1. Local anesthetics Flashcards

1
Q

A 50-year-old woman is scheduled to undergo bilateral deep inferior epigastric artery perforator (DIEP) flap breast reconstruction. A donor site regional block with liposomal bupivacaine is planned for analgesia. Which of the following injection locations is most likely to improve pain control and decrease narcotic use in this patient?

A) Between external oblique and internal oblique fascias
B) Between internal oblique and transversus abdominis fascias
C) Deep to rectus abdominis fascia
D) Deep to transversus abdominis fascia
E) Subcutaneous plane

A

The correct response is Option B.

The patient is undergoing a transversus abdominis plane (TAP) block. TAP blocks have become popular adjunctive pain control measures for a variety of abdominal surgeries. They can either be performed transcutaneously with ultrasound guidance or under direct visualization in the operating room prior to closure of the abdominal donor site in deep inferior epigastric artery perforator (DIEP) or transverse rectus abdominis musculocutaneous (TRAM) flap surgeries. The segmental innervation to be blocked in the TAP block is located between the internal oblique and transversus abdominis muscles. Either infiltration of liposomal bupivacaine or placement of epidural catheters in the TAP space has been described.
References

1. Zhong T, Ojha M, Bagher S, et al. Transversus abdominis plane block reduces morphine consumption in the early postoperative period following microsurgical abdominal tissue breast reconstruction: a double-blind, placebo-controlled, randomized trial. Plast Reconstr Surg. 2014 Nov;134(5):870-878.
2. Zhong T, Wong KW, Cheng H, et al. Transversus abdominis plane (TAP) catheters inserted under direct vision in the donor site following free DIEP and MS-TRAM breast reconstruction: a prospective cohort study of 45 patients. J Plast Reconstr Aesthet Surg. 2013 Mar;66(3):329-336. Epub 2012 Nov 9.
3. Rafi AN. Abdominal field block: a new approach via the lumbar triangle. Anesthesia. 2001 Oct;56(10):1024-1026.
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2
Q

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

A) Adenosine
B) ntralipid
C) Propranolol
D) Vasopressin
E) Verapamil
A

The correct response is Option B.

This patient has sustained a cardiovascular collapse secondary to local anesthetic systemic toxicity (LAST). The maximum safe dose of lidocaine with epinephrine in this patient is 35 to 55 mg/kg.

Lipid Rescue protocol recommends an initial intralipid 20% bolus of 1.5 mL/kg over 1 minute. This should be followed immediately with a continuous infusion at 0.25 mL/kg/min. A single bolus is typical, but should be repeated or the infusion increased if spontaneous circulation fails to return or blood pressure declines.

Cardiovascular collapse from LAST differs from that secondary to myocardial ischemia. In LAST, raising the peripheral vascular resistance with vasopressors like vasopressin, can impair cardiac output and impede resuscitation. Epinephrine should be given in small doses (

Adenosine is not useful in the management of LAST patients. It is typically used to treat supraventricular tachycardia.
References

1. Young VL. Lipid Rescue for Local-Anesthetic-Induced Cardiac Arrest. Available at: http://www.plasticsurgerypulsenews.com/7/article_dtl.php?QnCategoryID=67&QnArticleID=153. Accessed January 6, 2015.
2. Weinberg GL. Lipid emulsion infusion: resuscitation for local anesthetic and other drug overdose. Anesthesiology. 2012 Jul;117(1):180-187.
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3
Q

A 55-year-old woman is evaluated for an incisional hernia that developed after a complicated right hemicolectomy 5 years ago. Medical history includes hypertension. BMI is 34 kg/m2. She reports shortness of breath when trying to scrub floors at work but is able to climb a flight of stairs or walk up a hill without symptoms. There are no other respiratory or cardiovascular issues. Cardiovascular examination shows no abnormalities. Recent electrocardiography, complete blood count, and basic metabolic panel show no abnormalities. Hernia repair with separation of components is being considered. Which of the following is the most appropriate next step in the preoperative cardiac assessment of this patient?

A) Cardiac catheterization
B) Echocardiographic exercise stress testing
C) Echocardiography at rest
D) Nuclear cardiac pharmacologic stress testing
E) No further cardiac testing is needed

A

The correct response is Option E.

No further preoperative cardiac testing is needed for this patient being considered for an elective, greater-than-low-risk procedure, without any evidence of active cardiac conditions or clinical risk factors, and with moderate functional capacity (metabolic equivalents, or METs, >= 4).

Assessment of left ventricular function at rest, whether by echocardiogram, radionuclide angiogram, or contrast ventriculography, has not been shown to be a consistent predictor of perioperative ischemic events. Cardiac stress testing, including by exercise or drug induced, is not indicated in this patient.

