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 and sevoflura ne (and 66% nitrous oxide in oxygen) with vecuronium, using the EMG re sponse of the abductor digiti minimu to train-of-four (TOF) stimulatio n of the ulnar nerve. We constructed dose-response curves for vecuroni um in 54 patients. The curves for both isoflurane and sevoflurane had a significant leftward shift compared with that for fentanyl-nitrous o xide anaesthesia (P < 0.01). When the amplitudes of the first response (T1) had recovered to 50% of control in another 32 patients, subseque ntly we compared the spontaneous recovery rate of the ratio of the fou rth to the first TOF response (T4: T1) at 3-min intervals during the 1 5-min period, in the presence of two volatile anaesthetics or after di scontinuation of administration of anaesthetic. The rate of recovery o f T4:T1 was significantly greater when both anaesthetics were disconti nued. However, this rate was similar for both anaesthetics, suggesting that the mechanism of action of the two anaesthetics is similar.