Participants with stable COPD from the chest medicine outpatient department will be randomized into two groups receiving HFNC or nasal cannula (NC) for 10 min followed by a 4-week washout period and crossover alternatively. We used a novel analytical measurement technique, IOS, to detect the difference in airway impedance in the participants after the HFNC or NC interventions. All data, namely IOS parameters, transcutaneous partial pressure of carbon dioxide, peripheral oxygen saturation, body temperature, respiratory rate, pulse rate, blood pressure, and PFT results at the time of pre-HFNC, post-HFNC, pre-NC, and post-NC, were analysed using SPSS (version 25.0, IBM, Armonk, NY, USA).