In 2007, the American College of Cardiology and the American Heart Association published updated guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery (NCS), suggesting a stepwise algorithmic approach to perioperative cardiac risk assessment:

Is there need for emergency NCS? If yes, proceed with surgery.
Are there active cardiac conditions (unstable coronary syndromes, decompensated heart failure, significant arrhythmias, severe valvular disease)? If yes, evaluate and treat per specific guidelines before considering NCS.
Is the NCS considered low risk (e.g., superficial and ophthalmologic procedures)? If yes, proceed with low-risk NCS.
Does the patient have good functional capacity (METs >= 4) without symptoms? If yes, proceed with NCS.
Is there need for emergency NCS? If yes, proceed with surgery.
    Three or more clinical risk factors undergoing vascular surgery: consider testing if it will change management
    One or two clinical risk factors undergoing vascular surgery or one or more clinical risk factors undergoing intermediate-risk surgery: either proceed with surgery with heart rate control (beta blockade) or consider noninvasive testing if it will change management

Preoperative cardiac assessment should include an estimation of the patient’s functional capacity, based on his/her ability to perform a spectrum of common daily tasks. This has been shown to correlate well with maximum oxygen uptake by treadmill testing. Four METs is a common threshold used in many decision-making points in the perioperative cardiac evaluation.
References

1. Fleisher LA, Beckman JA, Brown KA, et al. ACC/AHA 2007 Guidelines on Perioperative Cardiovascular Evaluation and Care for Noncardiac Surgery: Executive Summary. J Am Coll Cardiol. 2007 Oct 23;50(17):1707-1732.
2. Cinello M, Nucifora G, Bertolissi M, et al. American College of Cardiology/American Heart Association perioperative assessment guidelines for noncardiac surgery reduces cardiologic resource utilization preserving a favourable clinical outcome. J Cardiovasc Med (Hagerstown). 2007 Nov;8(11):882-888.
3. Hlatky MA, Boineau RE, Higginbotham MB, et al. A brief self-administered questionnaire to determine functional capacity (the Duke Activity Status Index). Am J Cardiol. 1989 Sep 15;64(10):651-654.
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4
Q

A 65-year-old woman is scheduled to undergo unilateral breast reconstruction with tissue expander. Medical history includes placement of a drug-eluting stent 4 months ago. Current medications include aspirin and clopidogrel. The surgical oncologist does not want to wait longer to perform the mastectomy. Which of the following is the most appropriate management of preoperative medications in this patient?

A) Continue both aspirin and clopidogrel
B) Discontinue aspirin and continue clopidogrel
C) Discontinue both aspirin and clopidogrel
D) Discontinue both aspirin and clopidogrel; start prophylactic enoxaparin
E) Discontinue clopidogrel and continue aspirin

A

The correct response is Option A.

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

1. Brilakis ES, Patel VG, Banerjee S. Medical management after coronary stent implantation: a review. JAMA. 2013 Jul 10;310(2):189-198.
2. Iakovou I, Schmidt T, Bonizzoni E, et al. Incidence, predictors, and outcome of thrombosis after successful implantation of drug-eluting stents. JAMA. 2005 May 4;293(17):2126-2130.
3. Wilson SH, Rihal CS, Bell MR, et al. Timing of coronary stent thrombosis in patients treated with ticlopidine and aspirin. Am J Cardiol. 1999 Apr;83(7):1006-1011.
4. Devereaux PJ, Goldman L, Cook DJ, et al. Perioperative cardiac events in patients undergoing noncardiac surgery: a review of the magnitude of the problem, the pathophysiology of the events and methods to estimate and communicate risk. CMAJ. 2005 Sep 13;173(6):627-634.
5. American College of Cardiology, American Heart Association Task Force on Practice Guidelines. 2007 Focused update of the ACC/AHA/SCAI 2005 guideline update for percutaneous coronary intervention. A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Catheter Cardiovasc Interv. 2008 Jan 1;71(1):E1-40.
6. Darvish-Kazem S, Gandhi M, Marcucci M, et al. Perioperative management of antiplatelet therapy in patients with a coronary stent who need noncardiac surgery: a systematic review of clinical practice guidelines. Chest. 2013 Dec;144(6):1848-1856.
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5
Q

A critically ill 69-year-old man is observed to have new-onset atrial fibrillation complicated by rapid ventricular response. Angina and hemodynamic instability with hypotension and acute ST depression is noted. Which of the following is the next step in management?

A) Emergency cardiac catherization with AV nodal ablation followed by permanent ventricular pacing
B) Heparin anticoagulation and emergency transesophageal echocardiography (TEE) to rule out left atrial thrombus
C) Immediate external electrical cardioversion
D) Intravenous administration of amiodarone with loading dose and titrated infusion until sinus rhythm is restored
E) Intravenous administration of a beta blocker or nondihydropyridine calcium channel blocker to slow the ventricular heart rate

A

The correct response is Option C.

Immediate cardioversion is recommended for patients with atrial fibrillation (AF) or atrial flutter with rapid ventricular response associated with hemodynamic instability such as hypotension, ongoing myocardial ischemia, or decompensated heart failure. Both chemical and electrical cardioversion can be attempted according to established protocols until sinus rhythm is restored with a goal of optimizing hemodynamic parameters. If initial cardioversion is unsuccessful, repeated attempts at cardioversion may be made after adjusting the location of the electrodes, applying pressure over the electrodes, or following administration of an antiarrhythmic medication according to Advanced Cardiac Life Support (ACLS) algorithms.

A trial of medical management for rate control is appropriate in the absence of hemodynamic instability. In general, beta blockers are the most common agents used for rate control, followed by nondihydropyridine calcium channel blockers such as diltiazem, as well as other agents such as digoxin and amiodarone. Patient comorbidities influence the choice of medical therapy to minimize risk of adverse events such as heart failure decompensation, exacerbation of chronic obstructive pulmonary disease, or acceleration of conduction in patients with preexcitation physiology.

Appropriate anticoagulation management around the time of elective cardioversion is essential for reducing thromboembolic risk. When AF has clearly existed at 48 hours’ duration or duration is unknown, then anticoagulation for ? 3 weeks before and continuing for ? 4 weeks after cardioversion is recommended unless otherwise contraindicated. In case of relative contraindications to anticoagulation, TEE can be performed to help guide relative risk assessment related to thromboembolism of preexisting cardiac thrombi arising in the setting of prolonged atrial dysfunction. Importantly, when emergent cardioversion is indicated because of hemodynamic instability, initiation of anticoagulation and TEE should not delay acute interventions to stabilize the patient’s condition.

