NCT03865056.

Study name	Therapy with high‐flow oxygen by nasal cannula vs noninvasive ventilation in patients with acute hypoxemic respiratory failure: a crossover physiologic study
Methods	RCT, cross‐over design. Single‐centre study. Interventions applied for 20 minutes in random order
Participants	Estimated number of participants: 20 Setting: ICU, Canada Inclusion criteria: hypoxaemia; respiratory rate > 25 breaths/min; PaCO2 ≤ 45 mmHg; absence of underlying chronic respiratory failure Exclusion criteria: lack of consent; age < 18; invasive MV > 48 hrs; immediate need for intubation; previous inclusion in this study; systolic blood pressure < 90 mmHg; cardiogenic pulmonary oedema; GCS < 12; moribund; contraindications to NIV; tracheostomy
Interventions	Intervention group (HFNC): Optiflow Control group (NIV)
Outcomes	All outcomes measured: intra‐tidal ventilation heterogeneity index; global inhomogeneity index; tidal volume; respiratory muscle effort; SpO2; PaO2/FiO2; PaCO2; respiratory rate Outcomes relevant to this review: SpO2; PaO2/FiO2; PaCO2; respiratory rate
Starting date	6 March 2019
Contact information	Lorenzo Del Sorbo, lorenzo.delsorbo@uhn.ca. Felicity Backhouse, felicity.backhouse@uhn.ca
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