Do Heparin-Induced Thrombocytopenia (HIT) antibodies fluctuate with Plasma Exchange (PLEX) therapy in patients on Extracorporeal Membrane Oxygenation (ECMO)?

From the Research

Yes, HIT antibody levels can fluctuate with plasma exchange (PLEX) while a patient is on extracorporeal membrane oxygenation (ECMO). PLEX can temporarily reduce HIT antibody levels by removing the antibodies from circulation, but this reduction is often transient as antibody production continues. For patients with confirmed or suspected HIT on ECMO, the primary management should be immediate discontinuation of all heparin products and transition to non-heparin anticoagulants such as argatroban (starting dose 0.5-1.2 mcg/kg/min, adjusted based on aPTT), bivalirudin (starting dose 0.03-0.05 mg/kg/hr), or fondaparinux (dose based on weight) 1. While PLEX may be used as an adjunctive therapy in severe cases, it should not be relied upon as the sole management strategy. The temporary reduction in antibody levels occurs because PLEX removes the pathogenic anti-PF4/heparin antibodies from circulation, but without addressing the underlying immune response, antibody production will continue and levels may rebound between PLEX sessions 2. Regular monitoring of platelet counts and anticoagulation parameters remains essential throughout ECMO therapy regardless of PLEX use.

Some key considerations in managing HIT on ECMO include:

• Immediate discontinuation of heparin products
• Transition to non-heparin anticoagulants
• Use of PLEX as an adjunctive therapy in severe cases
• Regular monitoring of platelet counts and anticoagulation parameters
• Awareness of the potential for antibody levels to rebound between PLEX sessions

The use of bivalirudin as an alternative to heparin in ECMO patients with HIT has been shown to be effective, with no cases of in-circuit thrombosis reported in a study of 12 patients 3. Argatroban has also been shown to be a potential alternative to heparin in patients requiring ECMO, with comparable bleeding and thromboembolic complication rates to unfractionated heparin 1. However, the choice of anticoagulant should be individualized based on patient-specific factors and the clinical context.