AV nodal ablation with permanent ventricular pacing can be considered to improve rate control when other attempts at maintaining rate control through medical management are unsuccessful. This intervention is usually reserved for elderly patients, because it leads to pacemaker dependency. However, patients with symptoms refractory to medical therapy who are treated with AV nodal ablation and permanent pacemaker implantation have demonstrated an improvement in cardiac symptoms, quality of life, and health care utilization.
References

1. January CT, Wann LS, Alpert JS, et al. 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2014;64(21):e1-76.
2. Anderson JL, Adams CD, Antman EM, et al. 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2013;127:e663–828.
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6
Q

A 42-year-old woman is scheduled to undergo reduction mammaplasty. Medical history includes macromastia and von Willebrand disease. Preoperatively, administration of desmopressin (DDAVP) is planned for bleeding prophylaxis. The total preoperative dose is best determined by measuring the activity levels of vWF:RCoF (von Willebrand factor ristocetin cofactor) and which of the following coagulation factors?

A) II
B) V
C) VII
D) VIII
E) X
A

The correct response is Option D.

In surgical patients with von Willebrand disease (vWD) receiving desmopressin (DDAVP) for bleeding prophylaxis, total preoperative dose should be determined by preoperative measurement of activity levels of von Willebrand factor ristocetin cofactor (vWF:RCoF) and coagulation factor VIII.

The other listed coagulation factors are not associated with isolated vWD.

vWD is the most common congenital bleeding disorder, with estimated prevalence as high as 1.3%. It is caused by deficiency (types I and III) or dysfunction (type II) of von Willebrand factor (vWF), leading to impaired platelet adhesion and possibly lower levels of coagulation factor VIII. In its normal state, vWF is a plasma protein that mediates the initial adhesion of platelets at sites of vascular injury and also binds and stabilizes coagulation factor VIII in the circulation. Both vascular endothelial cells and platelets synthesize and store vWF.

DDAVP is a synthetic derivative of ADH (vasopressin, antidiuretic hormone) that is used for treatment and prophylaxis of bleeding in patients with vWD. It promotes release of stored vWF from endothelial cells into the plasma, being particularly effective in patients with partial quantitative deficiency of vWF, or type I (about 75% of cases of vWD). Patients who do not appropriately respond to DDAVP administration should receive vWF concentrate.

For bleeding prophylaxis for minor surgery, the preoperative goal should be to achieve vFW:RCoF and factor VIII activity levels of at least 30 IU/dL (preferably >50 IU/dL). Such levels should be maintained for 1 to 5 days postoperatively. For prophylaxis for major surgery, preoperative activity levels should be at least 100 IU/dL and maintained above 50 IU/dL for at least 7 to 10 days.

To decrease risk of perioperative thromboembolism, vWF:RCoF levels should not exceed 200 IU/dL and factor VIII activity should not exceed 250 IU/dL. Fluid restriction is advised for patients receiving DDAVP perioperatively, to avoid hyponatremia and seizures.
References

1. Nichols WL, Hultin MB, James AH, et al. von Willebrand disease (vWD): evidence-based diagnosis and management guidelines, the National Heart, Lung, and Blood Institute (NHLBI) Expert Panel report (USA). Haemophilia. 2008 Mar;14(2):171-232.
2. Stone ME, Mazzeffi M, Derham J, et al. Current management of von Willebrand disease and von Willebrand syndrome. Curr Opin Anaesthesiol. 2014 Jun;27(3):353-358.
3. Svensson PJ, Bergqvist PB, Juul KV, et al. Desmopressin in treatment of haematological disorders and in prevention of surgical bleeding. Blood Rev. 2014 May;28(3):95-102. Epub 2014 Mar 22.
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7
Q

A 55-year-old woman is evaluated for mild cellulitis after undergoing cosmetic excision of a facial mole 7 days ago. Cephalexin is prescribed. Approximately 30 minutes after taking her first dose, she returns to the office because of sudden and progressive onset of generalized hives, periorbital edema, and flushing. The patient appears confused and then collapses. Blood pressure is 85/50 mmHg. An audible wheeze is noted. Which of the following is the most appropriate next step in management?

A) Administration of albuterol nebulizer
B) Administration of diphenhydramine and ranitidine intravenously
C) Injection of epinephrine (1 mg/mL) 0.3 to 0.5 mg intramuscularly
D) Injection of methylprednisolone 125 mg intramuscularly
E) Rapid infusion of 0.9% saline 1 to 2 L intravenously

A

ption C.

This patient is presenting with anaphylaxis. The first and most crucial step in managing acute anaphylaxis is the administration of epinephrine.

Anaphylaxis is a serious and life-threatening hypersensitivity reaction. Medications and insect stings are the most common triggers in adults, with beta-lactam antibiotic exposure among the most implicated medications. In this setting, anaphylaxis is diagnosed when two or more of the following are observed minutes to hours after exposure:

Skin-mucosal tissue reactions (such as generalized urticaria, swollen lip, pruritus, and flushing)
Respiratory compromise (such as dyspnea, wheeze, bronchospasm, stridor, and hypoxemia)
Hypotension or associated findings (such as syncope, confusion, collapse, and incontinence)
Persistent gastrointestinal reactions (such as crampy abdominal pain and vomiting)

Intramuscular epinephrine can be repeated every 5 to 15 minutes as needed. If given promptly, most patients respond to one or two doses. Simultaneous with this treatment, an emergency team can be summoned. The patient should be placed in a recumbent position with legs elevated and supplemental oxygen administered.

