Anesthesia and pain control questions OMSITE Flashcards
A 79-year-old white male presents to your office for removal of carious teeth. Medical history review reveals chronic obstructive pulmonary disease (COPD), hypertension, peptic ulcer disease, athlerosclerosis with occasional angina, and osteoarthritis. Daily medications include isosorbide dinitrate, furoseminde, and acetaminophen. After conscious sedation with midazolam and local anesthesia with prilocaine, you note that in recovery he has slowly become ashen looking and the pulse oximetry reading has fallen to 85%. Which of the following measures is most appropriate?
A. Intubation and hyperventilation with 100% oxygen
B. Titrated administration of 0.4 mg flumazenil IV
C. Methylene blue administration 1 mg/kg IV D. Assisted ventilation by face mask with room air
C. Methylene blue administration 1mg/kg IV
This situation may appear to be pulmonary in origin, but in face represents acquired methemoglobinemia. This condition can be precipitated by nitrates, (such as isosorbide dinitrate) acetaminophen, prilocaine, articaine, and a number of other medications, especially in generically susceptible individuals. The oxidized (ferric) state of the methemoglobin molecle cannot be reversed by increasing the FIO2, which also may decrease the respiratory drive in COPD. Sedation reversal by flumazenil will have no effect on the condition. Cautious administration of methylene blue will reduce methemoglobin back to a ferrous state, normalizing the oxygen binding/delivering capacity of hemoglobin
What is the recommended maximum dose of 4% articaine 1:200,000 epinephrine for a 70 kg adult? A. 280 mgs B. 350mgs C. 420 mgs D. 490 mgs
Answer: D
Rationale:
Manufacture’s recommended maximum dose is 7.0 mg/kg or 3.2 mg/lb. For children between the ages of 4 and 12 years, the manufacturer recommends a dose 5 mgs/kg or 2.27 mgs/lb.
Reference:
Malamed SF: Handbook of Local Anethesia, 4th Edition. St. Louis, Mosby, 1997 p. 63-64
Which of the following local anesthetics has the slowest onset time? A. Lidocaine B. Prilocaine C. Bupivicaine D. Mepivicaine
Answer: C
Rationale:
The pKa of a local anesthetic determines its onset time. The closer the pKa of the anesthetic is the pH of tissue (7.4), the more rapid the onset time. The pKa of a local anesthetic is the pH at which equal concentrations of ionized and unionized forms exist. C is the correct answer. Pka bupivicaine is 8.1 (slowest), pka of prilociane is 7.9
Reference:
Malamed SF: Handbook of Local Anethesia, 4th Edition. St. Louis, Mosby, 1997 p. 49-73
The lipid solubility of a local anesthetic determines its: A. duration of anesthesia. B. onset time. C. potency. D. toxicity.
Answer: C
Rationale:
The lipid solubility of a local anesthetic appears to be related to its intrinsic potency. Increased lipid solubility permits the anesthetic to penetrate the nerve membrane (which is 90% lipid) more easily. This is reflected biologically in an increased potency of the anesthetic. Local anesthetics with greater lipid solubility produce more effective conduction blockade at lower concentrations (lower percentage solutions or smaller volumes deposited) than the less lipid soluble solutions. Onset time is related to the pKa of the anesthetic. The degree of protein binding will determine the duration of the local anesthetic.
Reference:
Malamed SF: Handbook of Local Anethesia, 4th Edition. St. Louis, Mosby, 1997 p. 20
A 36 year-old atopic male presents for the extraction of a tooth. He has a past history of an anaphylactic reaction when undergoing a previous dental procedure under local anesthesia. Which of the following solutions would be best to use in this individual for future dental procedures?
A. Lidocaine 2% with epinephrine 1:100,000 (multidose vial)
B. Prilocaine 4% plain (dental cartridge)
C. Mepivacaine 3% (multidose vial)
D. Bupivacaine 0.5% with epinephrine 1:200,000 (dental cartridge)
Answer: B
Rationale:
With a history of atopy, one can assume that the greatest number of potential allergens should be eliminated from any medications administered. Multi-dose vials of local anesthetics often contain preservatives such as parabens which are allergenic; this is not the case with single use dental cartridges. The presence of a vasoconstrictor usually is accompanied by an antioxidant such as a bisulfite which also may be allergenic, and should be avoided in cases of atopy. Therefore, a non-epinephrine containing solution without preservatives would be most indicated: prilocaine 4% in a dental cartridge.
