2005 Flashcards
A 36-year-old obese female is in your office requesting a general anesthetic for extraction of a carious tooth. Your primary concern in regards to her obesity and pulmonary function is:
A. a decreased FEV1.
B. a decreased functional residual capacity.
C. a decreased minute ventilation.
D. a decreased residual volume
B
Rationale:
Morbid obesity is characterized by reductions in functional residual capacity (FRC= volume remaining in the lungs after a normal quiet expiration), expiratory reserve volume (ERV=volume of air that can forcefully expired after a normal resting expiration) and total lung capacity (TLC). These changes have been attributed to mass loading and splinting of the diaphragm. Anesthesia compounds these problems and impairs the ability of the obese to tolerate periods of apnea. Residual volume consists of the gases remaining in the lung after a forced expiration and is less variable than other parameters. FEV1 is the forced expiratory volume in 1 second and is most often used as a determinant of inflammation and small airway obstruction in obstructive lung diseases such as asthma.
Reference:
Stoelting RK & Dierdorf SF. Handbook for Anesthesia and Co-Existing Disease. 2nd ed. Churchill Livingston 2002 pages 333-342.
Which of the following is the least likely cause of acute respiratory distress in the traumatized patient who is conscious when presenting to the emergency department? A. Cervical fracture above C5 B. Cricoid fracture C. Flail chest D. Pneumothorax
Answer: D
Rationale:
All of the above can cause respiratory distress. Blunt trauma to the airway is most commonly secondary
to direct blows. A passenger in the front seat with only a lap belt is susceptible to hitting his symphysis or neck on the dashboard. Between 10% to 50% of the patients sustaining blunt airway trauma have a cervical spine injury. Respiratory complications are common with cervical spine injuries. The extent of the respiratory derangement is associated with the level of the injury to the cervical spine. While the patient will have some respiratory compromise, diaphragmatic paralysis is spared with injuries at C5 or below. Fractures of the cricoid cartilage are not common. When they do occur there is a 25% incidence of damage to the recurrent laryngeal nerve, which results in vocal cord paralysis and airway compromise. Mortality associated with cricoid fractures is reported to exceed 43%. Application of cricoid pressure to a patient with a cricoid fracture can result in airway obstruction. A flail chest is by definition fractures of three adjacent ribs and results in paradoxical chest wall movement. A pneumothorax may impair respirations but in most situations will not result in acute respiratory distress. This should be distinguished from a tension pneumothorax and an open pneumothorax which can cause acute distress.
Reference:
Benumof Airway management: Principles of Practice, Mosby 1995 Chapter 34 pages 742-743.
Which of the following is a property of metoclopramide?
A. Delays gastric emptying
B. Intensifies activity of the vomiting center
C. Increases gastroesophageal sphincter tone
D. Attenuates extrapyramidal effects
Answer: C
Rationale:
The incidence of aspiration is relatively low at 5 cases per 10,000. This incidence, however, is markedly increased in the traumatized patient. Pharmacologic measures may decrease the risk of aspiration. Metoclopramide stimulates gastric emptying, attenuates activity of the vomiting center and increases gastroesophageal sphincter tone. It must be administered at least 20 minutes prior to induction and its effect is decreased if administered in conjunction with an opioid. It acts on the dopamine receptor in the chemoreceptor trigger zone and thus can cause extrapyramidal effects. These effects can be treated with benzotropine or diphenhydramine.
Reference:
Benumof Airway management: Principles of Practice, Mosby 1995 Chapter 34 pages 746 – 748.
Which of the following interventions can facilitate a fiberoptic nasoendotracheal intubation in a patient with a right temporomandibular joint ankylosis?
A. Anesthetizing the pharyngeal branch of the glossopharyngeal nerve
B. A recurrent laryngeal nerve block
C. An inferior laryngeal nerve block
D. Transtracheal administration of lidocaine
Answer: D
Rationale:
Intubation of an awake patient causes significant airway stimulation and irritation.
Anesthetizing the mucosa of the upper airway can improve comfort and lessen unpleasant stimulation associated with this procedure. Topical application of local anesthetic agent can be accomplished orally (as a swish and swallow) or by transtracheal deposition into the tracheal lumen. However, these techniques may blunt the glottic and cough reflex, increasing the patient’s susceptibility to aspiration. The gag reflex can be further controlled by supplementary nerve blocks to the lingual branch of the glossopharyngeal nerve and the superior laryngeal nerve. The glossopharyngeal nerve block requires the bilateral deposition of local anesthetic agent into the caudad portion of the tonsillar pillar. The superior laryngeal nerve block is
accomplished by deposition of local anesthetic agent into the thyrohyoid membrane.
Reference:
Bennett JD, Flynn TR. Anesthetic Considerations in Orofacial Infections, in Oral and Maxillofacial
Infections, eds. Topazian, Goldberg, Hupp WB Saunders 4th ed 2002.
Which of the following drugs is most protective against bronchospastic activity?
A. B. C. D.
Etomidate Methohexital Propofol
Thiopental
C
Rationale:
Propofol can produce bronchodilation and decrease the incidence of intraoperative wheezing in patients with asthma. In one study comparing propofol, methohexital and thiopental propofol demonstrated a significantly decreased incidence of wheezing after induction and intubation compared to the other agents. Etomidate has less of a depressant effect on ventilation compared to barbiturates, however, but is not protective against bronchospasm.
Reference:
Pizov R.,Brown RH.,Weiss YS,Baranov D.,Hennes H. Baker ,. Hirshman CA. Wheezing during induction of general anesthesia in patients with and without asthma. A randomized, blinded trial Anesthesiology. 82(5):1111-6, 1995 May.
A 26-year-male, weighing 80 kg and 6 feet tall is sedated with midazolam 5 mg, fentanyl 100 mcg followed by methohexital 90 mg. The patient’s heart rate increases from 88 to 102 BPM and his oxygen saturation drops from 98% to 90%. The patient is making ventilatory efforts with respiratory noises. The desaturation is most likely secondary to: A. bronchospasm. B. hypoxic respiratory depression. C. Laryngospasm. D. supraglottic obstruction.
Answer: D
Rationale:
Most anesthetics depress the hypercapneic and hypoxic respiratory drive, diminish upper airway tone, blunt upper airway reflexes and decrease functional residual capacity. While the respiratory drive may be blunted and the reflexes diminished the anesthetic doses administered to this size patient will allow continual spontaneous ventilation if the airway is kept patent either with positioning (e.g. chin – forehead lift) or airway devices (e.g. nasopharyngeal airway). This patient is making ventilatory efforts. The respiratory noises are most likely associated with supraglottic obstruction. Alleviating the obstruction should facilitate ventilation and increase oxygen saturation. The increase in heart rate is most likely secondary to the methohexital.
Reference:
Stoelting and Miller, Basics of Anesthesia, Churchill Livingstone, 2002.
Which of the following medications is most likely to be a contributory factor towards post-operative agitation and combativeness? A. Glycopyrrolate B. Propofol C. Meperidine D. Midazolam
C
Rationale:
There are a number of factors that can contribute to a patient’s disorientation or combativeness after an anesthetic. Combativeness may be manifest as the patient emerges from a general anesthetic until oriented. The surgeon must always consider that the patient is hypoxic. Tertiary anticholinenergic drugs (atropine and scopolamine) can cross the blood brain barrier and lead to postoperative delirium. Glycopyrrolate is a quarternary agent and does not cross the blood brain barrier. Propofol is associated with rapid recovery and euphoria. Long acting benzodiazpines may also contribute to disorientation on emergence. In young healthy patients recovery from midazolam is generally not associated with disorientation. Meperidine, although rare, because of its atropine-like structure can cause post-operative agitation and combativeness.
Reference:
Harkin CP. Postoperative delirium page 192 – 194 in Complications in Anesthesia eds. Atlee JL WB Saunders 1999.
Which of the following antiemetic agents achieves its primary antiemetic effect by its strong blocking action on the dopamine receptor located in the chemoreceptor trigger zone? A. Prochlorperazine (Compazine) B. Diphenhydramine (Benadryl) C. Metoclopramide (Reglan) D. Scopolamine (Transderm Scop)
A
Rationale:
Serotonin, dopamine, acetylcholine and histamine receptors are located in the chemoreceptor trigger zone. All of the above agents act to some degree on the dopamine receptor. Of these agents, compazine achieves its effect by strongly binding to the receptor. Scopolamine and diphenhydramine bind only weakly.
Reference:
Yagiela J: Review of Antiemetic therapies. Oral and Maxillofacial Surgery Clinics November 1999, pages 647 – 658.
