A reduction of peripheral oxygen saturation (SpO2) commonly occurs during bronchoscopy and may be associated with both respiratory and cardiac adverse events. The type of breathing assistance that should be delivered to patients, in order to treat and/or to prevent acute respiratory failure, during or after bronchoscopy, is not universally standardized; studies comparing the impact of different respiratory supports on patient's outcome and on hospital resource use are very few. the risk of respiratory failure rises according to the type of procedure (i.e., increased risk with broncho-alveolar lavage and trans-bronchial lung biopsy) and to the use of sedative drugs. Conventional oxygen therapy with nasal cannula, continuous positive airway pressure and non-invasive ventilation are commonly applied during endoscopic procedures. High flow oxygen therapy (HFOT) is a relatively novel device, still under-used in the context of interventional pulmonology, providing an humidified air-oxygen blend up to 60 L/min. HFOT has been reported to be effective for the treatment of both hypoxemic and hypercapnic respiratory failure. The investigators hypothesize that HFOT could be feasible and safe in patients undergoing bronchoscopy under moderate sedation, affected by or at risk of hypoxemic and/or hypercapnic respiratory failure.

Inclusion Criteria:

• pH ≥7.30 e PaCO2 >45 mmHg and/or
• PaO2/FiO2 <300 mmHg o SpO2 <90 percent on room air
• Patient at risk of respiratory failure (COPD III-IV GOLD stage; OSAS; restrictive lung and chest wall diseases; cardiac failure)

Exclusion Criteria:

• Need of laryngeal mask and/or
• Patients on NIV for >16 hrs/day and/or
• pH <7.30 and/or
• Tracheostomy and/or
• Recent (<3 months) facial trauma and/or
• Hemodynamic instability and/or
• High risk of aspiration and/or
• Lacerated trachea