergo blepharoplasty. She has a history of postoperative nausea and vomiting. Administration of which of the following anesthetic agents is most appropriate for this patient?
A ) Inhalational nitrous oxide
B ) Inhalational sevoflurane
C ) Intravenous etomidate
D ) Intravenous ketamine
E ) Intravenous propofol
The correct response is Option E. Postoperative nausea and vomiting (PONV) is a multifactorial entity, comprising patient, surgical, and anesthetic factors. Attempts have been made to identify the risk factors. A recent study concluded that female gender, a history of motion sickness or PONV, nonsmoking status, and use of postoperative opioids were most predictive. The incidences of PONV with the presence of zero, one, two, three, or all four of these risk factors were 10%, 21%, 39%, 61%, and 79%, respectively. Some surgical procedures are associated with a higher incidence of PONV, eg, major breast procedures, strabismus surgery, laparoscopy, and laparotomy. Agents used during anesthesia, including opioids, nitrous oxide (N2O), and volatile inhalational anesthetics, are emetogenic. Pain, anxiety, and dehydration may also increase the incidence of PONV. Propofol is widely used in ambulatory surgery because of its favorable clinical characteristics, including rapid recovery and minimal PONV. When compared with propofol, sevoflurane is associated with a higher incidence of PONV. Etomidate has minimal cardiovascular side effects, but it has a high incidence of PONV and is not commonly used in outpatient anesthesia. Nitrous oxide has been found to increase PONV when used as a primary anesthetic agent but not when used in combination with other agents. Intravenous anesthesia with ketamine has a lower risk of pulmonary aspiration but may result in higher rates of PONV.
A 48-year-old man who sustained severe traumatic brain injury and extensive facial fractures in a motor vehicle collision 2 weeks ago is receiving ventilatory support and enteral nutrition via feeding tube. An indirect calorimetry assessment shows a respiratory quotient (RQ) value of 1.3. This value is most closely associated with which of the following types of metabolism?
A) Carbohydrate oxidation
B) Ketosis
C) Lipid oxidation
D) Lipogenesis
E) Protein oxidation
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.
The American Association for Accreditation of Ambulatory Surgery Facilities (AAAASF) standards mandate that all facilities must have which of the following drugs readily available for the treatment of malignant hyperthermia?
A ) Dalteparin
B ) Dantrolene
C ) Darifenacin
D ) Dicyclomine
E ) Dobutamine
The correct response is Option B.
Dantrolene is the only clinically available drug for the specific treatment of malignant hyperthermia. Malignant hyperthermia is a rare but potentially fatal sensitivity to volatile anesthetics and depolarizing neuromuscular blocking agents. When genetically susceptible individuals are given anesthesia with these agents, the classic findings include skeletal muscle rigidity, tachycardia, fever, cardiac arrhythmias, and metabolic and respiratory acidosis, leading to severe hypotension. Hyperthermia, the hallmark of malignant hyperthermia, is most often a late sign. The earliest signs are tachycardia and an increase in the end-expired carbon dioxide concentration. With the use of dantrolene, the mortality from malignant hyperthermia decreased from 80% in 1960 to less than 10%. Dantrolene is a skeletal muscle relaxant that depresses the intrinsic mechanisms of excitation-contraction coupling. The mainstay of treatment for malignant hyperthermia includes discontinuance of the inciting anesthetic agents, rapid body cooling, and dantrolene. Rapid dantrolene preparation and infusion are critical. Therapy is started by continuous rapid intravenous push beginning at a dose of 1 mg/kg to 2.5 mg/kg and continuing until symptoms subside or the maximum cumulative dose of 10 mg/kg is reached. If symptoms reappear, the regimen may be repeated. Dantrolene is packaged in powdered form as a 20-mg vial which must be reconstituted with 60 mL of sterile water for injection (without a bacteriostatic agent). Acidic solutions such as 5% dextrose and 0.9% sodium chloride should not be used. The effective dose to reverse the crisis will vary in each individual. Pediatric dosing is the same as for adults. Care must be taken during infusion to avoid extravasation because there is a possibility for tissue necrosis because of the high pH. Malignant hyperthermia may not occur during the first exposure to an anesthetic triggering agent, but it may develop during subsequent operations. Symptoms range from mild to life-threatening hyperthermic crisis. The only screening test for susceptibility is through muscle biopsy. Dantrolene should be administered preoperatively to patients prone to malignant hyperthermia; anesthetic drugs that are known to trigger malignant hyperthermia should be avoided. Medications considered safe for patients susceptible to malignant hyperthermia include both lidocaine and bupivacaine. General anesthesia can be performed with alternative anesthetic regimens including nondepolarizing paralytic agents, nitrous oxide, and opioids (eg, vecuronium, propofol [Diprivan], and fentanyl). Dobutamine is an inotropic agent that may be used to support circulation in severe malignant hyperthermia, but it is not specific for the disease. Dicyclomine is an anticholinergic used to treat irritable bowel syndrome. Darifenacin is a muscarinic receptor antagonist used to treat overactive bladder. Dalteparin is a low-molecular-weight heparin used as deep vein thrombosis prophylaxis.
A 63-year-old woman has a superficial surgical site infection at her abdominal incision two weeks following deep inferior epigastric perforator (DIEP) breast reconstruction. The CDC categorizes a “superficial incisional surgical-site infection” as occurring within how many days of the procedure?
A) No more than 7 days
B) No more than 14 days
C) No more than 30 days
D) No more than 60 days
E) No more than 90 days
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
Which of the following must be present in order to initiate a brain death examination?
A) Absence of deep tendon reflexes
B) Anoxia
C) Cause of brain death
D) Hypothermia
E) Ventilatory dependence with muscle relaxation (neuromuscular blockade)
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.
