ECMO

When the lungs are so damaged that even a ventilator cannot oxygenate the blood without harming them further, ECMO offers a way around them entirely. Blood is drained from a large vein, pumped through an artificial lung outside the body where it picks up oxygen and gives off carbon dioxide, and then returned warm and oxygen-rich — much like a temporary, external set of lungs (and sometimes heart) doing the gas exchange the body cannot.

The artificial lung is a membrane oxygenator: a bundle of fine hollow fibres across which oxygen flows on one side and blood on the other, exchanging gases just as the real lung membrane does. In the form used for lung failure (veno-venous ECMO), blood is taken from and returned to the venous side, supporting oxygenation while the patient's own heart still pumps. This lets the ventilator be turned down to very gentle, lung-protective settings, giving the injured lungs maximum rest to heal.

ECMO is reserved for the most severe, otherwise-fatal respiratory failure — such as profound ARDS — that has not responded to conventional ventilation and prone positioning. An honest caveat: it is highly invasive, demands large cannulas and continuous anticoagulation, carries serious risks of bleeding and clotting, and is delivered only in specialised centres. It is a bridge that supports life while the lungs recover or another treatment is arranged, not a cure in itself.