Extracorporeal membrane oxygenation (ECMO) is used to treat patients with severe, life-threatening conditions of the heart and lungs. ECMO uses a pump to replace the function of the heart and an oxygenator to perform the work of the lungs. The oxygenator both delivers oxygen to the blood and removes carbon dioxide from the blood. ECMO provides short-term support, allowing the heart and lungs time to recover from damage or injury. The ECMO machine is similar to the heart-lung bypass machine used in open heart surgery. Large tubes called cannulas are placed in the legs, neck, or chest and are connected to the ECMO machine. Venous blood, low in oxygen and high in carbon dioxide, is pumped into the ECMO unit where it is oxygenized, and carbon dioxide is removed. Then the blood is warmed and pumped back into a large artery. Small, portable ECMO units are available and are used to keep a patient alive during transport via ambulance or helicopter.
ECMO is used in cardiogenic shock, where the heart is unable to pump enough blood to meet the body’s demand. This may result from a heart attack, heart failure, pulmonary embolism (blood clot in the lungs), or severe infection like myocarditis (infection of the heart muscle). It is also used to treat respiratory failure where the lungs are not able to properly exchange oxygen for carbon dioxide. This may occur because of chronic lung disease, acute infections like pneumonia, influenza and COVID-19, or acute lung inflammation (acute respiratory distress syndrome or ARDS). ECMO is also used in postoperative heart failure following heart surgery or heart transplant where the heart may be in shock and requires time to recover. It is also used to keep people alive while they await heart or lung transplants. While on ECMO, patients are sedated, intubated on a ventilator, given intravenous nutrition, blood products, and blood thinners.
ECMO is intended to be a temporary procedure and there are serious risk factors to be considered. Foremost among the risk factors is bleeding. Blood thinners are given to prevent blood clots in the tubing that carries the blood. Bleeding can be life-threatening if it occurs in the gastrointestinal tract, lungs, or brain. Even with the use of blood thinners, blood clots can form, albeit rarely, and may cause a stroke. When cannulas are placed in blood vessels in the leg, the circulation to the lower portion of the limb may be compromised necessitating surgery or amputation.
Unfortunately, some patients fail to improve on ECMO if their disease is irreversible or does not respond to treatment. However, the use of ECMO gives a critically ill patient a better chance of recovery by providing time for their own organs, or transplanted ones, to recover. If you would like to learn more about ECMO go to the Extracorporeal Life Support Organization at www.elso.org/Resources/Introduction.aspx
By Peter Galvin, MDBLOG COMMENTS POWERED BY DISQUS