Congenital: Mechanical Circulatory Support| Volume 165, ISSUE 4, P1505-1516, April 2023

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



      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 (Do2i) 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.


      A single-institution, retrospective study, encompassing 396 pediatric patients, who underwent heart surgery between April 2019 and April 2021 was undertaken. Time spent below Do2i thresholds were compared to determine the critical value for all stages of AKI occurring within 48 hours of surgery. Do2i 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 Do2i predictive importance.


      Logistic regression models showed cumulative time spent below a Do2i value of 350 mL/min/m2 was associated with AKI. Random forest models, incorporating established risk factors, showed Do2i 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.


      The present data support previous findings that Do2i 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 Do2i management might reduce incidence of postoperative AKI in the pediatric cardiac surgery population.

      Graphical abstract

      Key Words

      Abbreviations and Acronyms:

      AKI (acute kidney injury), AUC (area under the curve), BSA (body surface area), CPB (cardiopulmonary bypass), Do2i (oxygen delivery indexed to body surface area), KDIGO (Kidney Disease Improving Global Outcomes), LVEF (left ventricular ejection fraction), ROC (receiver operating characteristic), sCr (serum creatinine), VIS (vasoactive inotrope score)
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      Linked Article

      • Commentary: Goal-directed perfusion in pediatric heart surgery
        The Journal of Thoracic and Cardiovascular SurgeryVol. 165Issue 4
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          Acute kidney injury (AKI) is common in infants and children undergoing cardiopulmonary bypass. A previous multi-institutional study has demonstrated a 42% incidence of postbypass AKI within 3 days of pediatric cardiac surgery and an association between AKI and worse outcomes, including prolonged mechanical ventilation, increased length of stay, and a trend toward increased mortality.1 Preventing postbypass AKI is an important objective of the pediatric cardiac surgery team in the overall mission of getting a child safely through open heart surgery.
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