Volume resuscitation can be initiated to compensate for severe loss of intravascular volume that can accompany fluid shifts of untreated anaphylaxis and to support blood pressure not responsive to epinephrine.

Bronchodilators, H1 and H2 antihistamines such as diphenhydramine and ranitidine, and glucocorticoids such as methylprednisolone are all reasonable but second-line treatments for acute anaphylaxis.

Intubation should be performed immediately in the setting of progressive upper airway closure such as stridor and tongue edema, or if respiratory arrest is present. However, first-dose epinephrine administration should not be delayed for intubation. Epinephrine works rapidly to reduce airway edema that might otherwise prevent successful intubation, if not completely reverse the underlying etiology of cardiopulmonary collapse in anaphylaxis.

While cardiovascular disease is a risk factor for poor outcome from anaphylaxis, it is not a contraindication for epinephrine administration. It is generally accepted that the risk of death or brain damage from prolonged or undertreated anaphylaxis outweighs the risk of appropriately administered epinephrine. If there is inadequate response to initial intramuscular epinephrine and volume resuscitation, then intravenous epinephrine can be introduced in an intensive care setting by slow infusion at 2 to 10 mcg per minute and titrated to effect.
References

1. Kemp SF, Lockey RF, Simons FE, et al. Epinephrine: the drug of choice for anaphylaxis. A statement of the World Allergy Organization. Allergy. 2008 Aug;63(8):1061-1070.
2. Sampson HA, Muñoz-Furlong A, Campbell RL, et al. Second symposium on the definition and management of anaphylaxis: summary report—Second National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium. J Allergy Clin Immunol. 2006 Feb;117(2):391-397.
3. Simons FE, Ardusso LR, Bilò MB, et al. World Allergy Organization anaphylaxis guidelines: summary. J Allergy Clin Immunol. 2011 Mar;127(3):587-593.
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8
Q

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
A

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.
References

1. Epstein CD, Haghenbeck KT. Bedside assessment of tissue oxygen saturation monitoring in critically ill adults: an integrative review of the literature. Crit Care Res Pract. 2014;2014:709683. Epub 2014 May 8.
2. Sinex JE. Pulse oximetry: principles and limitations. Am J Emerg Med. 1999 Jan;17(1):59-67.
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9
Q

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

A

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 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

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10
Q

A 5-year-old boy is brought to the emergency department 45 minutes after accidentally injecting his palm with epinephrine from an auto-injector (EpiPen). On physical examination, the ring finger is soft and pale, and capillary refill time is poor. A small puncture mark is noted on the flexor surface of the palm just proximal to the metacarpophalangeal (MCP) joint. Which of the following is the most appropriate next step in management?

A) Application of a hot pack
B) Emergent operative exploration
C) Subcutaneous injection of nifedipine
D) Topical nitroglycerin paste
E) Observation
A

The correct response is Option E.

Accidental self-injection of epinephrine with an EpiPen occurs in 1 in 50,000 syringes. There have been no documented cases of digital necrosis following injection, and observation is indicated in this case. The effect of epinephrine’s vasoconstriction lasts for approximately 90 minutes and will likely resolve on its own.

Phentolamine has been described as a reversal agent for epinephrine and has shown clinical efficacy, but there has been no study to show that there are better outcomes with phentolamine injection compared with observation. Also, the added volume of injection with phentolamine could cause pressure necrosis and the timing between EpiPen injection and definitive treatment would usually be outside of the 90 minutes it would take for the epinephrine to wear off on its own.

Topical nitroglycerin paste and subcutaneous injection of calcium channel blockers such as nifedipine have not shown to be viable treatment modalities. Application of a hot pack can lead to increased tissue damage and burns and is not indicated. Emergent exploration is indicated for compartment syndrome and is not indicated in this case where the finger is soft.
References

1. Greene AK. Management of epinephrine injection injury to the digit. Plast Reconstr Surg. 2005 May;115(6):1800-1801.
2. Chowdry S, Seidenstricker L, Cooney DS, et al. Do not use epinephrine in digital blocks: myth or truth? Part II. A retrospective review of 1111 cases. Plast Reconstr Surg. 2010 Dec;126(6):2031-2034.
3. Khairalla E. Epinephrine-induced digital ischemia relieved by phentolamine. Plast Reconstr Surg. 2001 Nov;108(6):1831-1832.
4. Hinterberger JW, Kintzi HE. Phentolamine reversal of epinephrine-induced digital vasospasm. How to save an ischemic finger. Arch Fam Med. 1994 Feb;3(2):193-195.
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11
Q

A 35-year-old man undergoes a 90-minute rhytidectomy procedure with intravenous sedation. The patient smokes 10 cigarettes daily, but is otherwise healthy. Which of the following factors most likely places this patient at increased risk for postoperative nausea and vomiting?

A) Duration of procedure
B) Gender
C) History of cigarette smoking
D) History of postoperative nausea and vomiting
E) Type of anesthesia
A

The correct response is Option D.

Risk factors for postoperative nausea and vomiting include: female gender, nonsmoking status, prior history of postoperative nausea/vomiting/motion sickness, use of volatile anesthetics/general anesthesia, opioid/narcotic use, facial rejuvenation procedures, and long duration of surgery.

