The use of high flow nasal oxygen therapy (HFNO) may improve clinical outcomes in acute hypoxemic respiratory failure (AHRF) compared to conventional oxygen. However, whether the use of HFNO improves clinical outcomes in COVID-19 pneumonia remains unclear. In this study, we describe the use of HFNO, as compared to conventional oxygen therapy (COT), in moderate to severe COVID-19 pneumonia.

This is a retrospective cohort study conducted at one academic medical center and one community hospital between March 1, 2020 and July 14, 2020. The primary purpose of the study was to determine the success of HFNO in preventing the composite outcome of invasive mechanical ventilation (IMV) or in-hospital death compared to COT. Secondary objectives included determining the predictors of this composite outcome, rate of endotracheal intubation, hospital mortality and outcomes of early versus late HFNO failure. Logistic and quantile regression were used to test for associations.

A total of 197 patients were included, 166 in the HFNO and 31 in the COT group. There was no significant difference between the groups in the composite outcome of IMV or death, odds ratio (OR) = 0.36, p = 0.08. Use of HFNO as opposed to COT was associated with a significant reduction in the rate of IMV (64 % versus 87 %, p = 0.03). Older age and coronary artery disease were associated with HFNO failure. There was no significant mortality difference between early and late IMV.

In our study, HFNO did not reduce our primary composite outcome of IMV or death in moderate to severe AHRF, although we found that HFNO was associated with lower rate of intubation compared to COT. We detected no benefit of early vs late IMV. Utilizing HFNO in COVID-19 patients with AHRF may be a reasonable initial respiratory support strategy with close monitoring. Additional studies are needed to determine subset(s) of such patients that would benefit the most from HFNO use.