A 63-year-old man with end-stage renal failure is evaluated for unilateral leg swelling and shortness of breath 2 days after undergoing bilateral axillary hidradenitis excision. Current medication includes aspirin. Oxygen saturation on room air is 88%. During diagnostic evaluation, empiric administration of which of the following drugs is most appropriate?
A) Intravenous heparin
B) Oral clopidogrel
C) Oral rivaroxaban
D) Oral warfarin
E) Subcutaneous enoxaparin
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.
A 30-year-old woman with a history of Crohn disease undergoes ventral hernia repair. BMI is 31 kg/m2. Which of the following is the greatest risk factor for postoperative nausea and vomiting in this patient?
A) Elevated body mass index
B) Perioperative fasting
C) Placement of nasogastric tube
D) Supplemental oxygen
E) Young age
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.
An otherwise healthy 45-year-old woman presents for abdominoplasty. Administration of liposomal bupivacaine for postoperative pain control is planned. Which of the following is the maximum dose of liposomal bupivacaine that can be administered in a single dose in this patient?
A) 50 mg
B) 133 mg
C) 200 mg
D) 266 mg
E) 399 mg
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.
A 71-year-old man with chronic obstructive pulmonary disease (COPD) is transferred to the hospital with multiple facial lacerations and fractures following a fall. He has increasing confusion on arrival at the hospital. His wife mentions that he had bled a significant amount after the fall. Laboratory studies show:
On the basis of these findings, this patient’s primary metabolic disorder is which of the following?
A) Respiratory acidosis due to exacerbation of his COPD
B) Metabolic acidosis due to hemodilution from bleeding
C) Metabolic alkalosis due to exacerbation of his COPD
D) Metabolic alkalosis due to hemodilution from bleeding
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.
A 30-year-old woman undergoes tumescent liposuction with fat transfer to the
buttocks (Brazilian butt lift). History includes anxiety, for which she takes
sertraline. Twelve hours after the patient is discharged from the recovery room,
she presents to the emergency department with nausea, vomiting, and anxiety.
Which of the following is the most appropriate next step in management?
A) Administer benzodiazepine
B) Administer supplemental oxygen, and measure plasma lidocaine concentration
C) Obtain blood cultures and complete blood count, and administer broad-spectrum antibiotics
D) Order electrocardiography
E) Order ultrasonography of the lower extremities
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.
REFERENCES:
1. Klein JA, Jeske DR. Estimated maximal safe dosages of tumescent lidocaine. Anesth
Analg. 2016;122(5):1350-1359. doi: 10.1213/ANE.0000000000001119
2. Klein JA. Lidocaine toxicity and drug interactions. In: Tumescent Technique: Tumescent
Anesthesia & Microcannular Liposuction. Mosby; 2000:162-169.
A 37-year-old man, who is American Society of Anesthesiologists (ASA) Class 2, comes to the office for evaluation and treatment of human immunodeficiency virus (HIV)–associated lipodystrophy. The patient has a CD4 count of 100 cells/mm3. Autologous fat grafting is planned. Which of the following factors is most likely to increase this patient’s risk of postoperative complications?
A) ASA Class
B) CD4 cell count
C) HIV seropositivity
D) Percutaneous surgery
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.
A 54-year-old woman undergoes abdominoplasty and hysterectomy. Postoperative rivaroxaban is initiated for prevention of deep venous thrombosis. Three days later, she presents for follow-up, and a hematoma requiring drainage is noted. This outcome is most likely related to the fact that rivaroxaban blocks the coagulation cascade in which of the following ways?
A) Binds factors II, VII, IX, and X
B) Prevents conversion of prothrombin to thrombin
C) Prevents degranulation of platelets
D) Prevents thrombin from activating fibrinogen
E) Prevents tissue factor:factor VIIa complex formation
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.
A 31-year-old woman is evaluated for augmentation mammaplasty and
mastopexy. She sees a local primary care physician who specializes in medical
weight loss. In addition to diet modifications and a rigorous exercise regimen, she
was also prescribed phentermine. Which of the following is the most common
perioperative complication associated with administration of this drug?
A) Cardiac dysrhythmia
B) Hypotension
C) Metabolic acidosis
D) Metabolic alkalosis
E) Seizures
Upon further review, this item was not scored as part of the examination.
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.
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.
REFERENCES:
1. Lim S, Rogers LK, Tessler O, Mundinger GS, Rogers C, Lau FH. Phentermine: a systematic
review for plastic and reconstructive surgeons. Ann Plast Surg. 2018;81(4):503-507. doi:
10.1097/SAP.0000000000001478
2. Kaplan LM. Pharmacologic therapies for obesity. Gastroenterol Clin North Am.
2010;39(1):69-79. doi: 10.1016/j.gtc.2010.01.001
3. Shiffman MA. Anesthesia risks in patients who have had antiobesity medication. Plast
Reconstr Surg. 1998;102(3):927-928.
4. Shi Q, Wang Y, Hao Q, et al. Pharmacotherapy for adults with overweight and obesity: a
systematic review and network meta-analysis of randomised controlled trials. Lancet.
2022;399(10321):259-269. doi: 10.1016/S0140-6736(21)01640-8
A 35-year-old woman comes to the office for consultation on augmentation mammaplasty. During preoperative workup, she reports that her mother has a history of malignant hyperthermia. The patient has never undergone surgery. Which of the following anesthetic agents is most appropriate for this surgery?
A) Desflurane
B) Halothane
C) Isoflurane
D) Propofol
E) Succinylcholine
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.
