The Effect of Cigarette Smoking on Propofol EC50of Airway Obstruction during Target Controlled Infusion of Propofol

Abstract

Background: Airway obstruction is a main cause of respiratory complications during sedation. The aim of this study was to identify the effect of smoking on the target plasma concentration of propofol () of airway obstruction during target controlled infusion (TCI) of propofol. Methods: Thirty healthy male adults scheduled for lower extremity surgery under regional anesthesia were randomly allocated to one of five target plasma concentrations () of propofol: 1.0, 2.0, 3.0, 4.0, 5.0/ml (n = 6 for each concentration). After performing regional anesthesia, oxygen was supplied and was measured. All patients received propofol TCI with the assigned . The occurrence of airway obstruction was observed until 5 minutes after effect site concentration () reached . When hypoxemia, apnea or total airway obstruction was observed, ventilation was assisted with 100% oxygen. The , smoking history, snoring history, age, body mass index, Mallampati's classification and thyromental distance were regarded as independent variables. The relationship of airway obstruction and the variables was analyzed with logistic regression with Wald-forward method. By the equation of the probability of airway obstruction 'P = 1/(1+)', we estimated the propofol of airway obstruction in smokers and nonsmokers. Results: The result of logistic regression was as following: z (airway obstruction) = 5.557 2.128 [/ml] 3.625 smoking (: P = 0.007, smoking: P = 0.047). The propofol of airway obstruction of non-smokers and smokers was 2.6 (1.5-9.4)/ml and 0.9 (-9.3)/ml, respectively. Conclusions: The propofol of airway obstruction of smokers was lower than that of nonsmokers.