Early reversal of rapacuronium with neostigmine

Background: Rapacuronium is a rapid-onset, short-acting neuromuscular relax ant. This multiple-center study determined neuromuscular recovery when neos tigmine was given 2 or 5 min after rapacuronium. Methods: One hundred seventeen patients were randomized to receive two diff erent doses of rapacuronium and to receive neostigmine in two different dos es and at two different times. During propofol anesthesia with nitrous oxid e, oxygen, and fentanyl, 1.5 or 2.5 mg/kg rapacuronium was given 1 min befo re tracheal intubation Neuromuscular block was measured by train-of-four ul nar nerve stimulation every 12 s: The adductor pollicis force of contractio n was recorded mechanomyographically. Two or five minutes after rapacuroniu m was administered, 0.05 or 0.07 mg/kg neostigmine was administered and rec overy was compared with that of control patients who received no neostigmin e. Results: Both doses of rapacuronium produced 100% block in all but one pati ent, who exhibited 97% block. Neostigmine accelerated recovery in all group s. After 1.5 mg/kg rapacuronium, the time to 25% T-1 twitch recovery decrea sed from a mean of 16 min in control patients to mean values of 8-10 min in the treatment groups: The time to train-of-four ratio of 0.7 decreased fro m 38 min to 17-19 min. After 2.5 mg/kg rapacuronium, the time to 25% T-1 wa s reduced from 23 min to 11-12 min, and the time to train-of-four ratio of 0.7 decreased from 54 min to 26-32 min. Recovery was not different among th e the groups that received different doses and timing of neostigmine. Conclusions: Recovery of intense rapacuronium block was accelerated by earl y neostigmine administration. When given 2 min after rapacuronium, neostigm ine was as effective as after 5 min, and 0.05 mg/kg neostigmine was compara ble to 0.07 mg/kg neostigmine.