Effect of age on potency of propofol inhibiting visceral pain during gastroscopy / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of age on the median-effective target plasma concentration (EC50) of propofol inhibiting body movement evoked by gastroscopy in the patients.Methods Ninety adult patients of both sexes,of ASA physical status Ⅰ or Ⅱ,with body mass index 19-25 kg/m2,scheduled for elective gastroscopy,were divided into 3 groups according to age (n =30 each)18-39 yr group (Ⅰ group),40-64 yr group (Ⅱ group) and 65-85 yr group (Ⅲ group).In Ⅰ,Ⅱ,Ⅲ groups,propofol was given by target-controlled infusion with the initial target concentrations of 2.5,2.0 and 1.5 μg/ml,respectively,and gastroscopy was performed when the target concentration was achieved.Body movement was defined as the directional movement in head or four extremities during gastroscopy.The target plasma concentration of propofol was determined by up-and-down sequential trial.Each time the plasma concentration of propofol increased/decreased by 0.5 μg/ml in the next patient depending on whether or not body movement developed.The EC50 and 95 ％ confidence interval of propofol inhibiting gastroscopy-evoked body movement were determined using Probit analysis.Results The EC50 (95 ％ confidence interval) of propofol was 4.2(3.8-4.5),4.1(3.7-4.4) and 2.4(1.8-2.7) μg/ml in Ⅰ,Ⅱ and Ⅲ groups,respectively.There was no significant difference in the EC50 of propofol between group Ⅱ and group Ⅰ.The EC50 of propofol was significantly lower in group Ⅲ than in Ⅰ and Ⅱ groups.Conclusion Age affects propofol-induced analgesia in patients with visceral pain,and the potency of propofol inhibiting visceral pain during gastroscopy in the elderly patients is significantly enhanced as compared with that in the young and middle-aged patients.