Comparison of duration of neuromuscular blocking effect of atracurium and vecuronium in young and elderly patients.

In a controlled, randomized study, we evaluated duration of neuromuscular block in 80 patients undergoing routine abdominal surgery. Forty patients were aged 18-50 yr (control group) and 40 patients were more than 65 yr (elderly group). All patients had normal plasma creatinine concentrations. After induction of anaesthesia, patients were allocated randomly to receive either atracurium 0.5 mg kg-1 or vecuronium 0.1 mg kg-1 to facilitate tracheal intubation. Monitoring of the evoked response of the adductor pollicis muscle to supramaximal single twitch ulnar nerve stimulation every 10 s was performed and measured with a strain gauge. Repeat doses of atracurium 0.1 mg kg-1 or vecuronium 0.02 mg kg-1 were administered when the adductor pollicis response recovered to 25% of the control twitch height. We found that the duration of action of the initial dose of atracurium was similar in the control and elderly groups, and it did not vary after repeated doses. However, the initial dose of vecuronium caused a significantly longer period of clinical block in the elderly group compared with the controls, and the duration of action of repeated doses was longer in the elderly group. We conclude that as there is a risk of prolonged effect of vecuronium in the elderly, monitoring of neuromuscular function is recommended in this group. Alternatively, atracurium should be preferred for prolonged surgery in elderly patients.