Application Of Up-and-down And Continual Reassessment Methods To Estimate BIS50 And BIS95 For Lack Of Recall Of Music During Post-operative Recovery Period

Background:Patients may remain aware not only during surgical operations but also during recovery from anaesthesia.Bispectral index(BIS)-guided anaesthesia reduces the risk of intraoperative awareness.The recommended BIS range to prevent the patient from awareness during surgery is 40–60,but the level necessary to prevent awareness during the recovery period from endotracheal anaesthesia is unclear.We used the up-and-down method and the continual reassessment method to estimate BIS50 and BIS95(50% and 95% patients had desired responses,respectively)for lack of recollection of music in the post-anesthesia care unit(PACU).Methods:A prospective clinical trial was performed on adult patients undergoing abdominal surgery with endotracheal general anaesthesia.They listened to randomly selected songs at different levels of BIS at PACU.This sequential clinical trial consisted of two stages,up-and-down sequential followed by continual reassessment.Probit analysis of theup-and-down sequential portion of the study was used to estimate the BIS50 and a priori probabilities of lack of recall of music of 0.5,0.75,0.90,0.95,0.98 and 0.99.In the second stage,the continual reassessment method was used to estimate the BIS95 for lack of recall of music.Results:Sixty-nine patients completed the trial(n = 29 for the first stage and n= 40 for the second stage).BIS50(95% CI)for lack of recall of music was estimated to be 84(80.9–87.6)and BIS95(95% CI)was estimated to be 79(95% CI,78.8–79.1).Conclusions:During the recovery from endotracheal anaesthesia,the BIS50 and BIS95 for lack of recall of music were found to be 84 and 79,respectively.These results suggest an optimal approach to manage the depth of anaesthesia to prevent awareness during the post-operative recovery period.Registry information:This study was registered in the Chinese Clinical Trial Registry(ID:ChiCTR-OPN-17012097).The registration information can be found on the following website: http://www.chictr.org.cn/showproj.aspx?proj=20262...