Effects of different priming doses of fentanyl on fentanyl-induced cough: a double-blind, randomized, controlled study.

BACKGROUND Fentanyl-induced cough is not an uncommon phenomenon during the induction of general anesthesia. A preliminary randomized controlled study was designed to observe the effects of different priming doses of fentanyl on fentanyl-induced cough during induction of anesthesia. METHODS Four hundred patients were randomized into four groups (n = 100 for each). Group I received 5 ml saline 0.9% 1 min before administration of fentanyl 2.5 μg/kg; group II received pre-emptive fentanyl 0.5 μg/kg 1 min before administration of fentanyl 2 μg/kg; group III received pre-emptive fentanyl 1 μg/kg 1 min before administration of fentanyl 1.5 μg/kg; and group IV received pre-emptive fentanyl 1.5 μg/kg 1 min before administration of fentanyl 1 μg/kg. The severity of cough was graded as none (0), mild (1-2), moderate (3-4), or severe (5 or more episodes). We defined T1 and T2 as the 1 min periods after the first and second injections, respectively, and recorded the number of patients whose first cough happened in the T1 or T2 period. RESULTS The incidences of fentanyl-induced cough were 68%, 5%, 40% and 64% in groups I, II, III and IV, respectively. The incidence of cough in group II was lower than those in groups III and IV in the T1 period. The incidences of cough in groups II, III and IV were lower than that in group I in the T2 period. CONCLUSIONS In summary, a priming dose of fentanyl 0.5 μg/kg suppressed fentanyl-induced cough during induction of anesthesia in clinical practice. Fentanyl-induced cough was positively correlated with the dose of fentanyl.