Early prediction of acute kidney injury using the furosemide stress test in pediatric cardiac surgery patients

Abstract

We evaluated the furosemide stress test as an early predictor of acute kidney injury following pediatric cardiac surgery, in comparison with the Kidney Disease: Improving Global Outcomes (KDIGO) diagnostic criteria. Materials and Methods: This single-centre retrospective study evaluated pediatric patients who underwent open cardiac surgery between March 2019 and September 2024 at Koç University Hospital. The evaluation included pre-operative, intra-operative, and postoperative variables; a two-hour assessment of urinary response to the first dose of furosemide upon admission to the intensive care unit; and rates of acute kidney injury. Results: A total of 254 patients were included, and 53 patients (20.8%) developed acute kidney injury according to KDIGO criteria. The mean furosemide stress test response was 9.86 ± 5.84 (median: 9.10) mL/kg/h in the non-AKI group and was significantly lower in the AKI group at 5.07 ± 4.73 (median: 3.33) mL/kg/h (p < 0.001). Receiver operating characteristic analysis demonstrated that the furosemide stress test has discriminative ability to predict acute kidney injury. The cut-off value was 6.104 mL/kg/h, and patients with a lower response had a higher risk of developing acute kidney injury. Sensitivity and specificity were 69.8% and 69.7%, respectively. Acute kidney injury was diagnosed at a median of 18 h using KDIGO criteria, whereas the furosemide stress test enabled earlier prediction of acute kidney injury risk at a median of 5 h. Conclusions: The findings support the potential clinical utility of the furosemide stress test in the early stages after pediatric cardiac surgery to predict acute kidney injury.