ECMO Anticoagulation and Hemostasis 4

Question 1

Which ECMO configuration carries the highest risk of arterial thromboembolism due to retrograde aortic blood flow interactions?

Accepted Answer

VA-ECMO with femoral artery return cannula

Answer

Femoral VA-ECMO creates a watershed zone where oxygenated retrograde ECMO flow meets anterograde native cardiac output, increasing thrombus and watershed infarction risk.

Question 2

In a patient on ECMO with suspected HIT, a 4T score of 6 is calculated. What is the appropriate next step?

Accepted Answer

Stop heparin immediately and start a direct thrombin inhibitor while confirmatory testing is sent

Answer

A 4T score of 6 represents high probability of HIT; heparin must be stopped immediately and an alternative anticoagulant started while awaiting confirmatory anti-PF4 antibody results.

Question 3

What is the primary reason aPTT is considered an inferior monitoring tool compared to anti-Xa for heparin dosing in ECMO?

Accepted Answer

aPTT is affected by many non-heparin variables including factor deficiencies and acute phase reactants

Answer

aPTT is influenced by multiple variables common in ECMO patients — factor consumption, lupus anticoagulant, elevated factor VIII — making it an unreliable surrogate for heparin effect.

Question 4

A patient on VV-ECMO for ARDS requires urgent surgical tracheostomy. How should anticoagulation be managed perioperatively?

Accepted Answer

Hold heparin 4–6 hours before and restart 2–4 hours post-procedure

Answer

For surgical procedures on ECMO, heparin is typically held 4–6 hours pre-procedure and restarted 2–4 hours post-procedure once hemostasis is achieved, balancing thrombotic and bleeding risk.

Question 5

What is the clinical significance of detecting a rising D-dimer trend in an ECMO patient whose ACT is therapeutic?

Accepted Answer

It may indicate developing circuit thrombosis or DIC requiring circuit inspection

Answer

Rising D-dimer despite therapeutic ACT suggests active thrombus formation and fibrinolysis within the circuit or patient vasculature, warranting urgent circuit inspection.

ECMO - Extracorporeal Membrane Oxygenation Practice Test

ECMO - Extracorporeal Membrane Oxygenation Practice Test

ECMO Anticoagulation and Hemostasis 4