Effect of low-dose propofol on the depth of anesthesia during coronary artery bypass grafting with different temperature

Abstract

Objective To investigate the effects of low dose propofol on the depth of anesthesia during coronary artery bypass grafting with mild hypothermia. Methods Forty patients scheduled for coronary artery bypass grafting were randomly divided into two groups: group I (mild hypothermia, n=20) and group Ⅱ (moderate hypothermia, n=20). ECG, invasive blood pressure, temperature of nasal cavity and Narcotrend were continuously monitored during the anesthesia. All the patients received fentanyl (interval infusion 30-50 μg/kg) before sawing sternum, and propofol maintenance infusion, 0.2 mg/(kg·h) during circulation pulmonary bypass(CPB). The lowest nasopharyneal temperature were 33-35 ℃ (mild hypothermia) in group I and 29-31 ℃(moderate hypothermia) in group Ⅱ during circulation pulmonary bypass. In the same time, mean artery pressure was kept 40-60 mm Hg(1 mm Hg=0.133 kPa),and Hct was 30%-35%. Narcotrend NI, nasopharyneal temperature,mean artery pressure and Hct were recorded at the following five time points: 5 min before CPB(T0), 5 min into CPB(T1), 30 min into CPB(T2), immediately stopping CPB and 15 min after CPB. Results No significant difference was found in NT, T, Hct and MAP in group I. NT was increased at T0 and T4 as compared with the baseline values at T1,T2 and T3 in group Ⅱ. NT at T2 was lower than at T0,T1,T3 and T4 in group Ⅱ. No significant difference was found in T, Hct and MAP in group Ⅱ. Conclusions Compared with that in moderate hypothermia, the depth of anesthesia did not significantly change in mild hypothermia during coronary artery bypass grafting. Key words: Temperature; Depth of anesthesia; Coronary artery bypass grafting