Optimal Dose-effect Relationship Of Remifentanil Combined With Propofol Target-controlled Infusion In Elderly Hypertensive Patients During Maintenance Of General Anesthesia

Objective:The aim of this study was to investigate the optimal dose-effect relationship of remifentanil with different effect-site concentrations by target-controlled infusion（TCI）under BIS monitoring in elderly hypertensive patients undergoing transurethral laser resection of prostate（TURP）under general anesthesia.Methods:60elderly patients with hypertension ASA II～III undergoing TURP under general anesthesia were selected and divided into 4 groups by random number table method:Group R₂,R₃,R₄and R₅,15 patients in each group,the effect-site concentration of remifentanil was set as:2、3、4、5ng/m L。At the beginning of anesthesia induction,the effect-site concentration of propofol was increased from 2ug/ml to 1ug/ml until BIS was stable at 45±5.Cisatracurium 0.15mg/kg was intravenously injected,and tracheal intubation was performed after 5min oxygen inhalation.The effect-site concentration of propofol was adjusted to keep BIS at 50±5 according to the fluctuation of BIS during the maintenance period.If the fluctuation of blood pressure and heart rate exceeded 30%of the basal value during the operation,propofol was discontinued 5min before the end of the operation,and remifentanil was discontinued 1min before the end of the operation.MAP,HR,PI at baseline,20min,40min,1 h after intubation,and at exit were recorded.The effect-site concentrations of propofol and remifentanil were recorded when BIS was stable at50±5.The best compound concentration was determined by statistical analysis.Results:There were significant differences in mean arterial pressure（MAP）,heart rate（HR）and perfusion index（PI）among the four groups（P<0.05）.Compared with T1,MAP values at T2,T3 and T4 were significantly decreased in all four groups.The decrease of MAP in R₂and R₅groups was significantly higher than that in R₃and R₄groups,and the decrease of MAP in R₂group was the most obvious.The PI of R₄and R₅groups were higher than that of R₂and R₃groups.HR in R₂group increased slightly,HR in R₃group decreased least,and HR in R₅group decreased most significantly（P<0.05）.There was a negative correlation between propofol and remifentanil during anesthesia maintenance.There was significant difference in the incidence of hemodynamic adverse reactions among the groups（P<0.05）.The hemodynamic was the most stable in R₃group,with 20%hypotension and 10%sinus bradycardia.Conclusion:When the target-controlled effect-site concentration of remifentanil 3ng/ml combined with the effect-site concentration of propofol 3.5±0.6μg/ml was used in the maintenance of general anesthesia in elderly hypertensive patients,the hemodynamics of the patients were stable.During the maintenance period of general anesthesia in elderly patients with hypertension,appropriate increase of remifentanil concentration can effectively reduce the dosage of propofol,and the BIS value remains relatively stable.PI can be used as a convenient and reliable pain monitoring method in elderly hypertensive patients with TCI target-controlled remifentanil combined with propofol infusion.