Reference:
Malamed S: Handbook of Local Anesthesia. Mosby, St. Louis, 1997
Which of the following is the cardiovascular manifestation of lidocaine toxicity? A. Bradycardia
B. Premature ventricular contractions (PVC’s)
C. Prolonged QT interval
D. Hypertension
Answer: A
Rationale:
Lidocaine has a depressor effect on the myocardium. Lidocaine toxicity causes sinus bradycardia because lidocaine increases the effective refractory period relative to the action potential duration and lowers cardiac automaticity. The bradycardia is followed by impaired contractility, massive peripheral vasodilation, hypotension and possible cardiac arrest. Lidocaine may be used to treat PVC’s and lidocaine toxicity produces hypotension, not hypertension.
Reference:
Malamed SF: Handbook of Local Anesthesia, 4th Edition. St. Louis, Mosby, 1997 p. 269- 270
Prolonged muscle relaxation can result from the concomitant use of succinylcholine and which of the following local anesthetics?
A. Bupivicaine B. Procaine
C. Mepivicaine D. Articaine
Answer: B
Rationale:
Procaine is an ester local anesthetic and metabolized in the blood by plasma cholinesterase. Succinylcholine is a depolarizing muscle relaxant that also requires plasma cholinesterase for hydrolysis. Prolonged apnea or paralysis may result form the concomitant use of these drugs. Bupivicaine, mepivicaine and articaine are all amides and thus metabolized in the liver.
Reference:
Malamed SF: Handbook of Local Anesthesia, 4th Edition. St. Louis, Mosby, 1997 p. 35
Geriatric increases in anesthetic sensitivity is most closely associated with:
A. a decrease in the number of neurons is compensated for by a increased cerebral metabolic rate.
B. an increase in cerebral metabolic rate, which is unrelated to cerebral blood flow.
C. a decrease in levels of neurotransmitters and receptors in different regions of the brain.
D. a decrease in the number of neurons, which is related to an increase in cerebral blood flow.
Answer: C
Rationale:
In the elderly, there is a reduction in the number of neurons; this is matched by an decrease in the cerebral metabolic rate. The cerebral metabolic rate is directly related to the cerebral blood flow. The decrease in the neurons and neurotransmitters is related to a decrease in the cerebral blood flow.
Reference:
Cole, D.J. and Schlunt, M.: Adult Perioperative Anesthesia 2004. Philadelphia, Mosby. Pp.249 and 466.
Power, I. and Kam, P.: Physiology for the Anaesthetist. 2001. London, Arnold, pp42-44.
Stoelting, R.K. and Dierdorf, S. F.: Anesthesia and Co-Existing Disease. 4th Edition. 2002. Philadelphia, Churchill Livingstone, pp. 238-9.
The efficiency of gaseous exchange in the elderly decreases as a result of:
A. a decrease in the closing volume.
B. a reduced alveolar surface area.
C. a decreased alveolar capillary membrane thickness.
D. a decreased V/Q ratio.
Answer: B
Rationale:
In the elderly there is an increase in the closing volume, an increase in the alveolar capillary membrane thickness and an increase in the V/Q (ventilation/perfusion) ratio. The gaseous exchange is decreased because of reduced alveolar surface area.
Reference:
Power, I. and Kam, P.: Principles of Physiology for the Anaesthetist 2001. London, Oxford Press. pp. 367-8 and 73-92.
Cole, D.J. and Schlunt, M.: Adult Perioperative Anesthesia. 2004. Philadelphia, Mosby. p. 467.
When comparing a morbidly obese patient to a non-obese patient, which of the following statements is correct?
A. Oxygen consumption is higher in the non-obese patient.
B. Functional residual capacity is the same.
C. Time to desaturation with a period of apnea is the same.
D. Positioning may diminish pulmonary reserve more in the obese patient.
Answer: D
Rationale:
Patients who are morbidly obese have changes in pulmonary, cardiovascular, gastrointestinal, and metabolic systems. Patients who are morbidly obese have increased minute ventilation at rest to meet the metabolic needs of the increased tissue mass. Changes in lung volumes at rest include reduced FRC, vital capacity, and total lung capacity. Closing volume is unchanged and reduced FRC can result in lung volumes below closing capacity in normal tidal ventilation. Anesthesia compounds these problems with greater reductions in FRC in obese patients compared to nonobese patients of the same age. As a result, obese patient’s ability to tolerate periods of apnea is reduced. Patient positioning aggravates these changes in lung volumes and contributes to poor respiratory reserve in obese patients. Reverse Trendelenberg is the most optimal position for lung volumes whereas supine position and Trendelenberg are worst in terms of safe apnea periods and recovery time.
Reference:
Stoelting RK, Dierdorf SF. Anesthesia and Co-Existing Disease, 2002.
