ECMO – Extracorporeal membrane oxygenation – has been in use for the past four decades to support persons who are unlikely to survive with mechanical ventilation. ECMO is used in both adult and pediatric practice, though in the initial years, use of ECMO was restricted to pediatric intensive care. The enthusiasm for use of ECMO in adults have been triggered by the beneficial effect noted during the last H1N1 influenza pandemic . In contrast from cardiopulmonary bypass which is used for a short period during cardiac surgery, ECMO is used to support for a long period, usually three to ten days, mostly in medical management outside the operation theatre, in the intensive care unit. While cardiopulmonary bypass allows cardiac surgery in the arrested heart, ECMO allows the heart and lung function to recover during an illness which has caused cardiopulmonary compromise.
Types of ECMO
ECMO circuits are of two types: Veno-arterial (VA-ECMO) and veno-venous (VV-ECMO) .
In veno-arterial ECMO, deoxygenated blood is drained from the femoral vein and oxygenated blood is delivered through a cannula introduced into the femoral artery. Veno-arterial ECMO supports both respiration and circulation.
Veno-venous ECMO involves drainage of deoxygenated blood from the femoral vein and delivery of oxygenated blood into the jugular vein. Veno-venous ECMO provides only respiratory support.
Central venoarterial ECMO by draining deoxygenated blood from the right atrium and delivery of oxygenated blood into the aorta is also rarely considered when the chest has already been opened and set up for cardiopulmonary bypass. Peripheral veno arterial ECMOreduces the left ventricular preload, but delivery of blood into the femoral artery can increase the ventricular wall tension. This problem is not seen in central venoarterial ECMO .
Extracorporeal Life Support Organization (ELSO) Registry Report 2012 documented that nearly 51,000 individuals had received extracorporeal life support. Half of them were for neonatal respiratory failure and overall survival to discharge or transfer was 75%. In this registry there were about 13,000 patient treated for cardiac support and documented 40-50% survival rates in different age groups .
ELSO Registry report 2016 had data on78,397 ECLS patients with 58% survival to hospital discharge .
The 2017 guidelines for management of ST elevation myocardial infarction from the European Society of Cardiology gives a Class IIb recommendation for the use of ECMO in the management of refractory cardiogenic shock .
ECMO can also be used as a bridge to ventricular assist devices or cardiac transplantation. Earlier initiation of ECMO is now being considered as prolonged use of mechanical high pressure ventilation and high dose inotropic support leads to multiorgan failure and reduces the chance of improvement with ECMO. ECMO gives a chance for considering other treatment options by maintaining circulation and respiration.
Potential complications of ECMO
Potential complications of ECMO include bleeding, thromboembolism, difficulty in access and access site complications and infection. Initiation after long periods of mechanical ventilation and the presence of multiorgan failure increases the chance of complications. Use of ECMO during cardiac arrest has been associated with cerebral hemorrhage.
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Punjabi PP et al. The science and practice of cardiopulmonary bypass: From cross circulation to ECMO and SIRS. Glob Cardiol Sci Pract. 2013;2013:249-60.
Khan MH et al. Mechanical circulatory support in acute cardiogenic shock. F1000Prime Rep. 2014;6:91.