How to manage Continuous Renal Replacement Therapy (CRRT) in patients on Extracorporeal Membrane Oxygenation (ECMO)?

Management of Continuous Renal Replacement Therapy (CRRT) in Patients on Extracorporeal Membrane Oxygenation (ECMO)

For patients requiring both ECMO and renal replacement therapy, CRRT connected to the ECMO circuit is the preferred approach as it provides better hemodynamic stability, improved filter life, and eliminates the need for additional vascular access. 1

Indications for CRRT in ECMO Patients

• Fluid overload is the most common indication for initiating CRRT in ECMO patients 2, 3
• Electrolyte imbalances that cannot be managed with medical therapy 2
• Acute kidney injury with metabolic derangements 1
• Removal of inflammatory mediators in septic patients 1

Connection Methods for CRRT on ECMO

Integrated Approach (Preferred Method)

• Connect CRRT inlet line after the ECMO centrifugal pump and outlet line before the oxygenator 4
• Benefits:
  • Prevents potential hemodynamic disturbances 2
  • Increased clearance of solutes using larger hemofilters 2
  • Improved filter life (mean filter life of approximately 138 hours) 4
  • No need for additional anticoagulation beyond what's used for ECMO 2

Pressure Management

• High ECMO blood flow may create high pressures in CRRT lines 5
• If high pressures occur:
  • First attempt connection between pump and oxygenator 5
  • If pressures remain high, change the connection segment according to standardized protocols 5
• Avoid modifying ECMO blood flow or inhibiting CRRT pressure alarms 5

Anticoagulation Considerations

• No additional anticoagulation is typically needed beyond what is used for ECMO circuit 2
• For patients at high risk of bleeding:
  • CRRT can be performed without additional anticoagulation, though circuit life may be less than 24 hours 6
  • Regional citrate anticoagulation may be considered for patients at high bleeding risk 6
• When using heparin:
  • Monitor activated clotting times (ACT) or systemic partial thromboplastin time (PTT) 6
  • Regularly check platelet counts to monitor for heparin-induced thrombocytopenia 6

Fluid Management

• Dialysate or substitution fluid should contain physiologic concentrations of electrolytes, except in patients with extreme imbalances 6
• Avoid supra-physiologic concentrations of glucose to prevent hyperglycemia 6
• Buffer selection:
  • Either lactate or bicarbonate can be used as buffer in most CRRT patients 6
  • Bicarbonate is preferred in patients with lactic acidosis and/or liver failure 6
• Pre-dilution fluid administration:
  • Enhances achievable ultrafiltration rate 6
  • Useful in patients with frequent filter clotting 6
• Maintain negative fluid balance when possible, especially in patients with acute lung injury 6

Special Considerations for ECMO-CRRT Combination

• For VA-ECMO patients with critical illness, use prophylactic-intensity over therapeutic-intensity anticoagulation if no other indication for higher anticoagulation exists 6
• In neonates or small patients with hemodynamic instability, consider HD or CRRT combined with ECMO as it:
  • Increases the patient's blood volume 6
  • Enables use of a larger cannula 6
  • Facilitates improved hemodynamic control 6

Monitoring and Complications

• Monitor for:
  • Electrolyte imbalances 2
  • Hypothermia 2
  • Bradykinin syndrome 2
  • Hemolysis 1
  • Air entrapment in the circuit 1
• Ensure regular assessment of:
  • Filter performance 6
  • Acid-base balance, especially with citrate anticoagulation 6
  • Fluid balance 6

Outcomes

• Mortality remains high (approximately 80%) in patients requiring both ECMO and CRRT 3
• Factors associated with improved survival:
  • Younger age 3
  • Higher arterial pH 3
  • Left ventricular dysfunction 3
  • Use of VA-ECMO (versus VV-ECMO) 3
• Among survivors, renal recovery occurs in approximately 60% of patients 2, 3