ECMO Physiology & Gas Exchange Flashcards

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

Answer: Femoral vein

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

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

Answer: Remove carbon dioxide from the blood

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

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

Answer: Support gas exchange while maintaining native cardiac function

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

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

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

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

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

Answer: The balance between systemic oxygen delivery and consumption

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

Oxygen delivery (DO2) in an ECMO patient is calculated using which of the following components?

Answer: Cardiac output multiplied by arterial oxygen content (CaO2)

DO2 = Cardiac output (native + ECMO) × CaO2; CaO2 includes hemoglobin-bound and dissolved oxygen.

In VA-ECMO, increasing pump flow rate will primarily have which effect?

Answer: Decrease venous return to the native heart, reducing native cardiac preload

Higher VA-ECMO flows drain more blood from the venous side, reducing preload to the right heart and diminishing native cardiac output.