1. Local anesthetics Flashcards
A 50-year-old woman is scheduled to undergo bilateral deep inferior epigastric artery perforator (DIEP) flap breast reconstruction. A donor site regional block with liposomal bupivacaine is planned for analgesia. Which of the following injection locations is most likely to improve pain control and decrease narcotic use in this patient?
A) Between external oblique and internal oblique fascias
B) Between internal oblique and transversus abdominis fascias
C) Deep to rectus abdominis fascia
D) Deep to transversus abdominis fascia
E) Subcutaneous plane
The correct response is Option B.
The patient is undergoing a transversus abdominis plane (TAP) block. TAP blocks have become popular adjunctive pain control measures for a variety of abdominal surgeries. They can either be performed transcutaneously with ultrasound guidance or under direct visualization in the operating room prior to closure of the abdominal donor site in deep inferior epigastric artery perforator (DIEP) or transverse rectus abdominis musculocutaneous (TRAM) flap surgeries. The segmental innervation to be blocked in the TAP block is located between the internal oblique and transversus abdominis muscles. Either infiltration of liposomal bupivacaine or placement of epidural catheters in the TAP space has been described.
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.
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
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.
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
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.
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
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.
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
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.
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
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.
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
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.
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
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.
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 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
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
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.
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
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.
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
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.
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.
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
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.
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.
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.
