ECMO - Extracorporeal Membrane Oxygenation Veno-Arterial (VA) ECMO Management Questions and Answers — Questions and Answers
Question 1: A patient on peripheral VA ECMO for acute myocardial infarction develops progressive pulmonary edema, a pulse pressure of less than 10 mmHg, and an echocardiogram showing a persistently closed aortic valve. These findings are most indicative of which critical complication?
- Inadequate venous drainage from cannula malposition
- Left ventricular (LV) distension (Correct answer)
- Massive pulmonary embolism
- Aortic dissection from the arterial cannula
Correct answer: Left ventricular (LV) distension
The combination of increased afterload from retrograde flow and a severely stunned myocardium can lead to an inability of the left ventricle to eject blood. This causes the aortic valve to remain closed, leading to a dangerous increase in LV end-diastolic pressure and volume (LV distension), which manifests as pulmonary edema and a non-pulsatile arterial waveform.
Question 2: Which of the following findings is the most reliable indicator of sufficient myocardial recovery to begin a weaning trial from VA ECMO?
- Normalization of the patient's body temperature and white blood cell count
- A chest X-ray showing resolution of pulmonary edema
- Consistent arterial line pulsatility and an LV outflow tract VTI > 10 cm on echocardiography (Correct answer)
- The ability to decrease the sweep gas flow to zero without a rise in PaCO2
Correct answer: Consistent arterial line pulsatility and an LV outflow tract VTI > 10 cm on echocardiography
The primary goal of VA ECMO is cardiac support. The most reliable signs of cardiac recovery are the heart's ability to generate its own effective stroke volume. This is demonstrated by a return of consistent pulsatility on the arterial waveform and objective echocardiographic measures like the left ventricular outflow tract velocity time integral (LVOT VTI), with a value >10 cm indicating readiness to wean.
Question 3: A patient on VA ECMO is receiving a heparin infusion with a target aPTT of 60-80 seconds. The most recent aPTT is 110 seconds, and there is new, significant oozing from the cannula insertion sites. Which is the most appropriate immediate action?
- Decrease or temporarily hold the heparin infusion and re-evaluate (Correct answer)
- Administer fresh frozen plasma (FFP) and cryoprecipitate
- Increase the ECMO blood flow to improve circuit dynamics
- Administer a dose of protamine sulfate to fully reverse the heparin
Correct answer: Decrease or temporarily hold the heparin infusion and re-evaluate
The patient is both clinically bleeding and has a laboratory value indicating excessive anticoagulation (aPTT above the target range). The most direct and appropriate first step is to reduce or stop the source of the anticoagulation, which is the heparin infusion. While blood products may be needed if bleeding is severe, the primary intervention is to correct the supratherapeutic anticoagulation.
Question 4: In a patient on full-flow peripheral VA ECMO for cardiogenic shock, which hemodynamic pressure is most directly and significantly reduced as a consequence of the circuit's function?
- Mean Arterial Pressure (MAP)
- Systemic Vascular Resistance (SVR)
- Central Venous Pressure (CVP)
- Pulmonary Artery (PA) pressure (Correct answer)
Correct answer: Pulmonary Artery (PA) pressure
VA ECMO functions by draining venous blood from the right atrium, bypassing the right ventricle and the pulmonary circulation entirely, and returning oxygenated blood to the aorta. This diversion of blood flow away from the pulmonary circuit causes a significant reduction in pulmonary artery pressures.
Question 5: A patient on femoral VA ECMO for severe respiratory failure with secondary cardiac dysfunction begins to show signs of myocardial recovery. The monitor shows a right radial SpO2 of 88% while the lower extremity SpO2 is 99%. Which is the most appropriate initial intervention to manage this differential hypoxia (Harlequin syndrome)?
- Increase the ECMO pump flow to maximum to override native cardiac output
- Optimize mechanical ventilation by increasing FiO2 and PEEP (Correct answer)
- Administer a negative inotrope to suppress native cardiac function
- Immediately convert the patient to a Veno-Venous (VV) ECMO configuration
Correct answer: Optimize mechanical ventilation by increasing FiO2 and PEEP
Differential hypoxia occurs when a recovering left ventricle ejects poorly oxygenated blood (due to underlying lung disease) preferentially to the upper body and coronaries. The first-line management is to improve the oxygenation of the blood passing through the native lungs by optimizing ventilator settings, such as increasing the FiO2 and PEEP.
Question 6: Which of the following is a standard, non-invasive, continuous monitoring modality used for the early detection of cerebral malperfusion or ischemic events in an adult patient on VA ECMO?
- Near-infrared spectroscopy (NIRS) for cerebral oximetry (Correct answer)
- Daily transcranial Doppler (TCD) ultrasounds
- Serial serum S100B protein measurements
- Continuous electroencephalography (EEG)
Correct answer: Near-infrared spectroscopy (NIRS) for cerebral oximetry
Near-infrared spectroscopy (NIRS) is a non-invasive technology that continuously monitors regional cerebral oxygen saturation (rSO2) at the bedside. It allows for real-time detection of imbalances in cerebral oxygen delivery and consumption, serving as an early warning for potential ischemic or hypoxic brain injury, which is a significant risk for patients on VA ECMO.
ECMO - Extracorporeal Membrane Oxygenation Veno-Arterial (VA) ECMO Management Questions and Answers
A patient on peripheral VA ECMO for acute myocardial infarction develops progressive pulmonary edema, a pulse pressure of less than 10 mmHg, and an echocardiogram showing a persistently closed aortic valve.
These findings are most indicative of which critical complication?