The goal of this study randomized single-center crossover study is to evaluate the impact of asymmetrical versus symmetrical nasal high flow (NHF) therapy on work of breathing (WOB). The main question it aims to answer are:
1\. Does the asymmetrical NHF interface improve the work of breathing compared to the symmetrical NHF interface? Researchers will compare the symmetrical NHF interface to the symmetrical NHF interface to see if the the asymmetrical interface has a greater impact on the work of breathing.
Participants will :
1. receive NHF via both interfaces (FiO₂ 0.21, 50 L/min) for 15 minutes, in random order, with esophageal pressure monitoring and bioelectrical impedance analysis performed. 2. baseline characteristics will me monitored throughout the interventions 3. Esophageal pressure and minute ventilation will be monitored.
age ≥18 years old
absence of symptoms and signs of respiratory failure (SpO2>95% at FiΟ2 0.21)
pregnancy
SpO2<94% at FiΟ2 0.21
neuromuscular disease
contraindications to esophageal pressure monitoring (e.g., uncontrolled coagulopathy, esophageal disease, nasal trauma, allergy to local lidocaine)