Extracorporeal Membrane Oxygenation (ECMO) is more than just word salad and the image above really oversimplifies the life saving measure of oxygenating your blood outside of the body [extracorporeal]. Hemodialysis would be another such example for patients experiencing end stage renal failure. We can all appreciate that there are varying levels of life support across the medical industry. As EMS professionals we provide care that supports life everyday (BLS vs. ALS , ACLS, PALS... just to name a few). ECMO however, is the pinnacle of life support. It is the most advanced care that can be initiated and for many patients in an ICU setting, it is the last thing they have left when all other aspects of critical care have been exhausted.
Imagine that the ECMO machine in its simplest form would represent a pair of lungs. It is a closed circuit in which blood leaves the body and gets oxygenated. In addition, waste products like CO2 get removed and then the freshly oxygenated blood is returned back to the patient. ECMO can exist in two different forms (V-V for veno/venous) for pulmonary support or V-A for veno/arterial) for hemodynamic support. Therapies like this have proven beneficial for critically ill ARDS patients who lungs are failing, their P/F ratios are extremely low, the ventilator is working overtime, and their lungs simply need a break. ECMO, specifically the V-V variety can provide this native pulmonary rest. Conversely, V-A ECMO can work wonders in a patient suffering from early cardiac arrest or cardiogenic shock that is unresponsive to pressors or other traditional treatment pathways.
Lots of team decision making is at play here to determine which patient may make ideal ECMO candidates. One of the most important criteria is the ability of the providers to identify a reversible underlying cause of the patient's condition. ECMO can provide the patient some valuable time and act as a bridge to definitive recovery while the causative agent is remedied by the team. In other circumstances ECMO can also act as a bridge to organ transplantation.
In summation:
V/V ECMO - bypasses the lungs and supporting gas exchange (more common)
Patient must have preserved cardiac function for this to be successful. Common cannulation configuration is where the drain cannula is placed in femoral vein, while the return cannula placed in the right internal jugular vein.
V/A ECMO - bypasses the lungs AND the heart, resting the heart by reducing their preload. Common cannulation can include placing the drainage (venous) cannula in the femoral vein or right IJ. The return (arterial) cannula is usually placed in the opposite femoral artery.
Keep in mind that if the patient is suffering from a process that is NOT going to get better, they will likely NOT be an ECMO candidate. Scoring systems exist in the ICU to help determine a patient's eligibility and multiple subspecialty physicians from varying service lines will also weigh in as well. Consensus decision making can be very powerful here. Medical ethics boards may also be added to the discussion as this has been done in pregnant women on occasion. Like any therapy this one comes with risks. Weve already established that the patient is critically ill with a high risk for morbidity and mortality before we even get started. As you can imagine, the risks for both bleeding and clot formation are high. Clot formation is proactively managed with heparin therapy. However, a consequence of this is a rare phenomenon called HIT or heparin induced thrombocytopenia, which obviously increases the risk of bleeding. In cases of HIT - expensive heparin alternatives like Argatroban can be given. Lastly, antibiotic prophylaxis will also be started because you are cannulating large vessels and introducing foreign materials into pretty sizeable openings.
This blog was meant to expose you to the basics of ECMO - realize the procedures are way more complex as teams try to support and save our most critically ill patient populations. More research is being done, more data is being collected and hopefully this currently sparse and limited resource will begin showing up at more health systems across the country in the future.
September 23, 2024
Author: Joshua Ishmael, MBA, MLS(ASCP)CM, NRP
Pass with PASS, LLC
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