The lower threshold of hypothermic oxygen delivery to prevent neonatal acute kidney injury

Background Oxygen delivery during cardiopulmonary bypass (CPB) is closely related to postoperative acute kidney injury (AKI). The value of critical indexed oxygen delivery (DO 2 i) is a key indicator to reflect oxygen supply in cardiovascular surgery. However, the target DO 2 i value for neonates undergoing hypothermic CPB remains unclear. Methods One hundred and twenty-six consecutive newborns (≤28 days) undergoing arterial switch operations were retrospectively divided into two groups according to AKI occurrence. Baseline characteristics, intraoperative variables, and clinical outcomes were collected. Multivariate logistic regression analysis and receiver-operating characteristic curve were performed to investigate the association between DO 2 i and AKI. Results Neonates in the no-AKI group ( n = 67) had significantly higher nadir bypass flow and DO 2 i during the hypothermic phase compared with the AKI group ( n = 59). AKI group had remarkably higher incidences of hepatic dysfunction and peritoneal dialysis requirement compared with newborns without AKI. Mixed venous oxygen saturation (SvO 2 ) was comparable between the two groups. Base excess (BE)( P = 0.011) value during the hypothermic phase of the AKI group was higher than the no-AKI group. Multivariate analysis showed that hypothermic DO 2 i was negatively associated with AKI. The cut-off value of hypothermic DO 2 i was 269 mL min −1 m −2 . Conclusions The importance of hypothermic DO 2 i should be highlighted, even when SvO 2 was satisfactory. A lower threshold of DO 2 i > 269 mL min −1 m −2 may help protect neonates from the risk of postoperative AKI. Impact The key message of our article is that the lower threshold of DO 2 i > 269 mL min −1 m −2 may help protect neonates from the risk of AKI after on-pump hypothermic cardiovascular surgery. The critical DO 2 i value for neonates undergoing hypothermic CPB remains unclear, and our study may add new evidence for this matter based on the 6-year experience of our center. In this study, the lowest critical value of DO 2 i in neonatal hypothermic CPB is determined for the first time, which provides a reference for intra-CPB management strategy to improve the postoperative outcomes of newborns.