A 65-year-old patient on cardiopulmonary bypass is cooled to 28°C during surgery. Vecuronium is used for neuromuscular blockade. How does this degree of hypothermia affect the duration of action of vecuronium?
- A Shortens duration by accelerating Hofmann elimination
- B Shortens duration by increasing renal excretion
- C Prolongs duration by reducing hepatic metabolism and renal excretion ✓
- D No significant change in duration
Correct answer: C. Prolongs duration by reducing hepatic metabolism and renal excretion
Explanation
Hypothermia below 32°C significantly prolongs the duration of action of non-depolarizing muscle relaxants like vecuronium by reducing hepatic metabolism and renal blood flow, thereby decreasing drug clearance. Hofmann elimination is not relevant for vecuronium (it applies only to atracurium and cisatracurium). Active warming is required to restore normal pharmacokinetics.
Reference: Miller's Anesthesia, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.