Use of cerebral oxygen saturation and hemoglobin concentration to predict acute kidney injury after cardiac surgery

OBJECTIVE: Acute kidney injury (AKI) is a common complication after cardiac surgery and is associated with significant morbidity and mortality. Near infrared spectroscopy (NIRS) is a noninvasive technique for real-time measurement of cerebral tissue oxygenation. The purpose of the present study was to evaluate the correlation of AKI with hemoglobin and regional cerebral oxygen saturation (rScO(2)) measured intraoperatively and postoperatively in patients undergoing cardiac surgery. METHODS: We retrospectively analyzed the prospectively collected data of 45 adult patients with normal renal function who underwent isolated coronary artery bypass grafting (CABG) from January 2014 to May 2014. Kidney injury was assessed according to the Acute Kidney Injury Network criteria. rScO(2) and hemoglobin were measured every hour intraoperatively and for the first 24 hours postoperatively. RESULTS: The hemoglobin concentration and rScO(2) were significantly lower in patients with than without AKI, and no linear trends were observed. No exact cut-off values were obtained. CONCLUSION: This retrospective study shows that a lower rScO(2) and hemoglobin concentration are correlated with AKI after CABG in patients with no peripheral vascular disease or recent myocardial infarction. We suggest that cerebral oximetry alone may predict postoperative AKI well.