DEFINITION OF EXTRACORPOREAL LIFE SUPPORT
Extracorporeal life support (ECLS), also known as extracorporeal membrane oxygenation (ECMO), is an artificial form of cardiopulmonary support that allows the heart, the lungs, or both to recover from severe, but potentially reversible, pathologies. ECLS can also function in some cases as a bridge to therapies such as a ventricular assist device or heart or lung transplantation.
BACKGROUND OF EXTRACORPOREAL LIFE SUPPORT
Early work in extracorporeal support dates to 1930 when Dr. John Gibbons built a roller pump device. In 1953, Dr. Gibbons created and successfully used the first heart–lung machine during an atrial septal defect repair. Four years later, silicone rubber membranes replaced the bubbler oxygenator, allowing the prolonged use of extracorporeal machines. These membranes serve as a gas–oxygen interface and thereby prevent severe hemolysis and plasma leakage.1,2
In 1972, Dr. JD Hill announced the first extended use of the extracorporeal circuit outside the operating theater. Dr. Hill’s patient survived posttraumatic respiratory failure after 75 hours of ECLS support. At the same time, Dr. Robert Bartlett and his colleagues at the University of Michigan took the lead in developing and implementing ECLS care, the results of which influenced ECLS care throughout the world.3
After the initial successful attempts, ECLS continued to make progress, albeit slowly. The medical community developed skepticism about the utility of ECLS in adults in the late 1970s when the first randomized controlled trial (RCT) reported poor survival rates.4 Another RCT published in 1994 likewise revealed no survival benefit with ECLS.5 ECLS regained interest in adult patients in 2009 after the publication of several landmark studies, specifically the efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR) trial in the United Kingdom of patients with acute respiratory distress syndrome (ARDS) and observational studies from several different countries of the use of ECLS in respiratory failure caused by H1N1 influenza.6-8 Although both the CESAR trial and the observation influenza pandemic studies had design limitations, these reports stimulated the growth of adult ECLS based on an apparent mortality benefit compared with contemporary conventional mechanical ventilation support.
In an effort to foster and organize ECLS, in 1989, the Extracorporeal Life Support Organization (ELSO) was established to support healthcare professionals and scientists who are involved in ECMO. Among its many activities, ELSO maintains a registry of both facilities trained to provide ECLS care and of patients placed on ECLS. The ELSO patient registry information is used to support clinical research, quality improvement, and regulatory action. ELSO also provides educational programs for ECLS centers and facilities that may be involved in the transfer of patients to higher levels of care.
MODES OF EXTRACORPOREAL LIFE SUPPORT
There are traditionally two modes of ECLS, venovenous (VV ECLS) and venoarterial ...