What is the most commonly used configuration for integrated Renal Replacement Therapy (RRT) in Extracorporeal Membrane Oxygenation (ECMO)?

Most Common Configuration for Integrated RRT in ECMO

The most common configuration for integrated Renal Replacement Therapy (RRT) in Extracorporeal Membrane Oxygenation (ECMO) is connecting the RRT device directly into the ECMO circuit with inlet and outlet lines positioned after the ECMO pump and before the oxygenator (40% of centers use this integrated approach). 1

Configurations for RRT in ECMO

Integrated Configuration (Most Common)

• RRT device connected directly to the ECMO circuit (40% of centers) 1
• Most frequent connection points:
  • Inlet and outlet lines positioned after the ECMO pump (58% of centers using integrated approach) 1
  • Before the oxygenator for return flow
• Benefits:
  • No need for additional vascular access
  • Increased filter life (mean of 138 hours) 2
  • Improved fluid balance management 2
  • Utilizes existing anticoagulation from the ECMO circuit

Parallel Configuration

• Independent RRT circuit with separate vascular access (30% of centers) 1
• Requires dedicated dialysis catheter
• Benefits:
  • Independent control of RRT parameters
  • No interference with ECMO circuit pressures
  • Can continue if ECMO is discontinued

Technical Considerations for Integrated RRT

Pressure Management

• 60% of practitioners report encountering pressure alarms when using the integrated approach 1
• Positioning after the ECMO pump helps maintain adequate pressure for RRT function
• Pressure monitoring is essential to prevent:
  • Air entrainment
  • Hemolysis
  • Circuit disruption

Anticoagulation

• Unfractionated heparin is the primary anticoagulant used (61% of centers) 1
• Regional citrate anticoagulation is used less frequently (16% of centers) 1
• Anti-Xa monitoring is preferred over aPTT for more accurate therapeutic range management 3

RRT Modality Selection

Continuous vs. Intermittent

• Continuous RRT (CRRT) is overwhelmingly preferred (97% of centers) 1
• Specific modalities:
  • Continuous veno-venous hemofiltration (CVVH): 64% 1
  • Continuous veno-venous hemodiafiltration (CVVHDF): 21% 1
• CRRT is more appropriate for ECMO patients due to their hemodynamic status 4

Indications for RRT in ECMO

• Persistent anuria (83%) 1
• Metabolic acidosis (80%) 1
• Fluid overload (78%) 1
• Hyperkalemia (80%) 1

Practical Implementation Tips

Circuit Integration

1. Connect RRT inlet line after the ECMO centrifugal pump
2. Connect RRT outlet line before the ECMO oxygenator
3. Ensure proper pressure monitoring at connection points
4. Set appropriate alarm parameters on both systems

Monitoring Requirements

• Regular assessment of:
  • Circuit pressures
  • Filter function
  • Fluid balance
  • Electrolyte levels
  • Anticoagulation parameters (anti-Xa levels)

Potential Complications

Integrated Configuration Challenges

• Pressure alarms (60% of centers report this issue) 1
• Risk of air entrainment
• Potential for hemolysis
• Interference with ECMO flow

General RRT-ECMO Complications

• Bleeding (most frequent complication in ECMO patients) 3
• Thrombosis
• Electrolyte imbalances
• Acquired von Willebrand syndrome (occurs in almost all ECMO patients) 4

Conclusion

The integrated configuration with RRT connected after the ECMO pump and before the oxygenator is the most commonly used approach for combining RRT with ECMO. This configuration offers advantages in terms of vascular access preservation and filter longevity, though it requires careful pressure monitoring and management. CRRT is the preferred modality, with CVVH being the most commonly utilized technique.