Feasibility assessment of double-blind, crossover, random controlled trial protocol comparing two oxygen-supplemented pulmonary rehabilitation for patients with chronic obstructive pulmonary disease v1

_Background_: Pulmonary rehabilitation (PR) for patients with chronic obstructive pulmonary disease (COPD) improves exercise tolerance and COPD assessment test score (CAT). Oxygen supplementation during PR facilitates exercise physiological benefits. This study aimed to assess the feasibility of a trial comparing two oxygen supplementation methods, with the hypothesis that both would be valid and produce distinct outcomes. _Methods_: This double-blind, crossover, randomized controlled trial compared two oxygen supplementations (FiO2 0.3 or 0.5) during PR for patients with COPD (n=6) using a high-flow nasal cannula. Data on the 6MWD, CAT, and physical measurements were collected. Participants underwent one month of regular PR followed by two months of oxygen-supplemented PR, with data collected again after this period. Statistical significance was set at 0.05 with a power of 0.8, and the required sample size was calculated accordingly. _Results_: The required sample size could not be calculated based on the 6MWD. The improvement in CAT by FiO2 0.3 PR was greater than that by FiO2 0.5 PR. The standardized effect size and the corresponding required sample sizes for the CAT, quadriceps muscle power, lower leg circumference, trunk muscle mass, and leg muscle mass were 0.32/81, 0.66/8, 0.17/114, 0.27/88, and 0.24/56, respectively. _Conclusions_: Given the small number of participants, the 6MWD and CAT were not appropriate primary endpoints for comparing the effectiveness of the two oxygen supplementations during PR in patients with COPD. However, the quadriceps muscle power was identified as the most suitable primary endpoint among all the investigated parameters.