Risk assessment of cardiac surgery-associated acute kidney injury in children with septal heart defects undergoing cardiopulmonary bypass: a cohort study

BACKGROUND: Cardiac surgery-associated acute kidney injury (CSA-AKI) is a leading adverse event in heart surgery involving cardiopulmonary bypass patients. In most cases, AKI is transient and does not require aggressive intervention such as renal replacement therapy, having no significant impact on treatment outcomes. However, when progressing to clinically significant stages, AKI leads to a complicated postoperative period and affects long-term outcomes. Current diagnostic criteria for CSA-AKI still fail to provide timely identification of children with early signs of renal dysfunction. Therefore, the search for diagnostic and prognostic strategies for risk assessment and prevention of this complication remains highly relevant.

AIM: To identify intraoperative risk factors for AKI in children with septal heart defects following cardiac surgery involving cardiopulmonary bypass and to evaluate their predictive significance.

METHODS: A single-center cohort study included 67 children aged 6 to 36 months who underwent elective septal heart defect total repair. In the postoperative period, AKI diagnostic algorithm was supplemented by assessing concentrations of kidney injury markers (neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), liver-type fatty acid-binding protein (L-FABP), and interleukin-18 (IL-18)) in serum and urine at three time points: 10 minutes after urethral catheter placement, prior to skin sutures, 16 h postoperatively.

RESULTS: Postoperative AKI (KDIGO criteria) developed in 20 children (29.85%). Preoperative risk factors were younger age, lower weight, smaller body surface area, anemia, and ventricular septal defect. The most significant intraoperative risk factors included cardiopulmonary bypass time, aortic cross-clamp time, and weight-adjusted transfusion volume. A transfusion volume threshold of 13.763 ml/kg (AUC 0.719, 95% CI 0.560–0.877, Se 0.75, Sp 0.698, p=0.006) was established as a predictor for AKI risk with optimal efficacy and clinical safety balance.

CONCLUSION: Risk factors for CSA-AKI in children with septal heart defects were identified. The leading contribution of transfusion to AKI was determined, particularly as a modifiable factor and the efficacy and safety of a restrictive transfusion strategy were demonstrated.. Threshold values for the most critical intraoperative risk factors were established, allowing early risk stratification of children into AKI risk groups to guide intensive care strategy immediately post-surgery. Given the small sample size and exclusion of other types of congenital heart defects, further multicentre research is required.