ECMO Veno-Venous (VV) ECMO Management 3 — Questions and Answers
Question 1: A VV ECMO patient has adequate oxygenation but develops progressive hypercapnia despite maximum sweep gas settings. What is the next step?
- Increase native ventilator respiratory rate
- Evaluate for membrane oxygenator clot or plasma leak (Correct answer)
- Convert to VA ECMO
- Administer sodium bicarbonate
Correct answer: Evaluate for membrane oxygenator clot or plasma leak
Plasma leak or thrombus within the oxygenator impairs gas exchange efficiency, causing CO2 retention despite maximal sweep settings.
Question 2: Which anticoagulation monitoring strategy is most commonly used during VV ECMO in adults?
- INR monitoring every 6 hours
- Anti-Xa levels with low-molecular-weight heparin
- Activated partial thromboplastin time (aPTT) with unfractionated heparin (Correct answer)
- Thromboelastography only
Correct answer: Activated partial thromboplastin time (aPTT) with unfractionated heparin
Unfractionated heparin titrated to aPTT (typically 60–80 seconds) is the most widely used anticoagulation strategy in adult VV ECMO.
Question 3: During VV ECMO, a patient develops acute hemolysis (plasma-free hemoglobin >500 mg/dL). What is the FIRST action?
- Administer intravenous haptoglobin
- Inspect the circuit for thrombus, kinks, or high negative inlet pressure (Correct answer)
- Start plasmapheresis
- Increase ECMO flow to reduce shear stress
Correct answer: Inspect the circuit for thrombus, kinks, or high negative inlet pressure
Hemolysis on ECMO is often caused by mechanical factors (thrombus, kinking, cavitation from excessive negative pressure), which must be identified and corrected first.
Question 4: What is the recommended target activated clotting time (ACT) range for most adult VV ECMO patients using unfractionated heparin?
- 120–140 seconds
- 160–200 seconds (Correct answer)
- 220–260 seconds
- 280–320 seconds
Correct answer: 160–200 seconds
Most centers target an ACT of 160–200 seconds on VV ECMO, balancing thrombosis prevention against bleeding risk.
Question 5: A VV ECMO patient requires a blood transfusion. Which hemoglobin threshold is most appropriate for initiating transfusion in a stable patient?
- Hgb < 10 g/dL
- Hgb < 8 g/dL (Correct answer)
- Hgb < 7 g/dL
- Hgb < 12 g/dL
Correct answer: Hgb < 8 g/dL
Most ECMO centers use a hemoglobin threshold of 8 g/dL for transfusion, as higher hemoglobin improves oxygen-carrying capacity on ECMO support.
Question 6: Which complication is unique to the bicaval dual-lumen (Avalon) cannula approach for VV ECMO compared to femoral-jugular configuration?
- Higher recirculation rates
- Cardiac perforation during insertion (Correct answer)
- Inability to prone the patient
- Requirement for systemic anticoagulation
Correct answer: Cardiac perforation during insertion
The stiff bicaval dual-lumen cannula can perforate the right atrium or superior vena cava during insertion, a risk not present with soft femoral-jugular cannulas.
Question 7: A VV ECMO patient on lung-rest ventilation (Vt 2–3 mL/kg, rate 10) suddenly desaturates to 70%. ECMO flows are unchanged at 5 L/min. What is the most important immediate assessment?
- Check for oxygenator failure by measuring post-membrane pO2
- Assess cannula position and circuit for obstruction (Correct answer)
- Immediately increase ventilator FiO2 to 1.0
- Check for pneumothorax with chest X-ray
Correct answer: Assess cannula position and circuit for obstruction
Sudden desaturation with unchanged ECMO flows suggests acute cannula malposition, kinking, or obstruction reducing effective circuit flow.
ECMO Veno-Venous (VV) ECMO Management 3
A VV ECMO patient has adequate oxygenation but develops progressive hypercapnia despite maximum sweep gas settings.
What is the next step?