­Evolving Outcomes of Extracorporeal Membrane Oxygenation During the First Two Years of the COVID-19 Pandemic: A Systematic Review and Meta-Analysis

Abstract

Background: Extracorporeal membrane oxygenation (ECMO) has been used extensively for coronavirus disease 2019 (COVID-19)-related acute respiratory distress syndrome (ARDS). Reports early in the pandemic suggested that mortality in patients with COVID-19 receiving ECMO were comparable to non-COVID-19-related ARDS. However, subsequent reports suggested that mortality appeared to be increasing over time. Therefore, we conducted an updated systematic review and meta-analysis, in order to characterise changes in mortality over time, and elucidate risk factors for poor outcomes.

Methods: We conducted a meta-analysis (CRD42021271202), searching MEDLINE, Embase, Cochrane, and Scopus databases, from 1 December 2019 to 26 January 2022, for studies reporting on mortality among adults with COVID-19 receiving ECMO. We also captured hospital and intensive care unit (ICU) lengths of stay, duration of mechanical ventilation and ECMO, as well as complications of ECMO. We conducted random-effects meta-analyses, assessed risk of bias of included studies using the Joanna Briggs Institute checklist and evaluated certainty of pooled estimates using GRADE methodology.

Findings: Of 4,522 citations, we included 52 studies comprising 18,211 patients in the meta-analysis. The pooled mortality rate among patients with COVID-19 requiring ECMO was 48·5% (95% confidence interval (CI): 44·4%-52·6%, high certainty). Mortality was higher among studies which enrolled patients later in the pandemic as opposed to earlier (1^st half 2020: 40·8%, 2^nd half 2020: 46·4%, 1^st half 2021: 61·2%, 2^nd half 2021: 46·5%, interaction p-value = 0·016). Predictors of increased mortality included age, the time of final patient enrolment from 1 January 2020, and the proportion of patients receiving corticosteroids, and reduced duration of ECMO run.

Interpretation: The mortality rate for patients receiving ECMO for COVID-19-related ARDS has increased as the pandemic has progressed. The reasons for this are likely multifactorial, however as outcomes for these patients evolve, the decision to initiate ECMO should include the best contextual estimate of mortality at the time of ECMO initiation.

Funding Information: There was no funding source for this study.

Declaration of Interests: Dr. Ramanathan serves as a co-chair of the Scientific Oversight Committee of the Extracorporeal Life support Organisation (ELSO), and reports honoraria for educational lectures from Baxter. Dr. Fan reports personal fees from ALung Technologies, Aerogen, Baxter, Boehringer-Ingelheim, GE Healthcare, Inspira, and Vasomune outside the submitted work. He is Chair of the ELSO Research Committee and a member of the Executive Committee of the International ECMO Network (ECMONet). Dr. MacLaren serves on the board of directors for ELSO. Dr. Brodie receives research support from ALung Technologies. He has been on the medical advisory boards for Abiomed, Xenios, Medtronic and Cellenkos. He is the President-elect of ELSO and the Chair of the Executive Committee ECMONet. All other authors declare no competing interests.