Extracorporeal Membrane Oxygenation is the process of pumping the blood from the body, running it through a membrane that oxygenates it, and then perfusing it back into the circulatory system. I went on a kick researching this when I was considering career paths. My mother, as a Pediatric Intensivist, managed ECMO for very sick children. ECMO basically replaces the heart and lungs of a patient temporarily. In critical care it is used to give the body time to heal the pulmonary and cardiovascular systems. It is also often used in surgeries such as hear bypass surgeries where ECMO is the bypass while they operate on the heart.
There are two basic types of ECMO: VV and VA. Veno-venous (VV) ECMO is when the blood is taken from and returned to a vein. Veno-arteiral (VA) is when the blood is taken from a vein and returned to an artery. VV-ECMO is used when the heart is in good condition, but the lungs have failed. VA-ECMO is used when both the heart and lungs need support.