POSTOPERATIVE NEUROPSYCHOLOGICAL DYSFUNCTION AND CEREBRAL OXYGENATIONDURING CARDIAC-SURGERY

In 41 patients undergoing cardiac operations with extracorporeal circu lation, oxidized cytochrome a,a3 (CtO(2)), deoxygenated hemoglobin (Hb ), and oxygenated hemoglobin (HbO(2)) were measured in brain tissue by near-infrared spectrophotometry (NIRS) intraoperatively. Monitoring a lso included electroencephalography (EEG) and jugular-bulb venous satu ration (SBJO2). All operations were performed using membrane oxygenato rs, moderate hypothermia (26-28 degrees C) and pH alpha-stat managemen t. During cardiopulmonary bypass (CPB) CtO(2) and HbO(2) were reduced, reaching minimal values when rewarming was instituted. At the end of the operation CtO(2) and HbO(2) had regained initial levels. During CP B, arterial PCO2, pH, and temperature were closely related to CtO(2) ( r = 1000, r = -0.964 and 0.929 respectively; p < 0.001, p < 0.001, and p < 0.003 respectively). Neuropsychological testing by the Mini-Menta l-State Test indicated reversible postoperative neuropsychologicai def icits in four patients. These patients had a lower CtO(2) minimum comp ared to those without these deficits (-4.5 mu mol/L v. -0.7 mu mol/L; p = 0.036). These findings support the hypothesis that neuropsychologi cal deficits in patients after cardiac surgery can be caused by intrao perative cerebral hypoxia.