ECMO Cannulation Techniques and Strategies 4

Question 1

In venoarterial ECMO, retrograde flow through the femoral artery can cause what phenomenon in patients with recovering cardiac function?

Accepted Answer

Differential hypoxia (Harlequin syndrome)

Answer

When the recovering heart ejects deoxygenated blood that meets retrograde ECMO flow in the aorta, the upper body may receive hypoxic blood — Harlequin syndrome.

Question 2

What does 'mal-position' of a venous drainage cannula into the hepatic vein most commonly cause?

Accepted Answer

Decreased venous drainage and 'chattering'

Answer

Hepatic vein malposition limits drainage volume, causing circuit chattering and inadequate ECMO support.

Question 3

For a patient with bilateral femoral vessel pathology needing VA-ECMO, which alternative arterial site is most commonly used?

Accepted Answer

Axillary or subclavian artery

Answer

The axillary or subclavian artery is the preferred alternative arterial access when femoral vessels are unusable, allowing antegrade cerebral and upper body perfusion.

Question 4

What is the rationale for placing a 'bridge' or purse-string suture around the arterial cannula insertion site during surgical cannulation?

Accepted Answer

To maintain cannula position and provide hemostasis upon decannulation

Answer

Purse-string sutures secure the cannula, prevent bleeding around it, and facilitate clean hemostasis when the cannula is removed.

Question 5

When using TEE to guide ECMO cannulation, what finding confirms the guidewire is in the correct venous structure rather than the aorta?

Accepted Answer

Guidewire seen in the right atrium or IVC, not the descending aorta

Answer

TEE visualizing the guidewire within the right atrium or IVC confirms venous placement and rules out inadvertent aortic cannulation.

ECMO - Extracorporeal Membrane Oxygenation Practice Test

ECMO - Extracorporeal Membrane Oxygenation Practice Test

ECMO Cannulation Techniques and Strategies 4