Extracorporeal membrane oxygenation (ECMO) is used to provide temporary mechanical support for severe cardiac, respiratory, or cardiorespiratory failure that is unresponsive to conventional therapies. While the principles of ECMO and cardiopulmonary bypass are similar in that they both support the cardiorespiratory system, ECMO is a bedside technology in the ICU that is used for much longer periods of support, and ideally should be a less complex and invasive procedure in terms of cannulation and perfusion techniques, durability of equipment, patient monitoring, and troubleshooting. ECMO cannulation is ideally extrathoracic (although for cardiac ECMO, direct cardiac cannulation is often used), and the miniaturized circuitry efficiently pumps blood through the extracorporeal circuit and provides excellent gas exchange through the membrane oxygenator, while minimizing complications of red cell trauma, embolization, clot, and mechanical failure.
The first reported successful outcome of ECMO support in the ICU was in 1971, in an adult trauma victim with severe acute respiratory distress syndrome who was supported for 75 hours on a custom-built ECMO circuit. Perhaps the most famous “first” in the history of ECMO was in 1975, when a newborn girl named Esperanza, who was dying of meconium aspiration syndrome, was rescued with the assistance of a research ECMO circuit. Esperanza (meaning hope in Spanish) became the symbol of the promise of this new therapy.
During the 1970s, there were a number of reports of the anecdotal use of ECMO in adults, in individual patients or small cohorts with variable outcomes, and then in 1979, a single randomized clinical trial from Zapol and colleagues demonstrated no benefit from ECMO over conventional treatment. ECMO was largely abandoned in adults for the next 2 decades.
The early pediatric and neonatal experience was different, and as a result of small but encouraging trials in neonates and children, pediatricians and pediatric surgical specialists continued to develop ECMO. The landmark UK Collaborative ECMO Trial in the early 1990s demonstrated improved survival in newborns with hypoxemic respiratory failure randomized for ECMO support compared to conventional therapy. The worldwide use of ECMO for neonatal acute hypoxemic respiratory failure continued to increase until the mid-1990s, with a decline over the past decade. The use of cardiac ECMO however began to take off in the late 1990s, and continues. The pandemic H1N1 influenza outbreak of 2009 resulted in a rapid surge in the international experience with ECMO to support respiratory failure in adults with encouraging outcomes reported at experienced ECMO centers in Australia, New Zealand, and the United Kingdom. Since then, the numbers of adults cannulated for ECMO has overtaken the annual number of pediatric (non-neonatal) cases worldwide. To date, since its inception in the mid-1980s, the Extracorporeal Life Support Organization (ELSO) registry (a voluntary international registry for pediatric and adult ECMO centers) reports more than 78 000 ECMO cases, with annual adult cardiac and respiratory ECMO numbers now exceeding their pediatric counterparts.