No relationship between the incidence of fentanyl-induced cough and smoking

Abstract

The purpose of the study was to investigate whether or not the incidence of cough after intravenous fentanyl depends on the patient's smoking state and the speed of injection. 530 ASA class I-III patients free of bronchial hyperreactivity and respiratory tract infection undergoing general anesthesia for elective surgery were randomized to 1.5 g . kg -1 fentanyl injected over 2, 5 or 10 sec or placebo via a peripheral intravenous cannula. The endpoint was cough within 5 min after completion of injection. Statistical evaluation was performed by factorial ANOVA and chi-square-test. Assuming around 25% smokers in our patient population calculated patient sample size was 340 per group. The study was terminated for futility after enrolment of 530 patients since an interims analysis yielded an incidence of cough of 2 % both in smokers (n=174) and nonsmokers (n=356, p= 0,970), which was unrelated to the speed of injection and not different from placebo.