SMOKING INCREASES THE REQUIREMENT FOR ROCURONIUM

Purpose: To compare the potency of rocuronium in non-smokers and smoke rs during general anaesthesia. Methods: In a randomized, open clinical study, 40 patients, 17-62 yr of age, were anaesthetized with propofol , alfentanil and nitrous oxide in oxygen. After obtaining individual d ose-response curves for rocuronium, bolus doses of rocuronium were giv en to maintain neuromuscular block at 90-99 % for 60 min. Evoked adduc tor policies electromyography (EMG) was used to monitor neuromuscular block. Results: The ED95 values (+/- SEM) for rocuronium were 460.5 +/ - 28.9 and 471.5 +/- 22.1 mu g.kg(-1) for non-smokers and smokers, res pectively (P:NS). However, doses of rocuronium to maintain 90-99 % neu romuscular block (+/- SEM) were 620.1 +/- 46.7 and 747.4 +/- 56.0 mu g .kg(-)1.hr(-1) for non-smokers and smokers, respectively (P = 0.0504). Conclusion: The results may indicate increased metabolism of rocuroni um in smokers rather than increased requirement of rocuronium at the r eceptor site.