Validation of intraoperative processed electroencephalography and cerebral oximetry for prediction of postoperative delirium in cardiac surgery: a prospective observational study.

PURPOSE: The introduction of combined cerebral monitoring using near-infrared spectroscopy (NIRS) and processed electroencephalography (pEEG) in cardiac surgery has led to changes in intraoperative management. We aimed to determine the incidence of four intraoperative states defined by the combined use of pEEG and NIRS and whether these states were associated with postoperative complications. METHODS: We conducted a prospective observational single-centre cohort study of adult patients scheduled for cardiac surgery. Bilateral cerebral NIRS and frontal pEEG were continuously recorded during the intraoperative period. The primary endpoint was the incidence of four states: cerebral desaturation and Patient State Index (PSi) < 25 and/or suppression ratio (SR) > 0 (State 1), cerebral desaturation combined with PSi ≥ 50 and SR = 0 (State 2), cerebral desaturation with normal pEEG activity (State 3), and normal cerebral saturation with PSi < 25 and/or SR > 0 (State 4). We developed logistic regression models to predict postoperative delirium and longer time of persistent organ dysfunction (TPOD). RESULTS: Of the 148 patients included in this analysis, 95% spent more than 1 min in State 4. A longer time spent in State 2 (odds ratio [OR], 1.17; 95% confidence interval [CI], 1.00 to 1.38), State 3 (OR, 1.15; 95% CI, 1.03 to 1.29), and State 4 (OR, 1.01; 95% CI, 1.00 to 1.02) increased the odds of developing postoperative delirium. A longer time spent in State 1 (β coefficient, 0.27; 95% CI, 0.07 to 1.60) increased TPOD. CONCLUSIONS: This study suggests that the combined use of NIRS and pEEG monitoring is an innovative approach for predicting delirium and TPOD in patients undergoing cardiac surgery. STUDY REGISTRATION: (ClinicalTrials.gov NCT04643834 ); registered 25 November 2020.