Effect of patients age on propofols pharmacodynamics while combining with low dose fentanyl in colonoscopy

Objective To determine the EC50and AAI50of propofol in plasma combined with fentanyl 1μg/kg in colonoscopy of different age group.Methods Ninety patients of ASA statusⅠor Ⅱ undergoing painless colonoscopy were divided into three groups(n=30)by age,which initial effect-site concentrations of propofol were 2.5,2.0,1.5μg/ml.After the target concentrations of plasma and effect-site of propofol were balanced,fentanyl 1.0μg/kg was infused.MAP,HR,SpO2 and AAI were recorded every minute.MAP,HR,SpO2and AAI at the time point before induction(T0),when insert colonoscope(T1),while colonoscope arrived at sigmoid colon(T2)and ileocecal valves(T3),before body movement(T4),after body movement(T5),when colonoscopy finished(T6) were recorded.The EC50and AAI50of propofol combined with fentany were measured.Results The EC50value and its 95% confidence interval of propofol in 3groups were:4.36(4.05-4.66),3.54(3.19-3.88)and 2.79(2.45-3.11)μg/ml.AAI50of these three groups were 22.13(18.54-24.80), 24.95(20.26-28.85),29.72(27.79-33.67)(P0.05).The ratios of reaction to spoken commands were 0,0,20%(P0.05).In three groups the numbers of patients who occurred low blood pressure were 0,2,8(P0.05),and respiratory depression were 1,3,8(P0.05).Conclusion Age was an important element to the pharmacodynamics of propofol while patients received propofol combined with fentanyl 1μg/kg undergoing colonoscopy.