Extracorporeal membrane oxygenation (ECMO) is an advanced, resource-intensive form of life support for patients with severe respiratory or cardiac failure, and is typically provided within specialized centers. Prior to the COVID-19 pandemic, evidence supported the use of ECMO for selected patients with severe forms of acute respiratory distress syndrome (ARDS) unresponsive to less invasive therapies. Clinicians considered using ECMO for severe COVID-19 early in the pandemic because the disease process appeared similar to ARDS from other causes. Nonetheless, the role of ECMO was unproven, lacking evidence specific to this disease.1
In the absence of outcome data from randomized clinical trials of ECMO for COVID-19, clinicians relied on data from observational studies, which suggested overall survival with venovenous ECMO for patients with COVID-19–related ARDS was similar to survival for patients with ARDS without COVID-19.2–4 However, these studies clearly lacked control groups of patients with COVID-19 of comparable severity of illness who did not receive ECMO, and many uncertainties remained. Specific clinical features of severe COVID-19, such as coagulopathy, raised concerns that the risks of ECMO (in particular, bleeding and thrombosis) would be exacerbated,2 although these concerns were not evident in subsequent observational data from large registry cohorts.4,5 Many clinicians also questioned whether COVID-19 might differ from other forms of ARDS, with a greater risk of circulatory dysfunction and shock, potentially requiring the more complex configuration of venoarterial ECMO.1 However, this has not been observed and less than 5% of patients who received ECMO for ARDS related to COVID-19 required mechanical circulatory support, such as venoarterial ECMO.