A 78-year-old man who was recently diagnosed with low rectal cancer presents to the office for evaluation. The patient is accompanied by his daughter, who fills out all the questionnaires for him. Medical history includes hypertension, osteoarthritis, and bilateral knee replacements 20 years ago. Vital signs are within normal range. BMI is 21.5 kg/m2. He ambulates with a walker. Physical examination is otherwise unremarkable. An abdominoperineal resection and perineal reconstruction are planned. Obtaining which of the following is the most appropriate next step in assessing this patient’s risk for perioperative complications?
A) APACHE II score
B) FEV1/FVC ratio
C) Frailty index
D) Liver function tests
E) Sequential Organ Failure Assessment (SOFA) score
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.
A 42-year-old man presents with partial degloving injury of the right leg and fracture of the pelvis sustained during a motorcycle collision 2 weeks ago. Medical history includes factor V Leiden. BMI is 31.1 kg/m2. Skin graft reconstruction of the degloving injury of the leg is planned. According to the Caprini Risk Assessment Model (2005), which of the following conditions in this patient represents the greatest risk for perioperative venous thromboembolism?
A) Age
B) BMI greater than 25 kg/m2
C) Major surgery (greater than 45 minutes in duration)
D) Pelvic fracture
E) Positive factor V Leiden
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.
A 69-year-old man is evaluated in the intensive care unit 5 days after undergoing abdominal wall reconstruction for a multiple-recurrence ventral hernia. Medical history shows no cardiac disease. Temperature is 103°F (39°C), heart rate is 110 bpm, and mean arterial pressure (MAP) is 50 mmHg. Airway and ventilation are secured, and supplemental oxygen is initiated. Hemoglobin concentration is 9 g/dL. Which of the following is the most appropriate next step in management?
A) Initiation of inotropic support
B) Initiation of vasopressor support
C) Introduction of a pulmonary artery catheter to monitor wedge pressures
D) Volume resuscitation with crystalloid
E) Volume resuscitation with packed red blood cells
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.
A 45-year-old woman undergoes abdominoplasty in an ambulatory surgery center. After induction of general anesthesia, the patient’s end tidal carbon dioxide level increases, her heart rate increases to 160 bpm, and her arms become rigid. Which of the following are the physiologic abnormalities associated with this condition?
A) Hyperkalemia, hyperphosphatemia, metabolic acidosis
B) Hyperkalemia, hyperphosphatemia, metabolic alkalosis
C) Hyperkalemia, hypophosphatemia, metabolic acidosis
D) Hypokalemia, hyperphosphatemia, metabolic acidosis
E) Hypokalemia, hyperphosphatemia, metabolic alkalosis
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.
A 63-year-old woman undergoes sternal reconstruction. On postoperative day 1,
she goes into cardiac arrest, advanced cardiac life support protocols are initiated,
and pulse resumes. Four days later, the patient remains ventilator-dependent,
unresponsive, and in a comatose state. Which of the following physical
examination findings provides the strongest support of brain death/death by
neurologic criteria in this patient?
A) Absent pupillary response to light
B) Loss of bicep reflexes
C) Positive Babinski reflex
D) Positive Hoffman sign
E) Urinary incontinence
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.
REFERENCES:
1. Greer DM, Shemie SD, Lewis A, et al. Determination of brain death/death by neurologic
criteria. JAMA. 2020;324(11):1078-1097. doi: 10.1001/jama.2020.11586
2. Russell JA, Epstein LG, Greer DM, et al. Brain death, the determination of brain death, and
member guidance for brain death accommodation requests: AAN position statement.
Neurology. 2019;92(6):228-232.
A 23-year-old woman is scheduled to undergo augmentation mammaplasty with intravenous administration of a sedative and local injection of 1% lidocaine with 1:100,000 epinephrine. Weight is 110 lb (50 kg). Which of the following is the maximum dose of lidocaine with epinephrine that can be administered to this patient?
A) 20 mL
B) 25 mL
C) 30 mL
D) 35 mL
E) 40 mL
The correct response is Option D.
The maximum dose of lidocaine with 1:100,000 epinephrine recommended for nontumescent injection is 7 mg/kg. In the 110-lb (50-kg) patient described, the maximum dose is 350 mg. One percent lidocaine with 1:100,000 epinephrine contains 10 mg per 1 mL; therefore, the maximum dosage for injection is 35 mL.
A 40-year-old woman is scheduled to undergo exploration and repair of an isolated tendon laceration. An infusion of 1% lidocaine with 1:100,000 epinephrine is administered from the mid palm to the middle phalangeal area. No tourniquet or additional anesthesia is planned. Which of the following conditions is the surgeon most likely to encounter during surgery?
A) Critical digital ischemia
B) Enhanced tendon mobility
C) Excessive patient anxiety
D) Optimal surgical field
E) Poor hemostasis
Please note: Upon further review, this item was not scored as part of the examination.
The correct response is Option D.
Generations of physicians, beginning in medical school, have been trained to avoid epinephrine use in fingers due to the fear of inducing ischemic necrosis. However, comprehensive literature reviews and large clinical outcome studies have failed to show any harmful effects resulting from the appropriate use of standard, current preparations of lidocaine with 1:100,000 epinephrine. The few cases of digital necrosis reported in the literature employed agents such as cocaine and procaine with undisclosed volumes of injection or concentrations of epinephrine.
Large case series of common hand procedures, such as carpal tunnel surgery and tendon repair, support the safety of a local anesthesia-only, tourniquet-free approach. Tourniquets and upper extremity blocks, while generally very safe, are not without morbidity or complication.
In patients who demonstrate excessive intraoperative blanching or concerning symptoms of ischemia, phentolamine can safely reverse the vasoconstrictive effects of epinephrine. In one study of over 3000 patients, not a single case required phentolamine reversal.
