Eosinopenia was shown to be associated with increased mortality in critically ill COVID-19 patients in general, but patients treated with extracorporal membrane oxygenation (ECMO) were not assessed separately.
We aimed to assess the relationship between blood eosinophil count and mortality in COVID-19 patients treated with ECMO and those treated with invasive ventilation. We retrospectively reviewed eosinophil count and its change during intensive care unit (ICU) stay, together with mortality of critically ill COVID-19 patients on ECMO (n=62) and on invasive ventilation (IV; n=330) treated between March 1, 2020 and Feb 28, 2022. Data are given as mean±SEM.
Though mean eosinophil counts increased during ICU stay both in non-survivors and survivors, at discharge values were significantly lower in non-survivors than in survivors both in the ECMO (0.09±0.02 vs. 0.29±0.14 G/L; p<0.05) and in the IV group (0.08±0.02 vs. 0.32±0.04 G/L; p<0.05), respectively. Eosinophil count at ICU admission had no effect on mortality. Depletion of eosinophils during treatment significantly increased the odds of mortality both in the ECMO and in the IV groups (OR: 3.98 and 1.41; respectively; p<0.05 for both) independently of age, change in neutrophil count and C-reactive protein. Moreover, in the ECMO group, all patients died who had a decrease in eosinophil differential count.
Conclusion: Eosinophil count has a strong prognostic value on treatment outcome and mortality not only in invasively ventilated, but also in ECMO-treated COVID-19 patients.