Survival Benefits of Extracorporeal Membrane Oxygenation for Selected Patients With Severe COVID-19

To the Editor:

Coronavirus disease 2019 (COVID-19) is associated with particularly frequent acute respiratory distress syndrome (ARDS), which is also associated with higher mortality. The poorer prognosis of COVID-19 ARDS is due mainly to widespread endothelial damage that promotes thrombogenesis and impairs vasoregulation in small pulmonary vessels, resulting in severe ventilation-perfusion mismatch.¹ Because the mortality rate with severe COVID-19 ARDS can reach 85% without the use of extracorporeal membrane oxygenation (ECMO),² the excellent 1-year outcomes with venovenous (VV) ECMO reported by Smith and colleagues³ are promising.

Evaluating exclusively patients supported by VV-ECMO, Smith and colleagues³ proved convincingly the feasibility and lifesaving value of VV-ECMO in appropriately selected patients with COVID-19 ARDS. The particularly good results of the study clearly speak against the initial hesitation toward the use of ECMO in the management of COVID-19 ARDS. The question still remains about the previously published discrepancies in the usefulness of VV-ECMO, which were discouraging because the survival outcomes were often lower than those expected for non-COVID ARDS. A possible explanation for those discrepancies could be differences in the prevalence of acute cardiorespiratory failure necessitating both extracorporeal gas exchange and temporary mechanical circulatory support. In 1 study, venoarterial or other ECMO configurations were necessary in 138 (9%) of the ECMO-supported patients with COVID-19 ARDS.⁴ Thus, the existence of COVID-19 ARDS associated with acute cardiorespiratory failure, necessitating both respiratory and circulatory support, must also be considered.

As proved by Smith and coworkers, selection of patients for VV-ECMO is reliably practicable. However, data about the selection of patients with severe COVID-19 ARDS who may necessitate another type of ECMO support are insufficient. Given the high incidence of diffuse pulmonary thrombotic microangiopathy with consequent afterload mismatch-induced right ventricular (RV) failure, careful echocardiographic monitoring of the right-sided heart for timely detection of RV pressure overloading becomes indispensable in patients with COVID-19 ARDS.¹ Echocardiography can help in optimizing the selection of ECMO candidates and decision-making about the most appropriate mechanical support strategy (VV-ECMO, venoarterial ECMO, or VV-ECMO plus RV or left ventricle temporary percutaneous mechanical support).