Extra-corporal Membrane Oxygenation is a special form of advanced life support used to treat the sickest patients. It gives temporary life-support for critically ill patients with severe forms of acute respiratory and cardiac failure, when other intensive care therapies cannot keep a patient alive.
It is a high-risk procedure that requires highly skilled and experienced clinicians, by putting a patient on ECMO, it gives extra time for the heart and lungs, or both to recover and repair themselves or allow time for other options to be considered.
A/Prof. Vincent Pellegrino, Intensivist and ECMO Specialist, explains the ECMO machine components and how ECMO works.
ECMO is delivered by using a number of components that form a circuit:
Cannulae (plural) or cannula (singular) are specialised tubes that enter the patients circulation (blood stream) to drain blood to the ECMO pump or return blood from the ECMO membrane. These usually enter the patient (through the skin) near large blood vessels and travel some way inside blood vessels (veins and arteries). Sometimes they enter through or near the chest. Cannulae are single use items that are size matched to meet the needs of the patient. They must be inserted by trained and accredited staff in Victoria.
The cannulae are connected to the ECMO Machine with tubes. These tubes are the most visible part of the ECMO system; the blood can be seen travelling through the clear, compressible thick disposable tubing.
The ECMO blood pump pulls blood from the patient and then pushes it toward the ECMO membrane. The pump is small (holds about 30mls of blood) but designed to move almost all of the patient his/her/their blood each minute. The ECMO membrane usually sits close to the pump or may be attached to it so that it forms a single combined unit. The membrane is where oxygen is added to the blood (the membrane is sometimes called the “oxygenator”) and carbon dioxide (a waste gas of human metabolism usually removed by breathing) is removed. Blood usually changes colour after it passes the membrane and then returns to the patient. Heat can also be added to the blood as it passes through the membrane.
The ECMO Machine is the “hardware” of the system and holds the pump and membrane as well as providing controls and monitoring of the circuit. Is sits atop a specialised trolley, usually, at the foot of the bed.
