Effects of target-controlled infusion of dexmedetomidine on the median effective concentration of effect-site of propofol at loss of consciousness / 临床麻醉学杂志

ABSTRACT

Objective To investigate the effects of target-controlled infusion (TCI)of dexme-detomidine on the median effective concentration of effect-site (Ce50 )of propofol at loss of conscious-ness (LOC)in patients.Methods Sixty-four patients,28 males and 36 females,aged 20-60 years, ASA physical status Ⅰ or Ⅱ,scheduled for elective surgery,were randomly allocated to receive dexmedetomidine of 0 ng/ml (group P),dexmedetomidine of 0.4 ng/ml (group D1),dexmedetomi-dine of 0.6 ng/ml (group D2)and dexmedetomidine of 0.8 ng/ml (group D3)for 1 5 min before TCI of propofol,n =1 6 in each group.The propofol infusion was started to provide an effect-site concen-tration of 1.0 μg/ml,and increased by 0.2 μg/ml when propofol effect-site concentration and target concentration were equilibrium until LOC.Results The Ce50 (95%CI )at loss of consciousness in groups P,D1,D2 and D3 were 2.30 (2.24-2.36)μg/ml,1.92 (1.87-1.96 )μg/ml,1.60 (1.55-1.65)μg/ml and 1.41 (1.35-1.45 )μg/ml,respectively.There was a negative correlation between the effect-site concentration of propofol-induced LOC and target concentration of dexmedetomidine (r=-0.84,P <0.01).Compared with groups P,D1 and D2,the incidence of bradycardia was higher in group D3 (P <0.05).Conclusion The Ce50 of propofol-induced LOC gradually decreases with in-creasing target concentration of dexmedetomidine.Combining propofol with dexmedetomidine of 0.4 or 0.6 ng/ml that can reduce the Ce50 of propofol-induced LOC,which is suitable for induction of an-esthesia with a lower incidence of bradycardia.