Extracorporeal Membrane Oxygenation(ECMO)
Extracorporeal Membrane Oxygenation (ECMO) is a specialized medical device used for Mechanical Circulatory Support. It works as a substitute for both the heart and lungs by oxygenating the blood externally. The process involves taking the blood out of the patient’s body and passing it through an ECMO machine, where an oxygenator oxygenates the blood before returning it to the body, where it is pumped to various organs. ECMO is used in two cases: when a person is experiencing heart failure or lung failure. A nurse or a perfusionist with advanced ECMO training controls the ECMO machine.
ECMO is primarily used as a bridge to transplant for patients suffering from heart failure who are waiting for a heart transplant. After the transplant, the patient can be removed from the ECMO machine. ECMO can also be used as a bridge to definitive therapy in patients with severe lung infections. The machine gives the lungs time to rest and recover, and once they have recovered, the patient can be removed from ECMO.
The ECMO machine is connected to the patient through cannulae, plastic tubes placed in the large veins and arteries of the leg, neck, or chest. The machine pumps oxygen-low blood from the patient’s body to an artificial lung (oxygenator), where it is oxygenated and carbon dioxide is removed, similar to the function of human lungs. After oxygenation, the ECMO machine sends the blood back to the patient’s body through a pump with the same force as the heart would. The machine settings can be adjusted to provide the necessary heart and lung support according to the patient’s condition.
In the past, sternotomy was used to open the chest and insert cannulae into the venous system or the right atrium to remove the blood from the body, and another cannula was placed into the aorta to return oxygenated blood to the body. However, today, with advanced technology, percutaneous peripheral ECMO is used, where the cannula is inserted into the femoral vein, and the oxygenated blood is returned to the femoral artery in the groin (VA-ECMO) or jugular vein (VV-ECMO).
ECMO has two types, venoarterial (VA) ECMO and venovenous (VV) ECMO. VA-ECMO is used for heart and lung support, while VV-ECMO is used for lung support only. In VA-ECMO, the blood is drained from the inferior vena cava, a large vein that carries deoxygenated blood from the lower body into the right atrium of the heart, through a cannula placed in the femoral vein. The blood is oxygenated in the oxygenator and then returned to the arterial system through the femoral artery. In VV-ECMO, blood is drained from the inferior vena cava through a cannula placed in the femoral vein, oxygenated in the oxygenator, and then returned to the venous system through the internal jugular vein.
