Fentanyl-induced cough does not depend on injection speed: a randomized study.

BACKGROUND

The aim of the study was to investigate whether the incidence of cough after intravenous fentanyl depends on the speed of injection.

METHODS

With ethics committee approval, 476 ASA class I-III nonsmoking patients free of bronchial hyperreactivity and respiratory tract infection undergoing general anaesthesia for elective surgery were randomized to either 1.5 microg/kg fentanyl injected over 2, 5 or 10 s or placebo (saline) via a peripheral intravenous cannula. The primary endpoint was the incidence of cough within 5 min after completion of injection.

RESULTS

The study was terminated for futility after enrollment of 476 patients because an interim analysis yielded an incidence of cough of 3%, 3% and 6% in the three fentanyl groups, respectively, and of 2% in the placebo group, with no difference between groups (P=0.374, chi(2) test for cough between fentanyl and placebo groups).

CONCLUSIONS

Under the conditions of our study, the incidence of cough after 1.5 microg/kg fentanyl injected intravenously over 2, 5 or 10 s was between 3% and 6%, unrelated to the speed of injection and not different from placebo.