ECMO Cheat Sheet 2026

The 30 highest-yield ECMO facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. In VA-ECMO, retrograde aortic flow from a femoral arterial cannula creates a 'mixing zone.' What determines where this zone is located? → Balance between native cardiac output and ECMO pump flow
2. What does 'mal-position' of a venous drainage cannula into the hepatic vein most commonly cause? → Decreased venous drainage and 'chattering'
3. What is the primary mechanism by which ECMO causes hemolysis? → Shear stress from the centrifugal or roller pump mechanism
4. A patient on VA-ECMO develops a new pulseless rhythm on telemetry but arterial line shows a stable waveform. What is the most likely explanation? → Ventricular fibrillation with full ECMO support
5. Flow monitoring via ultrasonic flow probes on the ECMO circuit measures flow based on: → Transit-time ultrasound detecting changes in sound wave travel time caused by moving blood
6. What is the most significant risk of advancing the venous drainage cannula too far into the right ventricle during ECMO cannulation? → Ventricular arrhythmias and potential perforation
7. A patient on ECMO has a platelet count that drops from 180,000 to 30,000 over 48 hours. The MOST likely cause in this clinical context is: → ECMO circuit consumption
8. What does the 'clot amplitude at 10 minutes' (CA10) on ROTEM primarily reflect in ECMO patients? → Platelet function and fibrin polymerization
9. During gradual flow reduction in VV-ECMO weaning, which laboratory value should be monitored most closely to detect inadequate native lung CO2 clearance? → Arterial PaCO2
10. The primary goal of ECMO support in pediatric myocarditis is: → Bridging to myocardial recovery or cardiac transplantation
11. During VV ECMO, a patient develops severe hypokalemia (K+ 2.8 mEq/L). Which factor unique to ECMO contributes to electrolyte depletion? → Continuous renal replacement therapy often co-administered
12. In pediatric VA-ECMO, central cannulation via the right atrium and aorta is often preferred over peripheral cannulation because: → Central cannulation avoids limb ischemia and allows higher flows in small patients
13. What is the recommended target activated clotting time (ACT) range for most adult VV ECMO patients using unfractionated heparin? → 160–200 seconds
14. In VA-ECMO, how does left ventricular (LV) afterload change compared to a patient without ECMO support? → LV afterload increases because retrograde ECMO flow opposes ventricular ejection
15. When transitioning from peripheral VA-ECMO to central cannulation, what is the main hemodynamic advantage? → Elimination of differential hypoxia by delivering oxygenated blood centrally
16. Polymethylpentene (PMP) hollow fiber oxygenators have largely replaced silicone membrane oxygenators in ECMO because PMP offers: → Lower resistance to blood flow and reduced plasma leakage
17. In neonatal ECMO, the right internal jugular vein is the preferred venous access site primarily because: → It provides the most direct path to the right atrium
18. When weaning VV-ECMO, the sweep gas flow is progressively reduced. What physiologic effect does reducing sweep gas primarily alter? → Carbon dioxide removal by the oxygenator
19. Why is systemic anticoagulation typically administered before the first dilator is placed during ECMO cannulation? → To prevent clot formation on instrumentation and in the cannula
20. Which test best differentiates heparin resistance from disseminated intravascular coagulation (DIC) in ECMO patients? → Anti-Xa level with concurrent AT III assay
21. Which cannulation strategy is preferred when ECPR is performed during active CPR in a pediatric patient under 10 kg? → Neck (carotid-jugular) cannulation
22. A neonate on ECPR has an arterial PaO2 of 400 mmHg. What is the most appropriate adjustment? → Reduce FiO2 in the sweep gas blender
23. Which anticoagulation monitoring strategy is most commonly used during VV ECMO in adults? → Activated partial thromboplastin time (aPTT) with unfractionated heparin
24. Which cannula configuration is used in veno-arterial-venous (VAV) ECMO? → One venous drainage, one arterial return, and one additional venous return cannula
25. Which hemodynamic goal during a VA-ECMO weaning trial best predicts successful decannulation? → Maintaining MAP > 65 mmHg on low-dose vasopressors with ECMO flow ≤ 1.5 L/min
26. In a patient on peripheral VA-ECMO, which monitoring site best reflects cerebral oxygenation? → Right radial arterial blood gas (pre-mixing zone)
27. When monitoring anticoagulation with anti-Xa levels during ECMO, what is the generally accepted therapeutic range? → 0.3–0.7 IU/mL
28. In VA-ECMO, retrograde aortic flow from a femoral arterial return cannula most significantly affects: → Left ventricular afterload
29. Which ECMO parameter directly reflects the efficiency of the membrane oxygenator's gas exchange capacity? → Post-oxygenator PaO2 and PaCO2
30. How does the 'oxygen transfer capacity' of an ECMO oxygenator change over time during prolonged use? → It decreases due to plasma leak, protein deposition, and thrombus formation