The effects of sevoflurane are similar to those of isoflurane on the neuromuscular block produced by vecuronium

We have examined the interactions of 1 MAC of isoflurane andsevoflurane (and 66% nitrous oxide in oxygen) with vecuronium,using the EMG response of the abductor digiti minimi to train-of-four(TOF) stimulation of the ulnar nerve. We constructed dose-responsecurves for vecuronium in 54 patients. The curves for both isofluraneand sevoflurane had a significant leftward shift compared withthat for fentanyl-nitrous oxide anaesthesia (P < 0.01). Whenthe amplitudes of the first response (T1) had recovered to 50%of control in another 32 patients, subsequently we comparedthe spontaneous recovery rate of the ratio of the fourth tothe first TOF response (T4:T1) at 3-min intervals during the15-min period, in the presence of two volatile anaestheticsor after discontinuation of administration of anaesthetic. Therate of recovery of T4:T1 was significantly greater when bothanaesthetics were discontinued. However, this rate was similarfor both anaesthetics, suggesting that the mechanism of actionof the two anaesthetics is similar. (Br. J. Anaesth. 1994; 72:465–467)