Variability in Oxygen Delivery Index during cardiopulmonary bypass is associated with acute kidney injury in neonates undergoing cardiac surgery

Background Oxygen delivery Index (DO2i) on cardiopulmonary bypass (CPB) is a well-established predictor of post-operative renal dysfunction after adult cardiac surgery. Limited data exists on DO2i in pediatric cardiac surgery. This study evaluates the association between DO2i and post-operative renal dysfunction in a neonatal cardiac surgery population. Methods Single center retrospective chart review for patients who underwent an initial congenital heart surgery requiring CPB at <30 days from July 2021 to July 2025. Intraoperative DO2i values were continuously collected during CPB. Post-operative outcomes were extracted from electronic medical records. Acute kidney injury (AKI) is defined as a serum creatinine increase of ≥0.3 mg/dl from baseline within 48 hours of surgery or an increase of 50% from baseline within 48 hours of surgery based on the pediatric Kidney Disease Improving Global Outcomes (KDIGO) standards. Univariate and multivariable logistic regression models were utilized. The final model included DO2i variables and any variable with a p<0.25 in univariate analysis. Results A total of 224 patients were identified with 99(44.2%) female, a median age at surgery of 7.3[IQR:5.3-11.4] days, and a median weight of 3.3[IQR:3.0-3.6] kg. Fifty-five (24.6%) were STAT 5 cases, median bypass duration was 161[IQR:123-207] minutes and median average arterial temperature was 31.8[IQR:28.3-38.9]C. Median average DO2i was 399.2[IQR:356.5-443.7] ml/min/m2 and median standard deviation of DO2i was 94.1[IQR:72.1-118.2] ml/min/m2. A total of 77 (34.3%) had an AKI. In univariate analysis neither average DO2i(OR: 1.000(95%CI:0.996-1.005), p=0.883) nor DO2i standard deviation(OR:1.008(95%CI:0.999-1.016), p=0.066) were significantly associated with AKI. In the final adjusted model, average DO2i remained non-significant(OR:1.001(95%CI: 0.996-1.006), p=0.752) and DO2i standard deviation became significant(OR:1.014(95%CI: 1.002-1.025), p=0.020). (Table) Conclusion After adjustment, increased standard deviation of DO2i was associated with increased risk of post-operative AKI in neonates undergoing cardiac surgery. Additional work is needed to further characterize the impact of oxygen delivery characteristics on post-operative outcomes.