# Cardiac surgery-associated acute kidney injury in neonatal Norwood procedure: incidence, risk factors and impact on mortality and outcomes

## TL;DR

This study finds that nearly a third of neonates undergoing the Norwood procedure develop severe acute kidney injury, which significantly increases in-hospital mortality risk.

## Contribution

The study identifies specific risk factors and quantifies the impact of acute kidney injury on outcomes after the Norwood procedure.

## Key findings

- Severe acute kidney injury occurred in 28.2% of neonates after the Norwood procedure.
- Low weight (<2.5 kg) and ECMO support were significant risk factors for acute kidney injury.
- Acute kidney injury was an independent risk factor for in-hospital death but not for long-term survival after discharge.

## Abstract

Acute kidney injury commonly complicates congenital heart surgery with cardiopulmonary bypass, increasing morbidity and mortality. This study aimed to evaluate risk factors for postoperative acute kidney injury and its impact on outcomes after the Norwood procedure.

Neonates undergoing the Norwood procedure from 2001 to 2022 were reviewed. Using modified neonatal Kidney Disease Improving Global Outcomes criteria, we assessed acute kidney injury and analysed its risk factors and impact on survival.

Among the 355 patients who were included, severe acute kidney injury occurred in 100 (28.2%). Risk factors were low weight at Norwood <2.5 kg (odds ratio: 3.0, P = 0.015) and extracorporeal membrane oxygenation support (odds ratio: 2.2, P = 0.013). Shunt type was not identified as a risk (P = 0.317). Acute kidney injury was an independent risk factor for in-hospital death (odds ratio 2.3, P = 0.010) but did not influence survival after hospital discharge (hazard ratio: 1.5, P = 0.230). The hazard ratio for mortality in patients with acute kidney injury compared to patients without acute kidney injury was 2.5, P < 0.001 with a modified Blalock–Taussig–Thomas shunt and 1.9, P = 0.010 with a right ventricle-to-pulmonary artery conduit.

Severe acute kidney injury occurred in approximately a quarter of patients after the Norwood procedure and is an independent risk for in-hospital mortality, both in patients with a modified Blalock–Taussig–Thomas shunt and right ventricle-to-pulmonary artery conduit.

Acute kidney injury (AKI) is a notable complication following congenital heart surgery, with a reported incidence of 9.6–52% and has been strongly associated with postoperative mortality, especially in young patients [1, 2].