ECMO ECPR and Special Populations 4 — Questions and Answers
Question 1: Which ECMO configuration is preferred for ECPR in a patient with severe pulmonary hypertension as the cause of cardiac arrest?
- VV-ECMO
- VA-ECMO via femoral-femoral
- VA-ECMO via right atrium to pulmonary artery (PA) (Correct answer)
- Axillary VA-ECMO
Correct answer: VA-ECMO via right atrium to pulmonary artery (PA)
Right atrium to pulmonary artery ECMO directly unloads the right ventricle, which is the failing chamber in severe pulmonary hypertension.
Question 2: In ECPR for pediatric myocarditis, which echocardiographic finding would most support initiating ECMO support?
- EF > 50% with diastolic dysfunction
- EF < 25% with biventricular dilation (Correct answer)
- Moderate mitral regurgitation
- Trivial pericardial effusion
Correct answer: EF < 25% with biventricular dilation
Severely reduced EF below 25% with biventricular dilation in myocarditis indicates cardiogenic shock unresponsive to conventional therapy, supporting ECMO initiation.
Question 3: When performing ECPR on a patient with a known bleeding disorder (hemophilia A), the anticoagulation strategy should be modified to:
- Use no anticoagulation at all
- Replace UFH with bivalirudin and target lower ACT (Correct answer)
- Use double-dose heparin to compensate for factor deficiency
- Switch to warfarin infusion
Correct answer: Replace UFH with bivalirudin and target lower ACT
Bivalirudin avoids heparin resistance and allows direct thrombin inhibition while targeting a lower ACT to reduce bleeding risk in coagulopathic patients.
Question 4: What is the primary reason ECPR outcomes in out-of-hospital cardiac arrest (OHCA) are inferior to in-hospital cardiac arrest (IHCA)?
- Femoral cannulation is harder in the field
- Longer no-flow and low-flow times in OHCA (Correct answer)
- Ambulances lack ECMO equipment
- OHCA patients are older on average
Correct answer: Longer no-flow and low-flow times in OHCA
OHCA results in longer periods of no-flow and low-flow before ECPR initiation, leading to greater ischemic injury compared to IHCA.
Question 5: In a septic patient on VA-ECMO after ECPR, which hemodynamic finding indicates the ECMO is adequately offloading the left ventricle?
- Pulsatile arterial waveform with wide pulse pressure
- Non-pulsatile arterial trace with narrow pulse pressure (Correct answer)
- Rising CVP
- Decreasing ECMO flow alarms
Correct answer: Non-pulsatile arterial trace with narrow pulse pressure
A non-pulsatile, narrow pulse-pressure arterial trace indicates the ECMO is providing most of the cardiac output, minimizing LV work.
Question 6: For ECPR in a patient with a previous coronary artery bypass graft (CABG), which additional intervention is most commonly required alongside ECMO?
- Repeat CABG
- Urgent percutaneous coronary intervention (PCI) of the culprit graft (Correct answer)
- Intra-aortic balloon pump insertion
- Pulmonary embolectomy
Correct answer: Urgent percutaneous coronary intervention (PCI) of the culprit graft
ECPR stabilizes the post-CABG patient hemodynamically while urgent PCI addresses acute graft failure or native vessel occlusion as the arrest etiology.
Question 7: Which blood gas parameter is the primary driver for adjusting sweep gas flow rate on the ECMO circuit during ECPR?
- PaO2
- PaCO2 (Correct answer)
- pH
- Serum bicarbonate
Correct answer: PaCO2
Sweep gas flow rate primarily controls CO2 removal; increasing sweep flow decreases PaCO2 and increasing oxygenation is managed separately via FiO2.
ECMO ECPR and Special Populations 4
Which ECMO configuration is preferred for ECPR in a patient with severe pulmonary hypertension as the cause of cardiac arrest?