Non-invasive Ventilation Versus High Flow Oxygen

Inclusion Criteria: * Diagnosis of pneumonia based on at least two clinical/laboratory criteria and 1 radiologic criterion among the following: * Clinical criteria: fever, cough, purulent sputum, pulmonary examination positive for signs consistent with pneumonia * Laboratory criteria: leukocytosis (White blood cells \>10000/mcL) or leukopenia (White blood cells \< 4000/mcL), rise of the inflammatory markers * Radiologic criteria: consolidations at Chest X-ray or CT scan * Hypoxemic respiratory failure, based on all the following criteria * PaO2/FiO2 \< 300 after at least 15 minutes conventional oxygen therapy with a FiO2 ≥ 50% * Respiratory Rate (RR) ≥ 25/min or need for use of accessory muscles * Informed consent to study participation Exclusion Criteria: * Age \< 18 years * Hypercapnic respiratory failure (pCO2 \> 60 mmHg at presentation) such as in Chronic Obstructive Pulmonary Disease * Presence of another cause of hypoxemic respiratory failure - e.g. pulmonary embolism, acute respiratory distress syndrome (ARDS), pulmonary oedema * Hemodynamic instability with necessity for use of inotropes and/or vasopressors * Indication for endotracheal intubation (ETI): Glasgow Coma Scale (GCS) \<8, agitation, device intolerance, respiratory arrest * Immunosuppression (chronic immunosuppressive therapy, clinical history positive for any immunodeficiency - congenital or acquired) * Do Not Resuscitate (DNR) and Do Not Intubate (DNI) indication * Tracheostomy * Nocturnal CPAP ventilation therapy * Any other condition which the clinician would considered an adjunctive risk for taking part in the study or that would not permit the participant to complete it