A multicenter evaluation of the time-course of action of two doses of rapacuronium after early and late reversal with neostigmine

Early reversal of rapacuronium may accelerate return of neuromuscular funct ion. This study was designed to compare early (2 min after rapacuronium) or late (at 25% recovery of the first twitch [T1] of train-of-four) reversal of rapacuronium with neostigmine. We studied 119 subjects between the ages of 18 and 75 yr. Anesthesia was induced with fentanyl and thiopental and ma intained with nitrous oxide, propofol, and fentanyl. Mechanomyographic neur omuscular monitoring was performed by using train-of-four stimulation of th e ulnar nerve. Two groups received 1.5 mg/kg rapacuronium followed by neost igmine (50 mug/kg) and glycopyrrolate (10 mug/kg) either at 2 min after rap acuronium bolus or at 25% TI recovery. The other two groups received 2.0 mg /kg rapacuronium, after which neostigmine was similarly given. For each rap acuronium dose, the time from the administration of rapacuronium to the sta rt of Tl recovery or 25% T1 recovery was significantly shorter in subjects who received the reversal 2 min after rapacuronium. However, late recovery, defined by times from administration of rapacuronium to 70%, or 80% T4/T1 recovery, was not influenced by early reversal administration. We conclude that initial recovery is accelerated by early administration of neostigmine . Time to full recovery after rapacuronium administration is, however, dose -dependent and not significantly altered by early administration of neostig mine.