Safety and effectiveness of a portable nasal high-flow device for improving exercise tolerance in patients with...

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by airflow limitation and exertional dyspnea, leading to reduced exercise tolerance and physical inactivity. Nasal high-flow (NHF) therapy delivers heated and humidified gas at a high flow rate through a nasal cannula, washing out anatomical dead space, providing a small degree of positive airway pressure, improving ventilation efficiency, and reducing the work of breathing. In addition, adequate humidification may enhance ciliary clearance. The AIRVO3^TM (Fisher & Paykel Healthcare, Auckland, New Zealand) is a novel portable NHF device that incorporates these features and can be used during ambulation. Using AIRVO3^TM during exertion may improve exercise tolerance in patients with COPD; however, its safety and effectiveness in ambulatory patients have not yet been established.

This is a single-center, early-phase, open-label, randomized, two-period crossover pilot trial conducted at Nagasaki University Hospital, designed to evaluate the acute, within-day effects of AIRVO3^TM on exercise tolerance during a single visit. Twenty patients with moderate to severe COPD will perform two 6-minute walk tests (6MWT) in a randomized order: one with AIRVO3^TM and one without the device. The primary outcome is the 6-minute walk distance (6MWD). Secondary outcomes include percutaneous oxygen saturation (SpO₂), transcutaneous partial pressure of carbon dioxide (PtcCO₂), respiratory rate, pulse rate, Borg dyspnea scale score, time to desaturation (SpO₂ ≤90%), time to PtcCO₂ ≥45 mmHg, time to respiratory rate ≥22/min, walking distance to the first rest, patient-reported comfort, and subjective symptoms. Safety outcomes include the incidence of SpO₂ <90%, adverse events (AEs), device-related discomfort, and withdrawal or dropout. Data will be analyzed primarily using paired t-tests and mixed-effects models that are appropriate for a crossover design.

This trial will evaluate whether a portable NHF device increases exercise tolerance and is safe during ambulation in patients with COPD who do not require long-term oxygen therapy. By using room air [finspiratory oxygen fraction (FiO₂) 21%] and focusing on high flow rather than high oxygen concentration, this study will clarify the pure effects of high-flow nasal therapy on exertional capacity. If the AIRVO3^TM device is shown to be effective and acceptable, it may expand the options for pulmonary rehabilitation and daily physical activity in patients with COPD. Because all assessments are performed during a single study visit, this trial specifically evaluates short-term, acute responses to AIRVO3^TM rather than long-term training effects of repeated use.

The study is registered in the Japan Registry of Clinical Trials (jRCT; trial ID jRCTs072240116; registered on February 20, 2025; https://jrct.mhlw.go.jp/latest-detail/jRCTs072240116). This article describes the protocol version 1.1 (March 11, 2025).