1. Patients with COVID-19-related acute respiratory distress syndrome (ARDS) had a comparable 90-day mortality rate to those with non-COVID ARDS on extracorporeal membrane oxygenation (ECMO).
2. Higher patient age, higher PaO2:FiO2 ratio and presence of significant acute or chronic disease were all associated with greater risk of mortality in COVID-19 patients on ECMO.
Evidence Rating Level: 2 (Good)
Study Rundown: SARS-CoV-2, the causative agent of COVID-19, has burdened health systems worldwide. Part of the difficulty in treating the illness is its broad spectrum of presentation. In its most extreme form, COVID-19 can cause acute respiratory distress syndrome (ARDS), which bears a particularly poor prognosis. The World Health Organization and Surviving Sepsis Campaign have both recommended extracorporeal membrane oxygenation (ECMO) for patients with COVID-19-related ARDS in which lung protective mechanical ventilation has failed. Despite this recommendation, early data suggested that ECMO might, in fact, be harmful to patients with COVID-19-related ARDS, and increase mortality. This retrospective cohort study utilized data from the international Extracorporeal Life Support Organization (ELSO) database to analyze the mortality rate associated with COVID-19-related ARDS patients on ECMO. Overall, in-hospital mortality at 90 days for COVID-19 patients had an estimated cumulative incidence comparable to that of non-COVID-19 patients with ARDS on ECMO (38.0%). A total of 57% of patients were discharged alive from the hospital. Several factors were associated with higher overall mortality on ECMO, including increased age, higher PaO2:FiO2 ratio, and presence of several significant medical conditions (acute kidney injury, chronic respiratory insufficiency, previous cardiac arrest, among others). A major strength of this study is the use of a large, international database to analyze mortality on ECMO. Importantly, however, given that it is not a randomized, controlled trial, no definitive statements can be made about the use of ECMO in COVID-19-related ARDS based on these results. Other limitations included the fact that the authors did not independently validate the information provided by the ELSO database; additionally, only 79% of patients in their cohort had actually been identified as having ARDS as per the Berlin criteria.
In-Depth [retrospective cohort]: This international, multicenter, retrospective cohort study analyzed ELSO data from 1093 patients aged over 16 years old at 213 centers in 36 countries across the world. Eligible patients had confirmed COVID-19 and were placed on ECMO. The median age was 49 years (IQR 41-57) and 74% were men. The majority had ARDS as defined by the Berlin criteria (79% of patients), and most were put on venovenous ECMO (94%). The primary outcome of the study was in-hospital death at 90 days after beginning ECMO; secondary outcomes included proportion of patients remaining in the intensive care unit (ICU) at 90 days, those discharged from ICU but remaining in hospital, discharged to home, or discharged to long-term acute care center. Overall, the estimated cumulative incidence of mortality in hospital at 90 days after initiative ECMO was 37.4% (95% CI 34.4-30.4), a rate comparable to mortality rates in patients with non-COVID-19-ARDS and acute respiratory failure on ECMO. In a subset of patients with COVID-19-related ARDS and receiving venovenous ECMO, mortality was 38.0% (95% CI 34.6-41.5). A total of 588 patients (57%) were discharged alive from hospital; 311 (30%) to an acute rehabilitation center, 101 (10%) to a long-term acute care center or unspecific, and 176 (17%) to another hospital. The results of this study, although not yet supported by a randomized, controlled trial, point towards ECMO as being a reasonable treatment option in COVID-19-relarted ARDS once mechanical ventilation has failed.
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