Several measures can be taken to decrease postoperative nausea and vomiting. A thorough history with identification of risk factors can aid stratification of patients preoperatively. Use of long-acting local anesthetic agents, nonsteroidal anti-inflammatory drugs (NSAIDs), and cyclooxygenase-2 selective inhibitors can decrease the need for postoperative opioid use. Avoidance of nitrous oxide, especially in combination with fentanyl and volatile inhalational gases, and multimodal use of serotonin antagonists combined with other antiemetic agents can also decrease postoperative nausea and vomiting.
References

1. Iverson RE, Lynch DJ. ASPS Committee on Patient Safety. Practice advisory on pain management and prevention of postoperative nausea and vomiting. Plast Reconstr Surg. 2006 Sep 15;118(4):1060-1069.
2. Marcus JR, Few JW, Chao JD, et al. The prevention of emesis in plastic surgery: a randomized, prospective study. Plast Reconstr Surg. 2002 Jun;109(7):2487-2494.
3. Mustoe TA, Buck DW 2nd, Lalonde DH. The safe management of anesthesia, sedation, and pain in plastic surgery. Plast Reconstr Surg. 2010 Oct;126(4):165e-176e.
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12
Q

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

A

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

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13
Q

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
A

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.
References

1. Gurunluoglu R, Swanson JA, Haeck PC, et al. Evidence-based patient safety advisory: malignant hyperthermia. Plast Reconstr Surg. 2009 Oct;124(4 Suppl):68S-81S.
2. Poore SO, Sillah NM, Mahajan AY, et al. Patient safety in the operating room: II. Intraoperative and postoperative. Plast Reconstr Surg. 2012 Nov;130(5):1048-1058.
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14
Q

A 42-year-old woman, with a history of anaphylactic reaction to procaine, comes to the office for consultation regarding augmentation mammaplasty. Anesthetics that contain which of the following should be avoided in this patient?

A) Acetaldehyde
B) Epinephrine
C) Iodine
D) Methylparaben
E) Para-aminobenzoic acid
A

The correct response is Option E.

True allergic reactions to local anesthetics are rare. Type I hypersensitivity reactions may include anaphylaxis, and are modulated by immunoglobulin E. Both ester-based local anesthetics, such as procaine, and amide-based local anesthetics may induce an allergic response. The most likely allergen is para-aminobenzoic acid (PABA). This compound consists of a benzene ring substituted with an amino group at the 4-position (leading to the analogous label of 4-aminobenzoic acid) as well as a carboxyl group. Preservatives such as methylparaben have also been shown to cause allergic reactions to local anesthetics, but are less likely than allergic reactions caused by PABA.

Epinephrine can induce vasoconstriction and increase the safe dosage of administered local anesthetic, though it would not be expected to cause an allergic response itself. Iodine and acetaldehyde should not be found in local anesthetic mixtures.
References

1. Liu SS, Lin Y. Local Anesthetics. In: Barash PG, Cullen BF, Stoelting RK, et al, eds. Clinical Anesthesia. 6th ed. Philadelphia: Lippincott Williams & Wilkins; 2009:531-548.
2. Becker DE, Reed KL. Essentials of local anesthetic pharmacology. Anesth Prog. 2006 Fall;53(3):98-108.
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15
Q

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
A

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.
References

1. Haeck PC, Swanson JA, Gutowski KA, et al. Evidence-based patient safety advisory: liposuction. Plast Reconstr Surg. 2009 Oct;124(4 Suppl):28S-44S.
2. Klein JA. Tumescent technique for regional anesthesia permits lidocaine doses of 35 mg/kg for liposuction. J Dermatol Surg Oncol. 1990 Mar;16(3):248-263.
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16
Q

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
A

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 

References

1. Mustoe TA, Buck DW II, Lalonde DH. The safe management of anesthesia, sedation, and pain in plastic surgery. Plast Reconstr Surg. 2010 Oct;126(4):165e-176e.
2. Hasen KV, Samartzis D, Casas LA, et al. An outcome study comparing intravenous sedation with midazolam/fentanyl (conscious sedation) versus propofol infusion (deep sedation) for aesthetic surgery. Plast Reconstr Surg. 2003 Nov;112(6):1683-1689.
17
Q

A 54-year-old woman has onset of ventricular fibrillation and severe hypotension 5 minutes after 30 mL bupivacaine 0.5% is administered to the ankle for postoperative pain control during reconstruction of the foot. After initiation of cardiopulmonary resuscitation, intravenous administration of which of the following is the most appropriate management?

A) Atropine
B) Dantrolene
C) Flumazenil
D) Lipid emulsion
E) Metoprolol
A

The correct response is Option D.

The most appropriate management of acute bupivacaine toxicity is a bolus and infusion of 20% lipid emulsion. Every facility where local anesthetic is used in large doses should have a lipid rescue kit clearly labeled and available should the need arise. Although lipid rescue mechanism of action is not completely understood, it may be that the added lipid in the bloodstream acts as a “sink,” allowing for the removal of lipophilic toxins from affected tissues. Major local anesthetic toxicity can have such symptoms as sudden loss of consciousness, tonic-clonic seizures, hypertension followed by progressive hypotension, tachycardia, ventricular fibrillation, bradycardia, asystole, and cardiac arrest. Arrhythmias may be refractory to treatment, and resuscitation may be prolonged, sometimes requiring more than 1 hour.