Todd DW. Anesthetic Considerations for the Obese and Morbidly Obese Oral and Oral and Maxillofacial Surgery Patient. J Oral and Maxillofacial Surgery 63:1348-1353, 2005.
n the elderly, differences in drug response include a/an:
A. increase in MAC.
B. decreased rate of hepatic glucuronidation of morphine.
C. lowered induction dose of thiopental.
D. shorter recovery time to the normal ventilatory response with fentanyl.
Answer: C
Rationale:
The elderly require a lower dose of thiopental for the induction of anesthesia. With increasing age, the MAC for inhalation anesthetics decreases. The recovery of normal ventilatory drive after fentanyl is delayed. Regarding the rate of hepatic synthetic reactions: glucuronidation of morphine is also unchanged in the elderly but the rate of hepatic oxidative and reductive reactions are decreased with an increase in age.
Reference:
Longnecker, DE et al.:Principles and Practice of Anesthesiology. 2nd Edition, 1997. St. Louis: Mosby. pp. 481-2.
Calvey, T.N. and Williams, N.E.: Pharmacology for Anaesthetists 4th Edition 2001, London, Blackwell Science pp 106-112.
Cole, D.J. and Schlunt, M.: Adult Perioperative Anesthesia. 2004. Philadelphia, Mosby, pp.468-470.
Which of the following agents is associated with the highest incidence of nausea and vomiting in the post-operative period? A. Etomidate B. Propofol C. Ketamine D. Clonidine
Answer: A
Rationale:
Etomidate is associated with a high incidence of nausea and vomiting. Although ketamine can cause nausea and vomiting the incidence is much lower. Propofol has antiemetic effects at higher dosages. Clonidine has a low incidence of post operative nausea and may be beneficial in the treatment of cyclical vomiting syndrome.
Reference:
Miller RD (ed) Anesthesia 4th edition. New York, Churchill Livingstone, 1994; p268
Stoelting RK: Pharmacology and Physiology in Anesthetic Practice, 2nd Edition. Philadelphia, JB Lippincott, 1991.
A 22 year-old female presents for removal of her third molars under deep sedation. She has a history of Wolff-Parkinson-White Syndrome (WPW). Midazolam, fentanyl and propofol are administered, and she develops atrial fibrillation consistent with the re-entry phenomenon of WPW. The most appropriate medication to treat this problem is: A. adenosine. B. diltiazem. C. esmolol. D. amiodarone.
Answer: D
Rationale:
Drugs such as adenosine, calcium channel blockers, and beta blockers can cause a paradoxical increase in the ventricular response to the rapid atrial impulses of atrial fibrillation. This increase in ventricular response occurs because these agents slow or block conduction through the AV node and in some instances may facilitate conduction to the ventricle via the accessory pathway. The treatment of choice for a atrial fibrillation associated with Wolff-Parkinson-White syndrome is direct cardioversion, which if inappropriate, is then followed preferentially by amiodarone.
Reference:
ACLS: Principles and Practice, Pp. 328, American Heart Association 2003
GE Morgan et al, Clinical Anesthesiology, pp. 385, Lange/McGraw-Hill, 2002
A 25 year-old female is sedated with nitrous oxide and intravenous ketamine. In the recovery area the patient is noted to be hallucinating. This could possibly have been prevented by concomitant use of A. scopolamine. B. phenothiazenes. C. propofol. D. droperidol.
Answer: C
Rationale:
Ketamine delirium may be prevented by concomitant use of a benzodiazepine or propofol. The other 3 answers may also be responsible for post operative / emergent excitement.
Reference:
Firestone, Lebowitz and Cook: Clinical Anesthesia Procedures of the Massachusetts General Hospital , Third edition, P. 497
Barash, Cullen and Stoelting, Handbook of Clinical Anesthesia, Fourth edition, P.864
16. Which of the following agents can be used to reverse the effects of dexmedetomidine? A. Flumazenil B. Narcan C. Atipamezole D. Atropine
Answer: C
Rationale:
Flumazenil and Narcan are used to reverse effects of benzodiazepines and narcotics, respectively. Atropine is an antimuscarinic and does not reverse deximedetomidine. Atipamezole is an alpha2-adrenoceptor antagonist with an imidazole structure. It rapidly reverses sedation/anesthesia induced by alpha2-adrenoceptor agonists. In humans, atipamezole at doses up to 30 mg produces no cardiovascular or subjective side effects, while at a high dose (100 mg) it produced subjective symptoms, such as motor restlessness, and an increase in blood pressure.
Reference:
Jones JG, Taylor PM. Receptor specific reversible sedation: dangers of vascular effects. Anesthesiology 1999;90: 1489-1490.