Study authors recommend direct volar digital injections of 2 mL of local anesthesia. Up to 30 mL may be used in the wrist and hand and more in the forearm, if needed. The tumescent effect provides a fully anesthetic, bloodless field for optimal visualization.
The use of local anesthesia should not impact tendon mobility. Intraoperative patient anxiety can occur in any awake patient, whether they receive local or regional anesthesia. In the numerous studies of local anesthesia hand surgery, patients appear to tolerate the procedure well. Avoiding tourniquet pain is particularly advantageous in patients who do not receive general anesthesia. The local anesthesia tumescent block technique should provide excellent analgesia and should not increase patient discomfort.
A 37-year-old woman undergoes left breast reconstruction with a deep inferior
epigastric artery perforator flap. During dissection of the internal mammary
vessels, a small tear is inadvertently made in the left parietal pleura. The decision
is made to repair the tear primarily, using a single figure-of-eight suture. Which of
the following ventilatory maneuvers is most appropriate immediately prior to
cinching the stitch for pleural closure?
A) Decreasing positive end-expiratory pressure
B) Disconnecting the endotracheal tube
C) Pausing at end-expiration
D) Sustaining maximal inspiration
E) Switching to volume-controlled ventilation mode
The correct response is Option D.
The most appropriate ventilatory maneuver to perform just before cinching the last stitch of the
repair of an isolated parietal pleura tear is sustaining maximal inspiration for a few seconds, also
known as a modified Valsalva maneuver. Once the parietal pleura is closed, normal lung
ventilation can resume. The goal is to fully inflate the lungs to maximize positive pressure in the
pleural cavity, displacing any residual pneumothorax through the pleural defect before finishing an
air-tight repair of the parietal pleura or chest wall. The maneuver is probably most commonly
performed manually by the anesthesiologist (using the ventilator’s built-in bag valve mask), but it
can also be done by holding ventilation at the end of an inspiratory cycle or by significantly
increasing the positive-end-expiratory pressure (PEEP).
Pausing ventilation at the end of expiration (without first increasing PEEP), disconnecting the
endotracheal tube, decreasing PEEP, or switching to volume-controlled ventilation would not
achieve the goal of increasing/maximizing pleural pressure.
REFERENCES:
1. Kelling JA, Meade A, Adkins M, Zhang AY. Risk of pneumothorax with internal mammary
vessel utilization in autologous breast reconstruction. Ann Plast Surg. 2021;86(3S Suppl
2):S184-S188. doi: 10.1097/SAP.0000000000002643
A 23-year-old woman with no history of surgery undergoes augmentation mammaplasty with administration of nitrous oxide, isoflurane, and propofol. Sixty minutes into the procedure, the nurse anesthetist notifies the surgeon that the patient has increasing end-tidal carbon dioxide concentrations, tachycardia, and severe masseter muscle rigidity. Which of the following is the most appropriate next step in management?
A) Administer intravenous saline
B) Administer a muscle relaxant
C) Stop isoflurane
D) Stop nitrous oxide
E) Stop propofol
The correct response is Option C.
The patient is experiencing signs of early malignant hyperthermia, which is a life-threatening crisis and requires immediate attention. The typical symptoms of malignant hyperthermia are caused by a hypercatabolic state with increased heart rate, increased breathing rate, increased carbon dioxide production, increased oxygen consumption, acidosis, masseter muscle rigidity, and rhabdomyolysis. Very high temperature (110.0°F [43.0°C]) usually presents late. Even if treated properly, death may occur as brain damage, muscle damage, renal failure, and multiple organ failure ensue. The malignant hyperthermia crisis is a biochemical chain reaction response that is “triggered” by commonly used general anesthetics and the paralyzing agent succinylcholine within the skeletal muscles of susceptible individuals. Volatile gaseous inhalation anesthetics like sevoflurane, desflurane, isoflurane, and halothane can trigger malignant hyperthermia. The exact incidence of malignant hyperthermia is not known. Estimates vary from a frequency of one in 5000 to one in 65,000. Over 80 genetic defects have been associated with malignant hyperthermia. Malignant hyperthermia susceptibility is inherited with an autosomal dominant inheritance pattern. Children and siblings of a patient with malignant hyperthermia susceptibility usually have a 50% chance of inheriting a gene defect for malignant hyperthermia. The medical antidote is dantrolene. Additional methods include use of a hypothermia blanket (under/over the patient) and cold isotonic saline for intravenous solution.
A 22-lb (10-kg), 8-month-old infant is undergoing cranial vault reconstruction. The anesthesiologist informs the surgeon that the estimated blood loss is 150 mL. Approximately which of the following percentages of this patient’s circulating blood volume has been lost?
A) 10%
B) 20%
C) 30%
D) 40%
E) 50%
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
For infants the formula is 75 to 80 mL/kg
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.
A 37-year-old woman is scheduled to undergo skin-sparing mastectomy of the left breast with immediate deep inferior epigastric perforator (DIEP) flap reconstruction. Which of the following interventions is most likely to decrease this patient’s postoperative narcotic needs?
A) Application of a preoperative compression garment
B) Hypnosis
C) Ondansetron therapy
D) Oxycodone therapy
E) Pregabalin therapy
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.
A 67-year-old woman is scheduled to undergo carpal tunnel release under monitored anesthesia care with local anesthetic. Her comorbidities include type 1 diabetes mellitus (recent hemoglobin A1c is 7.4%), current everyday smoking, and rheumatoid arthritis, for which she takes methotrexate. Which of the following is the most appropriate antibiotic therapy to reduce this patient’s risk for surgical site infection?
A) Intravenous cefazolin, 30 minutes prior to induction, cephalexin 500 mg four times a day for 7 days postoperatively
B) Intravenous cefazolin, 30 minutes prior to induction, with no postoperative therapy
C) Intravenous cefazolin, 60 minutes prior to induction, cephalexin 500 mg four times a day for 7 days postoperatively
D) Intravenous cefazolin, 60 minutes prior to induction, with no postoperative therapy
E) No antibiotics indicated
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.
