Oxygen delivery in pediatric cardiac surgery and its association with acute kidney injury using machine learning.

Objective: Acute kidney injury (AKI) after pediatric cardiac surgery with cardiopulmonary bypass (CPB) is a frequently reported complication. In this study we aimed to determine the oxygen delivery indexed to body surface area (Doi) threshold associated with postoperative AKI in pediatric patients during CPB, and whether it remains clinically important in the context of other known independent risk factors.

Methods: A single-institution, retrospective study, encompassing 396 pediatric patients, who underwent heart surgery between April 2019 and April 2021 was undertaken. Time spent below Doi thresholds were compared to determine the critical value for all stages of AKI occurring within 48 hours of surgery. Doi threshold was then included in a classification analysis with known risk factors including nephrotoxic drug usage, surgical complexity, intraoperative data, comorbidities and ventricular function data, and vasoactive inotrope requirement to determine Doi predictive importance.

Results: Logistic regression models showed cumulative time spent below a Doi value of 350 mL/min/m was associated with AKI. Random forest models, incorporating established risk factors, showed Doi threshold still maintained predictive importance. Patients who developed post-CPB AKI were younger, had longer CPB and ischemic times, and required higher inotrope support postsurgery.

Conclusions: The present data support previous findings that Doi during CPB is an independent risk factor for AKI development in pediatric patients. Furthermore, the data support previous suggestions of a higher threshold value in children compared with that in adults and indicate that adjustments in Doi management might reduce incidence of postoperative AKI in the pediatric cardiac surgery population.