Scheinin H, Aantaa R, et al. Reversal of the sedative and sympatholytic effects of dexmedetomidine with a specific alpha 2 adrenoceptor antagonist atipamezole: a pharmacodynamic and kinetic study in healthy volunteers. Anesthesiology 1998;89:574- 584.
What effect will ketamine have on the degree of regurgitation in a patient with mitral valve prolapse with regurgitation? A. Increase B. Decrease C. No effect D. Variable
Answer: A
Rationale:
Ketamine is discouraged in patients with mitral valve prolapse with regurgitation, due to its sympathomimetic actions. It will increase vascular resistance and worsen regurgitant flow.
Reference:
Waxman K, Shoemaker WC, Lippman M: Cardiovascular effects of anesthetic induction with ketamine. Anesth Analg 1980; 59:355-8.
White PF, Way WL, Trevor AJ: Ketamine: Its pharmacology and therapeutic uses. Anesth 1982; 56:119-36.
Barbiturates have which of the following effects on the myocardium?
A. Directly sensitize the myocardium to arrhythmias
B. Directly increase myocardial contractility
C. Indirectly increase heart rate by inducing venodilation
D. Indirectly increase myocardial contractility
Answer: C
Rationale:
Barbiturates have no effect on myocardial sensitization. They decrease myocardial contractility. Reflex tachycardia is common after an induction dose of barbiturate to compensate for the vasodilatation.
Reference:
Miller RD (ed) Anesthesia 4th edition. New York, Churchill Linignstone, 1994; p238
Lieblich SE. Methohexital Versus Propofol of Outpatient Anesthesia Part 1: Methohexatal is Superior. JOMS 58:811-815, 1995
Ketamine’s direct effect on the heart is: A. chronotropic depression. B. chronotropic stimulation. C. inotropic depression. D. inotropic stimulation.
Answer: C
Rationale:
Ketamine direct action on the myocardium is a negative inotropic effect. Its centrally mediated sympathetic responses (indirect activation of the sympathetic nervous system) usually override the depression. Ketamine causes an increase in circulating catecholamines, especially norepinephrine, by inhibiting reuptake at postganglionic sympathetic neurons.
Reference:
Reich DL, Silvay G. Ketamine: an update on the first twenty-five years of clinical experience. Can J Anaesth 1989;36:186–97.
Hirota K, Lambert DG. Ketamine: its mechanism(s) of action and unusual clinical uses. Br J Anaesth 1996; 77:441–4.
Which of the following is a side effect associated with etomidate?
A. Decreased venous return and myocardial contractility
B. Intra-arterial injection causing nerve injury and gangrene
C. Adrenal suppression lasting at least 6 hours
D. Triggering of porphyria in susceptible individuals
Answer: C
Rationale:
Etomidate maintains hemodynamic stability and has little effect on the heart. Barbiturates are known to have severe effects associated with intra-arterial injection. This group is also responsible for porphyria in susceptible individuals. Etomindate causes adrenal suppression and steroid administration may be necessary in patients already having adrenal axis suppression.
Reference:
Miller RD (ed) Anesthesia 4th edition. New York, Churchill Livingstone, 1994; p268
Dembo JB. Methohexital Versus Propofol of Outpatient Anesthesia Part II: Propofol is Superior. JOMS 58:816-820, 1995
Which of the following neuromuscular blockers requires little if any dosage .change in the elderly patient? A. Pancuronium B. Vecuronium C. Cisatracurium D. Mivacurium
Answer: C
Rationale:
Cisatracurium is the neuromuscular blocker that is metabolized by Hoffman degeneration and organ-independent elimination. This process is non-enzymatic and occurs spontaneously and thus needs little if any change in the routine dose in the elderly. Also the clinical effect is not prolonged. Pancuronium is dependent on renal function and excretion which decreases with age. Vecuronium is dependent on hepatic function which also decreases with age; and mivacurium is metabolized by plasma cholinesterase which also decreases with age. Because of the age dependent nature of metabolism for these three neuromuscular blockers, they all require a reduction in dosage for the elderly.
Reference:
Cole, D.J and Schlunt, M: Adult Perioperative Anesthesia. 2004. Philadelphia, Mosby, p. 471.
Vickers, M.D. and Power, I.: Medicine for Anaesthetists. 4th Edition, 1999. London, Blackwell Science, p. 114
Which effect is seen with propofol? A. Elevation of intracranial pressure B. Increases in intraocular pressure C. Potentiation of neuromuscular blockade D. Increases in bronchodilation
Answer: D
Rationale:
Propofol has a direct smooth muscle effect on the bronchi, causing bronchodilation. Propofol decreases intracranial and intraocular pressure, and it does not potentiate neuromuscular blockade.
