Most people have heard the term ECMO by now, it’s the last chance for the most critically ill COVID patients when mechanical ventilation is no longer enough to keep them alive. It performs the function of a patient’s lungs allowing their lungs to heal, if they can. Mechanical ventilation continues while the patient is on ECMO.
ECMO functions like healthy lungs would—it oxygenates (O2) the blood and removes the carbon dioxide (CO2). Healthy lungs do this as we breathe. Our lungs send the oxygenated blood to the heart and receive the depleted blood from the heart. The heart circulates the blood. Lungs are spongy—inside each is a structure similar to a tree with branches, called bronchi, out to smaller and smaller structures like twigs on a tree, called bronchioles. Alveoli are the tiny air sacs on the bronchioles that make the gas exchange.
ECMO patients are hooked up to the machine using large bore cannulas and tubing. One cannula is inserted into the femoral artery at the groin and follows that artery up into the heart—it delivers the oxygenated blood to the heart. The other cannula is inserted into the IJV (internal jugular vein) at the side of the neck and follows the vein down into the heart—it drains the depleted blood from the heart. Both cannulas are sutured in place and connected to tubing which goes into the ECMO machine.
Two of the more important controls on the ECMO machine are the sweep and the flow. The sweep controls the removal of the CO2 from the blood and the flow controls the rate at which the blood is oxygenated. Visually the blood color in each tube are quite different—the arterial blood is bright red while the venous is a dull, rust color.
Blood gas testing is critical to ensuring the ECMO process is working properly—it is done multiple times per shift. Blood gas testing is used to determine the level of O2 and CO2 in the blood. We do two types of testing—one on the patient drawn from an ART (arterial) line and a circuit from the ECMO unit. Blood is drawn both the arterial and venous lines on the ECMO unit. The arterial blood gas stats should be significantly better than the venous. If not, there is problem. There are diagnostic tests we run but usually it is the filter membrane that is failing.
When an ECMO unit fails, we switch out the entire unit because the process is time critical. The unit that is taken off line is cleaned, parts replaced and waits for the next patient. We use a team of 5 or 6 ECMO nurses to change out the unit. There are 2 drizzlers, 2 cutters, a primer and a ALS certified RN on backup. The drizzlers keep a steady flow of saline in the catheters to prevent air bubbles which could cause an air embolism and kill the patient. The cutters clamp and cut the tubes, then connect them to the new unit. The primer shuts the old machine down and starts up the new one, once it has been reconnected to the patient. The primer sets the swish and flow and also has to balance the mechanical ventilation and the ECMO. The ALS nurse is there for to perform CPR if the patient’s heart stops. The goal is speed without mistakes which could very well kill the patient. It takes coordination and teamwork—the primer, always an ES3, is team leader.
That’s it, the basics of ECMO. I have tried to make it understandable for the community of non-medical readers. A lot has been left out with the intent of not boring the readers. I hope it has been successful—informative and interesting. ECMO nursing is a highly skilled, specialized nursing and the pay is commensurate with the education, skills, and experience required. It took me over a year of hands on training, 30 hours of education on my own time, and exhaustive testing to attain my ECMO ES1 certification. The next levels two are ES2 and ES3 (called a primer)— require even greater commitment to ECMO nursing. This type of one-to-one bed side nursing is intense because the life of my patient is literally in my hands. I enjoy the challenge but it’s hard because about 50% of ECMO Delta variant COVID patients die. I know without ECMO 100% would die but the memories of those that have died do stay with you.