Renal Replacement Therapy During ECMO

Introduction to RRT in ECMO

• Continuous renal replacement therapy (CRRT) is the most appropriate modality for patients undergoing extracorporeal membrane oxygenation (ECMO) due to their hemodynamic instability and sensitivity to fluid overload 1, 2

Indications for RRT

• The indications for RRT in ECMO patients are generally similar to those for other critically ill patients, with fluid overload being particularly important 3, 2
• Earlier initiation of RRT may be required in ECMO patients specifically for preventing and managing fluid overload compared to non-ECMO patients 3, 2

Modality Selection

• The hemodynamic instability typical in ECMO patients makes CRRT physiologically more appropriate than intermittent modalities 1

Circuit Configuration Options

• The decision between integrated vs. parallel configuration should be based on institutional expertise, available technology, and a multidisciplinary approach 3, 2

Anticoagulation Management

• Anticoagulation for RRT circuits when ECMO is already running is not standardized 3, 2
• The choice of anticoagulation depends on patient factors (bleeding risk), circuit setup, and institutional protocols 3, 2
• Citrate anticoagulation during RRT with ECMO is possible but its comparative effectiveness remains untested 3, 2

Dosing and Delivery

• When using CRRT, an effluent volume of 20-25 ml/kg per hour should be delivered 1, 4
• Higher prescription may be required to achieve this target delivery 1, 4

Practical Considerations

• Vascular access for RRT (if using a parallel configuration): first choice is the right jugular vein or femoral vein 4, 5
• Femoral site is inferior in patients with increased body mass 4, 5
• An uncuffed non-tunnelled dialysis catheter of appropriate length and gauge should be used initially 4, 6

Monitoring and Discontinuation

• RRT should be discontinued when kidney function has recovered or when RRT becomes inconsistent with shared care goals 1, 7
• Transition from CRRT to intermittent hemodialysis should be considered when vasopressor support has been stopped, intracranial hypertension has resolved, or positive fluid balance can be controlled by intermittent hemodialysis 1, 7

Caveats and Pitfalls

• The KDIGO guidelines note that more research is needed on optimal approaches to patient selection, techniques, timing/indications, circuit integration, and monitoring for ECLS with concomitant blood-purification techniques 1, 8