Asymmetrical High Flow Nasal Cannula and End-Expiratory Lung Impedance

Objective: The primary aim is to assess end-expiratory lung impedance (EELI) changes during the application of high-flow oxygen therapy using asymmetric nasal cannulae, comparing conditions with the mouth closed and open in healthy volunteers in various positions. The secondary objective includes evaluating respiratory rate, shortening fraction, and diaphragm excursion via ultrasound. Study Design: This is a prospective observational cohort study conducted in the Critical Care Unit of Sanatorio Parque Rosario from November 5 to December 31, 2024. It will involve 20 healthy adult volunteers without respiratory conditions, with informed consent obtained from all participants. Volunteers with contraindications for electrical impedance tomography (EIT) will be excluded. Methods: Equipment Used: PulmoVista 500 Dräger (EIT), AIRVO 2 (high-flow oxygen generator), asymmetric nasal cannula (Optiflow OPT 966), Toshiba iStyle ultrasound machine. Procedures: The study includes EELI measurements in different positions (semi-seated, supine Fowler, prone, and prone Fowler) with various high-flow oxygen settings (40 and 60 L/min). Diaphragm excursion and thickening will be assessed using ultrasound. Scenarios and Measurements: 17 different testing scenarios will be conducted, with 16 intervals for washout breathing at room air between scenarios. Data on EELI, respiratory rate, and diaphragm measurements will be collected.