A 45-year-old woman with breast cancer is scheduled to undergo bilateral mastectomy. Immediate breast reconstruction with deep inferior epigastric perforator (DIEP) flaps is planned. Which of the following factors is most likely to increase this patient’s risk for microsurgical thrombotic complications?
A) BRCA-2 genetic mutation
B) Caprini Risk Assessment Model score of 5
C) History of prior irradiation following lumpectomy
D) History of prior thrombotic event
E) Sickle cell trait
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.
An otherwise healthy 22-lb (10-kg), 2-year-old boy undergoes extirpation of a 5 × 5-cm arteriovenous malformation of the face. To decrease intraoperative blood loss, infusion of which of the following solutions around the lesion is most appropriate?
A) 20 mL of 0.25% bupivacaine with 1:100,000 epinephrine
B) 20 mL of 0.25% bupivacaine with 1:200,000 epinephrine
C) 20 mL of 1.0% lidocaine with 1:100,000 epinephrine D) 20 mL of 1.0% lidocaine with 1:200,000 epinephrine E) 20 mL of 1:200,000 epinephrine
The correct response is Option E.
The most appropriate solution to infuse around the lesion to decrease intraoperative blood loss is 20 mL of 1:200,000 epinephrine. Although the maximum dose of subcutaneous epinephrine is unknown in a healthy child, large amounts have been shown to be safe in patients undergoing liposuction. The most conservative estimate for the amount of epinephrine (1:200,000) that can be safely injected in this child is 30 mL (3 mL/kg) every 10 minutes. Because this estimate was used in the past when halothane anesthesia was being administered (halothane lowered the arrhythmogenic threshold to epinephrine), greater volumes could likely be infused because other inhalational anesthetics are now used. Twenty mL of 1% lidocaine or 0.25% bupivacaine with epinephrine cannot be given to this 22-lb (10-kg) child because it exceeds the maximum dose. The maximum dose of lidocaine with epinephrine that can be administered is 7 mg/kg; because the concentration of 1% lidocaine is 10 mg/mL, only 7 mL of this solution could be injected. The maximum dose of bupivacaine with epinephrine that can be given is 3 mg/kg; because the concentration of 0.25% bupivacaine is 2.5 mg/mL, only 12 mL of this solution could be administered.
Which of the following patients is eligible to be an organ donor?
A) 30-year-old HIV-positive patient
B) 10-year-old whose family does not want to donate
C) 42-year-old with a diagnosis of Creutzfeldt-Jakob disease
D) 49-year-old with a recent diagnosis of stage IV melanoma
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.
An otherwise healthy 17-year-old boy is brought to the emergency department after sustaining a laceration of the distal middle toe. On examination, the toe is bleeding. Infusion of which of the following local anesthetics is most appropriate at the wound site before repair?
A) 0.5% Lidocaine
B) 1% Lidocaine
C) 1% Lidocaine with sodium bicarbonate
D) 1% Lidocaine with 1:200,000 epinephrine
E) 2% Lidocaine
The correct response is Option D.
The most appropriate local anesthetic to infuse at the wound site before repair is 1% lidocaine with 1:200,000 epinephrine. The addition of epinephrine to the local anesthetic increases the safety of the lidocaine and facilitates the laceration repair. Epinephrine slows the absorption of the local anesthetic, which allows lower doses to be used. Epinephrine also increases the duration of action of lidocaine, which provides longer pain relief. Vasoconstriction from the epinephrine reduces bleeding at the site of the injury, which shortens the operative time, lowers the risk of iatrogenic injury, and facilitates the repair. Epinephrine is not contraindicated in the fingers or toes. The vasoconstrictive effects of epinephrine only last for 60 to 90 minutes; much longer ischemia times are necessary to cause skin necrosis. For example, amputated digits may be successfully replanted after 33 hours of warm ischemia time. Although epinephrine diluted to a concentration of 1:1,000,000 (which is commonly used in tumescent solution for liposuction) will cause vasoconstriction, its onset is prolonged and its duration of action is shortened compared with epinephrine 1:200,000. Lidocaine or bupivacaine without epinephrine does not reduce bleeding at the site of injury, which increases the difficulty of the repair. In addition, without epinephrine, lower doses of local anesthetic must be used, and the patient has a shorter duration of pain relief.
A critically ill 65-year-old woman is brought to the intensive care unit, where she sustains respiratory arrest. Temperature is 101.3ºF (38.5ºC), heart rate is 105 bpm, and blood pressure is 85/60 mmHg. Hematocrit is 35%. She is immediately intubated. Noninvasive pulse oximetry is initiated to monitor oxygen saturation (SaO2). Which of the following conditions is most likely to alter pulse oximetry values in this patient?
A) Anemia
B) Fever
C) Hypotension
D) Tachycardia
E) Tachypnea
The correct response is Option (sic)
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.
Which of the following is LEAST sensitive to increasing plasma levels of lidocaine?
(A) Blood pressure
(B) Central nervous system activity
(C) Heart rate
(D) Muscle tone
The correct response is Option A.
