Evaluation of cerebral oxygenation measured by near-infrared spectroscopy in predicting cerebral ischemic injury in patients undergoing cardiac valve replacement under cardiopulmonary bypass

Abstract

Objective To assess the accuracy of cerebral oxygenation measured by near-infrared spectroscopy (NIRS) in predicting ischemic cerebral injury in patients undergoing cardiac valve replacement under cardiopulmonary bypass (CPB). Methods Seventeen patients undergoing cardiac valve replacement under CPB were enrolled in this study. During operation, NIRS was used to measure regional oxygen saturation (rScO2),tissue hemoglobin index ( THI ), changes in concentrations of oxyhemoglobin (△ O2 Hb ), deoxyhemoglobin (△ HHb) and total hemoglobin (△ cHb) of the frontal lobes. The parameters mentioned above and patients whose minimal rScO2 decreased to less than 50% were recorded after entering the operation room, immediately after tracheal intubation, aortic cannulation and superior and inferior vena cava cannula, at the beginning of CPB, at the lowest temperature during CPB, after rewarming to 36.5 ℃, immediately after termination of CPB, and at 1 h after termination of CPB. Blood samples were taken from right internal jugular vein immediately before anesthesia induction, before rewarming, after rewarming to 36.5 C, and at 1, 5 and 20 h after termination of CPB to detect plasma concentrations of S100 protein and neuron-specific enolase (NSE) by ELISA. The cognitive function of patients was assessed 1 day before surgery and 8 days after surgery, and postoperative cognitive dysfunction (POCD) was recorded. Results Nine patients presented with minimal rScO2 less than 50%. Among them,7 patients developed POCD. The plasma concentrations of S100 protein and NSE were significantly higher at 1 and 5 h after termination of CPB in patients whose minimal rScO2 decreased to ≤ 50% than in those whose rScO2 ＞50% .Conclusion Cerebral oxygenation measured by NIRS can accurately predict cerebral ischemic injury in patients undergoing cardiac valve replacement under CPB. Key words: Spectroscopy, near-infrared; Cardiopulmonary bypass; Heart valve prosthesis implantation; Brain ischemia; Monitoring, intraoperative