COMPARISON OF DURATION OF NEUROMUSCULAR BLOCKING EFFECT OF ATRACURIUMAND VECURONIUM IN YOUNG AND ELDERLY PATIENTS

In a controlled, randomized study, we evaluated duration of neuromuscu lar block in 80 patients undergoing routine abdominal surgery. Forty p atients were aged 18-50 yr (control group) and 40 patients were more t han 65 yr (elderly group). All patients had normal plasma creatinine c oncentrations. 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 twitc h 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 r ecovered to 25 % of the control twitch height. We found that the durat ion of action of the initial dose of atracurium was similar in the con trol and elderly groups, and it did not vary after repeated doses. How ever, the initial dose of vecuronium caused a significantly longer per iod of clinical block in the elderly group compared with the controls, and the duration of action of repeated doses was longer in the elderl y group. We conclude that as there is a risk of prolonged effect of ve curonium in the elderly, monitoring of neuromuscular function is recom mended in this group. Alternatively, atracurium should be preferred fo r prolonged surgery in elderly patients.