Table 1.

Summary of key randomized clinical trials of non-invasive ventilation (NIV) and high-flow nasal cannula oxygen (HFNC)

Study	No. of patients	Cause of AHRF	P/F	Interventions (cmH2O)	VT (ml/ kg)	Comparator	Primary outcome	Results	Time to intubation
Frat [4]	310	CAP (63.5%)	155	NPPV-PS, face mask, PS 5, PEEP 8	9.2	HFNC, COT	Intubation at 28 day	38% with HFNC, 47% with COT, and 50% with NPPV (p = 0.18 for all comparisons)	23 h
Lemiale [5]	374	Pneumonia (68.7%)	142	NPPV-PS, face mask, PS 2–10, PEEP N/A	9.1	COT	Mortality at 28 day	24.1% vs. 27.3%, p = 0.47	Half of the intubation events occurred in 1 day
Azoulay [6]	776	Pneumonia (77.6%)	132	HFNC	−	COT	Mortality at 28 day	35.6% vs. 36.1%, p = 0.94	Half of the intubation events occurred in 1 day
He [7]	200	CAP (94%)	231	NPPV-PS, face mask, PS 6, PEEP 8	8.1	COT	Intubation	10.8% vs. 9.2%, p = 0.72	3.65 days
Coudroy [8]	299	Pneumonia (74.5%)	147	NPPV-PS alternating with HFNC, face mask, PS 7, PEEP 7	9.6	HFNC alone	Mortality at 28 day	35% vs. 36%, p = 0.83	24 h
Ospina- Tascon [9]	220	COVID-19	104	HFNC	−	COT	Intubation within 28 days	34.3% vs. 51.0%, HR 0.62 (0.39–0.96), p = 0.03	25.75 h
Perkins [10]	1273	COVID-19	114	NPPV-CPAP, mostly face mask, PS 8.3, PEEP N/A	N/A	COT	Intubation or mortality within 30 days	36.3% vs. 44.4%, p = 0.02	1.5 days
				HFNC	−	COT	Intubation or mortality within 30 days	44.3% vs. 45.1%, p = 0.69	1 day

AHRF acute hypoxemic respiratory failure, P/F PaO₂ FiO₂ ratio, V_T tidal volume, COT conventional oxygen therapy, NPPV non-invasive positive pressure ventilation, PEEP positive end-expiratory pressure, CPAP continuous positive airway pressure, PS pressure support, CAP community-acquired pneumonia, COVID coronavirus disease, HR hazard ratio