ECMO - Extracorporeal Membrane Oxygenation ECMO Physiology and Principles Questions and Answers

Question 1

In a patient on Veno-Venous (VV) ECMO for severe ARDS, the primary determinant of carbon dioxide removal (decarboxylation) is the:

Accepted Answer

Sweep gas flow rate (L/min)

Answer

ECMO blood flow rate (L/min)

Answer

Fraction of delivered oxygen (FdO2) in the circuit

Answer

Patient's hemoglobin concentration

Question 2

A patient is on peripheral Veno-Arterial (VA) ECMO via the femoral vessels for cardiogenic shock. The patient begins to show signs of myocardial recovery, and the team notes that the SpO2 on the right hand is consistently lower than the SpO2 on the foot. This phenomenon is best described as:

Accepted Answer

Harlequin Syndrome (Differential Hypoxia)

Answer

Recirculation

Answer

Oxygenator failure

Answer

Systemic inflammatory response

Question 3

Which of the following physiological changes is an expected effect of initiating Veno-Arterial (VA) ECMO in a patient with profound cardiogenic shock?

Accepted Answer

Increased left ventricular afterload

Answer

Increased left ventricular preload

Answer

Decreased mean arterial pressure

Answer

Decreased pulmonary artery pressure

Question 4

A patient on Veno-Venous (VV) ECMO for respiratory failure develops worsening hypoxemia despite a high FdO2 of 1.0. The pre-oxygenator saturation (venous blood entering the circuit) is noted to be rising, and the post-oxygenator saturation remains high. Which of the following is the most likely cause?

Accepted Answer

Significant recirculation

Answer

Inadequate anticoagulation

Answer

High patient cardiac output

Answer

Membrane lung thrombosis

Question 5

In managing a patient on VV ECMO, increasing the ECMO blood flow rate (Qb) will have the most direct and significant impact on which of the following parameters?

Accepted Answer

Patient's arterial oxygenation (PaO2)

Answer

Patient's arterial pH

Answer

Patient's PaCO2

Answer

Circuit recirculation fraction

Question 6

Which statement accurately describes a fundamental physiological difference between Veno-Venous (VV) and Veno-Arterial (VA) ECMO?

Accepted Answer

VA ECMO bypasses the pulmonary circulation, while VV ECMO does not.

Answer

VV ECMO provides direct hemodynamic support, while VA ECMO only supports gas exchange.

Answer

VV ECMO requires central cannulation, while VA ECMO can only be done peripherally.

Answer

VA ECMO is used for isolated respiratory failure, while VV ECMO is used for cardiogenic shock.