| Background EEG monitoring techniques are receiving increasing clinical attention as a common method of reflecting the depth of sedation in the perioperative period.The influence of depth of sedation indices such as the bispectral index(BIS)generated by the processed electroencephalogram(p EEG)machine to guide the management of anesthetic depth of sedation on postoperative outcome remains controversial.Previous studies from our group have shown that raw electroencephalogram(r EEG)-based visual analysis of EEG monitoring and modulation can be used to guide anesthesia in patients undergoing cardiac surgery and help reduce the incidence of POD,but its value in noncardiac surgery in the elderly is unclear.The aim of this study was to investigate the effect of raw EEG-based anesthetic sedation depth management on postoperative outcome in elderly patients undergoing major abdominal surgery compared with usual anesthetic management,with the aim of providing a clinical reference.Methods This was a randomized,controlled clinical trial in which patients aged ≥ 60 years,of either sex,undergoing elective major abdominal surgery were randomly divided into the r EEG-guided anesthesia management group and the usual care group.REEG-guided anesthesia group maintained a constant slow wave/δ oscillation on the EEG spectrum by adjusting the propofol infusion rate to keep the r EEG waveform at the C-D sedation depth during surgery,while in the usual care group the anesthetist was masked to the patient’s r EEG waveform and guided the anesthetic management only through clinical experience.Intraoperative mean arterial pressure(MAP)movement was maintained within ± 20% of the basal value in both groups.Preoperative general information was recorded;intraoperative vital signs,r EEG data,anesthetic drug use and resuscitation were recorded;postoperative complications during hospitalization and allcause mortality within 30 days after surgery were assessed.The primary outcome was the occurrence of postoperative complications,and secondary outcomes included the intraoperative dose of anesthetic drugs and EEG parameters.Results A total of 141 patients undergoing elective major abdominal surgery were included in this study.After excluding related cases,a total of 125 patients were included for data analysis(61 in the r EEG-guided group and 64 in the usual care group).There were no statistically significant differences in preoperative general data including age,sex ratio,and preoperative comorbidities between the two groups(P > 0.05);no statistically significant differences in intraoperative anesthesia and operating time,anesthetic drug dosage,and anesthesia recovery time,etc.The duration of burst suppression(BS)was shorter in the r EEG-guided group than in the usual care group(P < 0.05);no significant differences were found in the occurrence of postoperative respiratory,circulatory,neurological and gastrointestinal complications.Further EEG analysis revealed that lower frontal alpha power was significantly associated with a higher incidence of POD,and that r EEG-guidance not only reduced the duration of deeper anesthesia in patients with lower frontal alpha power,but also allowed patients with higher frontal alpha power to receive deeper and more appropriate depths of anesthesia than in the usual care group.Conclusions In elderly patients undergoing major abdominal surgery,r EEG-guided anesthesia did not reduce the incidence of postoperative respiratory,circulatory,neurological and gastrointestinal complications.REEG-guided anesthesia management reduced the duration of intraoperative BS in patients and the duration of over-deep sedation in patients with lower frontal alpha waves under anesthesia,and there was a strong association between lower frontal alpha power under anesthesia and the development of POD.r EEG-guided anesthesia may improve the prognosis of patients with vulnerable brains by improving the early identification of frail elderly patients and providing them with a more effective individualized anesthetic managements. |
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