Predicting Postoperative Delirium and Postoperative Cognitive Decline with Combined Intraoperative Electroencephalogram Monitoring and Cerebral Near-Infrared Spectroscopy in Patients Undergoing Cardiac Interventions

Studies have associated electroencephalogram (EEG) suppression with postoperative delirium (POD) and postoperative cognitive decline (POCD). Otherwise, improving cerebral tissue oxygen saturation (rScO₂) seems beneficial. No study has evaluated the impact of EEG suppression and decreased rScO₂ on the incidence of POD and POCD when the intraoperative management of patients is performed with a depth-of-anesthesia (DOA) monitor and a cerebral oximetry. In this prospective study patients undergoing cardiac interventions were monitored with the NeuroSENSE^® DOA monitor and bilateral cerebral oximetry. An algorithm was used to optimize cerebral oxygenation. EEG suppression was presented as total area under the curve (AUC) of suppression ratio (SR) > 0 s (AUC_EEGSR>0s). Cerebral desaturation was defined as AUC of 25% drop of oximetry values as compared to baseline. POD was evaluated by the chart review method. POCD was defined as a Z-score ≤ 2 based on Mini Mental State Examination at baseline and day 5 or if the patient reported any cognitive decline at 3 and at 6 months postoperatively. Among the 1616 patients, 1513 underwent normothermic surgery and were further analyzed. POD and POCD were respectively evaluated in 1504 and 1350 patients of whom 303 (20%) and 270 (20%) were respectively diagnosed positive. Having experienced high magnitudes of EEG suppression (fourth quartile of AUC_EEGSR>0s) was significantly associated with POD (OR = 2.247; 95% CI = 1.414–3.571; P = 0.001). Low rScO₂ at the end of surgery was statistically associated with POCD (OR = 0.981; 95% CI = 0.965–0.997; P = 0.018). The results of our study show that the degree of intraoperative EEG suppression on one hand, and low rScO₂ at the end of procedure on the other hand, are associated with respectively POD and POCD in patients undergoing cardiac interventions.