ECMO - Extracorporeal Membrane Oxygenation Anticoagulation and Hemostasis Questions and Answers

Question 1

A patient on VA ECMO is managed with a continuous unfractionated heparin (UFH) infusion.
The primary laboratory test that directly measures the functional effect of UFH by quantifying its inhibition of a specific clotting factor is the:

Accepted Answer

Anti-Factor Xa assay

Answer

Activated Clotting Time (ACT)

Answer

Prothrombin Time (PT/INR)

Answer

Activated Partial Thromboplastin Time (aPTT)

Question 2

A 48-year-old patient on VV ECMO for ARDS for the past week develops a sudden drop in platelet count from 160,000/µL to 55,000/µL. Simultaneously, new thrombus is visualized in the oxygenator. This clinical presentation is most suspicious for which of the following complications?

Accepted Answer

Heparin-Induced Thrombocytopenia (HIT)

Answer

Hemodilution from fluid overload

Answer

Disseminated Intravascular Coagulation (DIC)

Answer

Sepsis-induced thrombocytopenia

Question 3

A patient on ECMO develops significant bleeding from the cannulation site. Laboratory results show an aPTT of 120 seconds (goal 60-80s), hemoglobin of 7.0 g/dL, and platelets of 50,000/µL. Which of the following represents the most appropriate sequence of initial interventions?

Accepted Answer

Stop the heparin infusion, transfuse packed red blood cells and platelets.

Answer

Increase ECMO blood flow and administer protamine sulfate.

Answer

Administer fresh frozen plasma (FFP) and request a surgical consult.

Answer

Administer protamine sulfate and then transfuse platelets.

Question 4

Unfractionated heparin achieves its anticoagulant effect in the ECMO circuit primarily through which mechanism of action?

Accepted Answer

Binding to antithrombin, greatly accelerating its inactivation of thrombin and Factor Xa.

Answer

Directly binding to and inhibiting thrombin (Factor IIa).

Answer

Chelating calcium ions, which are essential for the coagulation cascade.

Answer

Preventing the aggregation of platelets on the circuit surface.

Question 5

Which of the following is a direct thrombin inhibitor commonly used as an alternative anticoagulant for patients on ECMO who have confirmed Heparin-Induced Thrombocytopenia (HIT)?

Accepted Answer

Bivalirudin

Answer

Warfarin

Answer

Fondaparinux

Answer

Clopidogrel

Question 6

Beyond the effects of administered anticoagulants, a significant contributor to the acquired coagulopathy in patients on ECMO is:

Accepted Answer

Continuous platelet activation and consumption due to shear stress and contact with circuit surfaces.

Answer

A deficiency of Vitamin K due to poor nutrition.

Answer

Hypothermia from the heat exchanger impairing clotting factor function.

Answer

An increase in circulating antithrombin produced in response to inflammation.