The ED₅₀ Of Remiffentanil In Inhibiting Body Movement Response During Induced Abortion With Propofol

Objective:To evaluate the median effective dose(ED₅₀)and 95%CI of remifentanil in combination with propofol in the induced abortion by using sequential method and bliss method respectively.Methods:A total of 87 patients（aged 18-50 years,with BMI of18.0-25.0/²,ASA I-II）undergoing painless abortion were enrolled in this study from July to December 2019,1%Propofol was used in induce anesthesia in all patients with induced abortion,so as to achieve the appropriate sedation depth,that is,the Modified Ramsay Sedation Scale（RSS）reached 6 to 7.Then remifentanil was slowly injected（Before vaginal disinfection）to assist analgesia.The two experimental methods used were as follows:Frist,Sequential method:The initial concentration of remifentanil is 0.277μg/kg,The dose range was 0.1-1.0μg/kg,and the ratio of adjacent doses was 1.29.The patient’s body movement response within 5 minutes after the operation beginning was taken as the index of analgesic effectiveness.The remifentanil dose of the next patient was determined by the intraoperative body movement of the previous patient.If there is a body movement reaction within 5 minutes after the operation,it was considered effective,the dose would be increased in the next case;otherwise,the dose would be reduced.The experiment was stopped when the study progressed to 10 valid and invalid crosses.The Dixon-Massey calculation formula was used to calculate ED₅₀and its 95%CI.Second,Bliss method:50 patients were randomly stratified divided into 5 groups（n=10）.The concentrations of remifentanil were 0.215μg/kg（group A）,0.277μg/kg（group B）,0.357μg/kg（Group C）,0.461μg/kg（Group D）and 0.594μg/kg（Group E）.The anesthesia induction method is the same as the sequential method.The number of patients without body movement within 5 minutes after the operation beginning,the total amount of propofol and vital signs at three time points（T1 before anesthesia induction,T2during dilatation,T3 10 minutes after the operation）were recorded.Record the wake-up time,orientation recovery time,hospital leaving time,visual analogue scale（VAS）10 and 30 minutes after operation,and the incidence of postoperative adverse reactions（nausea,vomiting and dizziness）.Probit regression analysis was used to calculate ED₅₀and 95%CI of remifentanil.Results:A total of 37 patients,aged 21-41 years,with BMI of 18.0-24.5/²,ASA I-II,were enrolled in the sequential method.The ED₅₀of remifentanil was 0.28μg/kg,95%CI was 0.223-0.335μg/kg.The estimated ED₅₀of remifentanil for intraoperative analgesia was0.35μg/kg（95%CI 0.212-0.457μg/kg）and ED₉₅was 0.74μg/kg（95%CI0.576-1.559μg/kg）.SPO₂at T2 was lower than that at T1 in each group,Among them,SPO₂of E group at T2 point decreased significantly than that of A group（P<0.05）.No hypotension or sinus bradycardia occurred in all patients.There were 6 cases of respiratory depression during the operation,which were improved after the jaw was lifted and oxygen flow increasing.The time of leaving hospital in group A,B was longer than that in group C（P<0.05）.There were no significant differences in the total dose of propofol,wake-up time,orientation recovery time,postoperative 10 min VAS,30 min VAS score among the five groups.Conclusion:When combined with propofol,the ED₅₀of remifentanil in inhibiting body movement during abortion were 0.28μg/kg（95%CI was0.223-0.335μg/kg）,and 0.35μg/kg(95%CI 0.212-0.457μg/kg,respectively.Through clinical practice,it is believed that remifentanil at0.28μg/kg～0.35μg/kg combined with propofol is safe and reliable for painless abortion under standard anesthesia monitoring.All patients wake up quickly and have good postoperative recovery quality.