The neuromuscular blocking effects of vecuronium during sevoflurane, halothane and balanced anaesthesia in children.

Abstract

Forty-five children aged 5-12 years were randomly allocated to receive 1.0 MAC of sevoflurane or halothane, or balanced anaesthesia with propofol and alfentanil. The ulnar nerve was stimulated every 20 s supramaximally with a train-of-four pattern and adductor pollicis electromyography was recorded. A cumulative log-probit dose-response curve of vecuronium was established. Thereafter, spontaneous recovery of neuromuscular function was monitored until complete. Effective doses of vecuronium were lowest in the sevoflurane group and greatest during balanced anaesthesia; for 50% neuromuscular blockade these were 13.3% micrograms.kg-1, 21.8 micrograms.kg-1 and 36.6 micrograms.kg-1 during sevoflurane, halothane and balanced anaesthesia, respectively, p < 0.05. Recovery of neuromuscular function was slower during sevoflurane than during halothane or balanced anaesthesia. Sevoflurane potentiated vecuronium more than halothane; when compared to balanced anaesthesia the dose requirements of vecuronium were reduced by approximately 60% and 40%, respectively.