A 42-year-old patient with a history of asthma, hypertension, and TMD presents for the extraction of multiple carious teeth. The patient smokes 1 pack per day. Medications include hydrochlorothiazide (HCTZ) 25 mg, singulair (montelukast) 10 mg and elavil (amitriptyline) 75 mg. Vital signs are BP 142/92, heart rate 92 regular, oxygen saturation 98%. The patient’s lungs are clear to auscultation and he has not required intervention with his albuterol inhaler for over 10 months. Which of the following anesthetic agents should be avoided in this case? A. Fentanyl B. Ketamine C. Methohexital D. Midazolam
Answer: B
Rationale:
Tricylcic antidepressants (elavil) prevent the reuptake of catecholamines. Ketamine has sympathomimetic effects and will be associated with an increase in heart rate and blood pressure. These effects will be potentiated by the tricyclic antidepressant and compounded by the patient’s history of hypertension. Methohexital is not contraindicated in a patient with controlled asthma.
Reference:
Faberowski LW & Black S. Antidepressants in Complications in Anesthesia eds. Atlee JL WB Saunders 1999 page 99.
Which statement is accurate pertaining to the intramuscular administration of the combination of ketamine and glycopyrrolate?
A. The onset of the antisialogogue effect of glycopyrrolate parallels the onset of the dissociative effect of ketamine.
B. The incidence of tachycardia with the combination of glycopyrrolate & ketamine is less than that which occurs with atropine & ketamine.
C. The incidence of emergence phenomenon is lower with the combination of glycopyrrolate and ketmaine that that which occurs with atropine and ketamine.
D. The incidence of emesis is lower with the combination of atropine and ketamine that that which occurs with glycopyrrolate and ketamine.
Answer: B
Rationale:
Ketamine is associated with an increase in salivation. An anticholinergic agent is frequently combined with ketamine to decrease the hypersalivation. Intramuscularly administered glycopyrrolate has a peak effect in approximately 30 minutes, while intravenously administered glycopyrrolate has a peak effect in approximately 1 minute. Robinal is a quaternary amine and does not cross the blood brain barrier compared to atropine, which is a tertiary amine and does cross the blood brain barrier. However, the incidence of emergence phenomenon is not higher with atropine when compared to glycopyrrolate. Ketamine has sympathomimetic effects resulting in an increase in heart rate. Atropine has a greater potential to potentiate the tachycardia associated with ketamine.
Reference:
Morgensen F, Muller D, Valentin N: Glycopyrrolate during ketamine/diazepam anaesthesia: a double blind comparison with atropione. Acta Anaesthesiol Scand 30:332;1986.
A patient with a history of coronary heart disease presents for removal of mandibular tori. Of the following medications which is most likely to cause the greatest imbalance in myocardial oxygen supply and oxygen demand? A. Fentanyl B. Ketamine C. Midazolam D. Propofol
B
Rationale:
Ketamine has sympathomimetic effects and causes prominent changes in heart rate, cardiac index, and systemic vascular resistance. These changes cause an increase in myocardial oxygen consumption that may be detrimental to the patient with CAD.
Reference:
Stoelting, RK, Miller RD: Basics in Anesthesia Churchill Livingston 4th edition 2000.
Which of the following medications has the least effect on functional residual capacity? A. Etomidate B. Ketamine C. Midazolam D. Propofol
Answer: B
Rationale:
Most anesthetics depress the hypercapneic and hypoxic respiratory drive, diminish upper airway tone, blunt upper airway reflexes and decrease functional residual capacity. Ketamine is unique in that it does not produce significant depression of ventilation. Upper airway muscle tone is maintained, upper airway reflexes remain intact and FRC is not diminished.
Reference:
Stoelting, RK, Miller RD: Basics in Anesthesia Churchill Livingston 4th edition 2000.
Which of the following local anesthetic agents has the slowest onset? A. Articaine B. Bupivicaine C. Lidocaine D. Mepivicaine
B
Rationale:
Bupivicaine has a slower onset of action compared to the other agents because of its greater degree of ionization at physiologic pH.
Reference:Jastak JT, Yagiela JA, Donaldson D: Local Anesthesia of the Oral Cavity. WB Saunders 1995 pg 101.
Which of the following agents has the shortest half life? A. Articaine B. Bupivicaine C. Lidocaine D. Mepivicaine
Answer: A
Rationale:
The molecular structure of articaine contains an ester side chain which is rapidly inactivated by hydrolysis. The ester metabolite is not para-aminobenzoic acid; and thus not associated with allergic reactions as were the ester local anesthetics (e.g. procaine). The half life for articaine is 27 minutes, lidocaine 96 minutes, bupivicaine 162 minutes, and mepivicaine 114 minutes.
Reference:
Oertel R, Rahn R, Kirch W. Clinical pharmacokinetics of articaine. Clin Pharmacokinet 33:417;1997.
A local anesthetic with epinephrine will have what potential effect when administered to a patient taking propranolol?
A. Decrease heart rate and decrease blood pressure
B. Decrease heart rate and increase blood pressure
C. Increase heart rate and decrease blood pressure
D. Increase heart rate and increase blood pressure
Answer: B
Rationale:
Propranolol, a nonselective beta-blocker will inhibit the effect of epinephrine binding to the 2 receptor resulting in a more pronounced effect of the epinephrine binding to the -receptor. This will result in an exaggerated hypertensive response and a reflex bradycardia. The suggestion is to administer 1 mL of local anesthetic with epinephrine 1:100,000 and evaluate the response in 5 minutes.
Reference:
Jastak JT, Yagiela JA, Donaldson D: Local Anesthesia of the Oral Cavity. WB Saunders 1995 pg 132.
At the level of the lingula, the inferior alveolar artery and vein are located \_\_\_\_\_\_\_ relative to the inferior alveolar nerve. A. anterior B. medial C. posterior D. superior
C
Rationale:
The inferior alveolar artery and vein are located posteriorly and laterally relative to the inferior alveolar nerve.
Reference:
Jastak JT, Yagiela JA, Donaldson D: Local Anesthesia of the Oral Cavity. WB Saunders 1995 pg 244.
The plasma clearance of which of the following drugs is least affected by a four hour continuous infusion? A. Fentanyl B. Alfentanil C. Methohexital D. Propofol
D
Rationale:
The concept of context-sensitive half-time describes the time necessary for the drug concentration to decrease a predetermined percentage after discontinuing a continuous intravenous infusion of a specific duration. Depending on the drug’s lipid solubility and the efficiency of its clearance mechanism, the context-sensitive half-time increases in parallel with the duration of continuous intravenous administration. The time necessary for the plasma concentration of barbiturates like thiopental and methohexital is prolonged as drug sequestered in fat and skeletal muscles reenters the circulation to maintain plasma concentration. When multiple doses of fentanyl or alfentanil are administered or when there is continuous infusion of the drug, progressive saturation of inactive tissue sites occurs prolonging the duration of action and clearance of the drug from the plasma. Propofol is rapidly cleared from the plasma by tissue uptake and metabolism. The clearance of propofol is not significantly influenced by the duration of continuous intravenous infusion.
Reference:
Stoelting, RK, Miller, RD, Basics of Anesthesia (4th Edition) Churchill Livingstone, 2000.
An extremely apprehensive patient presents for the extraction of four teeth. The patient’s medical history is significant for congestive heart failure that is managed with digoxin. His METs (metabolic equivalents) are les than 4. Which of the following drugs would be most appropriate for induction of general anesthesia for this patient? A. Etomidate B. Propofol C. Thiopental D. Sevoflurane
A
Rationale:
Etomidate is one of the few anesthetics that suppresses the adrenocortical axis. Etomidate causes adrenocortical suppression by producing a dose-dependent inhibition of the enzyme 11-beta-hydroxylase which is necessary for conversion of cholesterol to cortisol. This suppression lasts 4 to 8 hours after an induction dose of etomidate. Propofol, ketamine, methohexital do not suppress the adrenocortical axis.
Reference:
Stoelting, RK, Miller, RD, Basics of Anesthesia (4th Edition) Churchill Livingstone, 2000.
A patient with a history of grand mal seizures controlled with Tegretol (carbamazepine) presents for extraction of third molars under general anesthesia. Which of the following drugs is contraindicated for this patient? A. Methohexital B. Phenobarbital C. Thiamylal D. Thiopental
A
Rationale:
Most of the barbiturates cause a decrease CNS activity and a suppression of seizure activity. Methohexital is an exception and has been shown to activate epileptic foci.
Reference:
Stoelting, RK, Miller, RD Basics of Anesthesia (4th Edition) Churchill Livingstone, 2000.
A healthy 10-year-old presents for the extraction of a mobile tooth. The patient is extremely apprehensive and a single intravenous injection of anesthetic is planned for this patient. His parents reported that he had general anesthesia for placement of ear tubes and when he emerged from anesthesia he was nauseated and vomited. Which of the following agents is most appropriate for this patient? A. Etomidate B. Ketamine C. Methohexital D. Propofol
Answer: D
Rationale:
Propofol is the only agent in the group that has antiemetic effects. There is a low incidence of postoperative nausea and vomiting associated with propofol. The barbiturates do not have antiemetic properties and postoperative nausea and vomiting may be more common with etomidate and ketamine.
Reference:
Stoelting, RK, Miller, RD Basics of Anesthesia (4th Edition) Churchill Livingstone, 2000.
