Butorphanol suppresses fentanyl-induced cough during general anesthesia induction: A randomized, double-blinded, placebo-controlled clinical trial

Fentanyl-induced cough (FIC) is unwanted in the patients requiring stable induction of general anesthesia. This study was designed to evaluate the suppressive effects of butorphanol pretreatment on the incidence and severity of FIC during the induction of general anesthesia. A total of 315 patients of American Society of Anesthesiologists physical status I and II, scheduled for elective surgery under general anesthesia were randomized into 3 equally sized groups (n = 0105). Two minutes before fentanyl bolus, group I received intravenously 5 mL normal saline, groups II and III received butorphanol 0.015 and 0.03 mg/kg (diluted with saline to 5 mL), respectively. Patients were then administrated with fentanyl 2.5 μg/kg within 5 s. The incidence and severity of FIC was recorded for 2 minutes after fentanyl bolus. During experimental period, the mean arterial pressure, heart rate, and peripheral capillary oxygen saturation (SpO(2)) were recorded before the administration of butorphanol or normal saline (T0), 2 minutes (T1) after butorphanol injection, and 2 minutes (T2) after fentanyl injection. The incidence of FIC was 31.4% in group I, 11.4% in group II, and 3.8% in group III. Group III had a lowest incidence of FIC among 3 groups (P < 0.001, vs group I; P < 0.05, vs group II). The severe FIC was not observed in groups II and III, but was recoded from 6 patients in group I. At 2 minutes after fentanyl injection (T2), the mean arterial pressure was significantly higher in group I than that in groups II and III (P < 0.01, vs group II; P < 0.05, vs group III), but the values remained within safe limits. In conclusion, pretreatment with butorphanol could effectively and safely suppress FIC during anesthesia induction.