Cerebral Oxygen Desaturation Predicts Cognitive Decline and Longer Hospital Stay After Cardiac Surgery

Background Previous studies have reported an 11% to 75% incidence of postoperative cognitive decline among cardiac surgery patients. The INVOS Cerebral Oximeter (Somanetics Corp, Troy, MI) is a Food and Drug Administration approved device that measures regional cerebral oxygen (rSo 2 ) saturation. The purpose of this study is to examine whether decreased rSo 2 predicts cognitive decline and prolonged hospital stay after coronary artery bypass grafting (CABG). Methods The rSo 2 was monitored intraoperatively in a cohort of primary CABG patients. Patients were prospectively randomized to a blinded control group or an unblinded intervention group. Cognitive function was assessed preoperatively, postoperatively, and at 3 months using a battery of standardized neurocognitive tests. Cognitive decline was defined as a decrease of one standard deviation or more in performance on at least one neurocognitive measure. The rSo 2 desaturation score was calculated by multiplying rSo 2 below 50% by time (seconds). Multivariate logistic regression models were used to assess cognitive decline and hospital stay. The change in cognitive performance was also assessed using a multivariate linear regression model. Results Patients with rSo 2 desaturation score greater than 3,000%-second had a significantly higher risk of early postoperative cognitive decline [ p = 0.024]. Patients with rSo 2 desaturation score greater than 3,000%-second also had a near threefold increased risk of prolonged hospital stay (>6 days) [ p = 0.007]. Conclusions Intraoperative cerebral oxygen desaturation is significantly associated with an increased risk of cognitive decline and prolonged hospital stay after CABG.