The predominant cardiovascular effect of intravenous methohexital is: A. decreased heart rate. B. depressed myocardial contractility. C. increased cardiac output. D. peripheral vasodilatation.
Answer: D
Rationale:
Administration of methohexital produces modest decreases in systemic blood pressure that are transient due to compensatory increase in heart rate. This decrease in systemic blood pressure is principally due to peripheral vasodilatation. The resulting dilation of peripheral capacitance vessels leads to pooling of blood, decreased venous return and the potential for decreases in cardiac output and systemic blood pressure.
Reference:
Stoelting, RK, Miller, RD Basics of Anesthesia (4th Edition) Churchill Livingstone, 2000.
The short duration of a single dose of methohexital is due to: A. a low pH. B. low fat solubility. C. rate of metabolism. D. rate of redistribution.
Answer: D
Rationale:
Maximal brain uptake of methohexital occurs within 30 seconds after intravenous administration, accounting for the rapid induction of anesthesia. Prompt awakening after a single intravenous dose of methohexital reflects redistribution of these drugs from the brain to inactive tissue sites, especially skeletal muscles and fat. Large or repeated doses of methohexital may saturate inactive tissues sites, resulting in prolonged effects. When the inactive tissue sites are saturated, drug clearance becomes dependent on the rate of elimination.
Reference:
Stoelting, RK, Miller, RD Basics of Anesthesia (4th Edition) Churchill Livingstone, 2000.
Which drug may induce Serotonin Syndrome when combined with a selective serotonin reuptake inhibitor (SSRI)? A. Alfentanil B. Fentanyl C. Meperidine D. Morphine
Answer: C
Rationale:
Serotonin syndrome is characterized by confusion, agitation, tachycardia, fever, hyperreflexia, and myoclonus. Normeperidine is an active metabolite of meperidine metabolism and has a half-life of 15 to 30 hours in an adult. Normeperidine’s elimination is dependent upon renal function and can accumulate with high repeated dosages or in the presence of renal impairment. Serotonin antagonists, SSRI and tricyclic antidepressants all may enhance the adverse/toxic effects of meperidine that results in serotonin syndrome.
Reference:
Stoelting RK, Dierforf F: Anesthesia and Co-existing Disease, 4th Edition, 186-199, 2002.
A patient who is a heavy-smoker had their last cigarette 2 hours before anesthesia is induced. A SpO2 of 90% might be a PaO2 of which value using standard pulse oximetry?
A. B. C. D.
55 – 60 mm Hg 60 - 75 mm Hg 75 - 90 mm Hg 90 - 100 mm Hg
Answer: A
Rationale:
Oxygenated hemoglobin absorbs less red light (600-750nm) and more infrared light (850-1000 nm) than deoxygenated hemoglobin. All pulse oximeters utilize 2 wavelengths of light, one in the red band and one in the infrared band. IN a healthy individual, maintenance of SpO2 of above 90% is evidence that the
PaO2 is most likely higher than 60 mmHg. Dyshemoglobins include carboxyhemoglobin (COHb) and methmoglobin (MetHb) can affect the accuracy of pulse oximetry readings. COHb absorbs very little
light in the infrared spectrum but much light in the visible red spectrum (hence the “cherry red” appearance of the patient with carbon monoxide poisoning), thus overestimating the O2 saturation as measured by pulse oximetry. Heavy smokers have COHb levels of 10-15% that may persist for up to 8 hours after the last cigarette.
Reference:
Blitt CD, Hines RI: Monitoring in Anesthesia and Critical Care Medicine, Churchill Livingston Inc., NY NY pp 374-380, 1995.
The recommended preoperative fasting status for infant formula in infants and children is how many hours? A. 2 hours B. 4 hours C. 6 hours D. 8 hours
Answer: C
Rationale:
Gastric emptying is influenced by volume (distention), osmolarity (protein and sugar), fat, and sold vs liquid (fat slows gastric emptying greater than carbohydrates or proteins). Cavell et al reported that the gastric emptying in healthy infants at 1 and 6 months of age was 48 minutes for human milk and 78 minutes for infant formula. There is insufficient evidence but the Task Force supports a fasting period of 6 hours or more before an elective procedure.
Reference:
Cavell B: Gastric emptying in infants fed human milk or infant formula. Acta Pedaitr Scand 70:639-641, 1981.
American Society of Anesthesiologists: Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures. Anesthesiology 90:896-905, 1999.
You begin a deep sedation procedure in the office setting with a bolus administration of an opioid. Two minutes later you note a marked cutaneous splotchy erythema, an increase in basal heart rate from 80 to 110 per minute, a drop in diastolic blood pressure from 70 to 50, and profound bradypnea. Which of the following opioids is the most likely to cause this change in physiostasis? A. Butorphanol B. Fentanyl C. Meperidine D. Remifentanil
Answer: C
Rationale:
Meperidine is a phenylpiperidine opioid, but differs from other drugs in this category by its atropine-like characteristic with marked tachycardic effects and prominent histamine releasing propensity. This would account for the cutaneous erythema and vasodilative hypotension. Like other phenylpiperidines, it has a strong mu-receptor agonism which can cause significant respiratory depression. Remifentanil is largely devoid of histamine releasing effects which would mitigate against cutaneous erythema, but can cause peripheral vasodilation and hence drop blood pressure with a small amount of reflex increase in heart rate. Remifentanil, like other pure mu receptor agonists, can cause significant respiratory depression. Butorphanol is a mu receptor antagonist and pentazocine is a partial mu receptor antagonist while both are agonists of kappa receptors, hence their limited respiratory depression but significant analgesic properties. Neither of these agonist/antagonist medications exhibits significant histamine releasing propensities.
Reference:
Stricker J, Laurito C: Opioid Pharmacology, in: Weinberg G (ed.): Basic Science Review of Anesthesiology, McGraw-Hill, New York, 1997 pp. 28-32.
Duthie DJ, Nimmo WS: Adverse effects of opioid analgesic drugs. Br J Anaesth 1987;59:61-77.
The pharmacokinetics of which opioid most closely resembles a one-compartment model? A. Fentanyl B. Meperidine C. Morphine D. Remifentanil
Answer: D
Rationale:
A one-compartment model involves administration of an intravenous medication intravascularly, and (relatively rapid) metabolism or elimination causing a more or less linear decrease in plasma drug concentration. A two-compartment model involves both more rapid initial elimination or metabolism of an intravascular drug plus the slower release of a drug into the blood from non-vascular tissues such as muscle or fat, causing a secondary beta phase of more slow decrease in plasma drug concentration by metabolism and/or elimination. The initial rapid pharmacologic onset of opioids is via their rapid initial crossing of the blood/brain barrier. With one bolus administration, many opioids are then rapidly redistributed to other tissues and the central nervous system effects are then ended. However, with continuous infusion or multiple bolus administration, depot storage of an opioid can occur and prolonged opioid effects can be manifest by a two-compartment release of drug over time. However, remifentanyl is so rapidly metabolized by ester hydrolysis that significant depot storage does not occur, and a one- compartment model of pharmacokinetics is approximated, causing rapid emergence from its effects after cessation of administration. Meperidine, morphine, and fentanyl undergo more slow hepatic degradation and follow a two-compartment model.
Reference:
Alston T: Pharmacokinetics and Drug-Receptor Interactions, in: Weinberg G (ed.): Basic Science Review of Anesthesiology, McGraw-Hill, New York, 1997 pp. 1-7.
Which agent is most likely to precipitate withdrawal symptoms in the heroin addicted patient? A. Levallorphan B. Meperidine C. Propoxyphene D. Tramadol
Answer: A
Rationale:
Levallorphan (a structural analog to the mu receptor agonist levorphanol) is an opioid antagonist; and its administration causes competitive binding at mu opioid sites throughout the nervous system. However, levallorphan exhibits mild kappa receptor agonism with analgesic properties. A patient with a heroin addiction may suffer acute withdrawl symptoms with administration of this or other opioid antagonist medications. Other opioid antagonists include naloxone and naltrexone. Tramadol is a synthetic analog of codeine and exhibits weak mu receptor agonism, and is useful for mild to moderate pain. Meperidine is a phenylpiperidine opioid agonist. Propoxyphene is a methadone analog with somewhat less mu agonist activity than codeine. Tramadol, meperidine, and propoxyphene will not precipitate opioid withdrawl.
Reference:
Gustein H, Akil H: Opioid Analgesics, in: Hardman J, Limbird L (eds.): The Pharmacological Basis of
Therapeutics 10th ed., McGraw-Hill, 2001 pp 569-611.
After bolus administration of fentanyl 5 micrograms/kg as part of a general anesthetic induction, the patient cannot be ventilated with positive pressure via facemask. After insertion of a laryngeal mask airway, positive pressure ventilation is still quite difficult and cuff leak is noted. Auscultation shows some ventilatory sounds over the lung fields. What would be the most appropriate next step?