Blood pressure is typically insensitive to increasing plasma levels of lidocaine and other local anesthetics because a compensatory increase in systemic vascular resistance prevents the blood pressure from increasing. Adverse reactions in the central nervous system are much more common and are biphasic. Initially, an excitatory phase occurs, which may be due to inhibition of the amygdala. This phase may produce muscle twitching in the face and extremities followed by tremors that can progress to seizures. As the amount of local anesthetic increases, a depressive phase occurs and is characterized by drowsiness, unconsciousness, and respiratory arrest. The cardiovascular system is thought to be more resistant than the central nervous system to the effects of local anesthetics. However, it can sustain dangerous reactions, usually at higher plasma levels. With toxic doses of local anesthetics, cardiovascular reactions may include arrhythmias, cardiovascular depression, and shock. Cardiovascular depression tends to be serious and difficult to treat. The more lipid-soluble local anesthetics, such as bupivacaine, tend to have a higher toxicity than the less lipid-soluble drugs, such as lidocaine. Toxic effects of local anesthetics result from inappropriately high dosage or unintentional intravascular injection. Management of lidocaine toxicity consists of ECG monitoring and oxygen administration. If seizures occur, they are typically controlled with diazepam or midazolam. If mechanical ventilation is required, paralytic agents may be administered. Because of the seriousness of the toxic effects, appropriate monitoring and personnel trained in advanced cardiac life support are required during local anesthetic use, regardless of the magnitude of the procedure.
A previously healthy 38-year-old woman has onset of a brief tonic-clonic seizure 30 minutes after a lidocaine-based tumescent anesthesia is administered during large-volume liposuction of the abdomen, hips, and thighs. After 3 minutes, she has onset of asystole, and cardiopulmonary resuscitation is initiated. She is unresponsive to the standard ACLS resuscitation protocols for asystole. Administration of which of the following is the most appropriate next step?
A) Dantrolene
B) Dimercaprol
C) Lipid emulsion
D) N-acetylcysteine
E) Naloxone
The correct response is Option C.
This is a case of inadvertent lidocaine toxicity with subsequent seizure and cardiac arrest. Furthermore, lipid emulsion has been used with apparent success early in the spectrum of local anesthetic systemic toxicity to preempt cardiac arrest. The role of lipid emulsion has expanded to treatment of cardiac toxicity due to other lipophilic drugs. Dantrolene is a treatment for malignant hypothermia. Dimercaprol is a chelating agent used for the treatment of heavy metal toxicities. N-acetylcysteine is used as a mucolytic and also in cases of acetaminophen overdose. Naloxone is used to treat narcotic overdose. There are no data to suggest that any of these medications are otherwise helpful in lidocaine toxicity.
A 165.3-lb (75-kg), 76-year-old woman is scheduled to undergo wide local excision of a large, invasive basal cell carcinoma of the cheek with flap reconstruction during general anesthesia. Medical history includes nonvalvular atrial fibrillation, hypertension, and an embolic stroke 3 months ago. Current medications include warfarin. Renal function is normal. Which of the following is the most appropriate preoperative anticoagulation management for this patient?
A) Discontinue warfarin 5 days prior to the procedure and initiate low-molecular-weight heparin bridging 3 days prior to the procedure
B) Discontinue warfarin 5 days prior to the procedure without bridging
C) Discontinue warfarin 7 days prior to the procedure and initiate low-molecular-weight-heparin bridging 3 days prior to the procedure
D) Immediately initiate low-molecular-weight heparin bridging and discontinue warfarin 5 days prior to the procedure
E) Do not discontinue warfarin
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.
A 36-year-old health-care worker sustains a needle-stick injury from a hepatitis C–seropositive patient. Immediate testing for anti-HCV antibodies and confirmatory immunoassays for HCV-RNA are performed. Initial follow-up testing after exposure should be performed at which of the following time periods?
A) 1 week
B) 3 weeks
C) 6 weeks
D) 12 weeks
E) 24 weeks
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.
A 25-year-old man with profound hyperhidrosis is undergoing botulinum toxin type A (BOTOX Cosmetic) injection. EMLA (prilocaine-lidocaine) cream is applied to the injection site. Which of the following best represents the minimum amount of time necessary to achieve anesthesia?
A ) 5 Minutes
B ) 15 Minutes
C ) 30 Minutes
D ) 60 Minutes
E ) 90 Minutes
The correct response is Option D.
EMLA (eutectic mixture of local anesthetic) is a highly effective method of inducing topical anesthesia. A eutectic mixture consists of two substances that when mixed have a lower melting point than either substance alone. EMLA uses a combination of lidocaine and prilocaine. It has excellent penetration and produces remarkably little sensitivity reaction. The efficacy of EMLA varies according to the relative thickness of the skin and its vascularity. The cream is applied fairly thickly (1-2 g of EMLA per 10 cm2 of skin) and a dressing such as Opsite or Tegaderm is used to keep it in place. Gentle regular massage to the area can be applied for at least an hour.
A 75-year-old woman with type 1 diabetes mellitus undergoes closure of a sternotomy wound using pectoralis major muscle flaps. On postoperative day 2, her plasma creatinine level has increased to 2.2 from 1.1 mg/dL preoperatively. The patient is hemodynamically stable in the ICU, and her central venous pressure is within normal range. An intravenous infusion of normal saline is initiated. Which of the following is the most appropriate next step in management?
A) Administration of a diuretic
B) Discontinuation of enteral nutrition and initiation of parenteral nutrition
C) Discontinuation of protein intake
D) Infusion of low-dose dopamine intravenously
E) Plasma glucose control protocol
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
A 42-year-old woman undergoes wide local excision and sentinel node biopsy of an invasive melanoma of the forearm. After uneventful induction of general anesthesia, 1 mL of isosulfan blue dye is injected intradermally around the healing biopsy site on the forearm. The operation begins with excision of the axillary sentinel lymph node, which is identified high in the axilla. During removal of the sentinel node, blood pressure decreases to 60/40 mmHg. After discontinuing the procedure and administering a bolus of intravenous fluid, which of the following is the most appropriate next step?
A) Administer dexamethasone
B) Administer diphenhydramine
C) Administer lipid emulsion
D) Administer phenylephrine
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.