In the event of a local anesthetic toxicity event, airway management, seizure suppression, and, if needed, cardiopulmonary resuscitation should be performed. Alert the nearest facility having cardiopulmonary bypass capability and administer 20% lipid emulsion (values in parentheses are for 70 kg) as follows:

Bolus 1.5 mL/kg intravenously over 1 minute (~100 mL)
Continuous infusion 0.25 mL/kg/min (~500 mL over 30 minutes)
Repeat bolus every 5 minutes for persistent cardiovascular collapse
Double infusion rate if blood pressure returns but remains decreased
Continue infusion for a minimum of 30 minutes 

Although beta-adrenergic blockers may be useful in treating the excitatory cardiovascular phase of local anesthetic toxicity, the potential to progress to more advanced phases with myocardial depression and collapse preclude their routine use. In addition to lipid emulsion, the treatment for local anesthetic–induced cardiac toxicity is generally supportive, and may include amrinone, closed-chest cardiac massage, and cardiopulmonary bypass.

Flumazenil is used to reverse the effects of benzodiazepine toxicity.

Dantrolene is administered in the acute treatment of malignant hyperthermia.

Atropine and dopamine are administered as part of the Advanced Cardiac Life Support protocol for bradycardia or asystole and would not be used in the scenario described.
References

1. Young VL. Patient safety in aesthetic surgery. In: Nahai F, ed. The Art of Aesthetic Plastic Surgery: Principles and Techniques. 2nd ed. St. Louis, MO: Quality Medical Publishing; 2011; 1: 35-69.
2. Man D, Podichetty VK. Lipid rescue in resuscitation of local anesthetic-induced cardiac arrest in aesthetic surgery. Plast Reconst Surg. 2010 Jun;125(6):257e-9e.
18
Q

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
A

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.
References

1. Lalonde D, Bell M, Benoit P, et al. A multicenter prospective study of 3,110 consecutive cases of elective epinephrine use in the fingers and hand: the Dalhousie Project clinical phase. J Hand Surg Am. 2005 Sep;30(5):1061-1067.
2. Mann T, Hammert WC. Epinephrine and hand surgery. J Hand Surg Am. 2012 Jun;37(6):1254-1256.
3. Nodwell T, Lalonde D. How long does it take phentolamine to reverse adrenaline-induced vasoconstriction in the finger and hand? A prospective randomized blinded study: the Dalhousie project experimental phase. Can J Plast Surg. 2003;11(4):187-189.
4. Singer AJ. Accidental digital self-injection of epinephrine: debunking the myth. Ann Emerg Med. 2010 Sep;56(3):275-277.
5. Tavares M, Goodson JM, Studen-Pavlovich D, et al. Reversal of soft-tissue local anesthesia with phentolamine mesylate in pediatric patients. J Am Dent Assoc. 2008 Aug;139(8):1095-1104.
19
Q

A 53-year-old woman comes to the office for removal of multiple nevi. On injection of lidocaine, which of the following signs and symptoms is most likely to suggest lidocaine toxicity in this patient?

A) Bronchospasm
B) Hypertension
C) Tachycardia
D) Tinnitus
E) Urticaria
A

The correct response is Option D.

Signs and symptoms of lidocaine toxicity include dizziness, agitation, lethargy, tinnitus, metallic taste, perioral paresthesia, slurred speech, euphoria, hypotension, and bradycardia.

Tachycardia is not a sign of lidocaine toxicity. Bradycardia is more common.

Bronchospasm and urticaria are not signs of lidocaine toxicity.
References

1. Horton JB, Reece EM, Broughton G II, et al. Patient safety in the office-based setting. Plast Reconstr Surg. 2006 Apr;117(4):61e-80e.
2. Rao RB, Ely SF, Hoffman RS. Deaths related to liposuction. N Engl J Med. 1999 May 13;340(19):1471-1475.
20
Q

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

A

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.
References

1. Karl HW, Swedlow DB, Lee KW, Downes JJ. Epinephrine-halothane interactions in children. Anesthesiology. 1983 Feb;58(2):142-145.
2. Brown SA, Lipschitz AH, Kenkel JM, et al. Pharmacokinetics and safety of epinephrine use in liposuction. Plast Reconstr Surg. 2004 Sep 1;114(3):756-763.
3. Liu AS, Nargozian CD, Greene AK. Subcutaneous epinephrine for vasoconstriction: an evidence-based evaluation. Plast Reconstr Surg. 2010 Sep;126(3):157e-158e.
21
Q

A 7-year-old boy with a history of anaphylactic reaction to bee stings is brought to the office 45 minutes after epinephrine was mistakenly injected to the tip of the index finger from his automatic injection device. Physical examination of the finger shows swelling, tenderness, and decreased capillary refill. Which of the following is the most appropriate next step in management?

A) Apply a cold compress
B) Apply a warm compress
C) Elevate the extremity
D) Perform a stab incision and saline irrigation
E) Subcutaneously administer an antidote
A

The correct response is Option C.

The most appropriate next step in management is elevation of the extremity. Elevation facilitates venous return of the infiltrate, decreases swelling, and minimizes the risk of skin necrosis. 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.

The use of warm or cold compresses on an infiltration site is controversial. Heat may theoretically stimulate the evacuation of the infiltrate through vasodilation and increased blood flow. Ice may theoretically limit the inflammatory reaction as well as the diffusion of the infiltrated substance by causing vasoconstriction. However, warm or cold compresses may worsen tissue damage. Heat can cause thermal injury, and ice can cause ischemia from vasoconstriction, resulting in a “second hit” at the extravasation site. A partial-thickness skin injury may be converted to a full-thickness wound.

