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ECMO is the little known, hail Mary option to save patient when a ventilator doesn’t work
ECMO stands for extracorporeal membrane oxygenation and is used when a ventilator can no long keep a patient alive. It works by either bypassing the heart or lungs and artificially oxygenates blood, then pushes this oxygen rich blood back into the body.
But why do we need to use ECMO and why do ventilators fail to keep a patient alive? According to Professor John Fraser, an intensive care specialist, the lungs are like dry sponges, bouncing in and out. But unhealthy lungs, like those suffering from Pneumonia, the lungs are like wet, gluggy sponges.
Ventilators help to push oxygen down to the lungs and into the alveoli into the base of the lungs. The blood then picks up this oxygen as it travels past the alveoli and carries around the body. However, in severe COVID patients, the blood flow past the alveoli is abnormal.
COVID can cause the blood to form clots and hyper-viscosity, where the blood cannot flow as easily. This reduces the amount of oxygen being transported around the body and why ventilators can fail to keep a patient alive. This is where ECMO comes into play.
In order to be placed on ECMO, the blood must be artificially thinned, which can overcome the problem of blood clots and hyper-viscosity. There are two types of ECMO, the first supports the lungs (veno-venous) and the second supports the heart (veno-arterial). In veno-venous, the blood is being drawn from a vein and returned to a vein. This supports damaged lungs and helps to oxygenate the blood, but the heart is still pumping the blood around the body.
Veno-arterial supports both the heart and lungs as the blood is drawn from a vein and returned to an artery. This may be necessary as according to Professor Fraser, “COVID also causes cardiac dysfunction.”
Many hospitals from around the world are utilizing ECMO and according to Professor Fraser, about 60% of patients placed onto the device have survived. However, according to Dr. Chethan Sathya, using ECMO is high risk with complications including, infection, stroke and uncontrollable bleeding. It is also monetarily costly, but also resource intensive.
Right now, hospitals are having to weigh the costs against the benefits of resorting to ECMO for severe COVID patients.