Reference:
Miller RD (ed) Anesthesia 4th edition. New York, Churchill Livingstone, 1994; p270-272
Dembo JB. Methohexital versus Propofol of Outpatient Anesthesia Part II: Propofol is Superior. JOMS 58:816-820, 1995
Which drug must be used with caution in a patient with a history of epilepsy? A. Propofol
B. Fentanyl
C. Dexmedetomidine D. Methohexital
Answer: D
Rationale:
Methohexital can cause seizure activity; and therefore is contraindicated in patients with temporal lobe seizures. The other three drugs are not associated with seizure-like activity.
Reference:
Cote, Charles J., Pediatric Anesthesia, pg. 2375 in Miller’s Anesthesia, Sixth Edition, Volume 2, by Elsevier Inc.
Stoelting, Robert K. MD, Dierdorf, Stephen F, MD, Chapter 17, Anesthesia and Coexisting Disease, Fourth Edition, pg. 284,
A 61 year-old patient presents for removal of tooth #2, and general anesthesia He has aortic regurgitation. The perioperative management of this patient includes which of the following? A. Relative hypovolemia B. Negative inotropic agents C. Increase afterload D. Positive chronotropic agents
Answer: D
Rationale:
The perioperative goals of managing aortic regurgitation are to promote forward flow by decreasing afterload and to maintain a normal to slightly increased heart rate.
Reference:
Goldman et al. (Multifactorial index of cardiac risk in non-cardiac surgical procedures. N Engl J med 1977;297:845-50.
DE Longnecker, FL Murphy, Introduction to Anesthesia, 9th ed., pp. 291, Saunders, 1997 GE Morgan et al, Clinical Anesthesiology, pp. 414, Lange/McGraw-Hill, 2002
A 49-year-old patient presents for removal tooth #15 under general anesthesia. His clinical examination is significant for a IV/VI holosystolic murmur heard at the apical area and radiates to left axilla. The perioperative management should include which of the following?
A. Decrease intravascular volume
B. Decrease myocardial contractility
C Increase peripheral vascular resistance D Increase heart rate
Answer: D
Rationale:
A holosystolic murmur heard at the apex and radiating to the left axilla is consistent with a mitral regurgitation. The perioperative goals of managing mitral regurgitation are to promote forward flow by decreasing afterload and to maintain a normal to slightly increased heart rate.
Reference:
DE Longnecker, FL Murphy, Introduction to Anesthesia, 9th ed., pp. 291, Saunders, 1997
GE Morgan et al, Clinical Anesthesiology, pp. 414, Lange/McGraw-Hill, 2002
An 18 year-old with Cerebral Palsy (CP) requires intubation for a general anesthetic. Succinylcholine is contraindicated in this patient secondary to
A. structural similarity to acetylcholine.
B. potential for a significant increase in circulating levels of potassium.
C. deficiency of pseudocholinesterase.
D. fasciculation and post-operative muscle pain.
Answer: B
Rationale:
Circulating potassium increases significantly in patients with CP following administration of succinylcholine and may lead to lethal arrhythmias.
Reference:
Firestone, Lebowitz and Cook: Clinical Anesthesia Procedures of the Massachusetts General Hospital , Third edition, P. 171
Barash, Cullen and Stoelting, Handbook of Clinical Anesthesia, Fourth edition, P.585
A patient with which condition is least likely to be an aspiration risk during an outpatient non-intubated general anesthetic? A. Systemic lupus erythematosus B. Parkinson’s disease C. Myasthenia gravis D. Diabetes mellitus
Answer: A
Rationale:
Parkinson’s disease, myasthenia gravis, a transection of the vertebral column above T4, and diabetes mellitus all increase the risk of aspiration. Parkinson’s disease and myasthenia gravis impair the patient’s ability to control their airway. Parkinson’s’ disease is a neurodegenerative disease characterized by a loss of dopaminergic neurons in the substantia nigra of the basal ganglia. Clinical signs and symptoms include a resting tremor, rigidity, postural instability and bradykinesia. Myasthenia gravis is an autoimmune disease of the neuromuscular junction. Clinical symptoms include fatigue, weakness of the striated muscles, diplopia, inspiratory muscle weakness, and bulbar weakness with impaired ability to handle secretions and swallow. The diabetic patient may have autonomic dysfunction resulting in gastroparesis. Frequently gastroparesis is undiagnosed and asymptomatic. This increases the risk of gastric aspiration. The patient with systemic lupus erythematosus may present anesthetic airway and pulmonary concerns such as reduced TMJ range of motion, decreased arytenoid movement, diaphragmatic dysfunction, pulmonary infiltrates and reduced PFTs. However, the patient is not at increased risk for aspiration.
