Comparison of Thiopental and Midazolam on the Neuromuscular Responses to Succinylcholine or Pancuronium in Humans

Abstract

Midazolam (0.3 mg/kg) was compared to thiopental (4.0 mg/kg) for possible interactions with succinylcholine or pancuronium when used for induction of anesthesia. Neuromuscular function was monitored by recording the force of thumb adduction in response to ulnar nerve stimulation. Following induction of anesthesia with either midazolam (N = 10) or thiopental (N = 10), stable muscle-twitch tension was obtained and succinylcholine (1 mg/kg) was given intravenously. The duration of blockade, recovery time, intensity of fasciculations, or adequacy of relaxation for tracheal intubation did not differ between patients receiving midazolam or thiopental. An additional group of patients anesthetized and monitored in the same manner received pancuronium (0.025 mg/kg) in incremental doses until a 99% depression of muscle-twitch tension was obtained. Dose-response curves for pancuronium, duration of blockade, and adequacy of relaxation for tracheal intubation did not differ between patients receiving midazolam (N = 10) or thiopental (N = 10). We conclude that the neuromuscular blockade produced by succinylcholine or pancuronium was no different in patients receiving either midazolam or thiopental for induction of anesthesia.