Reappearance of the train-of-four after neuromuscular blockade induced with tubocurarine, vecuronium or atracurium.

The characteristics of train-of-four recovery after atracurium or vecuronium were studied, under enflurane anaesthesia, and compared with those associated with tubocurarine-induced blockade. Ten patients each received vecuronium 0.1 mg kg-1, atracurium 0.5 mg kg-1 or tubocurarine 0.5 mg kg-1. Neuromuscular blockade was calculated as the percent depression of the first twitch, and was determined at the time of reappearance of the second, third and fourth twitches of the train-of-four. The pattern during recovery from blockade induced by the three neuromuscular blocking agents was similar, with T2, T3 and T4 reappearing at approximately 93%, 89% and 86% residual blockade, respectively. These results are different from those previously reported by Lee (1975) indicating that, under enflurane anaesthesia, the train-of-four count may give an incorrect estimate of the degree of neuromuscular blockade.