Although phentolamine, an alpha-adrenergic antagonist, has been used to treat epinephrine infiltrations, the added volume of phentolamine can worsen the injury. Injection of an antidote adds more fluid to the subcutis and may increase the risk of pressure necrosis. In addition, because epinephrine causes vasoconstriction for only 60 to 90 minutes, its effects have usually worn off by the time the extravasation is noted, the patient is evaluated by a physician, the phentolamine is ordered, and the antidote is obtained from the pharmacy.

Saline flush-out, using stab incisions through which saline is flushed, may be helpful for the infiltration of chemotherapeutic agents, but it requires several incisions and would be considered after elevation of the extremity.

References

1. Yilmaz M, Demirdover C, Mola F. Treatment options in extravasation injury: an experimental study in rats. Plast Reconstr Surg. 2002 Jun;109(7):2418-2423.
2. Greene AK. Management of epinephrine injection injury to the digit. Plast Reconstr Surg. 2005 May;115(6):1800-1801.
3. Greene AK, Hergrueter CA. Intravenous extravasation injuries. In: Hansen A, Puder M, eds. Manual of Neonatal Surgical Intensive Care. 2nd ed. Hamilton, Ontario: BC Decker; 2009: 481-488.
22
Q

A 48-year-old woman is evaluated because of a unilateral fixed, dilated, and nonresponsive pupil 1 day after she underwent prophylactic mastectomy and immediate reconstruction with a superior gluteal artery perforator free flap. History includes marked postoperative nausea. Multimodal antiemetic prophylaxis therapy was implemented during the procedure. Which of the following is the most likely causal agent of the fixed and dilated pupil?

A) Intravenous dexamethasone
B) Intravenous droperidol
C) Intravenous ondansetron
D) Oral metoclopramide
E) Scopolamine patch
A

The correct response is Option E.

Postoperative nausea and vomiting (PONV) is a distressing complication of general anesthesia and occurs in 25 to 30% of surgeries. Oftentimes, multimodality treatment is implemented for prophylaxis.

Transdermal scopolamine is a potential long-acting prophylactic antiemetic initially developed to prevent motion sickness but approved in 2001 by the US Food and Drug Administration (FDA) for the prevention of PONV. Scopolamine is a centrally acting anticholinergic agent and is designed as a patch placed behind the ear that will deliver 1.5 mg of scopolamine transdermally at a constant rate over 3 days. It has been shown to be effective in decreasing PONV for up to 24 hours after surgery. Several adverse events can occur including sedation, dry mouth, and blurred vision. In addition, mydriasis, usually ipsilateral to the side of patch application, can occur if direct contamination to the eye occurs from rubbing the eyes after manipulating the patch without hand washing. The diagnosis of scopolamine contamination can be confirmed by placing 0.5 to 1.0% pilocarpine hydrochloride in the affected eye. A dilated pupil from pharmacologic mydriasis will not constrict, whereas a dilated pupil from paralytic mydriasis will constrict. Misdiagnosis can result in an unnecessary and extensive workup for an intracranial etiology.

The other options including dexamethasone, droperidol, metoclopramide, and ondansetron are effective antiemetic agents but have no anticholinergic profile.

References

1. Vasselon P, Weiner L, Rossi-Pujo F, et al. Unilateral mydriasis due to scopolamine patch. Int J Clin Pharm. 2011 Oct;33(5):737-739. Epub 2011 Aug 26.
2. Apfel CC, Zhang K, George E, et al. Transdermal scopolamine for the prevention of postoperative nausea and vomiting: a systematic review and meta-analysis. Clin Ther. 2010 Nov;32(12):1987-2002.
3. Price BH. Anisocoria from scopolamine patches. JAMA. 1985 Mar 15;253(11):1561.
23
Q

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
A

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.

References

1. Gurunluoglu R, Swanson JA, Haeck PC, et al. Evidence-based patient safety advisory: malignant hyperthermia. Plast Reconstr Surg. 2009 Oct;124(4 Suppl):68S-81S.
2. www.mhaus.org. Accessed May 17, 2012.
24
Q

A 53-year-old man is brought to the emergency department after sustaining a laceration of the index flexor digitorum profundus, superficialis, and radial digital nerve of the nondominant left hand. He is scheduled to undergo urgent repair with single-cuff Bier block anesthesia. Which of the following would be the best reason to use an axillary block in this patient?

A) Age
B) Gender
C) Occupation
D) Surgical duration
E) Urgency of surgery
A

The correct response is Option D.

The advantages of Bier block include reliability with low incidence of block failure, safety with rapid onset and recovery. The block is limited to tourniquet pain often occurring after 20 to 30 minutes and limits its use to shorter procedures on the upper extremities.

Sudden cardiovascular collapse or seizures may occur if local anesthetic is released into the circulation too early. Disease processes in which a tourniquet is contraindicated include Raynaud disease, sickle cell disease, and severe hypertension. Uncooperative patients and young children are also contraindications.

Short duration procedures, including carpal tunnel release, tendon contracture release, foreign body extraction, and trigger finger release, are examples of procedures where Bier blocks may be considered.

Age, gender, occupation, and urgency of surgery are not contraindications to this procedure. Bier block anesthesia is a contraindication in the very young and very old, but not in a 53-year-old patient.

References

1. Bannister M. Bier’s block. Anaesthesia. 1997 Jul;52(7):713.
2. Casey WF. Intravenous regional anaesthesia (Bier’s block). In: Practical Procedures. 1992;1(2):1.
25
Q

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
A

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.