D. Administer epinephrine 0.5 mg IV
E. Administer sevoflurane
F. Administer succinylcholine 1mg/kg
D. Remove the laryngeal mask airway and place a cuffed endotracheal tube
Answer: C
Rationale:
Fentanyl can cause skeletal (including respiratory) muscle static contraction, especially when given as a bolus dose. This centrally mediated action can occur with bolus administration of any opioid, but is much more common with fentanyl and its cojoiners. If the patient cannot be adequately ventilated, opioid antagonist administration can be used to displace fentanyl from central nervous system binding sites thus this phenomenon, but this may not be advisable in the patient in whom a laryngeal mask airway has been inserted since gagging may result. Administration of a rapidly acting muscle relaxant can effect skeletal (hence respiratory) muscle paralysis and allow ventilation in this scenario. Addition of a volatile anesthetic agent, although causing some skeletal muscle relaxation, would not resolve the respiratory muscle tonic contracture quickly enough. Use of epinephrine for its beta-2 adrenergic effect would do nothing for this patient who is not suffering from bronchial muscle constriction. Insertion of a cuffed endotracheal tube might allow higher peak inspiratory pressure than is possible with a laryngeal mask airway, but would not treat the causative problem.
Reference:
Stolting R, Miller R: Basics of Anesthesia 4th ed., Churchill-Livingstone, New York, 2000 pp71-73.
As part of a balanced sedation technique, which of the following would be best suited to intermittent bolus intravenous administration? A. Alfentanil B. Meperidine C. Sufentanil D. Remifentanil
Answer: A Rationale:
Alfentanil has a potency 1/10th that of fentanyl and is relatively rapidly metabolized by hepatic degradation. These two properties allow relative safety in intermittent bolus administration in a sedation technique, and have made this drug popular as an agent in an outpatient general anesthetic technique. Sufentanil has a shorter alpha half-life (by redistribution) and a shorter beta half life (by hepatic and renal metabolism) than does fentanyl. However, its potency is 10 times that of fentanyl and it is recommended for continuous intravenous infusion only, since a bolus administration of this extremely potent opioid can yield very high peaks of pharmacologic effect and side-effect. Remifentanil is equipotent to fentanyl. However, its rapid onset is associated with bradypnea, trunchal rigidity and bradycardia. Although it has been used as a bolus administration for procedures such as a retrobulbar block it is generally recommended for continuous infusion. Meperidine undergoes slower metabolization and repetitive administration can prolong recovery.
Reference:
Vezeau PJ: Anesthetic Agent Update, in: Oral and Maxillofacial Surgery Update Vol. 3, AAOMS, 2002.
Of the following agents, the one with the lowest therapeutic index in the presence of epinephrine is:
A. desflurane. B. halothane. C. isoflorane. D. sevoflurane.
Answer: B
Rationale:
A dose of epinephrine greater than 2.1 mcg/kg can induce a dysrhythmia in a patient anesthetized with halothane. Correct dosing of epinephrine with the use of halothane is especially important in the pediatric population. The maximum safe epinephrine dose when halothane is used is generally considered to be 1.0 mcg/kg.
Reference:
Elamana V: Anesthetic considerations in patients with cardiac arrhythmias, pacemakers and AICDs. International Anes Clin 39(4): 21-42, 2001.
The binding of carbon monoxide to the hemoglobin molecule in smokers results in:
A. a direct hyperventilatory response.
B. falsely elevated oxygen saturation.
C. a rightward shift in the oxyhemoglobin desaturation curve.
D. more oxygen released to peripheral tissues to compensate for lower carrying capacity.
B
Rationale:
Carbon monoxide, produced as an end product of burning tobacco has 200x greater affinity than oxygen to the Hgb molecule. Carboxyhemoglobin which can be as high as 15%, predisposes a patient to perioperative hypoxia. Pulse oximetry fails to recognize the presence of carboxyhemoglobin as distinct from oxyhemoglobin. Therefore a patient with 10% COHb may display a saturation of 100% when in fact the actual saturation may be closer to 90%. In addition, carboxyhemoglobin has the effect of shifting the oxygen-dissociation curve to the left (less oxygen delivered to tissues). Ventilation, the mechanism of air exchange between the environment and the lungs, is not directly effected by carbon monoxide.
Reference:
Mardirossan G, Schneider RE, Limitations of pulse oximetry. Anesth Prog 39: 194-196, 1992.
A 27-year-old individual has suffered from acute head trauma. He has been noted to be urinating 2 to 3 Liters per four hours of light yellow urine over 4 hours with only a small presence of blood noted. A preoperative ECG demonstrates flattened T- waves on his chest leads. Prior to taking this individual to the operating room to repair his fractured mandible, you should consider:
A. obtaining a cardiac work up.
B. obtaining a renal arteriogram.
C. replacing potassium losses.
D. replacing potassium and magnesium losses.
D
Rationale:
This individual is likely experiencing diabetes insipidus secondary to head trauma. The flattened T- waves are consistent with hypokalemia, however in order to correct his potassium level he should have his magnesium level adjusted as well (with replacement using 1g of MgSO4).
Reference:
Adam P: Evaluation and management of diabetes insipidus. Amer Fam Physician 55(6), May 1, 1997.
During surgical removal of a lower third molar under sedation using midazolam, fentanyl and propofol, your patient coughs and begins to have stridorous breath sounds, which lead to absent breath sounds. The throat pack is removed and a jaw thrust is attempted without improvement in air exchange. Chest movement continues. What is the most likely diagnosis? A. Allergic reaction B. Bronchospasm C. Laryngospasm D. Upper airway obstruction.
Answer: C
Rationale:
Midazolam, fentanyl, and propofol all cause a relaxation of the upper airway musculature, a depression of the hypoxic/hypercapneic respiratory drive and a depression of the pharyngeal and laryngeal reflexes. The patient’s cough followed by stridorous sounds is suggestive of an irritation of the vocal cords resulting in a laryngospasm. Chest movement without air exchange which is implied may be secondary to upper airway obstruction, however, while this may not be completely relieved by a jaw thrust it would be anticipated that there would be some improvement.
Reference:
Stoelting RK, Miller RD: Basics of Anesthesia. 2000. New York. Churchill Livingstone.
Davison JK, Eckhardt WF, Perese DA: Clinical Anesthesia Procedures of the Massachusetts General Hospital. 1993. Boston. Little, Brown and Company.
Ochs MW: Pulmonary complications and their management. Oral Maxillofac Surg Clin North Am; 1992;4:769.
Which of the following statements regarding pediatric airway anatomy is true?
A. The tongue is positioned higher in the oral cavity impinging on the soft palate.
B. The posterior attachment of the vocal cords is more caudal in children as compared to adults.
C. The epiglottis is small and relatively easy to manipulate with the laryngoscope in children as
compared with adults.
D. The larynx in pediatric patients is at a more inferior level than the corresponding level in adults.
Answer:
Rationale:
Pediatric patients have anatomic differences that make tracheal intubation more challenging. Their epiglottis is floppy and more difficult to manipulate. Their larynx lies at a more superior level; C3-C4 as
opposed to the adult, where lies at C4-C5. This is an important anatomic consideration to have in mind for the correct placement of the ETT and position of the tip. The anterior attachment of the vocal cords is
more caudal so they are not perpendicular to the airway as they are in the adults. These factors make it necessary to displace the tongue and mandible more in order to visualize the infant’s vocal cords. Therefore, straight laryngoscopes blades are used more commonly to intubate the trachea of children.
Reference:
Gregory, GA Pediatric Anesthesia 4th edition. Churchill Livingstone, 2002.
Which one of the following factors could potentially prolong a mask induction by a volatile agent?
A. High alveolar ventilation
B. Right to left intracardiac shunt
C. Small functional residual capacity
D. Volatile agent with a low blood-gas solubility
B
Rationale:
A right to left intracardiac shunt will result in less blood perfusing the lungs. This will result in an increase in alveolar partial pressure but also a decrease in arterial partial pressure. A right to left intracardiac shunt could potentially speed up an intravenous induction because venous blood carrying the IV induction agent will return to the heart and bypass the pulmonary circulation, reaching the brain more quickly. A patient with Tetralogy of Fallot is a classic example of a patient with a right to left intracardiac shunt.
Functional residual capacity is the volume of lung after the end of a normal TV expiration. A smaller volume will reach a higher anesthetic concentration more quickly than a larger volume. A small functional residual capacity will allow the alveolar concentration to quickly approach the inspired concentration, speeding up induction.
Pediatric patients have a small FRC and high alveolar ventilation resulting in more rapid inhalation induction compared to adults. Increasing alveolar ventilation will replace more anesthetic taken up by the pulmonary bloodstream, maintaining a higher alveolar concentration and thus speeding induction.
An agent with low blood gas solubility will equilibrate rapidly resulting in a more rapid induction.
Reference:
Morgan, Mikhail, Murray. Clinical Anesthesiology 2002 Lange/McGraw-Hill.
Miller. Anesthesia 5th Ed. 2000 Churchill Livingstone.
