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

Femoral artery

Answer

Subclavian vein

Answer

Internal jugular vein

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

Increase blood flow through the circuit

Answer

Control the temperature of circulating blood

Answer

Prevent thrombus formation in the membrane

Question 3

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

Accepted Answer

Support gas exchange while maintaining native cardiac function

Answer

Provide mechanical cardiac support

Answer

Reduce pulmonary vascular resistance directly

Answer

Increase systemic vascular resistance

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

Blood flowing backward through the pump head

Answer

Air entrainment on the venous side of the circuit

Answer

Clot formation causing retrograde flow in the oxygenator

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

The function of the membrane oxygenator

Answer

The patient's native pulmonary function

Answer

The degree of systemic anticoagulation

Question 6

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

Accepted Answer

Cardiac output multiplied by arterial oxygen content (CaO2)

Answer

ECMO flow rate multiplied by sweep gas FiO2

Answer

Pump speed (RPM) multiplied by hemoglobin concentration

Answer

Post-oxygenator PO2 multiplied by blood flow rate

Question 7

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

Accepted Answer

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

Answer

Increase arterial PaCO2 by reducing membrane dwell time

Answer

Increase afterload on the left ventricle

Answer

Increase mixed venous oxygen saturation by reducing recirculation