Effect of Continuous Infusion of Remifentanil on Propofol Dose and Hemodynamics using Bispectral Index during Anesthetic Induction

Kim, Young Jae; Kim, Myoung Hun; Kim, Young Hwan; Lim, Se Hoon; Lee, Jeong Han; Lee, Kun Moo; Cheong, Soon Ho; Choe, Young Kyun; Shin, Chee Mahn

Abstract

BACKGROUND: Remifentanil combined with propofol is usually used to induce anesthesia. However, remifentanil and propofol depress the cardiovascular system. This study investigated the effects of a continuous infusion of remifentanil on the propofol dose and hemodynamics using the bispectral index (BIS) during anesthetic induction.
METHODS
Sixty female ASA physical status class I or II patients, who were scheduled to undergo gynecologic surgery were randomly assigned to one of three groups (n = 20). Normal saline 20 ml/hr (Group S), remifentanil 0.25microgram/kg/min (Group 0.25), or remifentanil 0.5microgram/kg/min (Group 0.5) was infused intravenously. Propofol was administered slowly two minutes after administering remifentanil or normal saline. The heart rate, mean arterial pressure (MAP) and BIS were measured at baseline, preintubation and postintubation. RESULT: There were no significant differences in the changes in the BIS among the groups. The MAP and heart rate decreased at preintubation compared with baseline (P < 0.05). The MAP of Group 0.5 at postintubation was lower than that in the other groups (P < 0.05). The heart rate in all groups increased at postintubation compared with baseline (P < 0.05). The heart rate of Group 0.5 at postintubation was lower than that of Group S (P < 0.05). The propofol requirement for unconsciousness was lower in Groups 0.25 and 0.5 than in Group S. The propofol requirement in Groups S, 0.25 and 0.5 was 1.56+/-0.2 mg/kg, 1.07+/-0.2 mg/kg and 0.9+/-0.1 mg/kg, respectively.
CONCLUSIONS
A combined injection of 0.5microgram/kg/min remifantanil with 0.9 mg/kg of propofol decreases the heart rate and MAP at preintubation without adverse effects and appropriately prevents the cardiovascular responses to tracheal intubation, and reduces the propofol dose needed for a loss of consciousness.