Anticoagulation During ECMO: Challenges and Protocols

1. Rationale for Anticoagulation

  • Prevent thrombosis in patient and ECMO circuit.

  • Balance between clotting risks (systemic emboli, oxygenator clot) and bleeding risks.

2. Anticoagulation Protocols

  • Heparin is standard: bolus at cannulation, then continuous infusion.

  • Targets vary by center:

    • ACT (80–180 sec), aPTT, anti-Xa.

    • Platelets maintained >50–60.

  • Other monitoring: daily clotting profile, fibrinogen, D-dimer.

3. Monitoring Methods

  1. ACT: rapid bedside, but altered by hypothermia/hemodilution.

  2. aPTT: widely used, but influenced by sepsis, liver disease.

  3. Anti-Xa: measures heparin activity, may reveal AT-III deficiency.

4. High Bleeding Risk Patients

  • Reduce anticoagulation targets or withhold completely.

  • Maintain high ECMO flow to reduce stasis/clot risk.

  • Vigilant circuit inspection, D-dimer, platelets, hemoglobin.

  • MDT discussion essential for daily decisions.

5. VV vs VA ECMO

  • VV ECMO: lower systemic clot risk, more flexible anticoagulation.

  • VA ECMO: bypasses lungs, higher risk of systemic emboli → stricter targets.

6. Complications

  • Bleeding: common at cannula sites, GI tract, or intracranial (neurosurgical options limited).

  • Thrombosis: circuit clot, systemic emboli, valve thrombus.

  • Circuit change may be required in clotting/hemolysis.

7. Heparin-Induced Thrombocytopenia (HIT)

  • Suspect with >50% platelet drop, new thrombosis.

  • Confirm with antibody and functional assays.

  • Stop all heparin (including flushes, coated lines).

  • Switch to Argatroban or Bivalirudin; monitor with aPTT.

8. Key Takeaways

  • Anticoagulation in ECMO is a dynamic balance.

  • Bleeding complications are more common, but thrombotic events are often catastrophic.

  • Protocol-driven, MDT-based management is essential to safely support patients.

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