The Effect of High Flow Oxygen Therapy Via Tracheostomy on Diaphragm Function in Patients With Prolonged Weaning From Mechanical Ventilation

Critically ill patients who experience difficulties in weaning from the ventilator often undergo tracheostomy. These patients usually undergo spontaneous breathing trials receiving oxygen via T-piece. While the high flow oxygen therapy (HFOT) respiratory support system, delivered through nasal cannulas, has demonstrated clinical benefits on respiratory function, limited data exist on whether such effects are also present in HFOT through tracheostomy. Therefore, we plan to perform a study to examine the short-term effects of HFOT on diaphragmatic function in tracheostomized patients with prolonged weaning from mechanical ventilation.

After disconnection from the ventilator, patients will undergo a 30-minute spontaneous breathing trial receiving oxygen either conventionally via T-piece, or by HFOT delivered via tracheostomy, followed by a washout period of 15 min breathing through T-piece and 30 min receiving oxygen with the other modality in a randomized manner. At the start and end of each study period, patients will undergo an assessment through diaphragm ultrasonography, which includes excursion of diaphragmatic dome and thickness of diaphragmatic zone of apposition at end-inspiration and end-expiration. Subsequently, the diaphragmatic thickening fraction will be calculated as the difference between end-inspiratory and end-expiratory thickness divided by end-expiratory thickness. Also. arterial blood gases as well as respiratory rate (RR) and tidal volume (TV) (through a Wright's spirometer) will be measured.