Optimum dose of fentanyl for gastroscopy in elderly patients when combined with propofol / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effects of different doses of fentanyl on the median effective target plasma concentration (EC50) of propofol inhibiting body movement evoked by gastroscopy in the elderly patients.Methods Ninety patients of both sexes,aged 75-89 yr,with a body mass index of 19-25 kg/m2,of ASA physical status Ⅱ or Ⅲ,scheduled for elective gastroscopy,were randomly divided into 3 groups (n =30 each)control group (group C) and different doses of fentanyl groups (F0.5 and F1.0 groups).Fentanyl 0.5 and 1.0 μg/kg were injected intravenously in F0.5 and F1.0 groups,respectively.Propofol was then administered by target-controlled infusion.The initial target plasma concentrations (Cps) of propofol were 2.0,1.5 and 1.0 μg/ml in C,F0.5 and F1.0 groups,respectively.Gastroscopy was performed after the target effect-site and plasma concentrations were balanced.Body movement was defined as movement in head or four extremities during gastroscopy.The target Cp of propofol was determined by up-and-down sequential trial.Each time the Cp 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 (CI) of propofol inhibiting gastroscopy-evoked body movement were determined using Probit analysis.Results The EC50 (95 ％ CI) of propofol was 2.24 ng/ml (1.67-2.47 ng/ml) in group C,1.79 (1.55-1.95) μg/ml in group F0.5,and 1.13 (1.08-1.62) μg/ml in group F1.0.There was no significant difference in the EC50 of propofol between F0.5 and C groups.The EC50 of propofol was significantly lower in F1.0 group than in C and F0.5 groups.Conclusion When combined with propofol,fentanyl 1.0 μg/kg is recommended for gastroscopy in the elderly patients.