What is the most likely cause for hypoxia to rapidly develop in children versus adults during general anesthesia?
A. Smaller airway pathways as compared to adults
B. Smaller blood volume per kilogram as compared to adults
C. Smaller functional residual capacity
D. Smaller lung capacities as compared to adults
Answer: C
Rationale:
While undergoing a general anesthetic, children without lung disease may lose as much as 45 percent of their FRC. Owing to a higher oxygen consumption and greater loss of FRC in children during general anesthesia, hypoxia develops in a matter of seconds. To compensate for the higher oxygen consumption, children have a higher blood volume per kg or compared to adult-(80-100 cc/kg children and 65-70cc/kg for adults). Children should have their ventilation controlled during anesthesia because hypoventilation exacerbates their tendency toward hypoxia. Atelectasis may occur in mechanically ventilated children, but is more likely to occur in children who breathe spontaneously. Children with pulmonary diseases may lose even more of the FRC, exposing them to increasing ventilation-perfusion mismatch and hypoxia. An increased inspired oxygen concentration and application of positive end-expiratory pressure (PEEP) may partially restore FRC. However, PEEP must be applied carefully.
Reference:
Gregory, GA Pediatric Anesthesia 4th edition. Churchill Livingstone 2002.
Zaglaniczny, K. Clinical Guide to Pediatric Anesthesia. W. B. Saunders Co. 1999.
Neonates, infants and children experience a greater heat loss than adults because:
A. they have a less body surface area to weight.
B. they cannot shiver to maintain body heat.
C. they have less brown fat than adults.
D. during cold stress oxygen consumption decreases.
Answer: B
Rationale:
Neonates, infants, and children have an increased body surface area relative to weight. Because they cannot shiver to create or maintain body heat they rely on a less efficient process called non-shivering thermogenesis. This process is dependent upon the fact that children have a greater amount of brown fat (so named because of its rich vascular supply) than adults. When the newborn is cold stressed, oxygen consumption will increase and result in the release of norepinephrine (NE). NE will react with the Lipases in the brown fat to breakdown fat into triglycerides. The cascade continues to as triglycerides are metabolized to glycerol and non-esterified fatty acids (NEFA). These NEFA are further degraded under the needed heat generating process to form carbon dioxide and water.
Reference:
Behrman, Kliegman, Jenson, Nelsons, Textbook of Pediatrics, W.B. Saunders Company:2000.
Miller, Anesthesia Fifth Edition, Churchill Livingstone, 2000.
Which statement is accurate regarding the morbidly obese patient?
A. Functional residual capacity is maintained.
B. Obesity imposes an obstructive ventilation defect.
C. PaO2 is decreased reflecting ventilation – perfusion mismatching.
D. PaCO2 increases slightly secondary to a slight decrease in the ventilatory response to CO2.
C
Rationale:
Morbid obesity is defined as a body weight in excess of 100 lbs over ideal weight or a body mass index of 40 or greater. There are a variety of adverse changes associated with obesity. Pulmonary function changes in obese patients suggest restrictive pulmonary disease characteristics. PaO2 is decreased by obesity as a result of ventilation/perfusion mismatches. Despite this, PaCO2 and the ventilatory response to PaCO2 remains normal. Functional residual capacity is decreased and is accentuated by supine positioning and under anesthesia.
Reference:
Stoelting and Dierdorf: Handbook for Anesthesia and Co-existing disease. Churchill-Livingstone, 2nd ed 2002.
A 47-year-old male patient returns to your office 6 hours after a nitrous oxide sedation for extractions of several teeth complaining of shortness of breath and lethargy. He has ashen skin. He is complaining of palpitations. The ECG shows sinus tachycarida. The pulse oximeter shows 96%. Review of the records shows that the patient received 9 cartridges of 4% prilocaine and 2 cartridges of 0.5% bupivicaine with 1:200,000 epinephrine. Which medication would you consider administering for the patients condition? A. Diphenhydramine B. Nitroglycerin C. Methylene blue D. Physostigmine
C
Rationale:
Large doses of prilocaine, generally greater then 600 mg, can result in methemoglobinemia in selected patients. Intravenous doses of articaine have been reported to cause similar problems. This occurs as a result of one of the metabolites of the drug converting reduced hemoglobin to methemoglobin. The patient will experience cyanosis with dark blood. Pulse oximetry remains normal since the monitor mistakenly interprets methemolgobin as oxyhemoglobin but the actual oxygen carrying capacity is decreased resulting in the cyanosis. Small doses of methylene blue ( 1-2 mg/kg) will convert the methemoglobin back to reduced hemoglobin
Reference:
Stoelting and Miller, Basics of Anesthesia, Churchill Livingstone, 2002
The earliest sign of impending malignant hyperthermia is: A. elevated core temperature. B. increased end tidal CO2. C. skeletal muscle rigidity. D. tachycardia.
D
Rationale:
An increase in heart rate is usually the earliest and most consistent sign to be detected. An increase in end-tidal CO2 is usually the most sensitive sign in detecting malignant hyperthermia. While increase temperature and muscle rigidity are hallmark signs of malignant hyperthermia, these manifestations are less sensitive and may not present as early as the tachycardia and elevated end-tidal CO2. Masseter muscle rigidity should be distinguished from skeletal muscle rigidity and occurs early.
Reference:
Stoelting RK, Dierdorf SF; Handbook for Anesthesia and Co-existing Disease, Churchill Livingston 2nd ed 2002.
Which of the following drugs is contraindicated in a patient with acute intermittent porphyria? A. Methohexital B. Midazolam C. Ketamine D. Propofol
A
Rationale:
Patients who have acute intermittent porphyria do not tolerate barbiturates. The use of these drugs could precipitate an attack, which would present with abdominal pain, tachycardia and hypertension, seizures and autonomic nervous system disorders. Propofol is safe to use. Midazolam and ketamine are probably safe to use.
Reference:
Stoelting RK, Dierdorf SF; Handbook for Anesthesia and Co-existing Disease, Churchill Livingston 2nd ed 2002.
The first drug in the management of paraoxysmal supraventricular tachycardia is: A. adenosine. B. diltiazem. C. esmolol. D. verapamil.
A
Rationale:
Vagal maneuvers, such as the Valsava maneuver can be tried first. Vagal maneuvers are most effective if attempted immediately after onset. Adenosine is the first drug of choice if vagal maneuvers are ineffective.
Reference:
Faust RJ: Anesthesiology Review. 3rd ed Churchill Livingston 2002.
Which is the first drug of choice in the management of torsades de pointes? A. Calcium B. Epinephrine C. Lidocaine D. Magnesium
D
Rationale:
Magnesium should be considered the first drug of choice in the treatment of torsades de pointes. It is administered as magnesium sulfate 1 to 2 grams over 1 to 2 minutes. Traditional anti-arrhythmic therapy is not likely to be successful.
Reference:
Faust RJ: Anesthesiology Review. 3rd ed Churchill Livingston 2002.
A 60-year-old man is undergoing intravenous general anesthesia for full mouth extractions when he shows signs of labored breathing and cyanosis. The ECG shows evidence of wide complex tachycardia at a rate of 160. The pulse oximeter is registering poor pulse signal. The systolic blood pressure is 65 mm HG. Initial treatment should include: A. administering amiodarone. B. administering epinephrine. C. administering vasopressin. D. defibrillation.
Answer: D
Rationale:
The patient is presenting with an unstable ventricular tachycardia which is treated with prompt defibrillation.
Reference:
Handbook of Emergency Cardiovascular Care .2002 ed.
During sagittal split osteotomy, the possibility of direct injury to the inferior alveolar neurovascular bundle can be minimized when the vertical component of the osteotomy is made over which of the following regions? A. Lateral to the first molar B. Lateral to the second molar C. Lateral to the third molar D. Lateral to the retromolar region
Answer: B
Rationale:
The position of the inferior alveolar neurovascular bundle is an important determinant in the design of the sagittal split osteotomy. The neurovascular bundle travels just under the facial cortical plate of the mandible. Whether the osteotomy is made with rotary instruments or a reciprocating saw, the vertical cut must be carried just through the cortical plate (i.e. monocortical). The thickness of the bone over the neurovascular bundle is greatest in the area of the second molar. The vertical osteotomy should be placed lateral to the second molar unless circumstances dictate otherwise.
Reference:
Rajchel J., Ellis E., and Fonseca R.J. The anatomical location of the mandibular canal: its relationship to the sagittal ramus osteotomy. Int J Adult Orthod Orthogn Surg 1:37-47, 1986.
In a distraction osteogenesis procedure, the latency phase of treatment corresponds to which of the following stages of bone healing? A. Hematoma formation and inflamation B. Soft callus formation C. Hard callus formation D. Bony maturation
Answer: B
Rationale:
Bony healing after a fracture or osteotomy consists of four histologically distinct stages: an inflammatory phase, soft callus formation, hard callus formation, and bony maturation/remodeling. During soft callus formation, fibrovascular structures bridge the osteotomized bone segments and there is recruitment of fibroblasts and mesenchymal stem cells within the fracture zone. It is this flexible soft callus which is lengthened via gradual traction during the subsequent distraction phase.
