Impact of bridging veno-venous extracorporeal membrane oxygenation to COVID-19 lung transplantation

Background: Veno-venous extracorporeal membrane oxygenation (VV-ECMO) therapy is being increasingly used as respiratory support for patients with severe coronavirus disease 2019 (COVID-19)associated acute respiratory distress syndrome (ARDS). However, the long-term outcome of VV-ECMO as a bridge to lung transplantation in COVID-19-associated ARDS remains unclear, hence the purpose of this study aimed to evaluate its long-term outcome, safety, and feasibility. Methods: This was a retrospective cohort study from an institutional lung transplantation database between June 2020 and June 2022. Data on demographics, pre-transplantation laboratory values, postoperative outcomes, preoperative and postoperative transthoracic echocardiography findings, and survival rates were collected. Chi-square, Mann-Whitney U, Student's t, Kaplan-Meier, and Wilcoxon signed-rank tests were used for analysis. Results: Twenty-five patients with COVID-19-associated ARDS underwent lung transplant surgery with VV-ECMO bridge. Unfortunately, six patients with COVID-19-associated ARDS using VV-ECMO died while waiting for transplantation during the same study period. Patients with VV-ECMO bridge were a more severe cohort than 16 patients without VV-ECMO bridge (lung allocation score: 88.1 vs. 74.9, P<0.001). These patients had longer intensive care unit and hospital stays (P=0.03 and P=0.02, respectively) and a higher incidence of complications after lung transplantation. The one-year survival rate of patients with VV-ECMO bridge was lower than that of patients without (78.3% vs. 100.0%, P=0.06), but comparable to that of patients with other lung transplant indications (84.2%, P=0.95). Echocardiography showed a decrease in the right ventricular systolic pressure (P=0.01), confirming that lung transplantation improved right heart function. Conclusions: Our findings suggest that VV-ECMO can be used to safely bridge patients with COVID-19 associated ARDS with right heart failure.