Chart — Critical Care
ECMO Comparison Chart
VV ECMO vs. VA ECMO — support type, cannula sites, indications, complications, and nursing monitoring differences side-by-side.
Educational use only. ECMO management is directed by specialized teams under strict institutional protocols; this comparison supports concept review only. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
VV ECMO
Veno-Venous ECMO
Respiratory Support Only
Drains blood from venous system, oxygenates it, returns it to venous circulation. Heart must still pump. Used for severe respiratory failure.
VA ECMO
Veno-Arterial ECMO
Cardiac + Respiratory Support
Drains blood from venous system, oxygenates it, returns it to arterial circulation. Provides cardiac output support. Used for cardiogenic shock and cardiac arrest.
Feature-by-Feature Comparison
| Feature | VV ECMO | VA ECMO |
|---|---|---|
| Support Type | Respiratory only (gas exchange) | Cardiac + Respiratory (gas exchange + cardiac output) |
| Circuit Path | Vein → Oxygenator → Vein | Vein → Oxygenator → Artery |
| Heart Bypassed? | No — native heart still pumps | Partially or fully — circuit provides cardiac output |
| Lungs Bypassed? | Yes — ECMO provides gas exchange | Yes — ECMO provides gas exchange |
| Peripheral Drainage Site | Femoral vein or right internal jugular | Femoral vein |
| Peripheral Return Site | Right atrium (jugular or femoral vein) | Femoral artery |
| Typical ECMO Flow | 3–5 L/min | 4–6 L/min |
| Primary Indication | Severe ARDS, refractory hypoxemia | Cardiogenic shock, refractory cardiac arrest (eCPR), post-cardiotomy failure |
| Recirculation Risk | Yes (oxygenated return re-enters drainage) | No |
| Harlequin (North-South) Syndrome | No | Yes — upper body may receive hypoxic blood from native cardiac ejection |
| Limb Ischemia Risk | Low | High — femoral artery cannula obstructs distal flow; distal perfusion catheter usually placed |
| LV Distension Risk | No | Yes — retrograde arterial flow increases LV afterload; may need LV venting (Impella or septostomy) |
| Pulse Waveform | Normal (heart pumping) | Dampened / pulseless (circuit provides flow; limited by residual native cardiac output) |
| Anticoagulation | Heparin; ACT 180–220 sec (protocol-dependent) | Heparin; ACT 180–220 sec (protocol-dependent) |
| Primary SpO₂ Monitoring | Pulse oximetry (single site acceptable) | Right radial SpO₂ (upper body) AND left pedal SpO₂ (lower body) — detect Harlequin syndrome |
| Bleeding Risk | High (anticoagulation) | High (anticoagulation + arterial access) |
| Weaning Indicator | Improved lung compliance; tolerance of FiO₂ reduction and sweep gas reduction | Improving native cardiac function on echo; tolerance of flow reduction |
Complication Summary
| Complication | VV ECMO | VA ECMO |
|---|---|---|
| Bleeding | High risk (anticoagulation required) | High risk (anticoagulation + arterial site) |
| Thromboembolism / Stroke | Risk | Higher risk (arterial return; higher thromboembolic burden) |
| Limb Ischemia | Low | Significant risk (femoral artery cannula) |
| Harlequin Syndrome | Not applicable | Present in peripheral VA ECMO when native cardiac output is hypoxic |
| LV Distension | Not applicable | Risk from retrograde arterial flow increasing LV afterload |
| Recirculation | Risk (especially with femoral-femoral configuration) | Not applicable (different vascular compartments) |
| Infection | Risk (large-bore cannulas, prolonged therapy) | Risk (large-bore cannulas, prolonged therapy) |
Key Pearls
- ›VV ECMO = lung support only; VA ECMO = heart + lung support.
- ›In VA ECMO: check BOTH right radial AND pedal SpO₂ to detect Harlequin syndrome.
- ›Limb ischemia is a VA-specific complication — check hourly distal pulse/Doppler; a distal perfusion catheter (DPC) does not guarantee perfusion.
- ›LV distension in VA ECMO may require an Impella or atrial septostomy to unload the left ventricle.
- ›Recirculation (in VV ECMO) reduces effective oxygenation — repositioning cannulas or adjusting flow may be required.
- ›Bleeding is the most common complication of both configurations — monitor ACT and all access sites closely.
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with Society of Critical Care Medicine (SCCM) · Surviving Sepsis Campaign · American Association of Critical-Care Nurses (AACN). It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →