Intraoperative renal and cerebral tissue oxygen saturation measurements to predict postoperative acute kidney injury in pediatric cardiac surgery: a prospective observational study

Purpose Pediatric patients undergoing cardiac surgery are at risk of developing postoperative acute kidney injury (AKI). We hypothesized that a reduction in intraoperative renal (SrO 2 ) or cerebral (ScO 2 ) tissue oxygen saturation is associated with postoperative AKI. Methods We conducted a prospective observational study including fifty pediatric patients with non-cyanotic heart disease undergoing elective surgical repair with cardiopulmonary bypass. Intraoperative SrO 2 and ScO 2 were monitored using near-infrared spectroscopy (O3 ® Regional Oximetry). Relative decreases of 10% and 20% from baseline SrO 2 and ScO 2 were analysed, calculating the total time below the threshold, area under the threshold, and time-weighted average. The primary outcome was the association between intraoperative SrO 2 and ScO 2 decreases, and the occurrence of postoperative AKI defined with the ‘Kidney Disease: Improving Global Outcomes’ criteria. Secondary outcomes included the association between other known or potential risk factors for AKI and postoperative AKI. Results The incidence of postoperative AKI was 18.4%. There was no association between the duration and extent of intraoperative reductions of SrO 2 and ScO 2 below 10% and 20% from baseline, and postoperative AKI (e.g., area under the threshold for ScO 2 decreases below 10%: 36.8 [11.8 to 419.9] % min in patients with AKI vs. 9.6 [0.6 to 92.8] % min in patients without AKI, P = 0.117). Preoperative serum creatinine, body mass index, intraoperative hypotension, and blood lactate were associated with postoperative AKI. Conclusion A decrease in intraoperative renal or cerebral tissue oxygen saturation was not associated with postoperative AKI in pediatric patients undergoing surgery for non-cyanotic congenital heart disease.