EEG-derived Pain Threshold Index-guided Versus Standard Care During Propofol-remifentanil Anesthesia ——A Randomized Controlled Trial

Objective:To investigate whether perioperative anesthesia analgesia guided by PTI can reduce the incidence of therapeutic analgesia rate in PACU（post anesthesia care unit）and level of postoperative pain for gynecological patients.Methods : One hundred and twenty-two females undergoing elective gynecologic surgeries were randomized to receive PTI-guided analgesia（PTI group）or standard clinical care（control group）.Remifentanil administration in the PTI group was guided by PTI value to maintain the value between 40 and 65.Remifentanil administration in the control group was guided by hemodynamic changes.After the surgery,patients were transferred into PACU.In the PACU,NRS scores were queried by PACU nurses who were blind to group assignment,sufentanil 5 ug,as the remedial analgesic,was used to control postoperative acute pain when numeric rating scales（NRS）≥ 4.Sufentanil 5 ug could be administrated at 10 min intervals until NRS<4.The primary outcome of the study was remedial analgesia rate in the PACU.The postoperative pain score,intraoperative remifentanil requirement,inadequate anesthesia events,opioidrelated adverse events and perioperative serum stress hormone concentrations were also compared between the two groups.Results : A total of 151 patients were assessed for eligibility,and 29 patients were excluded.Nine patients did not meet the inclusion criteria,6 patients declined to participate in the trial,2 patients used opioids before surgery,3 patients had central nervous system diseases,3 patients had acute pain before surgery,and 6 patients scheduled to received nerve block anesthesia.Then 122 patients were randomized to the PTI group and the control group,and 61 patients in each group.Two patients did not receive allocated intervention for technical reasons and 1 patient refused to accept the postoperative analgesia plan in the PTI group.One patient lost to follow up with incomplete data and 2 patients refused to accept the postoperative analgesia plan in the control group.There were 58 patients in each group included in final analysis Twentythree of 58 patients（39.7%）in the control group and 8 of 58 patients（13.8%）in the PTI group needed remedial analgesia.In comparison to the PTI group,the relative risk of receiving remedial analgesia was 2.88（95% CI,1.40–5.89,P=0.002）.Postoperative pain scores were higher in the control group compared with the PTI group at each evaluation time point.The relative risk of receiving at least two vasoactive drugs was 3.250（95%CI,1.126–9.380,P=0.018）compared with PTI group.Remifentanil and propofol consumption,opioid-related adverse events such as PONV or time to first flatus were comparable between the two groups.Conclusion:PTI-guided analgesia during gynecological operation resulted in 25.9%less remedial analgesia.However,studies with different PTI threshold and larger more diverse populations should be implemented to further demonstrate the clinical availability of PTI.