Neonatal Renal Replacement Therapy

Key Points

• RRT is a life-saving intervention for critically ill neonates with acute kidney injury (AKI) or inborn errors of metabolism
• Timing of initiation is crucial for outcomes
• Technical challenges exist due to small patient size and vascular access limitations
• Requires specialized expertise and equipment

Introduction

Renal replacement therapy in neonates represents a complex intervention requiring careful consideration of patient size, hemodynamic stability, and underlying pathology. The decision to initiate RRT must balance the potential benefits against the significant risks inherent to these procedures in this vulnerable population.

Absolute Indications

• Severe metabolic acidosis (pH < 7.1) refractory to medical management
• Severe hyperkalemia (K+ > 7 mEq/L) or rapidly rising potassium
• Fluid overload > 10-15% of body weight
• Uremia with clinical symptoms
• Inborn errors of metabolism causing severe hyperammonemia

Relative Indications

• Oliguria/anuria > 24 hours
• Progressive azotemia
• Nutrition support limitation due to fluid restrictions
• Refractory electrolyte imbalances

Peritoneal Dialysis (PD)

Preferred initial modality in most neonates due to:

• Technical simplicity
• No need for anticoagulation
• Better hemodynamic tolerance
• Continuous gentle fluid removal

Continuous Renal Replacement Therapy (CRRT)

Indicated when PD is contraindicated or ineffective:

• CVVH (Continuous Veno-Venous Hemofiltration)
• CVVHD (Continuous Veno-Venous Hemodialysis)
• CVVHDF (Continuous Veno-Venous Hemodiafiltration)

CRRT Considerations

• Circuit size: Priming volume should be <10% of patient's blood volume
• Blood flow rates: Typically 5-15 mL/kg/min
• Anticoagulation: Usually heparin-based or regional citrate

Common Complications

Peritoneal Dialysis Complications

• Catheter-related
  • Leak
  • Obstruction
  • Migration
  • Exit-site infection
• Peritonitis
• Hemodynamic instability
• Respiratory compromise due to increased intra-abdominal pressure

CRRT Complications

• Vascular access problems
• Circuit clotting
• Bleeding due to anticoagulation
• Hypothermia
• Electrolyte imbalances
• Hemodynamic instability

Management Principles

Pre-RRT Assessment

• Detailed clinical examination
• Laboratory evaluation
  • Complete blood count
  • Coagulation profile
  • Comprehensive metabolic panel
  • Blood gas analysis
• Imaging studies as indicated

Monitoring During RRT

• Continuous vital sign monitoring
• Fluid balance assessment every 1-2 hours
• Regular blood gas and electrolyte monitoring
• Circuit pressures and parameters
• Temperature monitoring

Prescription Considerations

• Individualized ultrafiltration goals
• Dialysate/replacement fluid composition
• Anticoagulation protocol
• Nutrition support