Reference:
Crago C.A., Proffit W.R., and Ruiz R.L. Maxillofacial Distraction Osteogenesis. Pp. 357-393. Proffit W.R., White R.P., and Sarver D.M. (Eds) Contemporary Treatment of Dentofacial Deformity, Philadelphia. Mosby. 2003.
An 8-month-old female infant undergoes early mandibular advancement with distraction osteogenesis in order to alleviate airway obstruction related to severe mandibular hypoplasia. Bilateral mandibular osteotomies are completed and internal distractors are placed and confirmed. Surgery is followed by a 9 day latency phase. Upon activation of the right distractor, heavy resistance is encountered and the bone segments appear immobile. Which of the following is the most likely cause of this complication?
A. Excessive soft tissue resistance
B. Incomplete osteotomy at the time of surgery
C. Malfunction of the distractor
D. Early consolidation of the osteotomy
Answer: D
Rationale:
In most patients, a latency phase of 5 to 7 days allows for adequate formation of a soft callus before active distraction is initiated. If activation of the distractors is initiated too early, decreased bone formation results. If the latency period is too long, conversion to a hard callus begins and early healing of the osteotomy will prevent mandibular lengthening. In young children, bone healing occurs much faster and little or no latency phase is required.
Reference:
Crago C.A., Proffit W.R., and Ruiz R.L. Maxillofacial Distraction Osteogenesis. Pp. 357-393. In: Proffit W.R., White R.P., and Sarver D.M. (Eds), Contemporary Treatment of Dentofacial Deformity. Philadelphia. Mosby. 2003.
The “Holdaway Ratio” is most useful in planning which of the following procedures? A. Maxillary osteotomy B. Mandibular osteotomy C. Bimaxillary osteotomies D. Genioplasty
Answer: D
Rationale:
The Steiner analysis is a cephalometric approach utilized to directly evaluate the protrusion of the upper and lower incisors. The position of the maxillary and mandibular incisors is related to Nasion-A point (N-A) and Nasion-B point (N-B) lines using both angular and linear measurements. Within this analysis, the “Holdaway Ratio” is used to evaluate the prominence of the mandibular incisors and bony chin. The ratio is calculated by comparing the distance of the lower incisor edge and pogonion to the N-B line. Ideally, the Holdaway Ratio should be approximately 1.0 in males and 0.5 to 1.0 in females. This relationship is useful in planning for genioplasty.
Reference:
Proffit W.R., Sarver D.M. Diagnosis: Gathering and Organizing the Appropriate Information. Pp. 127- 170. In: Proffit W.R., White R.P., and Sarver D.M. (Eds) Contemporary Treatment of Dentofacial Deformity, Philadelphia. Mosby. 2003.
A 17 year old female patient presents for correction of her Class III dentoskeletal deformity consistent with a diagnosis of mandibular hyperplasia. A 4 mm of reverse overjet is noted. A submentovertex radiograph obtained during the initial evaluation reveals a “V” shaped mandible with divergent rami. Which surgical procedure for mandibular setback would result in the greatest alteration in intercondylar width in this patient?
A. Bilateral sagittal split osteotomies with lag screw fixation
B. Transoral vertical ramus osteotomies with lag screw fixation
C. Bilateral Inverted “L” osteotomies with miniplate fixation
D. Bilateral “C” osteotomies with miniplate fixation
Answer: A
Rationale:
One of the technical considerations that must be considered when choosing a specific procedure for mandibular setback surgery is the actual shape of the mandibular arch form and rami. In patients with a “U” shaped mandible, either bilateral sagittal split osteotomies (BSSO) or a transoral vertical ramus osteotomy may be utilized for mandibular setback in Class III patients. When the mandible is “V” shaped with flared rami, then the procedure that results in the least condylar width change is the transoral vertical ramus osteotomy. If a patient with a “V” shaped mandible undergoes BSSO, a gap is created posteriorly between the cortical plates of the proximal and distal segments. If lag screws are used for rigid fixation, the gap is closed and there is narrowing of the intercondylar width.
Reference:
Tucker M.R. Surgical correction of mandibular excess: technical considerations for mandibular setbacks. Atlas Oral Maxillofac Surg Clin North Am. 1993 Mar;1(1):29-39.
Which of the following is a special consideration when performing sagittal split osteotomy for mandibular advancement in children?
A. The lingula and inferior alveolar foramina are located in a more superior and posterior position in the ramus of children than in adults.
B. The sagittal bone cuts should be positioned as far medially as possible.
C. The propensity for “greenstick” fracture of the inferior border of the mandible is lower in children
than in adults.
D. Simultaneous removal of partially developed third molar teeth is not possible in children.
Answer: A
Rationale:
The lingula and inferior alveolar foramina are located in a more superior and posterior position in this age group. This has technical implications in determining the vertical placement of the medial osteotomy of the ramus. If the medial bone cut is positioned high on the ramus, then injury to the nerve is avoided , but the risk of unfavorable split (i.e. buccal plate fracture) increases. In children, the sagittal component of the osteotomy design should be placed as far laterally as possible in order to avoid injury to the developing teeth. Children will have a higher propensity for “greenstick” fracture along the inferior border of the mandible. Their bone is more cancellous in nature and this often results in a longer area of fracture along the inferior border of the mandible. Developing third molars can be removed after the mandibular ramus has been split. In cases where the third molar teeth are only partially developed, they can still be enucleated while the proximal and distal segments are separated
Reference:
Bell WH: Mandibular Advancement in Children Special Considerations. In Bell WH, Modern Practice in Orthognathic and Reconstructive Surgery, Vol. 3, 1992, WB Saunders, pp. 2516.
Which of the following is a contraindication for the use of a total mandibular subapical osteotomy?
A. Condylar hypoplasia
B. Relapse after sagittal split osteotomy
C. Skeletal apertognathia
D. Mandibular vertical alveolar deficiency
Skeletal anterior open bite (i.e. apertognathia) is the result of a maxillary growth problem and is frequently associated with a concomitant transverse maxillary discrepancy. The use of a total mandibular subapical osteotomy for correction of an anterior open bite requires counterclockwise movement of the dentoalveolar segment, does not address the maxillary deformity, and is associated with a high rate of skeletal relapse. Appropriate management of apertognathia requires correction of the maxillary problem usually consisting of segmental Le Fort I level surgery.
The use of the total mandibular subapical osteotomy is limited to correction of malocclusions that can be addressed by repositioning the mandibular alveolar process only. The subapical osteotomy does not change the anatomical position of the mandibular body or symphysis. As a result, application of the total mandibular subapical osteotomy is limited to situations where there is retrusion of the dentoalveolar process with an otherwise normal facial morphology.
Reference:
Frost DE: Orthognathic Surgical Techniques. In Ward-Booth et al, Maxillofacial Surgery. Vol. 2, 1999, Harcourt Brace. pp. 1291.
A 16-year-old female patient undergoes a Le Fort I osteotomy for maxillary impaction. Two days after surgery, guiding elastics are removed and assessment of the patient’s occlusion reveals an anterior open bite. What is the most likely cause of this complication?
A. Severe condylar resorption associated with fixation
B. Failure of maxillary hardware
C. Incomplete seating of the condyles during surgery
D. Incomplete downfracture of the maxilla during surgery
Answer: C
Rationale:
Le Fort I level osteotomy may be complicated by intraoperative malpositioning of the maxillomandibular complex after the jaws have been wired together. Pressure applied to the chin may bring the maxillary osteotomy together while unintentionally displacing the mandibular condyles. This is often caused when bony interferences along the posterior maxilla exist.
Reference:
Bays R.A. Complications of Orthognathic Surgery. In: Kaban L.B., Pogrel M.A., and Perrott D.H. (Eds), Complications in Oral and Maxillofacial Surgery. W.B. Saunders, Philadelphia, pp. 193-221. 1997.
A 23-year-old female undergoes maxillary superior positioning with a midline splitting of the maxilla to widen the transverse dimension 9 mm. Following an uneventful early post-operative course, she returns one year later with an anterior open bite. Which of the following would most likely explain the open bite?
A. Poor positioning of the mandibular condyles intra-operatively
B. Relapse of the transverse widening of the maxilla
C. Idiopathic condylar resorption
D. Failure of the hardware placed in the anterior maxilla
Answer: B
Rationale:
Transverse expansion of the maxillary arch is often complicated by lack of long term stability. This is especially true when large movements are undertaken. As transverse relapse occurs, the lingual cusps of the maxillary posterior teeth move along the lingual inclines of the lingual mandibular cusps and the anterior open bite deformity is recreated.
Reference:
Long Face Problems in Contemporary Treatment of Dentofacial Deformity. Eds. Proffit WR, White RP, Sarver DM. Mosby 2003. Page 491.
