Airway Occlusion Measured During Non-invasive Ventilation to Assess Respiratory Effort

Flow, airway pressure (Paw), and esophageal pressure (Pes) will be recorded for 10 minutes on different NIV settings: during each one, three end-expiratory airway occlusions will be applied at random intervals. Each occlusion was maintained for the duration of a single breath deflection in Paw from PEEP, confirmed by the return of Paw to baseline.