ECMO Circuit Components and Management 5

Question 1

During ECMO circuit change-out, the most critical step to prevent air embolism is:

Accepted Answer

Ensuring all tubing connections are primed and bubble-free before unclamping

Answer

Any air introduced during circuit change-out can cause fatal embolism, so meticulous priming and de-airing of all new components is mandatory before reconnecting to the patient.

Question 2

Hemolysis in an ECMO circuit is best monitored by measuring:

Accepted Answer

Plasma-free hemoglobin and lactate dehydrogenase (LDH) levels

Answer

Plasma-free hemoglobin and LDH are direct markers of red cell destruction, indicating mechanical trauma from pump cavitation, high negative pressures, or circuit thrombosis.

Question 3

Inlet pressure (P-in) monitoring on the venous drainage limb of ECMO is important because extreme negative pressures can cause:

Accepted Answer

Hemolysis, cavitation, and venous collapse around the cannula tip

Answer

Excessive negative suction pressures on the venous drainage side cause red cell destruction, gas bubble formation (cavitation), and vessel wall collapse at the cannula.

Question 4

Which anticoagulant is used as an alternative to heparin in patients with heparin-induced thrombocytopenia (HIT) on ECMO?

Accepted Answer

Bivalirudin (a direct thrombin inhibitor)

Answer

Bivalirudin is the preferred anticoagulant alternative for ECMO patients with HIT because it directly inhibits thrombin and has a short half-life allowing rapid titration.

Question 5

The ECMO specialist notes that the post-membrane PO2 has dropped from 450 to 180 mmHg despite unchanged sweep gas settings. The most likely explanation is:

Accepted Answer

Oxygenator clotting reducing functional membrane surface area

Answer

Clot accumulation within the fiber bundle reduces available gas exchange surface, causing a fall in post-oxygenator PO2 even with maintained sweep gas flow.

ECMO - Extracorporeal Membrane Oxygenation Practice Test

ECMO - Extracorporeal Membrane Oxygenation Practice Test

ECMO Circuit Components and Management 5