What is the recommended connection site for dialysis lines in Extracorporeal Membrane Oxygenation (ECMO) support?

Recommended Connection Sites for Dialysis Lines in ECMO

The optimal approach for connecting dialysis lines in ECMO is direct connection to the ECMO circuit rather than using a separate dialysis catheter, as this provides improved filtration efficiency and avoids additional vascular access complications. 1

Connection Options and Considerations

Direct Connection to ECMO Circuit

• Direct connection of continuous renal replacement therapy (CRRT) to the ECMO circuit is the preferred approach, especially in patients with limited vascular access options 2
• The dialysis inlet should be attached to the post-oxygenator Luer-Lock, while the return line should be connected to the pre-oxygenator Luer-Lock, both with a dual lumen pigtail 3
• This configuration maximizes safety by not requiring modifications to the ECMO cannulas or tubing 3
• Direct connection to the ECMO circuit shows superior filtration outcomes with greater rates of decline in serum BUN and better preservation of platelet counts compared to separate dialysis catheter access 1

Pressure Management Considerations

• High pressures in CRRT lines can occur due to high ECMO blood flow, requiring careful management 4
• If high pressures occur in CRRT lines, changing the connection segment between pump and oxygenator can successfully manage these pressures without modifying ECMO settings or inhibiting pressure alarms 4
• A standardized protocol for connection should be followed to maintain CRRT lines in the correct pressure ranges 4

Specific Technical Aspects

• For patients using Quadrox, Nautilus, or Cardiohelp HLS oxygenators, specific connection techniques have been established to ensure safe and effective dialysis 3
• When performing CRRT via the ECMO circuit, the most common technical challenge is unmanageable pressure alarms in RRT devices 2
• The risk of air embolism is the most frequently reported concern with direct connection to the ECMO circuit, though actual incidence is low with proper technique 2

Clinical Outcomes and Efficacy

• RRT performed via the ECMO circuit demonstrates similar efficacy as RRT performed via a dedicated dialysis catheter 5
• Direct connection to the ECMO circuit is associated with improved urea nitrogen ultrafiltration during CRRT compared to using a separate hemodialysis catheter 1
• Patients requiring new RRT while on ECMO support generally have worse outcomes, with longer ECMO support duration and lower survival rates 5

Institutional Considerations

• There is significant heterogeneity in RRT practices for patients on ECMO across institutions globally 2
• Pediatric centers and those with longer ECMO experience are more likely to use direct connection to the ECMO circuit rather than separate dialysis catheters 2
• Protocols and training can help overcome technical difficulties and reluctance to use direct connection methods 2

Pitfalls and Cautions

• Proper management of anticoagulation is crucial when combining RRT and ECMO circuits 6
• The administration of heparin may depend on patient factors (e.g., risk of bleeding), circuit set-up, and institutional protocols 6
• Continuous RRT is generally more appropriate than intermittent hemodialysis for ECMO patients due to their hemodynamic status 6
• Patients on ECMO are very sensitive to fluid overload, so earlier RRT initiation may be required for preventing and managing fluid overload compared to non-ECMO patients 6