Physiological Effect High-flow Tracheal Oxygen on Viscosity of Airway Mucus and Respiratory Effort in Patients Weaning from Invasive Mechanical Ventilation

Rationale: Tracheostomized patients weaning from mechanical ventilation are at risk for dryness of airway mucosa and sputum accumulation during disconnection from mechanical ventilation. High-flow tracheal oxygen (HFTO) is being used as supportive therapy during disconnection sessions in tracheostomized patients weaning from invasive mechanical ventilation (IMV) to limit dryness while maintaining oxygenation. We recently summarized the studies comparing physiological effects HFTO as compared to other interfaces, collectively referred to as conventional oxygen therapy (COT), in a systematic review and identified areas of lacking knowledge: effect on sputum viscoelasticity, respiratory effort early in the weaning process and dyspnea sensation. We hypothesize that HFTO, compared to COT, decreases viscoelasticity of the sputum and provides respiratory support during weaning. This may improve weaning by facilitating clearance of airway mucus, preventing respiratory failure, and providing comfort by decreasing dyspnea. Objective: To determine the physiological effect of HFTO compared to COT on sputum viscoelasticity, respiratory effort and dyspnoea. Study design: Pilot study with randomized crossover design, single-center. Study population: Twenty adult patients weaning from mechanical ventilation with tracheostomy. Intervention (if applicable): Crossover with COT and HFTO during two days in the weaning phase. Main study parameters/endpoints: Primary endpoint: sputum viscoelasticity measured by rheology during long disconnection sessions in the final phase of weaning. Secondary endpoints: respiratory effect measured by swings in esophageal pressure (PES) and prevalence and severity of dyspnoea sensation by visual analogue scale (VAS). Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The study compares two therapeutic modalities both used in clinical care without side-effects or complications. Study procedures and