ECMO Veno-Arterial (VA) ECMO Management 5 — Questions and Answers
Question 1: Which pharmacological agent is most commonly used to reduce LV afterload and facilitate LV ejection in VA ECMO patients?
- Norepinephrine
- Vasopressin
- Nitroprusside or milrinone (Correct answer)
- Phenylephrine
Correct answer: Nitroprusside or milrinone
Vasodilators like nitroprusside or inodilators like milrinone reduce systemic vascular resistance, helping the LV eject against the increased afterload imposed by VA ECMO.
Question 2: When should anticoagulation be withheld or minimized during VA ECMO?
- During routine daily care
- In the presence of active life-threatening hemorrhage (Correct answer)
- When lactate levels are elevated
- During echocardiographic assessment
Correct answer: In the presence of active life-threatening hemorrhage
Active life-threatening hemorrhage may require temporarily reducing or withholding anticoagulation despite the risk of circuit thrombosis.
Question 3: Which factor most directly determines the maximum blood flow achievable in a VA ECMO circuit?
- Oxygenator membrane surface area
- Venous cannula size and venous drainage (Correct answer)
- Arterial cannula pressure rating
- Patient's native cardiac output
Correct answer: Venous cannula size and venous drainage
Venous drainage is the limiting factor in ECMO flow; the venous cannula size and position determine how much blood can be returned to the pump.
Question 4: In post-cardiotomy cardiogenic shock, VA ECMO is initiated. After 72 hours, there is no evidence of cardiac recovery. What is the next appropriate step?
- Continue VA ECMO indefinitely until recovery
- Reduce ECMO flow and accept lower MAP
- Evaluate for advanced therapies: LVAD or cardiac transplantation (Correct answer)
- Convert to VV ECMO for lung recovery
Correct answer: Evaluate for advanced therapies: LVAD or cardiac transplantation
Absence of cardiac recovery at 72–96 hours should prompt evaluation for durable mechanical circulatory support (LVAD) or cardiac transplantation as bridge therapies.
Question 5: What is the effect of increasing ECMO pump speed (RPM) in a patient with severe aortic regurgitation on VA ECMO?
- It reduces LV volume overload by increasing forward flow
- It worsens LV distension by increasing retrograde regurgitant volume (Correct answer)
- It has no hemodynamic effect on the native ventricle
- It reduces pulmonary artery pressure directly
Correct answer: It worsens LV distension by increasing retrograde regurgitant volume
In severe aortic regurgitation, higher ECMO flow increases retrograde pressure in the aortic root, worsening the degree of regurgitation and LV volume overload.
Question 6: A VA ECMO patient develops white discoloration of the toes on the cannulated leg despite a functioning distal perfusion cannula. The next step is:
- Increase heparin dose to therapeutic PTT
- Reassess DPC position and flow with Doppler ultrasound (Correct answer)
- Remove the arterial cannula immediately
- Apply topical vasodilators to the foot
Correct answer: Reassess DPC position and flow with Doppler ultrasound
Persistent limb ischemia despite a DPC requires Doppler assessment to confirm cannula patency and adequate flow, as the DPC may be kinked, clotted, or malpositioned.
Question 7: What is the primary goal of parallel venoarterial-venous (VAV) ECMO configuration?
- Increase total circuit flow above single-pump capacity
- Treat both respiratory failure and cardiogenic shock simultaneously (Correct answer)
- Allow LV venting through the venous return limb
- Reduce circuit priming volume in pediatric patients
Correct answer: Treat both respiratory failure and cardiogenic shock simultaneously
VAV ECMO simultaneously addresses biventricular failure and severe respiratory failure by delivering oxygenated blood to both the pulmonary and systemic circulations.
ECMO Veno-Arterial (VA) ECMO Management 5
Which pharmacological agent is most commonly used to reduce LV afterload and facilitate LV ejection in VA ECMO patients?