Evaluation of Scarcity Allocation Scores for Venovenous Extracorporeal Membrane Oxygenation

Abstract

Introduction: Venovenous extracorporeal membrane oxygenation (V-V ECMO) improves survival in patients with ARDS from COVID-19 pneumonia. Due to equipment shortages throughout the pandemic, systems for allocation have been proposed, but not tested. In this study, we evaluate 3 systems of allocation for V-V ECMO in both pre-COVID-19 and COVID-19 patients with ARDS. Methods: We retrospectively evaluated 3 systems of ECMO allocation (MN, MDH, and OHI) across 4 ECMO Centers of Excellence. Logistic regression was used to assess the relationship between the scores and in-hospital and 30-day mortality. Cut points for priority groups were evaluated by maximizing the sum of sensitivity and specificity. Results: Of 124 patients, 38% were treated for COVID-19 ARDS. The median age was 48 years and 73% were male. The in-hospital mortality rate was 38% and increased to 42% at 30 days. For each additional point in the MN score, the odds ratio for mortality was 1.13 (p = 0.02) for in-hospital and 1.15 (p = 0.015) at 30 days. OHI and MDH scores were not significant for in-hospital or 30-day mortality. COVID-19 status did not change the findings significantly. For the MN score, a threshold between the low and medium priority groups was found to be 7 and the threshold between medium and high priority groups was found to be 9 (p = 0.05) (Fig. 1). Conclusions: Higher MN score is associated with increased mortality. Proposed priority groups can be used to identify patients that would more greatly benefit from V-V ECMO allocation in times of increasing scarcity. [Formula presented]