CES ECMO Physiology & Gas Exchange

Question 1

In peripheral veno-arterial (VA) ECMO, the venous drainage cannula is typically placed in which vessel?

Accepted Answer

Femoral vein

Answer

In peripheral VA-ECMO, blood is drained from the femoral vein and returned via the femoral artery, bypassing the heart and lungs.

Question 2

The primary function of increasing sweep gas flow in a membrane oxygenator is to:

Accepted Answer

Remove carbon dioxide from the blood

Answer

Sweep gas flow across the membrane lung primarily drives CO2 removal by creating a diffusion gradient that eliminates CO2 from the blood.

Question 3

In veno-venous (VV) ECMO, the primary physiologic goal is to:

Accepted Answer

Support gas exchange while maintaining native cardiac function

Answer

VV-ECMO supports oxygenation and CO2 removal in patients with respiratory failure while relying on the native heart to maintain cardiac output.

Question 4

Recirculation in VV-ECMO refers to which of the following phenomena?

Accepted Answer

Oxygenated return blood being immediately re-drained into the circuit before reaching the patient

Answer

Recirculation occurs when oxygenated blood exiting the return cannula is pulled back into the drainage cannula, reducing effective ECMO support.

Question 5

In a patient on VA-ECMO, mixed venous oxygen saturation (SvO2) primarily reflects:

Accepted Answer

The balance between systemic oxygen delivery and consumption

Answer

SvO2 represents the oxygen remaining after tissues extract what they need; a low SvO2 signals that DO2 is insufficient relative to VO2.

CES - Certified ECMO Specialist Practice Test