[Neuropsychological dysfunction after cardiac surgery: Cerebral saturation and bispectral index: A longitudinal study].

BACKGROUND Neuropsychological dysfunction is a major cause of morbidity and mortality after cardiac surgery. AIM To evaluate if intraoperative cerebral desaturation and depth of anesthesia measured by bispectral index are related to postoperative cognitive dysfunction in cardiac surgery. MATERIAL AND METHODS Prospective study in patients undergoing elective cardiac surgery with cardiopulmonary bypass. A comprehensive neuropsychological assessment was applied preoperatively and 3 months after surgery. Postoperative dysfunction was defined as a decrease of at least one standard deviation in two or more neuropsychological tests. Cerebral oxygenation and bispectral index were continuously recorded and corrected throughout surgery. Cerebral oxygenation data were analyzed by the mean value and at three thresholds: 50%, 40% and < 25% of the basal value. Bispectral index was analyzed at threshold of 45. RESULTS Fifty-six patients were initially enrolled and 48 completed the study. Nine of these (18.8 %) presented postoperative cognitive dysfunction. Mean cerebral saturation and bispectral index data were not different among the patients with or without cognitive dysfunction. There was no association between cerebral desaturation and bispectral index with changes in neurocognitive tests or with length of stay in the intensive care unit. A significant but weak correlation was found between baseline Ray-neurocognitive score and intensive care unit stay (rho = -0.46; P = 0.001). CONCLUSIONS We did not find a significant association between cerebral desaturation and depth of anesthesia with postoperative cognitive decline in this population of patients.