[Neuropsychological dysfunction after cardiac surgery: Cerebral saturation and bispectral index: A longitudinal study]. / Disfunción cognitiva después de cirugía cardiaca: Saturación cerebral e índice biespectral: estudio longitudinal.

ABSTRACT

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.