Total Intravenous Anesthesia With Different Concentration Of Propofol And Etomidate In Elderly Patients:A Clinical Trial

objective To evaluate the efficacy of total intravenous anesthesia?TIVA?with propofol and etomidate in elderly patients,and then titrate the concentration of the two drugs under the guidance of bispertral index.Method One hundred and twenty patienst?68male,52female?of American Society of Anesthesiologist physical status I or II,aged 65⁸0yr,scheduled for elective surgery under general anesthesia were studied after written informed consent.The patients were randomly divided into 4 groups?30 patients for each?.Patients in group A were induced?1.5²mg/kg?and maintained?TCI,Ce:2².5?g/ml?with propofol.The three other groups were inducted and maintained with propofol and etomidate to keep BIS within 45⁶0,and the induction was performed using propofol at 2/3 target concentration,1/2 target concentration,and 1/3 target concentration combing with etomidate,respectively.And the maintainances were performed with propofol?the target effect-site concentrations of propofol for group B?C and D were 1.4¹.6?g/ml?1¹.25?g/ml and 0.7⁰.8?g/ml,respectively?and etomidate,to keep BIS within 45⁶0.All the patients got into the operation room,underwent the routine ECG?MAP?SpO₂?BIS monitor.After the intravenous injection of induction drugs,patients were ventilated with pure oxygen for 3mins,then performed tracheal intubation.Patients were mechanically ventilated connected with anesthesia machine immediately,under the mode of volume control ventilation,the parameters were tidal volume at 8 ml/kg,respiratory frequency at 12times/min,absorption ratio?I:E?at 1:2,maintain the P_ETCO₂ between 35 and 45mm Hg.Remifentanyl was infused at the rate of 2⁴ng/ml for the maintenance of analgesia during anesthesia in all groups.MAP and HR were recorded at baseline?T₀?,1 min before tracheal intubation?T₁?,1?3 and 5min after tracheal intubation,respectively?T₂?T₃ and T₄?,they were also recorded at the time of skin incision?T₅?,15 min after skin incision?T₆?and at the end of operation?T₇?.Recovery time,side effects and the supplementary drugs used were also recorded.Results?1?There's no statistically significant difference for the average age?BMI?ASA?operation time,extubation time and the amount of analgesic drugs between the4 groups of patients?P>0.05,table 1?.?2?Compared with C and D groups,the average arterial pressure in group A and group B was significantly lower at T1?P<0.05?,Patients in group D had a significantly higher blood pressure at T2,T3,T4 and T5?P<0.05?;There were no significant differences in blood pressure between the four groups at T6 and T7 points?P>0.05?.At T1,patients in group A had pronounced decrease in heart rate?P<0.05?,Patients in group D experienced tachycardia at T2,which was significantly different from the other three groups?P<0.05,table 3?.?3?The incidence of injection pain was as high as 60%in group A,significantly higher than the other three groups.The incidences of nausea?vomit and myoclonus in group D were higher than that in other three groups?P<0.05,table 5?.?4?Etomidate was infusing in group B,C and D at the rate of 4⁴.5?g·kg^-1·min^-1,6⁸?g·kg^-1·min^-1,8¹1?g·kg^-1·min^-1,respectively.Conclusions The effect of propofol combined with etomidate total intravenous anesthesia in the induction and maintenance of anesthesia in eldly patients is superior to that of propofol alone with a more stable circulation condition,a lower incidence of myoclonus,postoperative nausea and vomit and pain of injection.Among all of this,propofol conducted with propofol at a half of the target effect-site concentration and etomidate at a good rate of 6⁸?g·kg^-1·min^-1is much better.