A patient arrives at the emergency department 2 weeks following a LeFort I osteotomy with advancement and impaction of the maxilla by another surgeon. The parents describe and uneventful course to date until profuse epistaxis lead them to call 911. On your arrival, the patient is stable with the exception of borderline hypotension and the bleeding has stopped without intervention. Which of the following would be the most prudent next step?
A. Place bilateral anterior nasal packs for 24 hours.
B. Return to the operating room for exploration of the surgical site.
C. Fluid resuscitation and referral back to the operating surgeon.
D. Arrange interventional angiography.
Answer: D
Rationale:
Bleeding during Le Fort I osteotomy and downfracture is usually the result of injury to the terminal branches of the internal maxillary artery including the descending palatine and sphenopalatine arteries. Even after the Le Fort I downfracture, intraoperative injury to the descending palatine vessels may occur as a result of significant maxillary advancement or impaction. Postoperative hemorrhage following maxillary surgery typically presents as epistaxis with bleeding into the anterior and/or posterior nasal cavity. This may occur at any point during the first month after the surgical procedure and may be the result of breakdown of previous clot or necrosis of arterial vessels which were stretched by the surgical movement. An initial “sentinel” episode of brisk bleeding may stop spontaneously giving the false impression that the problem has resolved. Angiography and interventional radiology techniques provide detailed visualization and localization of the source of bleeding. The bleeding vessel may be stopped by embolization without the need to reopen the wound, remove rigid fixation devices, and dismantle skeletal segments. Angiography also allows detailed visualization of the arterial system and detection and management of pseudoaneurysm involving the internal maxillary artery or its terminal branches.
Reference:
Preoperative, intraoperative and postoperative care in Fonseca Oral and Maxillofacial Surgery, Saunders 2000. Page 187.
Which of the following is the most common source of venous bleeding during maxillary osteotomy at the LeFort I level?
A. Facial vein
B. Pterygoid venous plexus
C. Laceration of the pterygoid musculature
D. Descending palatine veins
Answer: B
Rationale:
The pterygoid plexus of veins is located directly posterior and medial to the maxilla. Its location makes it vulnerable to injury during creation of the osteotomy and use of an osteotome for pterygomaxillary disjunction. It is the most common source of intraoperative venous hemorrhage in patients undergoing LeFort I osteotomy. Management of venous hemorrhage from the pterygoid plexus requires packing and application of topical hemostatic agents.
Reference:
Lanigan DT: Vascular Complications Associated with Orthognathic Surgery. Oral and Maxillofacial Surgery Clinics of North America. Volume 9, Number 2, May 1997. pp. 232.
Aside from serial cephalometric radiographs, which of the following is considered the next most reliable method of estimating the facial skeletal maturity?
A. Evaluation of the C-spine
B. Hand-wrist films
C. Panoramic evaluation of dental development
D. Tanner’s developmental stages
Answer: A
Rationale:
Radiographic assessment of the hand-wrist anatomy has been utilized to estimate a patient’s skeletal age when early orthodontic or surgical treatment is contemplated. The theoretical basis is that the chronology of ossification in the bones of the hand and wrist can be related to the rest of the skeleton. The relationship between the bony development of the hand-wrist complex and the facial skeleton is not well correlated. Recently, the radiographic assessment of the cervical spine vertebrae for estimating skeletal development has been proposes. Although not perfect, the use of cervical spine development as an indicator of skeletal age is better correlated with the facial skeleton and the adolescent growth spurt. This technique has the additional advantage that no additional radiographs are required since the cervical vertebrae are visible on a cephalometric radiograph.
Reference:
Franchi L., Baccetti T, McNamara JA Jr. Mandibular growth as related to cervical vertebral maturation. Am J Orthod Dentofac Orthop 118: 335-340. 2000.
The most unstable skeletal movement in orthognathic surgery procedures is: A. genioplasty – any direction. B. maxillary inferior repositioning. C. mandibular setback. D. segmental maxillary expansion.
Answer: D
Rationale:
Segmental surgery for transverse maxillary expansion is associated with the highest rate of relapse following orthognathic surgery. Palatal soft tissue resistance and dental compensations often add to this instability.
Reference:
Proffit WR, Turvey TA, Phillips C: Orthognathic Surgery A Hierarchy of Stability. Intl J Adult Orthod Orthognath Surg. 11:191-204, 1996.
A 16-year-old patient with a skeletal Class III malocclusion is beginning orthodontic treatment in preparation for eventual LeFort I osteotomy and bilateral sagittal split osteotomies. The patient has significant crowding in both maxillary and mandibular arches and dental compensations are present. If extraction of maxillary and mandibular premolars is indicated, which of the following combinations is most appropriate given the patient’s clinical findings and eventual surgical plan?
A. Extraction of maxillary first and mandibular second premolars
B. Extraction of maxillary second and mandibular first premolars
C. Extraction of maxillary and mandibular first premolars
D. Extraction of maxillary and mandibular second premolars
Extraction of maxillary first premolars in this clinical situation allows for adequate space for alignment of crowded maxillary incisors. The space created allows for correction of inclination for teeth that have drifted forward during development of dental compensations. As the maxillary first premolar spaces are closed, the anterior teeth are retracted maximizing the degree of maxillary skeletal advancement.
In Class III patients undergoing presurgical orthodontic treatment, extraction of mandibular first premolars is rarely indicated. This is because closure of the extraction spaces will require retraction of the anterior teeth resulting in less favorable tooth-lip balance. Extraction of the second mandibular premolars provides the necessary space for alleviation of crowding while avoiding retraction of the incisors.
Reference:
Bailey L.J., Sarver D.M., Turvey T.A., and Proffit W.R. Class III Problems. In: Contemporary Treatment of Dentofacial Deformity. Eds. Proffit WR, White RP, Sarver DM. Mosby 2003.
Which of the following statements regarding Passavant’s Ridge is correct?
A. It is observed only as part of the cleft palate malformation.
B. It does not facilitate velopharyngeal closure.
C. It forms along the palatopharyngeus muscle.
D. It forms along the superior constrictor muscle.
Answer: D
Rationale:
Passavant’s ridge is a soft tissue prominence which extends into the pharynx. The structure is usually described in association with cleft palate, but has been described in many normal subjects. The soft tissue structure also frequently contributes positively to velopharyngeal closure. The ridge usually forms along the superior border of the superior pharyngeal constrictor muscle, but its exact position on the posterior pharyngeal wall may vary.
Reference:
The Nature of the Velopharyngeal Mechanism. In: McWilliams B.J., Morris H.L., and Shelton R.L. (Eds), Cleft Palate Speech. B.C. Decker, Philadelphia, Pp. 197-235, 1990.
When performing Le Fort I osteotomy in an ungrafted bilateral cleft lip and palate patient, which of the following surgical techniques should be avoided?
A. Autogenous bone grafting and rigid fixation
B. Osteotome separation of the pre-maxilla from the nasal septum and vomer
C. Advancement of lateral segments for closure of cleft-dental gap
D. Circumvestibular incision and maxillary downfracture
Answer: D
Rationale:
Preservation of an anterior buccal mucosal pedicle is critical to preserving blood circulation to the premaxilla in patients that have not undergone previous bone graft reconstruction of bilateral cleft defects. A circumvestibular incision in the ungrafted bilateral cleft lip and palate patient would lead to aspectic necrosis of the premaxillary segment. Maxillary advancement in these patients is carried out through separate right and left vestibular incisions with limited tunneling anteriorly. A small vertical incision within the midline may be utilized for separation of the nasal septum and mobilization of the premaxillary segment.
Reference:
Turvey TA, Vig K, Fonseca RJ. Maxillary Advancement and Contouring in The Prescence of Cleft Lip and Palate. In Turvey et al Facial Cleft and Craniosynostosis, 1996 WB Saunders. pp. 460.
A child born with an isolated cleft palate presents with severe myopia early in life. The most likely diagnosis is which of the following syndromes? A. Pierre Robin Sequence B. Stickler Syndrome C. Van der Woude Syndrome D. Velocardiofacial Syndrome
Answer: B
Rationale:
Isolated cleft palate is associated with an underlying syndrome more frequently (as much as 50%) than cleft lip and palate. Stickler syndrome has been identified as the most common diagnosis causing both cleft palate and Robin sequence. Patients with Stickler syndrome demonstrate a collagen metabolism disorder. Relevant clinical findings include early myopia and an increased risk of retinal detachment which may go un-noticed early in life. It is recommended that infants with an isolated cleft of the secondary palate undergo formal ophthalmologic evaluation at some point during their first year of life.
van der Woude syndrome can be caused by deletions in chromosome band 1q32, and linkage analysis has confirmed this chromosomal locus as the disease gene site. van der Woude syndrome is an autosomal dominant syndrome typically consisting of a cleft lip or cleft palate and distinctive pits of the lower lips. The degree to which individuals carrying the gene are affected is widely variable, even within families. These variable manifestations include lip pits alone, absent teeth, or isolated cleft lip and palate of varying degrees of severity. Other associated anomalies have also been described. About 1-2% of patients with cleft lip or palate have van der Woude syndrome.
