Changes in Therapy Outcome of Veno-Venous Extracorporeal Membrane Oxygenation for Therapy-Refractory COVID-19 Infections Throughout the Pandemic

PURPOSE: Since the beginning of the current pandemic in late 2019, three accumulations of severe COVID-19 infections (so-called infective waves) caused a fulminant increase in hospitalization. In therapy-refractory patients, veno-venous extracorporeal membrane oxygenation (vv-ECMO) was used since the early beginning. However, potential developments in vv-EMCO therapy still need to be proven. METHODS: Between 2020 and 2021 a total of n=60 patients were treated with vv-ECMO for severe COVID-19 related acute respiratory distress syndrome in our department. The patients were prospectively enrolled into an institutional database, followed-up and subsequent retrospectively reviewed. Patients were divided concerning the date of vv-ECMO onset into three groups (03/2020-09/2020: 1. wave, n=11; 10/2020-02/2021: 2. wave, n=23; 03/2021-08/2021: 3. wave, n=26). RESULTS: From the first to the third wave, patients seemed to be younger, more likely to be female as well as more likely obese. While patients of the first wave regularly developed acute kidney failure (81.3 %), these adverse event was seldom in the second (21.7) and third wave (15.4 5)(p=0.01). In contrast to that, other device-related complications such as stroke, bleeding or visceral ischemia did not differ between the three waves. Most apparent changes during the pandemic were prolonged ECMO support duration (1. wave: 8.5 ± 2.1, 2. wave: 54.0 ± 122.7, 3. wave: 28.0 ± 18.6), ECMO weaning rate (1. wave: 18.2 %, 2. wave: 39.1, 3. wave: 44.0 %) and in-hospital mortality (1. wave: 81.8 %, 2. wave: 69.6, 3. wave: 56.0 %), although none of these effects reached statistical significance. CONCLUSION: Although our data cover only a small study population, we observed clear trends towards younger and heavier patients during the pandemic. Most likely, due to a learning effect, support duration of ECMO patients distinctly increased during the pandemic. Subsequently, weaning and survival also increased. However, differences in patient selection could act as a major confounder for these results.