The effect of cigarette smoking on washout time of sevoflurane anesthesia*

Background: Cigarette smoking affects the pharmacodynamic and pharmacokinetic behavior of several drugs. In addition, it can deteriorate the pulmonary mechanics. The aim of this study was to evaluate the effect of cigarette smoking on washout time after one minimum alveolar concentrationhour (1 MAC-h) sevoflurane anesthesia. Methods: We investigated the washout time of sevoflurane in 30 non-smoking and 30 healthy cigarette smoking (≥20 cigarettes/day for>1 year) ASA I-II physical status patients, aged 18–63 years, who were candidates for otorhinolaryngologic elective surgery under 1MAC-h standardized sevoflurane anesthesia. At the end of the surgery, the sevoflurane vaporizer was turned off and the time it took for the sevoflurane concentration to decrease to MAC-awake (0.3) and 0.1 MAC were recorded. In addition, the ratio of fraction of inspired concentration (Fi) of sevoflurane and fraction of expired concentration (Fexp) of sevoflurane at 1 MAC and Fexp of sevoflurane at 0.1MAC were recorded. The patients were mechanically ventilated during the washout time. Results: We didn’t find any differences between the two study groups with regard to washout time of sevoflurane. The times of 1MAC down to MAC-awake (106±48 sec in non-smokers, 97±37 sec in smokers, p>0.05) and down to 0.1MAC (491±187 sec in non-smokers, 409±130 sec in smokers, p>0.05) were similar between non-smokers and smokers. Similarly, there were no significant differences in the ratios of Fi/Fexp at 1MAC (1.18 in non-smokers vs. 1.19 in smokers, p>0.05) and Fexp of sevoflurane at 0.1MAC (0.26 in non-smokers vs. 0.25 in smokers, p>0.05) between the groups. Conclusions: Washout time of 1MAC-h sevoflurane anesthesia does not appear to be effected by cigarette smoking in patients without significant pulmonary disease.