Before you read:
ECMO - Extracorporeal Membrane Oxygenation
Reoxygenate - Adding oxygen back into the bloodstream.
Oxygen is a vital component to our survival. We breathe in through our lungs, allowing for oxygen to be introduced to the bloodstream. Then, our powerful heart pumps it to the rest of our body. This cycle repeats continuously for our entire lifespan. But what happens when the heart or lungs are damaged? Extracorporeal Membrane Oxygenation (ECMO) is a life-saving technique that bypasses these organs by reoxygenating blood outside the body as a temporary support, promoting rest and healing for the hardest workers in our body.
How did we get here?
All ideas start somewhere. Especially large, complicated machines like this one. So, where did this come from? Credit is given to Robert Hooke, an English scientist and philosopher, who demonstrated in 1667 that the inflation and deflation of the lungs was not necessary for reoxygenation (Lim, 2006). However, a prototype oxygenator would not come about until centuries later.
The next step in the next step in the process was the development of direct contact oxygenators. First demonstrated with shaking a blood sample in a balloon, this type of oxygenator works by exposing oxygen directly to the blood (Ludwig and Scmidt, 1868). Later, two new machines were developed: a bubble oxygenator and a film oxygenator. The bubble oxygenator used the concept of the balloon, where the bubbles increased oxygen contact with the blood, promoting absorption. Film oxygenator more closely resembles modern day ECMO, where the blood was exposed to oxygen with a separation of a biofilm (Lim, 2006). Years of development have improved this system to the ECMO machines used today.
Types of ECMO:
There are two types of ECMO predominant in the field: veno-arterial (VA) and veno-venous (VV). Similar techniques, but the distinction is important to what the life support is needed for. VA ECMO drains blood from a vein, pumps it to a machine which puts the blood in contact with a membrane to perfuse oxygen into the blood, and returns it to an artery (Cui et al., 2022). VV ECMO is similar, but blood is returned to the veins. Both provide pulmonary support, with the main difference being the addition of cardiac support in VA ECMO (Cui et al., 2022).
Uses:
So what specific things do we use ECMO for? These machines can be used at any age, and even in newborns! Notably, VA ECMO can be used for cardiogenic shock, where the heart is not pumping enough blood. Either following a myocardial infarction (heart attack), or other ailments such as sepsis, inflammation of the myocardium, pulmonary embolism, etc (Patel et al., 2019). VV ECMO has had important implications in patients in acute respiratory distress, which could be from traumatic lung damage, hypercapnic respiratory failure, and more. More recently, patients with severe COVID infections have been placed on ECMO to help recovery (Schmidt et al., 2020). ECMO is also a useful support therapy in cases of primary graft failure (Patel et al., 2019). A condition that may develop soon after an organ transplant, leading to rejection of the new tissue. ECMO is a life supporting technique when applied in situations of temporary support to the heart or lungs.
Complications:
Life support techniques such as ECMO do not come without complications. One of the highest reported issues are major bleeding events, often leading to poor patient outcomes. Nguyen et al., performed a single-center study and found 31.4% of patients treated with ECMO were reported to have a major bleeding event (2022). The majority of this risk is due to the heavy use of blood thinners when a patient is on ECMO. As the blood runs through the ECMO system, it causes damage to blood cells, leading to a complex response leading to blood clots. Untreated blood clots may travel to vital organs and get stuck, which can be a fatal complication of this system. Therefore, heavy use of anticoagulants such as Heparin are vital to preventing major clotting in the ECMO circuit (Oude Lansink-Hartgring et al., 2019). This leads to a careful balance that must be closely monitored. Other risk factors are due to post surgical complications, and unfortunately, equipment failure. Extracorporeal Membrane Oxygenation (ECMO) is a complicated and temporary form of life support which must be carefully managed to provide the best patient outcome.
References:
Cui Y, Zhang Y, Dou J, Shi J, Zhao Z, Zhang Z, Chen Y, Cheng C, Zhu D, Quan X, et al. 2022. Venovenous vs. Venoarterial Extracorporeal Membrane Oxygenation in Infection-Associated Severe Pediatric Acute Respiratory Distress Syndrome: A Prospective Multicenter Cohort Study. Front Pediatr. 10:832776. doi:10.3389/fped.2022.832776.
Lim MW. 2006. The history of extracorporeal oxygenators. Anaesthesia. 61(10):984–995. doi:10.1111/j.1365-2044.2006.04781.x.
Ludwig C, Schmidt A. Das Verhalten der Gase, Welche mit dem Blut durch die reizbaren Säugethiermuskelz strömen. Leipzig Berichte 1868; 20: 12–72.
Nguyen TP, Phan XT, Nguyen TH, Huynh DQ, Tran LT, Pham HM, Nguyen TN, Kieu HT, Ngoc Pham TT. 2022. Major Bleeding in Adults Undergoing Peripheral Extracorporeal Membrane Oxygenation (ECMO): Prognosis and Predictors. Tran QK, editor. Critical Care Research and Practice. 2022:1–10. doi:10.1155/2022/5348835.
Oude Lansink-Hartgring A, De Vries AJ, Droogh JM, Van Den Bergh WM. 2019. Hemorrhagic complications during extracorporeal membrane oxygenation – The role of anticoagulation and platelets. Journal of Critical Care. 54:239–243. doi:10.1016/j.jcrc.2019.09.013.
Patel Avani R, Patel Amar R, Singh Shivank, Singh Shantanu, Khawaja I. 2019 Jul 17. Applied Uses of Extracorporeal Membrane Oxygenation Therapy. Cureus. doi:10.7759/cureus.5163. [accessed 2023 Dec 31]. https://www.cureus.com/articles/20869-applied-uses-of-extracorporeal-membrane-oxygenation-therapy.
Schmidt M, Hajage D, Lebreton G, Monsel A, Voiriot G, Levy D, Baron E, Beurton A, Chommeloux J, Meng P, et al. 2020. Extracorporeal membrane oxygenation for severe acute respiratory distress syndrome associated with COVID-19: a retrospective cohort study. The Lancet Respiratory Medicine. 8(11):1121–1131. doi:10.1016/S2213-2600(20)30328-3. Assessed and Endorsed by the MedReport Medical Review Board