Question 6#

Which of the following neuromuscular blocking drugs do not depend on hepatic or renal function for clearance?

A. Rocuronium

Correct Answer: B

Cisatracurium (and certain other benzylisoquinolinium derivatives such as atracurium and mivacurium) does not depend on renal or hepatic function for its metabolism. More than 75% of cisatracurium undergoes spontaneous degradation via Hofmann elimination. Atracurium undergoes both Hofmann degradation and ester hydrolysis by nonspecific esterases. However, alterations in physiologic pH or temperature can affect the rate of Hofmann elimination. On the other hand, aminosteroid compounds (vecuronium, rocuronium, pancuronium, etc) have hepatic and/ or renal mechanisms of elimination.

Reference:

1. Miller RD. Miller’s Anesthesia. 8th ed.; San Diego: Churchill Livingstone; 2015 :Chap 29

Question 7#

Which of the statements is true regarding the choice of pharmacological agents for treatment of hypo- or hyperactive delirium in patients presenting with respiratory failure or shock?

A. Use of Haloperidol is associated with shorter duration of delirium when compared with placebo

Correct Answer: D

The recently concluded MIND-ICU trial compared Ziprasidone and Haloperidol with placebo in the treatment of hypo- or hyperactive delirium in critically ill patients on mechanical ventilation. Of the patients, 90% had hypoactive delirium. There was no difference between the groups with regard to primary end points of delirium-free days. Secondary analyses revealed no difference between groups with regard to duration of mechanical ventilation, 30 or 90 day mortality, oversedation, or days to ICU discharge. Overall choice of antipsychotics Haloperidol or Ziprasidone did not improve outcomes when compared to placebo.

Reference:

1. Girard TD, Exline MC, Carson SS, et al. Haloperidol and ziprasidone for treatment of delirium in critical illness. N Engl J Med. 2018;379:2506- 2516

Question 8#

Sugammadex has the HIGHEST affinity for which of the following neuromuscular blocking agents?

A. Rocuronium

Correct Answer: A 

Sugammadex binds aminosteroid neuromuscular blocking drugs such as rocuronium and vecuronium causing a quick reversal of their effects. Sugammadex has little to no affinity for nonsteroidal neuromuscular blocking agents such as mivacurium, atracurium, and cisatracurium. Although sugammadex does have significant affinity for vecuronium, it has a higher affinity for rocuronium.

Reference:

1. Bom A, Hope F, Rutherford S, Thomson K. Preclinical pharmacology of sugammadex. J Crit Care. 2009;24(1):29-35. 

Question 9#

Which of the following would be the LEAST useful to use as an analgesic adjunct with the goal of reducing opioid consumption in the ICU?

A. Dexmedetomidine

Correct Answer: D

Benzodiazepines do not have analgesic properties. Acetaminophen, ketamine, and dexmedetomidine have generalized analgesic effects. Gabapentin is helpful in managing neuropathic pain symptoms.

References:

1. Devlin JW, Skrobik Y, Gélinas C, et al. Clinical practice guidelines for the prevention and management of pain, agitation/sedation, delirium, immobility, and sleep disruption in adult patients in the ICU. Crit Care Med. 2018;46(9):e825-e873.
2. Habibi V, Kiabi FH, Sharifi H. The effect of dexmedetomidine on the acute pain after cardiothoracic surgeries: a systematic review. Braz J Cardiovasc Surg. 2018;33(4):404-417.
3. Jessen Lundorf L, Korvenius Nedergaard H, Møller AM. Perioperative dexmedetomidine for acute pain after abdominal surgery in adults. Cochrane Database Syst Rev. 2016;18(2):CD0103558. 

Question 10#

Which of the following medications has the HIGHEST increase in context-sensitive half-life during a prolonged infusion?

A. Ketamine

Correct Answer: E

The context sensitive half-life is the time required for blood or plasma concentrations of a drug to decrease by 50% after discontinuation of the drug administered by infusion. It factors in the effects of a prolonged infusion on half-life of a drug. In the context of continuous infusions many drugs that are short acting after a single bolus have an increase in their half-life as their volume of distribution becomes saturated. The half-life of fentanyl increases to over 300 minutes after an infusion of 5 hours. The half-life of midazolam increases to between 50 and 75 minutes after an infusion of 5 hours. The half-life of dexmedetomidine increases to around 100 minutes after an infusion of 5 hours. The half-life of propofol and ketamine both increase slightly but are around 25 minutes after an infusion of 5 hours.

References:

1. Miller RD. Miller’s Anesthesia. 8th ed.; San Diego: Churchil Livingstone; 2015:Chap 29 & 30.
2. Iirola T, Ihmsen H, Laitio R, et al. Population pharmacokinetics of dexmedetomidine during long-term sedation in intensive care patients. Br J Anaesth. 2012;108(3):460-468.