What does ECMO (Extracorporeal Membrane Oxygenation) mean?

What is ECMO?

ECMO (Extracorporeal Membrane Oxygenation) is a mechanical life support system that temporarily replaces heart and/or lung function by draining blood from the body, oxygenating it through a membrane device, removing carbon dioxide, and returning it to the circulation in patients with severe, potentially reversible cardiopulmonary failure. 1

Core Definition and Purpose

• ECMO is synonymous with extracorporeal life support (ECLS), though ECMO specifically denotes systems where the primary purpose is blood oxygenation 1
• The system uses a modified heart-lung machine at the bedside, distinct from cardiopulmonary bypass used in operating rooms, designed for prolonged support rather than brief surgical procedures 1
• ECMO provides life support but does not cure the underlying disease—it stabilizes patients physiologically, prevents ongoing iatrogenic injury from aggressive ventilation, and allows time for diagnosis, treatment, and organ recovery 2, 3

Two Main Types of ECMO

Venovenous (VV) ECMO: Respiratory Support Only

• VV ECMO provides isolated pulmonary support by draining blood from the venous system (femoral vein or internal jugular vein), pumping it through a membrane oxygenator, and returning oxygenated blood back to the venous circulation 1, 4
• Blood flow rates can reach up to 7 L/min, providing full or partial extracorporeal respiratory support 1
• Used when the heart is functioning adequately but lungs have failed, such as in severe ARDS, pneumonia, or respiratory failure from viral infections 4, 5
• A single bicaval double-lumen cannula inserted in the internal jugular vein can be used for both drainage and return 1

Venoarterial (VA) ECMO: Combined Cardiopulmonary Support

• VA ECMO provides both cardiac and respiratory support by draining blood from the venous system and actively pumping oxygenated blood into the arterial circulation (femoral artery, subclavian artery, or directly into the aorta) 1, 4
• Blood flow rates up to 7 L/min can provide full or partial cardiopulmonary support 1
• Indicated for cardiogenic shock, cardiac arrest, or combined heart-lung failure requiring hemodynamic stabilization 4, 6
• Requires more intensive hemodynamic monitoring than VV ECMO, including continuous ECMO flow recording 4

Extracorporeal Carbon Dioxide Removal (ECCO2R)

• ECCO2R is a low-flow venovenous system (200-1,500 mL/min) adequate for substantial CO2 removal but providing only minimal oxygenation 1, 7
• Potentially deployable in most ICUs similar to continuous renal replacement therapy, though still evolving 1

Clinical Applications and Survival Rates

• Survival rates vary dramatically by indication: ranging from 30% in extracorporeal cardiopulmonary resuscitation to 95% for neonatal meconium aspiration syndrome 2
• For respiratory ECMO, survival to hospital discharge is approximately 81% in neonates, 70% in pediatric patients, and 63% in adults 8
• ECMO is used as a rescue therapy when conventional intensive care fails, including mechanical ventilation, prone positioning, neuromuscular blockade, and other salvage therapies 1, 5

Critical Requirements for Safe ECMO Use

• ECMO requires systemic anticoagulation, making bleeding the major limitation to widespread application 2
• Should only be performed at high-volume centers with multidisciplinary teams available 24/7, as centers caring for more than 20-25 cases per year have significantly better outcomes 1, 4
• The learning curve requires at least 20 cases to establish competence 1, 4
• Hospitals without ECMO capability should establish transfer relationships with ECMO-capable institutions for timely patient retrieval 4

Common Pitfalls and Complications

• Bleeding complications are common and associated with high mortality, particularly intracranial hemorrhage 4
• Almost all ECMO patients develop acquired von Willebrand syndrome (AVWS) within hours of device implantation, contributing to bleeding risk 4
• Thrombotic and thromboembolic complications occur despite anticoagulation, with recent data showing 42% of VV-ECMO patients experience thrombotic events and 37% experience bleeding events 4
• ECMO is resource-intensive, complex, and costly—it should be used judiciously only after exhausting conventional therapies 4, 9