References

1. Leskiw U, Weinberg GL. Lipid resuscitation for local anesthetic toxicity: is it really lifesaving? Curr Opin Anaesthesiol. 2009 Oct;22(5):667-71.
2. Man D, Podichetty VK. Lipid rescue in resuscitation of local anesthetic-induced cardiac arrest in aesthetic surgery. Plast Reconstr Surg. 2010 Jun;125(6):257e-9e.
3. Martínez MA, Ballesteros S, Segura LJ, et al. Reporting a fatality during tumescent liposuction. Forensic Sci Int. 2008 Jun 10;178(1):e11-6.
4. Rao RB, Ely SF, Hoffman RS. Deaths related to liposuction. N Engl J Med. 1999 May 13;340(19):1471-5.
26
Q

A 5-year-old girl has subcutaneous extravasation of an epinephrine infusion in the upper extremity. On examination 1 hour later, the extremity is swollen, nontender, and well perfused. Which of the following is the most appropriate next step in management?

A)Application of a cold compress
B)Application of a warm compress
C)Elevation of the extremity
D)Incision and saline irrigation
E)Subcutaneous administration of phentolamine
A

The correct response is Option C.

The most appropriate next step in management is elevation of the extremity. Elevation facilitates venous return of the extravasate, reduces swelling, and minimizes the risk of skin necrosis.

The use of warm or cold compresses on the extravasation site is controversial. Heat may theoretically stimulate the evacuation of the infiltrate through vasodilation and increased blood flow. Ice may theoretically limit the inflammatory reaction, as well as the diffusion of the infiltrated substance, by causing vasoconstriction. However, warm or cold compresses may also worsen tissue damage. Heat can cause thermal injury, and ice can cause ischemia from vasoconstriction resulting in a ?second hit? at the extravasation site; a partial-thickness skin injury may be converted to a full-thickness wound.

Although phentolamine, an alpha-adrenergic antagonist, has been used to treat epinephrine extravasation, the added volume of phentolamine can worsen the injury. Injection of an antidote adds more fluid to the subcutis and may increase the risk of pressure necrosis. In addition, because epinephrine causes vasoconstriction for only 60 to 90 minutes, its effects have usually worn off by the time the extravasation is noted, the patient is evaluated by a physician, the phentolamine is ordered, and the antidote is obtained from the pharmacy.

Saline flush out, or using stab incisions through which saline is flushed, may be helpful for the extravasation of chemotherapeutic agents, but it requires several incisions and would be considered only after elevation of the extremity.
References

Yilmaz M, Demirdover C, Mola F. Treatment options in extravasation injury: an experimental study in rats. Plast Reconstr Surg. 2002 Jun;109(7):2418-2423.
Greene AK, Hergrueter CA. Intravenous extravasation injuries. In: Hansen A, Puder M, eds. Manual of Neonatal Surgical Intensive Care. 2nd ed. Hamilton, Ontario: BC Decker; 2009:481-489.
27
Q

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
A

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.

References

Chiu HY, Chen MT. Revascularization of digits after thirty-three hours of warm ischemia time: a case report. J Hand Surg Am. 1984 Jan;9A(1):63-67.
Chowdhry S, Seidenstricker L, Cooney DS, et al. Do not use epinephrine in digital blocks: myth or truth? Part II. A retrospective review of 1111 cases. Plast Reconstr Surg. 2010 Dec;126(6):2031-2034.
Liu AS, Nargozian CD, Greene AK. Subcutaneous epinephrine for vasoconstriction: an evidence-based evaluation. Plast Reconstr Surg. 2010 Sep;126(3):157e-158e.
28
Q

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

A

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.

References

Melendez E, Bachur R. Serious adverse events during procedural sedation with ketamine. Pediatr Emerg Care. 2009 May;25(5):325-328.
Green SM, Krauss B. Clinical practice guideline for emergency department ketamine dissociative sedation in children. Ann Emerg Med. 2004 Nov;44(5):460-471.
Hsu DC. Procedural sedation and analgesia in children. Up to Date Web site. Wiley JF II, ed. Available at: http://www.uptodate.com. September 22, 2010.
29
Q

Which of the following medications is most likely to trigger malignant hyperthermia?

A) Dantrolene
B) Isoflurane
C) Nitrous oxide
D) Pancuronium
E) Propofol
A

The correct response is Option B.

Malignant hyperthermia is a rare but potentially fatal sensitivity to volatile anesthetics and depolarizing neuromuscular blocking agents. A commonly used volatile inhalation agent is isoflurane. Succinylcholine is a depolarizing muscle relaxant frequently present in the operating room. 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.

Dantrolene is not a trigger for malignant hyperthermia. It is the only drug recommended for the treatment of malignant hyperthermia.

Propofol and nitrous oxide are not malignant hyperthermia triggers. Pancuronium is a non-depolarizing muscle relaxant and is therefore safe to use.

References

Gurunluoglu R, Swanson JA, Haeck PC, et al. Evidence-based patient safety advisory: malignant hyperthermia. Plast Reconstr Surg. 2009 Oct;124(4 Suppl):68S-81S.
Miranda AD, Donovan LA, Schuster LL, et al. Malignant hyperthermia. Am J Crit Care. 1997 Sep;6(5):368-374.
American Association for Accreditation of Ambulatory Surgery Facilities. Regular Standards and Checklist for Accreditation of Ambulatory Surgery Facilities. Version 12. Gurnee, IL: American Association for Accreditation of Ambulatory Surgery Facilities, Inc.; 2010.