ECMO (extracorporeal membrane oxygenation) is a life-support technique that temporarily replaces the function of the heart and/or lungs when they fail severely. A machine draws the patient's blood, oxygenates it and removes CO₂ through a membrane, then returns it to the body. There are two main types: VA ECMO (veno-arterial), supporting heart and lungs, and VV ECMO (veno-venous), replacing only lung function. The perfusionist is key to setting it up and running it.
What ECMO is
ECMO is essentially an external artificial lung and/or heart that keeps the patient alive while the damaged organ recovers or a treatment is decided. Unlike OR cardiopulmonary bypass, which lasts the hours of a surgery, ECMO can run for days or weeks in intensive care. See what ECMO is.
VA vs VV ECMO: the key difference
Understanding the two modes is the most important thing:
| Type | What it replaces | For whom |
|---|---|---|
| VA (veno-arterial) | Heart and lungs | Severe cardiac failure (cardiogenic shock), sometimes with respiratory failure |
| VV (veno-venous) | Lungs only | Severe respiratory failure with a working heart (e.g. ARDS) |
In VA the blood returns to the arterial system (adding circulatory support); in VV it returns to the venous system (oxygenation only). Choosing the right mode is a fundamental clinical decision.
How the circuit works
The ECMO circuit shares logic with CPB: cannulae connecting the patient, a pump driving the blood, a membrane oxygenator acting as the lung, a heat exchanger and sensors watching flow, pressure and gases. Anticoagulation is critical over days of support.
The perfusionist's role
The perfusionist helps with set-up and priming, cannulation (with the medical team), monitoring and adjustment of support, and finally decannulation as the patient improves. It demands responsibility and availability, because ECMO does not wait. Training the whole cycle, cannulation to decannulation, is exactly what ECMO simulators allow.
ECMO vs cardiopulmonary bypass
They share technology but are not the same: CPB is OR support during a specific cardiac surgery, while ECMO is prolonged support in intensive care.
Frequently asked questions
What is ECMO?
A life-support technique that temporarily replaces heart and/or lung function: a machine oxygenates the patient's blood and removes CO₂ through a membrane while the organ recovers.
What is the difference between VA and VV ECMO?
VA (veno-arterial) replaces heart and lungs and adds circulatory support; VV (veno-venous) replaces only lung function, for patients whose heart still works.
What does the perfusionist do in ECMO?
They help with set-up and priming, cannulation, monitoring and adjustment of support, and decannulation, with high availability because ECMO can last for days.
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