The Sedative Effect Of Remifentanil/propofol Regimen Via Plasma TCI During General Anesthesia Induction Assessed By BIS

OBJECTIVEThe purpose of this investigation was conducted to assess the sedative effect of remifentanil/propofol regimen via plasma target controlled infusion(TCI).The sedative effect was assessed by bispectral index(BIS)during general anesthesia induction.METHODSEighty adult ASAâ… orâ…¡patients undergoing elective laparoscopy cholecystectomy induced with remifentanil/propofol regimen via plasma TCI were randomly assigned to four groups according to the plasma concentration of remifentanil:group B 2ng/mL,group C 4ng/mL,group D 8ng/mL,and group A served as control and received no remifentanil.All patients received propofol plasma TCI at 2μg/mL and increased in steps of 0.5μg/mL at 1 min intervals.In addition,the remifentanil plasma TCI was coinfused at a group dependent,fixed plasma target concentration(0,2,4,8 ng/ml).The goal was to reach a BIS target of 50 in the period of induction free from stimuli.The duration of induction,the propofol requirements,the concentration of propofol at loss of consciousness and the endpoints of the study were recorded.BIS and haemodynamic variables(BP,HR and SPO₂)were also collected simultaneously.Statistical analysis was performed using SPSS 12.0 and differences of the data above were analysed between the groups,using analysis of variance(ANOVA)for repeated measurements.RESULTSIn the control group,the duration of induction was 352.4±76.4 s,the BIS value 69.0±5.3 at the loss of consciousness,the propofol consumption 13.6±3.5 mL,the plasma concentration of propofol were 3.45±0.51μg/mL and 4.72±0.70μg/mL when the patients got sleep and the BIS dropped to 50.Contrasted to the control group,the group B had no significant differences.In the C and D groups,otherwise, there was a significant decrease in the duration of induction (311.8±87.3s and 175.5±60.8s,p＜0.05)and propofol consumption (11.6±4.1 mL and 8.8±3.2 mL p＜0.05),while the BIS value was increased at the loss of consciousness(73.4±5.0 and 75.3±4.5,p＜0.001).In the D group,the plasma concentration differences of propofol at the loss of consciousness and when BIS dropped to 50, were observed significantly(2.90±0.61 and 4.03±0.74,p＜0.001 and p=0.001).The haemodynamic states were constant stabled in all patients.CONCLUSIONThe plasma concentration of propofol at loss of consciousness and BIS value at 50 decreased as the concentration of remifentanil ascending.Both the duration of induction and the propofol consumption were decreased when the plasma concentration of remifentanil increase to 4ng/mL.A linear correlation between the BIS value at loss of consciousness and the concentration of remifentanil was found.In the remifentanil/propofol regimen via TCI,remifentanil significantly strengthen the sedative effect of propofol when the plasma concentration ascends to 4ng/mL...