Recovery from vecuronium neuromuscular blockade following neostigmine administration in infants, children, and adults during halothane anesthesia

To determine whether neostigmine had different effects in pediatric patients during vecuronium neuromuscular blockade, the rate of recovery following neostigmine administration was compared in infants (n = 8), children (n = 10), and adults (n = 10) during nitrous oxide-halothane anesthesia. After induction of anesthesia, patients received 100 micrograms/kg of vecuronium. The EMG response of the adductor pollicis was monitored after train-of-four (TOF) stimulation of the ulnar nerve every 20 s. When the first twitch of TOF spontaneously recovered to 10% of control value, neostigmine was injected (40 micrograms/kg in adults, 30 micrograms/kg in infants and children). During the first few minutes following neostigmine administration, no differences were observed between the three groups. After the 8 min, recovery was more rapid in children than in infants and adults up to and including the 15th min. Ten minutes after neostigmine administration, the first twitch (mean +/- SD) reached 97 +/- 3%, 99 +/- 2%, and 97 +/- 5% of control value in infants, children, and adults, respectively; TOF ratio was greater in children (0.96 +/- 0.03) than in either adults (0.82 +/- 0.17) or in infants (0.83 +/- 0.14) (P less than 0.05). During the first minutes after neostigmine administration, the lack of difference in TOF recovery in the three groups suggests that neostigmine is the main factor of recovery. In contrast, the more complete recovery after the eighth minute in children could be due to the faster rate of spontaneous recovery from vecuronium induced neuromuscular blockade in children.