High-flow nasal oxygen therapy in the treatment of acute respiratory failure in severe COVID-19 pneumonia: a prospective observational study.

ABSTRACT

INTRODUCTION: A significant proportion of patients with COVID­19 present with a rapidly progressing severe acute respiratory failure. OBJECTIVES: We aimed to assess the efficacy of high­flow nasal oxygen (HFNO) therapy in severe acute respiratory failure in the course of COVID­19 in a noncritical care setting as well as to identify predictors of HFNO failure. PATIENTS AND METHODS: This prospective observational study was conducted between March and December 2020. We enrolled all consecutive patients hospitalized with confirmed SARS­CoV­2 infection in whom HFNO therapy was used. The primary outcome was death or endotracheal intubation within 30 days from admission. RESULTS: Of the 380 patients with COVID­19 hospitalized at our tertiary center, 116 individuals (30.5%) requiring HFNO due to severe pneumonia were analyzed. The primary outcome occurred in 54 patients (46.6%). The overall 30­day mortality rates were 30.2% (35 out of 116 patients) in the entire cohort and 64.7% (34 out of 51 patients) among individuals requiring endotracheal intubation. A multivariable analysis revealed that the ROX index (the ratio of oxygen saturation / fraction of inspired oxygen to respiratory rate) below 3.85 measured within the first 12 hours of therapy was related to increased mortality (hazard ratio, 5.86; 95% CI, 3.03-11.35) compared with the ROX index of 4.88 or higher. CONCLUSIONS: The results of our study suggest that nearly half of patients treated with HFNO due to severe COVID­19 pneumonia will require mechanical ventilation. The ROX index is a useful tool for predicting HFNO failure in this population.