Effect of raw electroencephalogram-guided anesthesia administration on postoperative outcomes in elderly patients undergoing abdominal major surgery: a randomized controlled trial.

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 (pEEG) machine to guide the management of anesthetic depth of sedation on postoperative outcome remains controversial. This research was designed to decide whether an anesthetic agent exposure determined by raw electroencephalogram (rEEG) can influence anesthetic management and cause different EEG patterns and affect various patient outcomes. METHODS: A total of 141 participants aged ≥ 60 years undergoing abdominal major surgery were randomized to rEEG-guided anesthesia or routine care group. The rEEG-guided anesthesia group had propofol titrated to keep the rEEG waveform at the C-D sedation depth during surgery, while in the routine care group the anesthetist was masked to the patient's rEEG waveform and guided the anesthetic management only through clinical experience. The primary outcome was the presence of postoperative complications, the secondary outcomes included intraoperative anesthetic management and different EEG patterns. RESULTS: There were no statistically significant differences 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 rEEG-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 routine care group. CONCLUSIONS: In elderly patients undergoing major abdominal surgery, rEEG-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. rEEG-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.

Preoperative prediction of adverse outcome after elective gastrointestinal surgery in older patients: three leading frailty instruments and the American Society of Anesthesiologists physical status.

OBJECTIVE: This study aimed to compare the ability of three frailty assessments to predict adverse outcomes after elective gastrointestinal surgery and analyze how frailty assessments impact the American Society of Anesthesiologists (ASA) risk prediction model. METHODS: Frailty was measured using the FRAIL scale, Fried Phenotype (FP), and Clinical Frailty Scale (CFS), alongside ASA assessments before surgery. Univariate and logistic regression analyses were used to determine the predictive value of each method. The predictive abilities of the tools were assessed by the area under the receiver operating characteristic curves (AUCs) and their 95% confidence intervals (CIs). RESULTS: After adjusting for age and other risk factors, logistic regression analysis revealed significant positive associations between preoperative frailty and postoperative total adverse systemic complications (odds ratios [ORs] [95% CIs]: FRAIL, 1.297 [0.943-1.785]; FP, 1.317 [0.965-1.798]; CFS, 2.046 [1.413-3.015]; P < 0.001). The CFS was the best predictor of any adverse systemic complications (AUC, 0.696; 95% CI, 0.640-0.748). The predictive abilities of the FRAIL scale (AUC, 0.613; 95% CI, 0.555-0.669) and FP (AUC, 0.615; 95% CI, 0.557-0.671) were similar. The CFS and ASA assessment combined (AUC, 0.697; 95% CI, 0.641-0.749) had a statistically improved AUC compared to the ASA assessment alone (AUC, 0.636; 95% CI, 0.578-0.691), illustrating their value for predicting any adverse systemic complications. CONCLUSION: Frailty instruments enhance the accuracy of predicting postoperative outcome in older adults. Clinicians should add frailty assessments before preoperative ASA, particularly the CFS, given its ease of use and clinical feasibility.