Velocardiofacial syndrome (VCFS) is a genetic condition characterized by structural or functional palatal abnormalities, cardiac defects, unique facial characteristics, hypernasal speech, hypotonia, developmental delay, and learning disabilities. As many as 15-20% of patients have Robin sequence.
Reference:
Wyszynski, DF, Cleft Lip and Palate in Origin to Treatment. Oxford University Press, 2002.
Which of the following surgical techniques for cleft palate repair retains an anterior soft tissue pedicle for improved flap perfusion? A. von Langenbeck technique B. Furlow Z-plasty technique C. Bardach (2-flap) technique D. Pushback procedure
Answer: A
Rationale:
The von Langenbeck palate repair technique involves the creation of two full thickness mucoperiosteal flaps with care taken to preserve anterior soft tissue pedicles. The theoretical advantage of the anterior soft tissue attachments is additional blood supply for the elevated flaps. During the Bardach (2-flap) and pushback procedures, similar soft tissue flaps are elevated, but no anterior pedicle is maintained. The Furlow procedure involves the use of double opposing Z-plasties with the musculature elevated with the posteriorly based flaps on the nasal and oral sides.
Reference:
Posnick JC: The Staging of Cleft Lip and Palate Reconstruction Infancy Through Adolescence. In Posnick JC Craniofacial and Maxillofacial Surgery in Children and Young Adults. pp. 804.
In the unrepaired cleft palate, the levator veli palatini muscle inserts abnormally into:
A. B. C. D.
the medial pterygoid plate. the lateral pterygoid plate. the posterior hard palate. Passavant’s ridge.
Answer: C
Rationale:
The goals of cleft palate repair are twofold; first, water tight closure of the oral-nasal communication, and second, the creation of a dynamic soft palate for normal speech production. The most important muscular component of the soft palate is the levator veli palatini muscle which functions to elevate the velum and allow for appropriate speech production. In patients with an unrepaired cleft palate, the levator musculature is clefted and has abnormal insertions along the posterior edge of the hard palate.
Reference:
Cutting, CB, Rosenbaum J, Rovati L: The technique of muscle repair in the cleft soft palate. Operative Techniques in Plastic and Reconstructive Surgery, Vol 2, No 4(November), 1995: pp 215-222
In an infant born with a unilateral complete cleft lip and palate, primary repair of the cleft lip should be carried out when the child is:
A. 1 week of age and weighs 5 lbs (2.2kg).
B. 10 weeks of age and weighs 10 lbs (4.5 kg).
C. 10 months of age and weighs 10 lbs (4.5 kg).
D. 10 months of age and weighs 20 lbs (9.1 kg).
Answer B
Rationale:
Generally, cleft lip repair is carried out when the child is 10 to 12 weeks of age. General guidelines were developed for reduction of anesthetic risk and suggested that the surgery be undertaken when the child is approximately 10 weeks of age, weighs at least 10 lbs, and has a serum hemoglobin of at least 10 mg/dl. This has often been referred to as the “rule of 10’s” for the timing of cleft lip repair.
Reference:
Posnick JC: The Staging of Cleft Lip and Palate Reconstruction Infancy Through Adolescence. In Posnick JC Craniofacial and Maxillofacial Surgery in Children and Young Adults. pp. 798.
During primary repair of the cleft palate, utilizing Bardach’s (two-flap) technique, the palatal mucoperiosteal flaps are based upon which artery? A. Ascending pharyngeal artery B. Facial artery C. Greater palatine artery D. Sphenopalatine artery
Answer: C
Rationale:
Two-flap palatoplasty techniques involve the elevation of full-thickness mucoperiosteal flaps on each side of the cleft defect for oral side closure. After the nasal mucosa is closed, these soft tissue flaps are sutured together in the midline for closure of the cleft defect. During the initial dissection and elevation of the flaps, the greater palatine neurovascular bundles are identified and protected. The result is that the axial soft tissue flaps are raised based upon the blood supply of the greater palatine arteries bilaterally. If the greater palatine artery is injured or cauterized, then the axial pattern soft tissue flap becomes a random pattern flap (i.e. not based on one specific arterial supply) with perfusion from the palatal soft tissue attachments.
Reference:
Bardach J: Two-flap palatoplasty: Bardach’s technique. Operative Techniques in Plastic and Reconstructive Surgery, Vol 2. No 4(November), 1995: pp 211-214.
Secondary bone graft reconstruction of the cleft maxilla and alveolus is undertaken:
A. at the time of the palate repair during infancy.
B. when the maxillary central incisor is 2/3rds formed.
C. when the maxillary canine is 1⁄4 to 2/3 developed.
D. after partial eruption of the maxillary canine.
Answer: C
Rationale:
By definition, secondary bone graft reconstruction is carried out after the initial closure of the hard and soft palate. Generally, bone grafting is performed between 6 and 10 years of age, but the specific timing is based upon the child’s dental development instead of chronological age. Bone graft reconstruction of the cleft maxilla is undertaken based on the development of the permanent maxillary canine tooth. If partial eruption of the canine is allowed prior to bone graft placement, unfavorable periodontal outcome results.
Reference:
Ochs MW: Alveolar Cleft Bone Grafting(Part II): Secondary Bone Grafting, J Oral Maxillofac Surg 54: 83-88, 1996.
The surgical technique for creation of a superiorly based pharyngeal flap requires elevation of which muscle from the posterior pharyngeal wall? A. Palatopharyngeus muscle B. Palatoglossus muscle C. Superior constrictor muscle D. Levator Veli Palatini
Answer: C
Rationale:
A superiorly based pharyngeal flap is commonly used for the management of velopharyngeal insufficiency related to cleft palate. A soft tissue flap is developed from the posterior pharyngeal wall. This is done by elevating the posterior pharyngeal wall soft tissues including the superior constrictor muscle off of the prevertebral fascia. This flap is then inset within the soft palate nasal side closure.
Reference:
Ilankovan V: Secondary cleft lip and palate repair. Operative Maxillofacial Surgery. Chapman and Hall 1998. pp215.
In the United States, the incidence of cleft lip or cleft lip with cleft palate is:
A. B. C. D.
equal among all races.
greatest among Caucasians. greatest among African-Americans. greatest among Asian-Americans.
Answer: D
Rationale:
Cleft lip with or without cleft palate is a common congenital malformation with an incidence of approximately 1 in 700 live births, but significant variation is encountered when different ethnic/racial populations are examined. African Americans have an incidence which is significantly lower than the general population while Asians have the highest rate of birth prevalence. By contrast, isolated cleft palate has a lower overall incidence of approximately 1 in 2,000 live births with similar distribution among the different racial and ethnic populations.
Reference:
Costello BJ, Ruiz RL. Cleft Lip and Palate: Comprehensive Treatment Planning and Primary Repair. In: Miloro M, Ghali GE, Larsen PE, and Waite PD (Editors): Peterson’s Principles of Oral and Maxillofacial Surgery, Second Edition. BC Decker. Hamilton. 2004. Pp: 839-858.
The successful creation of velopharyngeal competence after superior pharyngeal flap surgery requires:
A. adequate lateral pharyngeal wall mobility.
B. palatal elongation at the time of surgery.
C. the presence of Passavant’s ridge.
D. glottic closure.
Answer: A
Rationale:
The superiorly based pharyngeal flap remains the standard approach for surgical management of patients with velopharyngeal insufficiency after cleft palate repair. The procedure involves the creation of a soft tissue flap from the posterior pharyngeal wall which is subsequently inset within the soft palate. The result is that the size of the nasopharyngeal cavity is decreased. The larger nasopharyngeal opening which could not be completely closed by the patient is instead converted into two (right and left) smaller lateral pharyngeal ports. Closure of these ports is easier for the patient to accomplish as long as adequate lateral pharyngeal wall motion is present.
Reference:
Argamaso R V: Pharyngeal Flap Surgery for Velopharyngeal Insufficiency, Operative Techniques in Plastic and Reconstructive Surgery, Vol 2, No 4 (November), 1995: pp 233-238
Dynamic sphincter pharyngoplasty is performed by elevating myomucosal flaps which include which muscle? A. Superior constrictor muscle B. Palatopharyngeus muscle C. Palatoglossus muscle D. Tensor Veli Palatini
Answer: B
Rationale:
The dynamic sphincter pharyngoplasty procedure involves the use of two superiorly based myomucosal flaps created within each posterior tonsillar pillar. Each flap is elevated with care taken to include as much of the palatopharyngeous muscle as possible. The flaps are then attached to each other and inset within a horizontal incision on the posterior pharyngeal wall. The goal of this procedure is to create a single nasopharyngeal port that has a contractile ridge posteriorly in order to improve velopharyngeal closure.
Reference:
Gray SD, Pinborough-Zimmerman J: Diagnosis and Treatment of Velopharyngeal Incompetence. Facial Plastic Surgery Clinics of North America. 4:3 (August) 1996: pp. 405-413.