After an uneventful breast reconstruction with an abdominal flap, a healthy 45-year-old woman is started on ketorolac as part of her multi-modality pain control regimen. Inhibition of which of the following is the primary mechanism of action for the increased bleeding time associated with this drug?
A) Lipoxygenase
B) Nitric oxide
C) Prostacyclin
D) Prostaglandins
E) Thromboxane A2
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.
A 45-year-old woman is admitted to the hospital because of multiple fluid
collections in bilateral gluteal regions. She underwent abdominoplasty and gluteal
fat grafting 2 weeks ago while traveling out of the country. She has obstructive
sleep apnea, for which she uses a continuous positive airway pressure (CPAP)
device at night. She is obese with a BMI of 42 kg/m2. Vital signs are within normal
limits. Surgical exploration of the gluteal collections is planned in the next 48
hours. The use of a CPAP device for this patient’s obstructive sleep apnea is most
appropriate during which of the following perioperative periods?
A) Immediate postoperative only
B) Neither preoperative nor immediate postoperative
C) Preoperative and immediate postoperative
D) Preoperative only
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.
REFERENCES:
1. Chung F, Memtsoudis SG, Ramachandran SK, et al. Society of Anesthesia and Sleep
Medicine guidelines on preoperative screening and assessment of adult patients with
obstructive sleep apnea. Anesth Analg. 2016;123(2):452-473. doi:
10.1213/ANE.0000000000001416
2. American Society of Anesthesiologists Task Force on Perioperative Management of
patients with obstructive sleep apnea. Practice guidelines for the perioperative
management of patients with obstructive sleep apnea: an updated report by the American
Society of Anesthesiologists Task Force on Perioperative Management of patients with
obstructive sleep apnea. Anesthesiology. 2014;120(2):268-286. doi:
10.1097/ALN.0000000000000053
An otherwise healthy 60-year-old woman underwent breast reconstruction with right free transverse rectus abdominis musculocutaneous (TRAM) flap 1 day ago. Cardiac monitoring shows no P waves and an irregular QRS complex. The patient is asymptomatic. Blood pressure is 120/80 mmHg and heart rate is between 130 and 139 bpm. Which of the following is the most appropriate first-line therapy for this patient?
A) Amiodarone
B) Digoxin
C) Diltiazem
D) Metoprolol
E) Propafenone
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.
A 72-year-old man diagnosed with an oral squamous cell carcinoma undergoes
segmental mandibulectomy and reconstruction with free fibula flap. The surgery is
uneventful, and the patient is transferred to the floor on postoperative day 3. Two
days later, he suddenly becomes unresponsive while mobilizing out of bed. A
pulse cannot be palpated. Cardiopulmonary resuscitation is promptly started, and
a cardiac monitor is attached. The electrocardiography tracing is consistent with
pulseless electrical activity. Administration of which of the following drugs is the
most appropriate next step in management?
A) Adenosine
B) Atropine
C) Diltiazem
D) Dopamine
E) Epinephrine
The correct response is Option E.
Epinephrine is the initial drug of choice in the acute management of this patient with cardiac
arrest and pulseless electrical activity (PEA). The intravenous dose is 1 mg every 3 to 5 min,
always followed by a 20-mL normal saline flush.
PEA is characterized by the absence of a palpable pulse and a variety of ECG waveforms,
which can range from a near-flat line to resembling sinus rhythm. PEA does not respond to
electric shock. Successful treatment depends on early administration of cardiopulmonary
resuscitation and expeditious reversal of the cause of arrest. Hypovolemia and hypoxia are
common reversible causes of PEA.
At the time of the last advanced cardiovascular life support guidelines-focused update in
2019, there were few published studies on the optimal timing of initial epinephrine
administration for cardiac arrest. The majority of the authors reported higher rates of return of
spontaneous circulation with “early” administration (variably defined). Unfortunately, the
study protocols were inconsistent enough to preclude a meta-analysis, leading the American
Heart Association to release only limited recommendations on the timing of initial
epinephrine administration for cardiac arrests with a nonshockable rhythm (such as PEA or
asystole): namely “as soon as feasible.” Witnessed in-hospital cardiac arrests may be particularly well-suited for early administration of epinephrine by the physician providing the
initial evaluation, while the code team is mobilized.
The other drugs listed are not indicated in the initial treatment of PEA. Atropine may be used
in the treatment of bradyarrhythmias. Adenosine may be indicated for supraventricular
tachycardia. Dopamine is a catecholamine with dose-dependent cardiovascular effects.
Diltiazem is a calcium channel blocker commonly used for its vasodilatory effects, both
peripheral and of the coronary arteries.
REFERENCES:
1. Link MS, Berkow LC, Kudenchuk PJ, et al. Part 7: adult advanced cardiovascular life
support: 2015 American Heart Association guidelines update for cardiopulmonary
resuscitation and emergency cardiovascular care. Circulation. 2015; 132(18 Suppl 2):
S444-464.
2. Long B, Koyfman A. Emergency medicine myths: epinephrine in cardiac arrest. J Emerg
Med. 2017; 52(6): 809-814.
3. Panchal AR, Berg KM, Hirsch KG, et al. 2019 American Heart Association focused update
on advanced cardiovascular life support: use of advanced airways, vasopressors, and
extracorporeal cardiopulmonary resuscitation during cardiac arrest: an update to the
American Heart Association guidelines for cardiopulmonary resuscitation and emergency
cardiovascular care. Circulation. 2019;140(24): e881-e894.
4. Crowley CP, Salciccioli JD, Kim EY. The association between ACLS guideline deviations
and outcomes from in-hospital cardiac arrest. Resuscitation. 2020;153: 65-70.