Reference:
Altee John L. Complications in Anesthesia. WB Saunders 1999
Roizen MF, Fleisher LA. Essence of Anesthesia Practice. WB Saunders 1997
The use of succinylcholine is acceptable in which patient population? A. Behcet’s muscular dystrophy B. Four month old spinal cord injury C. Multiple sclerosis D. Myasthenia gravis
Answer: D
Rationale:
Myasthenia gravis (MG) is a neuromuscular disease that is characterized by weakness and fatigability of skeletal muscles. The MG patient is more sensitive to the use of nondepolarizing relaxants. However, because there are fewer functional receptors the MG patient may demonstrate increased resistance to depolarizing muscular relaxants. While many anesthesiologists may prefer to avoid neuromuscular blocking agents, succinylcholine (in higher doses) can be used in the MG patient and provide satisfactory intubating conditions. Succinylcholine may precipitate hyperkalemia in muscular dystrophy, spinal cord injuries less than 6 to 8 months and MS.
Reference:
Altee John L. Complications in Anesthesia. WB Saunders 1999
Roizen MF, Fleisher LA. Essence of Anesthesia Practice. WB Saunders 1997
A 17 year-old asthmatic with a preoperative FEV1/FVC of 85% requires which preoperative treatment prior to induction of general anesthesia? A. Ipratropium MDI B. Nebulized Racemic Epinephrine C. Advair MDI D. No treatment indicated
Answer: D
Rationale:
No treatment is required for a normal FEV1/FVC.
Reference:
Firestone, Lebowitz and Cook: Clinical Anesthesia Procedures of the Massachusetts General Hospital , Third edition, P. 35-7
Barash, Cullen and Stoelting, Handbook of Clinical Anesthesia, Fourth edition, P. 419-22
A 52 year-old obese patient with a hiatal hernia requires induction of general anesthesia. Which premedicant could be considered to minimize the patient’s risk of respiratory problems?
A. Glycopyrolate B. Amitriptyline C. Metoclopramide D. Meperidine
Answer: C
Rationale:
Metoclopramide would increase gastric emptying and increase esophageal sphincter tone. This would help decrease the risk of aspiration. All the other choices decrease esophageal sphincter tone and would increase the risk of aspiration.
Reference:
Firestone, Lebowitz and Cook: Clinical Anesthesia Procedures of the Massachusetts General Hospital , Third edition, P. 624-5
Barash, Cullen and Stoelting, Handbook of Clinical Anesthesia, Fourth edition, P. 549
Which of the following statements is correct regarding the LMA (laryngeal mask airway?
A. The classic LMA when in correct position protects against aspiration of stomach contents
B. Insufflation of the stomach can occur with excess pressure exerted through the LMA.
C. Administration of emergency drugs via a LMA or endotracheal tube has equivalent success rates.
D. A cuffless LMA is available for young children to minimize potential soft tissue potential ischemia.
Answer: B
Rationale:
The laryngeal mask airway is an airway device that is placed in the hypopharynx above the opening of the larynx. The LMA does not protect against aspiration of stomach contents and insufflation of the stomach can be expected with pressures above 20 cm of water. The black orientation line faces cephalad when in correct position. Delivery of emergency drugs through a LMA are less successful (approximately 20% successful administration) than via an endotracheal tube. All sizes of the LMA have a cuff that allows for seating of the LMA in the hypopharynx.
Reference:
The LMA Manual. The Laryngeal Mask Airway Company, LTD.
Todd DW. Use of the LMA for Outpatient General Anesthetics, Pro. J Oral and Maxillofac Surg, 61:2003.
A 7 year-old male needs a general anesthetic and intubation for an elective surgical procedure. He presents with malaise, a productive cough and thick nasal discharge. How long will you wait to reschedule the procedure? A. No delay necessary B. 7 to 10 days C. 2 to 3 weeks D. 11⁄2 to2months
Answer: D
Rationale:
It is likely that this child has an upper respiratory infection (URI). Signs of an URI include fever, fatigue, loss of appetite, productive cough, and thick nasal discharge. Children with URI have an irritable airway and are at increased risk for laryngospasm, bronchospasm, postintubation croup, pneumonia, and episodes of desaturation. Bronchial hyperreactivity may last 4 to 6 weeks after an URI; it is recommended to delay treatment for at least 6 weeks. If urgent or emergency surgery is necessary a LMA may reduce complications associated with an irritable airway.
Reference:
Cote, Charles J., Pediatric Anesthesia, pg. 2381 - 2382 in Miller’s Anesthesia, Sixth Edition, Volume 2, by Elsevier Inc.
