Background:. The efficacy of high flow nasal canula oxygen therapy (HFNO) to prevent invasive mechanical ventilation (IMV) is not well established in severe coronavirus disease 2019 (COVID-19). The aim of this study was to compare the risk of intubation between two strategies of oxygenation (conventional oxygenation and HFNO) in critically ill COVID 19 patientsMethods: This was a multicenter retrospective case series witch took place in two intensive care units (ICU) of tertiary hospitals in the Paris region from March 11, to May 3, 2020. We enrolled consecutive patients hospitalized for COVID-19 and acute respiratory failure (ARF) who did not receive IMV at ICU admission. The primary outcome was the rate of IMV after ICU admission. Secondary outcomes were death at day 28 and day 60, length of ICU stay, ventilator-free days and number of patients with ventilator-free days >14 days. Data from the HFNO group were compared with those from the standard oxygen therapy (SOT) group.ResultsAmong 138 patients who met the inclusion criteria, 62 (45%) were treated with SOT alone, and 76 (55%) with HFNO. In HFNO group, 39/76 (51%) patients were intubated and 46/62 (74%) in SOT group. After using a standard logistic regression on the original sample, HFNO was associated with significantly lower rate IMV (OR [IC-95%] 0.37 [0.18 – 0.76] p = 0.007). After propensity score application, HFNO was still associated with a lower rate of intubation (OR [IC-95%] 0.31 [0.14-0.66] p = 0.002). Length of ICU stay and mortality at day 28 and day 60 did not significantly differ between HFNO and SOT groups after propensity score application. In a univariate analysis, ventilator-free days at days 28 was higher in HNFO group (21 days vs 10 days, p=0.005). The number of patients with ventilator free-days >14 days was higher in HFNO group after propensity score application (66% vs 39%; OR 3.91[1.91-7.99], p=0.0002).ConclusionsHigh flow nasal canula oxygen for ARF due to COVID-19 reduces the need for intubation.