Use of atracurium during general surgery monitored by the train-of-four stimuli.

The use of atracurium in 25 patients undergoing general surgical procedures is described, neuromuscular function being monitored by the "train-of-four" stimuli. An initial dose of atracurium 0.5 mg kg-1 proved to be clinically acceptable, giving good conditions for endotracheal intubation and adequate muscle relaxation for about 40 min. Comparison of the results with those from 15 patients given suxamethonium 50 mg showed that atracurium in this dosage took longer to produce complete ablation of the twitch responses but that it lasted longer (about 40 min). Incremental doses of atracurium (of 0.2 mg kg-1) gave relaxation for about 30 min and there was no evidence of a cumulative effect. Reversal of the neuromuscular block with neostigmine was prompt and adequate. Using simple clinical means no evidence of an important change in heart rate or arterial pressure was found. There were no adverse reactions to the drug.