Clinical Research Of The Dose Of Etomidate And Propofol Inducing Electroencephalography Burst Suppression

The term burst suppression describes an electroencephalographic（EEG）pattern consisting of a continuous alternation between high-voltage slow waves（occasionally sharp waves）and depressed（or suppressed）electrographic activity,it is a sign of severe inhibition of electrical activity in the cerebral cortex.BS occurs frequently in clinical anesthesia.PART1 Effects of sufentanil of median effective dose of etomidate inducing electroencephalography burst suppression in surgical patientsObjectiveTo determine whether sufentanil could reduce the median effective dose(ED₅₀)of etomidate inducing BS in surgical patients.MethodsAmerican Society of Anesthesiologists physical statusⅠorⅡpatients of both sexes,with body mass index of 19²7 kg/m2,undergoing elective operation under general anesthesia,were enrolled in the study.They were divided into two groups according to the age,non-elderly group（group N）:18⁶4 yr and elderly group（group E）:65⁸4 yr,then were randomly allocated to receive etomidate with sufentanil（group NS,group ES）or normal saline（group NN,group EN）.In group NS and group ES,0.015mg/kg cisatracurium and 0.30ug/kg sufentanil was injected intravenously,and3.5 minutes later,etomidate was intravenously pumped,group NN and group EN received normal saline of the same quantity instead of sufentanil and the other procedures were as same as group NS and group ES,the ED50 of etomidate was determined by Dixon’s up-and-down method,starting at 0.30mg/kg in group NS and group NN,0.20mg/kg in group ES and group EN with 0.05mg/kg steps size,the subsequent dose of etomidate administered were determined by the presence or absence of burst suppression in the previous patient in the same group.We recorded the change of BP,HR,bispectral index,burst suppression ratio（BSR）within 6 minutes.BS was defined as at least one episode of BSR value>10%lasting more than 1 minute.The ED₅₀ and 95%confidence interval of etomidate inducing EEG BS were calculated using probit method in four groups.ResultsThe ED₅₀（95%CI）of etomidate inducing BS in group NN was0.70mg/kg（0.65⁰.77mg/kg）,in group NS was 0.63mg/kg（0.58⁰.69mg/kg）,in group EN was 0.59mg/kg（0.56⁰.61mg/kg）,in group ES was 0.52mg/kg（0.50⁰.55mg/kg）.Compared with group NN,the ED₅₀ of etomidate in group NS was decreased（P<0.05）;compared with group EN,the ED₅₀ of etomidate in group ES was decreased（P<0.05）;compared with group NN,the ED₅₀ of etomidate in group EN was decreased（P<0.05）;compared with group NS,the ED₅₀ of etomidate in group ES was decreased（P<0.05）.ConclusionsSufentanil can reduce the ED₅₀ of etomidate inducing BS in surgical patients.Compared with non-elderly patients,the ED₅₀ of etomidate inducing BS in elderly patients is decreased.PART2 The median effective dose of propofol for the mix of propofol and etomidate inducing electroencephalography burst suppression in surgical paientsObjectiveTo determine the median effective dose(ED₅₀)of propofol for the mix of propofol and etomidate inducing BS in surgical patients.MethodsIn a prospective,randomized,double-blind study,ASA physical statusⅠorⅡpatients of both sexes with BMI of 19²7 kg/m2undergoing elective operation were allocated to the non-elderly group（18⁶4 yr）or the elderly group（65⁸4 yr）according to the age.0.30ug/kg sufentanil was injected intravenously,and 3.5minutes later,the mix of propofol and etomidate was intravenously pumped.We recorded the change of BP,HR,bispectral index,burst suppression ratio（BSR）within6 minutes.BS was defined as at least one episode of BSR value>10%lasting more than 1 minute.The ED50 in the two groups of propofol was determined by Dixon’s up and down method,starting at 0.75mg/kg with 1.2 steps size.The subsequent dose of propofol administered were determined by the presence or absence of BS in the previous patient in the same group.The ED₅₀ and 95%confidence interval of propofol inducing EEG BS were calculated using probit method.ResultsThe ED₅₀（95%CI）of propofol inducing BS in the non-elderly group was 1.39mg/kg（1.22¹.58）mg/kg and in the elderly group was 1.10 mg/kg（0.97¹.32）mg/kg.Compared with group N,the ED₅₀ of propofol in group E was decreased（P<0.05）.ConclusionsThe ED₅₀（95%CI）of propofol inducing BS in the non-elderly group was 1.39mg/kg（1.22¹.58）mg/kg and in the elderly group was 1.10 mg/kg（0.97¹.32）mg/kg.Compared with non-elderly patients,the ED₅₀ of propofol for the mix of propofol and etomidate inducing BS in elderly patients is decreased.