The Dose-response Of Dexmedetomidine Combined With Low Dose Of Sufentanil For Postoperative Intravenous Analgesia In Patients Undergoing Video-assisted Thoracoscopic Pulmonary Lobectomy Operation

Objective:The aim of this trial is to investigate the analgesic effect of demedetomidine combined with 0.032 ?g/kg/h sufentanil for patient-controlled intravenous analgesia in patients undergoing video-assisted thoracoscopic pulmonary lobectomy operation and detemine the median effective dose and the 95%effective dose of demedetomidine when combined with0.032 ?g/kg/h sufentanil according to using the modified Dixon up-and-down method and provide clinical evidence for the postoperative analgesia.Methods:Thirty-six patients who were scheduled to undergo for elective video-assisted thoracoscopic pulmonary lobectomy operation under general anesthesia were enrolled in the General Hospital of Southern Theatre Command from January to July 2018.The cases were classified as age 18 to 65 years,the inclusion criteria were American Society of Anesthesiologists(ASA)physical status ? to ?,Body Mass Index(BMI)18 to 25 kg/m2.Written informed consent for the study was obtained from all cases.DEX and 0.032?g/kg/h sufentanil were adopted for patient-controlled intravenous analgesia(PCIA).The dose of DEX for each patient was determined by grade satisfaction,which was according to the previously investigated patient using the modified Dixon up-and-down method.The initial dose of DEX was 0.048 ?g/kg/h,the difference between adjacent patients dose was 0.008 ?g/kg/h.the DEX dose of the current patient was determined by whether the previous patient was satisfied with postoperative analgesic effect,for example,if the previous patient was satisfied with postoperative analgesic effect,the DEX dose of the current patient would decrease by 0.008 ?g/kg/h,otherwise,the DEX dose of the current patient would increase by 0.008 ?g/kg/h.The end point of the trial was:7 upper and lower cycles;DEX<0.008?g/kg/h,7 patients were observed continuously.The patient was evaluated according to the PCIA satisfaction criteria,that was the patient was considered satisfactory if PCIA protocol by DEX dose had been established,which could be summarized as:the pain scores at rest status during postoperative 48 h was ?3,and the pain scores at coughing status was?4,the sedation scores was 2 to 4,times of self-administer patient-controlled analgesia medications was ?3,there was no adjuvant other analgesia throughout the postoperative period,and the patient was considered a satisfaction.Otherwise the patient was considered an unsatisfactory when the patient didn't meet any of the above four indicators.Duration of PCIA,total times and times per hour of self-medications by PCIA pump,postoperative sufentanil,DEX and flurbiprofen axetil consumption were recorded by using the wireless analgesic pump system.Another researcher assessed the VAS(including rest and at coughing status)and Ramsay sedation score at 2 h,4 h,6 h,12 h,24 h,48 h and recorded with patient the heart rate and adverse events of the patients,such as nausea and vomiting,respiratory depression,and bradycardia.Results:A total of 36 patients were assessed for eligibility.Among them,25 patients completed the study,and 12 of the patients were considered satisfactory and the others were not.The dose of dexmedetomidine increased from 1.5?g/kg(0.024?g/kg/h)to 3 ?g/kg(0.048?g/kg/h)along with the probability of the postoperative analgesia from 0 to 100%.The postoperative Ramsay sedation score was between 2 and 4 at 48 h after the operation.The mean visual analogue scale score(VAS)at rest and coughing status of 0 h and 6 h after the operation were all higher than between that of 6 h and 48 h after the operation(Z=-5.128,P=0.000;Z=-6.642,P?0.000),and the same as the Ramsay sedation score(Z?-2.335,P=0.020).The ED50 and ED95(95%confidence interval)of DEX combined with 0.032 ?g/kg/h sufentanil were 0.0344 ?g/kg/h(95%CI 0.0323?0.0382 ?g/kg/h)and 0.0462 ?g/kg/h(95%CI 0.04?0.106 ?g/kg/h),respectively used for postoperative PCIA in patients undergoing video-assisted thoracoscopic pulmonary lobectomy operation.Conclusion:In patients undergoing video-assisted thoracoscopic pulmonary lobectomy operation.the 50%effective dose and 95%effective dose of DEX according to using the modified Dixon up-and-down method combined with 0.032 ?g/kg/h sufentanil for PCIA,were 0.0346 ?g/kg/h and 0.0459?g/kg/h respectively,and at the these doses of DEX and 0.032?g/kg/h sufentanil,the postoperative pain could be effectively controlled.