Portable High-Flow Nasal Oxygen during Walking in Patients with Severe Chronic Obstructive Pulmonary Disease: A Randomized Controlled Trial

High-flow nasal oxygen (HFNO) improves exercise capacity, oxygen saturation, and symptoms in patients with chronic obstructive pulmonary disease (COPD). Due to the need of electricity supply, HFNO has not been applied during free ambulation.We evaluated whether HFNO delivered during walking by a battery-supplied portable device was more effective than usual portable oxygen in improving exercise capacity in patients with COPD and severe exercise limitation. The effects on 6-min walking tests (6MWTs) were the primary outcome.After a baseline 6MWT, 20 stable patients requiring an oxygen inspiratory fraction (FiO2) <0.60 during exercise, randomly underwent 2 6MWT carrying a rollator, under either HFNO with a portable device (HFNO test) or oxygen supplementation by a Venturi mask (Control) at isoFiO2. Walked distance, perceived dyspnea, pulse oximetry, and inspiratory capacity at end of the tests as well as patients' comfort were compared between the tests.As compared to baseline, walked distance improved significantly more in HFNO than in the control test (by 61.1 ± 37.8 and 39.7 ± 43.8 m, respectively, p = 0.01). There were no significant differences between the tests in dyspnea, peripheral oxygen saturation, or inspiratory capacity, but HFNO test was appreciated as more comfortable.In patients with COPD and severe exercise limitation, HFNO delivered by a battery-supplied portable device was more effective in improving walking distance than usual oxygen supplementation.