# Early Prediction of Acute Kidney Injury Using the Furosemide Stress Test in Pediatric Cardiac Surgery Patients

## TL;DR

A test using furosemide can predict acute kidney injury in children after heart surgery earlier than current methods.

## Contribution

The furosemide stress test provides earlier prediction of acute kidney injury risk compared to KDIGO criteria in pediatric cardiac surgery patients.

## Key findings

- The furosemide stress test predicted acute kidney injury risk at a median of 5 hours, earlier than KDIGO criteria at 18 hours.
- A reduced urinary response to the furosemide stress test was independently associated with acute kidney injury.

## Abstract

What are the main findings?
The furosemide stress test enabled earlier prediction of acute kidney injury risk than KDIGO criteria after pediatric cardiac surgery.Reduced urinary response to the furosemide stress test was independently associated with acute kidney injury.

The furosemide stress test enabled earlier prediction of acute kidney injury risk than KDIGO criteria after pediatric cardiac surgery.

Reduced urinary response to the furosemide stress test was independently associated with acute kidney injury.

What are the implications of the main findings?
The furosemide stress test may serve as a simple bedside tool for early risk stratification.Early identification of high-risk patients may support closer monitoring and timely nephroprotective interventions.

The furosemide stress test may serve as a simple bedside tool for early risk stratification.

Early identification of high-risk patients may support closer monitoring and timely nephroprotective interventions.

Introduction: 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.