Extracorporeal Membrane Oxygenation in Adults

Extracorporeal membrane oxygenation (ECMO) is a life support modality for adults and children with life-threatening cardiac and pulmonary failure that is refractory to conventional therapy or unresponsive to cardiopulmonary resuscitation (CPR). The ECMO circuit consists of a pump and an oxygenator that temporarily replace cardiac and pulmonary function, allowing time for organ recovery. According to the Extracorporeal Life Support Organization (ELSO), ECMO was used in 151,683 patients through 2020, including 45,205 neonates, 30,743 children, and 75,735 adults. In 1990, ECMO was available in 83 centers; by 2020, the number of ECMO centers had grown to 492. As of July 2024, more than 185,000 cumulative ECMO runs have been reported across over 1200 centers worldwide, reflecting the rapid global expansion of this therapy.[ECLS International Summary of Statistics] Venovenous (VV) ECMO provides respiratory support, whereas venoarterial (VA) ECMO supports both cardiac and respiratory function. ECMO is a supportive therapy rather than a disease-modifying intervention. In 1944, Kolff and Berk demonstrated blood oxygenation using cellophane chambers in an artificial kidney. In 1953, Gibbon applied artificial oxygenation and perfusion during the first successful open-heart operation. Early oxygenators included film and bubble designs, both associated with intravascular hemolysis, systemic inflammation, platelet destruction, and embolization. In 1956, Clowes and Basler developed the first prototype membrane oxygenator suitable for cardiopulmonary bypass (CPB). Rashkind used a bubble oxygenator in 1965 to treat neonatal respiratory failure. In 1969, Dorson et al reported the use of a membrane oxygenator in infant CPB. Baffes et al described ECMO use during infant cardiac surgery in 1970. In 1972, Hill et al reported the first use of ECMO for adult respiratory failure, and Bartlett et al achieved the first successful neonatal ECMO case in 1975 for severe respiratory distress. From the 1980s to the early 2000s, ECMO circuits typically used either silicone membrane or polypropylene hollow fiber oxygenators. These oxygenators were prone to plasma leakage, prompting the development of polymethylpentene oxygenators. The newer generation polymethylpentene models are more durable, provide improved gas exchange, and result in less blood trauma. A recent single-center pilot study comparing 4 polymethylpentene oxygenators found low oxygenator failure rates, but notable differences in resistance and post-oxygenator PaO, emphasizing the need to tailor device choice to patient-specific requirements during long ECMO runs. Kolobow and colleagues analyzed ECMO outcomes in a National Institutes of Health trial conducted in 1981. That same year, Gattinoni et al demonstrated successful ECMO use in a large population of patients with acute respiratory distress syndrome (ARDS). By 1987, Gattinoni's group reported approximately 50% survival. In 1994, a randomized controlled trial by Morris et al did not show improved outcomes with low-flow VV ECMO versus conventional ventilation in ARDS. Survival in the control group was 42%, compared to 33% in the ECMO group. Interest in ECMO resurged after publication of the CESAR trial in 2009, which randomized 180 patients across 68 centers. CESAR demonstrated significantly improved outcomes—including reduced mortality and disability—among patients with severe respiratory failure treated with ECMO versus conventional management. ECMO use expanded dramatically during the COVID-19 pandemic. Large-scale ELSO registry analyses have confirmed hospital survival rates of 48% to 60% in patients with severe viral ARDS when ECMO is initiated at experienced centers.