ECMO Veno-Arterial (VA) ECMO Management 3 — Questions and Answers
Question 1: During VA ECMO, which strategy is used to vent the left ventricle percutaneously without additional surgery?
- Intra-aortic balloon pump insertion
- Transaortic catheter placed via the femoral artery
- Impella device placed across the aortic valve (Correct answer)
- Percutaneous pulmonary artery balloon occlusion
Correct answer: Impella device placed across the aortic valve
An Impella device positioned across the aortic valve provides active LV unloading and venting, reducing distension during VA ECMO support.
Question 2: What is the primary reason VA ECMO increases myocardial oxygen demand compared to VV ECMO?
- Higher oxygenator membrane surface area
- Increased LV afterload from retrograde aortic flow (Correct answer)
- Higher heparin requirements causing inflammation
- Faster pump speeds generating heat
Correct answer: Increased LV afterload from retrograde aortic flow
Retrograde ECMO flow into the aorta increases LV afterload, forcing the recovering heart to work harder and increasing myocardial oxygen consumption.
Question 3: A VA ECMO circuit suddenly shows decreased flow with increasing inlet pressure. The most likely cause is:
- Air in the arterial line
- Venous cannula malposition or hypovolemia (Correct answer)
- Oxygenator thrombosis
- Increased systemic vascular resistance
Correct answer: Venous cannula malposition or hypovolemia
Decreased flow with high negative inlet (suction) pressure indicates inadequate venous drainage, most often from cannula malposition or hypovolemia causing suction events.
Question 4: In cardiogenic shock treated with VA ECMO, which laboratory value most directly reflects tissue oxygen delivery adequacy?
- Arterial pH
- Mixed venous oxygen saturation (SvO2)
- Serum lactate trend (Correct answer)
- Hemoglobin concentration
Correct answer: Serum lactate trend
Serial lactate trending is the most direct indicator of whether tissue oxygen delivery is adequate, with falling lactate confirming successful resuscitation.
Question 5: What is the recommended ECMO blood flow rate (as % of cardiac output) to achieve adequate systemic support in cardiogenic shock?
- 10–20%
- 20–40%
- 60–80% (Correct answer)
- 100%
Correct answer: 60–80%
VA ECMO typically targets 60–80% of the patient's estimated cardiac output (approximately 3–4 L/min) to provide adequate systemic perfusion.
Question 6: Which complication is specifically associated with VA ECMO but NOT VV ECMO?
- Oxygenator failure
- Systemic arterial embolism (Correct answer)
- Circuit clot formation
- Hemolysis from pump
Correct answer: Systemic arterial embolism
Systemic arterial embolism is unique to VA ECMO because air or thrombus entering the arterial circuit is delivered directly into the systemic circulation, unlike VV ECMO.
Question 7: A patient being weaned from VA ECMO has ECMO flow reduced to 1 L/min. Which hemodynamic parameter should be monitored most closely?
- Central venous pressure
- Pulse oximetry waveform
- Arterial pulse pressure and mean arterial pressure (Correct answer)
- Core body temperature
Correct answer: Arterial pulse pressure and mean arterial pressure
During weaning trials, arterial pulse pressure (indicating native stroke volume) and MAP are the primary indicators of whether the heart can sustain adequate perfusion without full ECMO support.
ECMO Veno-Arterial (VA) ECMO Management 3
During VA ECMO, which strategy is used to vent the left ventricle percutaneously without additional surgery?