Reply To the Editor:
We appreciate the thoughtful Letter to the Editor by Dr Dandel1 regarding our publication, “One-Year Outcomes With Venovenous Extracorporeal Membrane Oxygenation Support for Severe COVID-19.”2 We believe these comments highlight two important issues regarding the use of extracorporeal membrane oxygenation in patients with coronavirus disease 2019 (COVID-19).
First, how is COVID-19 acute respiratory distress syndrome (ARDS) different? We agree that severe ARDS can result in diffuse pulmonary thrombotic microangiopathy, precipitating right ventricular (RV) failure in a subset of patients. What is less obvious is whether or not this is a phenomenon unique to patients with COVID-19. ARDS is often complicated by a varying degree of RV dysfunction, and its recognition is important. A 2017 retrospective study by Kon and colleagues3 reviewed the Extracorporeal Life Support Organization (ELSO) Registry for all cases of adult ARDS in patients that required inotropic agents, vasopressors, or both before ECMO initiation (2009-2013). The proportion of this patient cohort initially supported with venovenous (VV)-ECMO increased significantly over the study period and, compared with venoarterial-ECMO, was not associated with worse survival or complication rates. In their estimation, even intrinsic cardiac dysfunction associated with ARDS generally resolves with correction of marked hypercapnia and hypoxia. Thus, for patients with a primary respiratory indication for ECMO, we favor VV-ECMO as the initial support modality.
The second issue raised by Dr Dandel is important because it addresses the effort to improve outcomes for patients with severe COVID-19 ARDS supported with ECMO. Although we concur that echocardiography can be useful in managing patients with severe COVID-19 supported with ECMO, we have a slightly different perspective. Whereas many patients with severe ARDS will have evidence of RV dysfunction on bedside echocardiogram before cannulation, this should not be used to guide decision making about the ECMO support strategy for the reasons highlighted above.
Although some may consider this an oversimplification, our strategy with these patients has been to address respiratory pathophysiology first. Once the patient is cannulated for VV-ECMO, we regularly perform bedside echocardiography to confirm that there is no pericardial effusion and to establish a baseline for the function of both ventricles. Echocardiography is repeated if there is a change in the patient’s clinical condition that may require an adjustment in strategy.
We appreciate Dr Dandel’s interest in our manuscript, and we share the commitment to improve outcomes for patients with severe COVID-19 supported with VV-ECMO.
References
- 1.Dandel M. Survival benefits of extracorporeal membrane oxygenation for selected patients with severe COVID-19. Ann Thorac Surg. 2023;115:1085–1086. doi: 10.1016/j.athoracsur.2022.04.012. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Smith D.E., Chang S.H., Geraci T.C., et al. One-year outcomes with venovenous extracorporeal membrane oxygenation support for severe COVID-19. Ann Thorac Surg. 2022;114:70–75. doi: 10.1016/j.athoracsur.2022.01.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3.Kon Z.N., Bittle G.J., Pasrija C., et al. Venovenous versus venoarterial extracorporeal membrane oxygenation for adult patients with acute respiratory distress syndrome requiring precannulation hemodynamic support: a review of the ELSO Registry. Ann Thorac Surg. 2017;104:645–649. doi: 10.1016/j.athoracsur.2016.11.006. [DOI] [PubMed] [Google Scholar]