Dembo, Jeffrey B., Pediatric Consideration in Office Anesthesia, pg. 108, OMS Knowledge Update, Vol. 1, Part 1, August 1994
Which mode of mechanical ventilation is described as allowing the patient to trigger a breath; but can cause respiratory alkalosis when the patient is tachypneic?
A. Assist control ventilation
B. Synchronized intermittent mandatory ventilation
C. Pressure controlled ventilation
D. Controlled mechanical ventilation
Answer: A Rationale: Mechanical ventilation may be either volume or pressure controlled. Volume controlled ventilation consists of CMV(controlled mechanical ventilation), ACV (assist controlled ventilation), IMV (intermittent controlled ventilation), SIMV (synchronized intermittent controlled ventilation). Pressure controlled ventilation is either PSV (pressure support ventilation) which is patient triggered or PCV (pressure controlled ventilation) which is ventilator triggered. CMV is most commonly used during general anesthesia in the neuromuscularly blocked patient. The various other settings can be used for ventilatory support and weaning. The ACV mode requires that the patient trigger a breath. When the patient triggers a breath the ventilator delivers a preset volume. The disadvantage of the mode is that if the patient is tachypneic excessive volume and thus a respiratory alkalosis will develop. Alternatively, IMV allows the patient to breath spontaneously and delivers positive pressure ventilation at a preset volume and rate to ensure oxygenation and ventilation. SIMV prevents PVP (positive pressure ventilation) during a spontaneous breath. Reference: Miller, Stoelting, Basics in Anaesthesia
A 64 year-old female presents for removal of tooth #30 under general anesthesia. Her past medical history is significant for rheumatic heart disease, and subsequent mitral valve stenosis. The preoperative management of this patient would include which of the following? A. Decrease intravascular volume B. Increase intravascular volume C. Maintain a slower heart rate D. Maintain a faster heart rate
Answer: C
Rationale:
The principal hemodynamic goals of managing patients with mitral stenosis are to maintain a slower to normal sinus rhythm and to avoid tachycardia, large increases in cardiac output, and both hypovolemia and fluid overload by judicious fluid therapy.
Reference:
DE Longnecker, FL Murphy, Introduction to Anesthesia, 9th ed., pp. 290, Saunders, 1997
GE Morgan et al, Clinical Anesthesiology, pp. 411, Lange/McGraw-Hill, 2002
Twenty four hours after an ultralight general anesthesia procedure for third molar removal using intravenous fentanyl, methohexital, and nasal nitrous oxide/oxygen, your 40 year-old female patient calls complaining of intense abdominal pain in all quadrants and muscle weakness. Over the next several days, confusion develops and the urine turns dark. After successful medical management, the patient relates a family history of “severe reactions” to sulfonamide antibiotics, including prolonged hospitalizations. Which of the following agents would be safest to use on this patient in the future?
A. Morphine B. Ketamine C. Isoflurane D. Diazepam
Answer: A
Rationale:
The symptoms are classic for acute intermittent porphyria, an autosomal dominant condition leading to a deficiency in uroporphyrinogen synthetase activity, causing an accumulation of uroporphobilogen, which is excreted in the urine turning it a dark color. Classic symptoms of an acute attack include intense abdominal pain, motor weakness, (usually starting proximally in the upper limbs) and confusion/agitation. These are due to nervous system dysfunction and demylenization. Diagnosis is by family history, increased levels of urinary porphobilogen, and deficient uroporphyrogen synthetase in the red blood cells. Treatment for an acute episode is supportive, including withdrawal of precipitating agents, carbohydrate support, hydration, and careful administration of hematin.
Many agents have been implemented as potential triggering agents for acute intermittent porphyria. The most commonly cited are barbiturates. Morphine, fentanyl and its conjoiners, and nitrous oxide are considered safe. Other anesthetic agents implicated as causative or exacerbative agents for AIP include most potent inhalation volatile anesthetics, benzodiazepines, ketamine, etomidate, meperidine, and lidocaine.
Reference:
Weinberg GL (ed;): Basic Science Review of Anesthesiology, McGraw-Hill, New York, 1997 pp64-66
Benumof JL (ed.) Anesthesia and Uncommon Diseases, WB Saunders, Philadelphia, 1998 pp 162-163
Thirty minutes after extubating a 6 year old asthmatic male patient in your office you notice the child to be in respiratory distress characterized by high pitched coarse sounds occurring during inspiration. What is the most likely diagnosis and treatment?
