Late Failure of High-Flow Nasal Cannula May Be Associated with High Mortality in COVID-19 Patients: A Multicenter Retrospective Study in the Republic of Korea

The aim of this study was to determine whether the late failure of high-flow nasal cannula (HFNC) is associated with mortality in patients with coronavirus disease 2019 (COVID-19). This multicenter study included seven university-affiliated hospitals in the Republic of Korea. We collected the data of patients hospitalized with COVID-19 between 10 February 2020 and 28 February 2021. Failure of HFNC was defined as the need for mechanical ventilation despite HFNC application. According to the time of intubation, HFNC failure was divided into early failure (within 48 h) and late failure (after 48 h). During the study period, 157 patients received HFNC and 133 were eligible. Among them, 70 received mechanical ventilation. The median time from HFNC initiation to intubation of the early failure group was 4.1 h (interquartile range [IQR]: 1.1–13.5 h), and that of the late failure group was 70.9 h (IQR: 54.4–145.4 h). Although the ratio of pulse oximetry/fraction of inspired oxygen (ROX index) within 24 h of HFNC initiation tended to be lower in the early failure group than in the late failure group, the ROX index before two hours of intubation was significantly lower in the late failure group (odds ratio [OR], 5.74 [IQR: 4.58–6.98] vs. 4.80 [IQR: 3.67–5.97], p = 0.040). The late failure of HFNC may be associated with high mortality in COVID-19 patients with acute respiratory failure.