Prediction of cognitive dysfunction and patients' outcome following valvular heart surgery and the role of cerebral oximetry

Objective: Postoperative cognitive dysfunction (POCD) commonly develops after cardiac surgery affecting patients' outcome. Cerebral oximetry noninvasively measures regional cerebral oxygen saturation (rSO₂) and significant correlation has been reported between intraoperative cerebral desaturation and POCD, as well as patients' outcome following coronary artery bypass grafting. However, evidence is limited in valvular heart surgery (VHS). We investigated the relationship of intraoperative rSO₂ values with POCD and length of postoperative hospitalization in patients undergoing VHS. Methods: One hundred patients undergoing elective VHS were enrolled. Neurocognitive evaluation was performed with Mini-Mental State Examination, Trail-Making Test (Part A), and Grooved Pegboard Test at 1 day before and 7th day after surgery. During surgery, rSO₂ was continuously monitored and the incidence and duration of decrease in rSO₂ values for five consecutive minutes were recorded as follows; (1) decrease in absolute rSO₂ values to less than 50%, (2) 40%, and (3) a 20% decrease compared to baseline value. Results: Twenty-three patients (23%) demonstrated POCD. We could not observe any significant differences in either the incidence or duration of decrease in rSO₂ values between patients with and without POCD. Low education level and higher baseline temperature had significant correlation with POCD. Patients with cerebral desaturation required significantly longer postoperative hospitalization. Conclusion: In patients undergoing VHS, POCD could not be predicted with cerebral oximetry. However, patients with intraoperative cerebral desaturation required significantly longer postoperative hospitalization and cerebral oximetry appears to be promising in terms of monitoring the brain as the index organ for systemic perfusion and improving patients' outcome.