A. Partial laryngospasm initially managed with positive pressure ventilation
B. Bronchospasm initially managed with albuterol inhaler
C. Postextubation stridor initially managed with racemic epinephrine
D. ost-obstructive pulmonary edema initially managed with supplemental oxygen
Answer: C
Rationale:
Postextubation stridor is a result of laryngeal inflammation reducing the airway DIMENSION. In a young child it may be secondary to irritation of the endotracheal tube infringing on the narrowest part of the child’s airway – being the cricoid cartilage. Maneuvers to avoid such include using a cuffless tube and ensuring that there is an air leak around the tube. Movement of the patient’s head during surgery can cause a displacement of the tube superiorly (essentially extubating the patient) or inferiorly (irritating the mucosa around the region of the cricoid cartilage). The risk of the child developing postextubation stridor persists for up to 24 hours after the extubation. Aerosolized 2.25% racemic epinephrine produces mucosal vasoconstriction and reduces laryngeal edema. The patient has a history of asthma and could have developed a bronchospastic event post- operatively. However, the clinic presentation was an inspiratory sound where bronchospasm would more likely demonstrate an expiratory wheeze. Laryngospasm is also a possibility but there is nothing in the history to put the patient at risk for a laryngospasm 30 minutes postextubation and it should not be highest on your differential.
Reference:
Altee John L. Complications in Anesthesia. WB Saunders 1999
Roizen MF, Fleisher LA. Essence of Anesthesia Practice. WB Saunders 1997
Initial acute management of intraoperative bronchospasm under inhalational general anesthesia includes which of the following?
A. Decadron IV
B. Reducing the depth of anesthesia
C. Albuterol MDI through the endotrachial tube
D. Epinephrine IV
Answer: C
Rationale:
Intraoperative bronchospasm should be first treated by confirming that there is no mechanical obstruction of the tracheal tube, tube placement is correct and adequate depth of anesthesia is present. The initial treatment consists of the administration of a -agonist such as albuterol. Epinephrine should be reserved for a severe bronchospasm refractory to initial -agonist therapy because of the potential for severe adverse effects. Steroids are not helpful in the acute management and muscle paralysis will not improve the situation. Differential diagnosis should also include pneumothorax, pulmonary edema, pulmonary embolus, and pulmonary aspiration.
Reference:
Stoelting RK, Dierdorf SF. Anesthesia and Co-Existing Disease, Churchill Livingstone, 2002.
AAOMS Office Emergency Manual, AAOMS, Chicago 2004.
In the infant and young child, the narrowest portion of the larynx is located at which anatomical position? A. Vocal cords B. Cricoid cartilage C. Thyroid cartilage D. V alecula
Answer: B
Rationale:
In infants or young children, the narrowest portion of the larynx is at the cricoid cartilage. In a child, an endotracheal tube might pass easily through the vocal cords but not through the subglottic region. The cricoid is the only complete ring of cartilage in the laryngotracheobronchial tree and is therefore nonexepandable. A tight fitting endotracheal tube that compresses the tracheal mucosa at this level may cause edema and result in increased airway resistance at the time of extubation. For this reason, uncuffed endotracheal tubes are usually preferred for infants or young children. As the child matures (age 10 to 12 years of age), the cricoid and thyroid cartilages have grown, eliminating the narrowing of the subglottic area and angulation of the vocal cords.
Reference:
Cote, Charles J., Pediatric Anesthesia, pg. 2376 in Miller’s Anesthesia, Sixth Edition, Volume 2, by Elsevier Inc.
Which of the following is contraindicated in management of cardiac arrhythmias during a malignant hyperthermia episode? A. Procainamide B. Cardizem C. Regular insulin and D50 D. Sodium bicarbonate
Answer: B
Rationale:
Etiologic treatment of an MH episode requires dantrolene at an initial dose of 2-3 mg/kg. Cardiac dysrrhythmias should be treated by procainamide at an initial dose of 100mg IV. Management of hyperkalemia to correct the arrhythmia can be achieved with regular insulin 10 units IV together with 1 amp of D50, as well as sodium bicarbonate to help drive potassium intracellularly. Calcium channel blockers such as cardizem are contraindicated because they can cause severe myocardial depression in the presence of dantrolene.
Reference:
MHAUS, Emergency Therapy for MH Crisis
Stoelting RK, Dierdorf SF. Anesthesia and Coexisting Disease, Churchill- Livingston, 2002.
Which medication is contraindicated for office-based anesthesia in a patient with partially controlled tonic-clonic seizure activity? A. Propofol B. Fentanyl C. Ketamine D. Methohexital
ANSWER: D
RATIONALE:
Although many thiobarbiturates decrease cerebral metabolism and electrical activity and are used as anticonvulsants, the oxybarbiturate methohexital has increased central nervous system excitatory effects and may precipitate seizures in epileptics. Propofol, fentanyl, and ketamine have no such pro-convulsant effects.
