Correlation among decreased regional cerebral oxygen saturation, blood levels of brain injury biomarkers, and cognitive disorder

OBJECTIVE: This study was performed to investigate the correlation among decreased regional cerebral oxygen saturation (rSO(2)), blood levels of brain injury biomarkers, and postoperative cognitive disorder (POCD) after cardiac surgery with cardiopulmonary bypass (CPB). METHODS: This prospective observational study included 59 patients undergoing coronary artery bypass graft surgery with CPB. All patients underwent neuropsychological tests (Mini Mental State Evaluation, Rey Auditory Verbal Learning Test, digit span test, digit symbol substitution test, and Schulte table) the day before and 10 days after the surgery. The blood levels of two brain injury biomarkers, neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP), were measured before and 1 day after the surgery. RESULTS: The rSO(2) decreased during surgery in 21 (35%) patients. POCD was detected in 22 (37%) patients. After the surgery, no significant changes in the GFAP blood level occurred in any patients. No significant correlations were found among the decreased rSO(2), increased NSE blood level, and rate of POCD. CONCLUSION: These results suggest that a decrease in rSO(2) during cardiac surgery is not necessarily related to the development of POCD or an increased blood level of the brain injury biomarker NSE.