Methods: 

• COVID-19 patients with PaO2/FiO2 ≤300 while treated with HFNO ≥40 L/min, or NIV with PEEP ≥5 cmH2O (comparator) were analyzed from the available literature.
• ARDS severity during HFNO/NIV and soon after IMV was compared in patients switched from HFNO/NIV to IMV.
• 28-day mortality was compared between patients treated solely with HFNO/NIV and those transitioned to IMV. 

Results: 

184 patients receiving HFNO and 131 patients receiving NIV were analyzed. 

112 HFNO and 69 NIV patients were switched to IMV. About 92.9% HFNO patients and 95.7% NIV patients still showed PaO2/FiO2 ≤300 under IMV. 

28-day mortality in patients who continued on HFNO and in those shifted to IMV was 4.2% and 28.6%, respectively. 

28-day mortality in patients who continued on NIV and in those shifted to IMV was 1.6% and 44.9%, respectively. 

Overall mortality was found to be 19.0% for HFNO and 24.4% for NIV.

Conclusions: 

Widening ARDS definition to include HFNO patients with PaO2/FiO2 ≤300 may help to recognize patients at earlier stages of the disease but with lower mortality. 

Source- Ranieri VM, Tonetti T, Navalesi P, et al. High Flow Nasal Oxygen for Severe Hypoxemia: Oxygenation Response and Outcome in COVID-19 Patients. Am J RespirCrit Care Med. 2021 Dec 3. doi: 10.1164/rccm.202109-2163OC.