Effects of butorphanol and fentanyl on the BIS-propofol effect-site concentration curve during total intravenous anesthesia induction

Abstract

Objective To compare the effects of butorphanol and fentanyl on the bispectral index (BIS)-propofol effect-site concentration curve during total intravenous anesthesia induction. Methods One hundred and twelve patients, scheduled for selective surgery of the thyroid or breast between February 2009 and May 2009 in our hospital under total intravenous anesthesia (ASA Ⅰ-Ⅱ), were randomly divided into four groups: control group (Group C) , fentanyl group (Group F) , butorphanol group (Group B) , and butorphanol plus fentanyl group (Group BF) , 28 patients in each group. Target controlled infusion of propofol was used for anesthesia induction in all groups. Group C received an intravenous (Ⅳ) bolus of 4 μg/kg fentanyl and 0.2 mg/kg cis-benzene atracurium after loss of consciousness. Group F was given an Ⅳ bolus of 4 μg/kg fentanyl at two minutes before induction; Group B was given an Ⅳ bolus of 40 μg/kg butorphanol at five minutes before induction; Group BF was given an Ⅳ bolus of 20 μg/kg butorphanol at five minutes and fentanyl 2 μg/kg at two minutes before induction. Moreover, a post-induction Ⅳ bolus of 0.2 mg/kg cis-benzene atracurium was given to groups B, F and BF. Endotracheal intubation was used for mechanical ventilation. Bispoctral index (BIS) and corresponding effect-site concentrations (Ce) of propofol were recorded and graphed. Results At each corresponding effect-site concentration, the bispectral indexes were lower in Group F compared to Group C (68±14 vs 76±12, P=0.036), and in Group B compared to Group F (61±11 vs 68±14, P=0.041). Compared with the Group BF, Group B had a higher BIS when the effect-site concentration of propofol was below 1.4 mg/L, and a lower BIS when the effect-site concentration of propofol was above 1.4 mg/L. The group B was the quickest to fulfill the sedation level required of surgery,followed by Group BF, Group F and Group C. Conclusions Both butorphanol and fentanyl may reduce the BIS at each corresponding effect-site concentration of propofol, with greater reduction of BIS by butorphanol.Butorphanol plus fentanyl may lead to the greatest reduction in BIS when the effect-site concentration of propofol is below 1.4 mg/L. Key words: Butorphanol; Fentanyl; Propofol; Target controlled infusion; Bispectral index