Correlation between cerebral oxygenation and neurocognitive function after cardiac surgery

Brain hypoperfusion is a major contributor to neurocognitive impairment following cardiac surgery. To mitigate this risk, target intraoperative values include a mean arterial blood pressure of 50–80 mmHg and cerebral oxygen saturation levels between 60% and 80%. This study aims to examine the relationship between cerebral oxygenation levels, as measured by near-infrared spectroscopy (NIRS) during cardiac surgery, and postoperative neurocognitive outcomes. This prospective clinical study included 59 patients who underwent open-heart surgery. Patients were categorized into four groups based on intraoperative NIRS values: NIRS-1: Bilateral saturation >60%; NIRS-2: Unilateral saturation >60%; NIRS-3: Saturation between 40% and 60%; NIRS-4: At least one value <40%. Postoperative cognitive function was assessed using the Mini-Mental State Examination (MMSE). The study population included 59 patients (34 male, 25 female) with a mean age of 63.8±7.6 years. In the NIRS-1 and NIRS-2 groups (28 patients), the mean MMSE score was 24.6, with 10 patients exhibiting mild cognitive impairment. The NIRS-4 group included eight patients, two of whom developed neurological dysfunction; the remaining patients in this group had a mean MMSE score of 13.6. A statistically significant difference was observed between gender distribution and the NIRS-1 and NIRS-3 groups (p=0.02). Our findings indicate that lower intraoperative NIRS values (40%–60% or <40%) and prolonged cardiopulmonary bypass are associated with a higher incidence of postoperative neurocognitive dysfunction. Correspondingly, MMSE scores were lower in these patients, highlighting the potential impact of intraoperative cerebral oxygenation on cognitive outcomes.