A 32-year-old man, who is a football player, is brought to the emergency department after being found unconscious and facedown in his home. It is estimated that he was in that position for 6 hours. Physical examination shows swelling of the right forearm and hand. Which of the following physiologic abnormalities is most likely in this patient?
A) Hyperkalemia, hypercalcemia, metabolic acidosis
B) Hyperkalemia, hypocalcemia, metabolic acidosis
C) Hypokalemia, hypercalcemia, metabolic alkalosis
D) Hypokalemia, hypocalcemia, metabolic acidosis
E) Hypokalemia, hypocalcemia, metabolic alkalosis
The correct response is Option B.
The physiological abnormalities that result from rhabdomyolysis are caused because of crush injury to the muscle. The crush injury causes pressure or stretching of the muscle and sarcolemmal membrane. As the sarcolemmal membrane is stretched, sodium, calcium (hypocalcemia), and water leak into the sarcoplasm, trapping extracellular fluid inside muscle cells. In addition to the influx of these elements into the cell, the cell releases potassium (hyperkalemia) and other toxic substances such as myoglobin, phosphate, and urate into the circulatory system (metabolic acidosis). The end result of these events is shock, hyperkalemia, hypocalcemia, metabolic acidosis, compartment syndrome, and acute renal failure. Acute renal failure results because of a combination of hypovolemia with subsequent renal vasoconstriction, metabolic acidosis and the influx of nephrotoxic substances such as myoglobin, urate, and phosphate.
A 30-year-old woman undergoes augmentation mammaplasty in an office-based operating room. Intravenous midazolam and fentanyl are used, and a lidocaine field block is administered. An hour later, while in the recovery room, the patient experiences disorientation, muscle twitching, and light-headedness. Administration of which of the following drugs is the most appropriate next step in management?
A) Dantrolene
B) Fat emulsion
C) Flumazenil
D) Naloxone
E) Propofol
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.
An otherwise healthy 35-year-old woman, gravida 3, para 3, presents for abdominoplasty. When combined with non-opioid analgesics and/or NSAIDs, which of the following is the most appropriate pain management for this patient?
A) Administration of epidural anesthetic
B) Infiltration of wound with liposomal bupivacaine
C) Intraoperative dexamethasone administration
D) Intraoperative ketamine infusion
E) Intraoperative lidocaine infusion
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.
A
57-year-old woman undergoes right mastectomy with immediate deep inferior epigastric perforator flap breast reconstruction for treatment of right breast cancer. BMI is 28 kg/m2. Preoperative Caprini RAM score is 6. Perioperative pneumatic compression boots and low-dose heparin are initiated. On postoperative day 2, the patient becomes tachycardic after walking to the bathroom. Resting heart rate is 110/bpm, blood pressure is 118/40 mm Hg, respiratory rate is 24/min, and pulse oximetry is 93% on 6 L nasal cannula oxygen supplementation. Urine output is 50 mL per hour over the past 8 hours. Which of the following is the most likely diagnosis?
A) Active bleeding
B) Anxiety
C) Caffeine withdrawal
D) Hypovolemia
E) Pulmonary embolism
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.
A 61-year-old woman presents to discuss oncoplastic reduction mammaplasty. Medical history includes a femur fracture sustained during a fall 4 months ago. Recovery was complicated by a pulmonary embolus. Current medications include warfarin therapy. Her hematologist has recommended bridging therapy to prevent recurrent embolus. Which of the following is the most appropriate regimen to bridge anticoagulation with low-molecular weight heparin (LMWH) in this patient?
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.
A 42-year-old woman undergoes deep inferior epigastric artery perforator flap breast reconstruction. An ultrasound-guided transversus abdominis plane regional block with liposomal bupivacaine is planned. The ultrasound probe is placed directly over the abdominal wall musculature in the anterior axillary line. The sonographic image is shown. Injection at which of the following levels is most appropriate?
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.
A 42-year-old woman who is BRCA2-positive undergoes delayed reconstruction of both breasts with deep inferior epigastric artery perforator (DIEP) flaps. Medical history includes prophylactic mastectomy and failed implant reconstruction 3 months ago. After closure of the fascia of the rectus abdominis muscles, the triangle bounded by the latissimus dorsi, external oblique, and iliac crest is identified on each side. Infiltration of bupivacaine into which of the following planes is most likely to provide postoperative pain control of the abdominal flap donor site in this patient?
A) Between the external oblique and the internal oblique
B) Between the internal oblique and the transversus abdominis
C) Between the transversalis fascia and the peritoneum
D) Between the transversus abdominis and the transversalis fascia
E) In the deep subcutaneous tissues, superficial to the external oblique
The correct response is Option B.
The peripheral nerve block described is a transversus abdominis plane, or TAP, block. The lumbar (Petit) triangle, which is located at the lateral extent of the abdomen, is formed by the borders of the latissimus dorsi muscle posteriorly, the external oblique anteriorly, and the iliac crest inferiorly. Furthermore, the location can be estimated by the intersection of a horizontal line through the umbilicus and the vertical anterior axillary line. The intercostal nerves providing sensation to the anterior abdominal wall from T6 to L1 are located in the plane between the internal oblique and the transversus abdominis muscles. Long-acting local anesthetic infiltration in this plane is generally approached through the lumbar triangle. Multiple techniques have been described. These include visualized injection with the assistance of ultrasound guidance, catheter insertion under direct vision with surgical cutdown to the appropriate plane, and blind injection using a blunt needle, feeling for the two punctures of the external and internal obliques, respectively. Multiple studies have shown improved postoperative pain control in the abdominal donor site with this technique in breast reconstruction, and patients have demonstrated marked decreases in opioid consumption as well. The other options would be inappropriate for nerve block as the intercostal nerves are not found in those tissue planes.
