document 020 : ECMO VA vs. VV
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content:
Cannulas are inserted to permit drainage of deoxygenated blood from a large vein or veins. The blood is circulated through an artificial lung for oxygenation and returned to the body through a major artery such as the aorta.
VA (venoarterial)
- Cannulas placed in right internal jugular vein and right common carotid artery.
- Advantages:
- Provides both respiratory and cardiac support.
- Positive pressure ventilation can be reduced to minimal parameters.
- Disadvantages:
- Emboli (air or particulate) can be infused into the arterial circulation.
- Permanent carotid artery ligation
- > potential for left ventricular cardiac stun
VV (venovenous)
- Only the venous system is used for both drainage and return of blood.
- Double cannula is placed right internal jugular into right atrium (holes must be properly placed—typically echo guided).
- Advantages:
- No ligation of carotid
- Oxygenated blood flows through pulm circulation-may help reverse pulm htn.
- Emboli less likely to result in severe compromise.
- Disadvantages:
- Can only be used with adequate cardiac function because systemic flow is dependent on cardiac output. (may have to be converted to VA if cardiac stun ensues).
- Recirculation of oxygenated blood can occur. (rather than flow through the tricuspid valve)
- Higher vent support may be required.
- Vasopressor support may be needed
- Increased risk for right ventricular cardiac stun.