Renal replacement therapy in the paediatric intensive care unit

Acute kidney injury (AKI) and chronic kidney disease (CKD) are significant concerns in paediatric intensive care units (PICUs), with AKI affecting up to 50% of critically ill children. Renal replacement therapy (RRT) is essential for managing these conditions, with available modalities including intermittent haemodialysis (IHD), continuous renal replacement therapy (CRRT), and peritoneal dialysis (PD). This article defines AKI and CKD based on the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines and outlines the key indications for RRT, such as severe electrolyte abnormalities, fluid overload exceeding 10%, metabolic acidosis and toxin clearance. The fundamental principles of solute clearance in RRT—including diffusion, ultrafiltration, convection, and adsorption—are explained. Additionally, the article reviews essential considerations such as vascular access, anticoagulation strategies and the unique challenges of RRT in neonates and children requiring extracorporeal life support (ECLS). CRRT allows precise and gradual solute and fluid removal, making it ideal for haemodynamically unstable patients. However, it requires an extracorporeal circuit, large-bore vascular access and anticoagulation which can pose challenges, particularly in neonates. In contrast, PD can be initiated quickly via a percutaneous catheter, avoiding the risks associated with central venous access (thrombosis and bleeding). Conversely PD solute and fluid clearance rates are less effective than CRRT, and it is unsuitable for patients with recent abdominal surgery or congenital anomalies. The choice of RRT modality depends on the child's clinical condition, available resources, and institutional expertise. This review highlights the need for individualised RRT strategies to improve outcomes and survival in critically ill children.