Effect of antagonism of mivacurium-induced neuromuscular block on postoperative emesis in children

The routine use of cholinesterase inhibitors to antagonize residual neuromuscular block may be associated with increased postoperative emesis. Rapid spontaneous recovery from mivacurium may obviate the need for these drugs. In this randomized, double-blind, placebo-controlled study of 113 healthy children who had received mivacurium as part of a standardized anesthetic regimen, we compared the incidence of postoperative complications after spontaneous recovery and after the use of neostigmine-glycopyrrolate or edrophonium-atropine. The anesthetic regimen consisted of halothane, nitrous oxide, fentanyl, 2 μg/kg intravenous (IV), mivacurium in an initial dose of 0.2 mg/kg, followed by an infusion, adjusted to maintain ≥1 evoked contraction response to a supramaximum train-of-four stimulus. At the end of the procedure, patients received by random assignment one of three drug combinations: 1) neostigmine 70 μg/kg + glycopyrrolate 10 μg/kg, IV, 2) edrophonium 1 mg/kg + atropine 10 μg/kg, IV, and 3) saline. The trachea was extubated when evoked responses to peripheral nerve stimulation and clinical signs of adequate neuromuscular recovery were present. Postoperative pain was treated with morphine and emesis with metoclopramide. There were no significant differences between the three groups with respect to age, surgery, intraoperative fentanyl, and mivacurium use, time from the end of surgery to tracheal extubation, postanesthesia care unit (PACU) arrival and discharge, or in postoperative oxygen saturation values and analgesic requirements. Compared to the placebo group, emesis occurred more often in the PACU in patients receiving the neostigmine-glycopyrrolate combination, but not after edrophonium-atropine. However, after discharge from the PACU, emesis rates were similar in the three study groups. We conclude that spontaneous recovery or reversal with edrophonium from a moderate degree of mivacurium-induced block may offer advantages over the use of neostigmine, without increasing time to PACU arrival.