Development of a new ambulatory oxygen delivery method combining continuous oxygen flow and demand oxygen delivery systems: A prospective, single-blind, randomized crossover pilot trial

<bold>Background and aim:</bold> Although demand oxygen delivery system (DODS) prolongs ambulatory oxygen supply, the efficacy of preventing hypoxemia is likely to be lower than continuous oxygen flow (CF) as oxygen concentration to be inhaled with DODS depends on breathing pattern. This study aimed in comparing the efficacy between conventional oxygen delivery methods and a new method, which combined CF and DODS (CF+DODS), by assessing oxygen saturation (SpO₂) during walking in patients with COPD. <bold>Methods:</bold> After 6-min walk test (6MWT) familiarization, stable COPD patients performed three 6MWTs with different oxygen delivery methods in random order with CF, DODS and CF+DODS. Primary outcome was SpO₂ during the 6MWT. <bold>Results:</bold> Fourteen COPD patients completed the test. The linear mixed model on SpO₂ revealed significant main effects of oxygen conditions (F = 67.66, P < 0.001) and time (F = 126.69, P < 0.001), however no significant interaction (F = 0.56, P = 0.875). In the post-hoc analysis, SpO₂ in DODS was significantly lower than CF and CF+DODS throughout the 6MWT (Figure 1). There were no significant differences in distance walked and dyspnea at the end of the 6MWTs among each oxygen delivery condition. <fig><object-id>erj;64/suppl_68/OA5547/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig> <bold>Conclusion:</bold> CF+DODS enables a longer duration of ambulatory oxygen supply, while preventing hypoxemia to the same degree as CF.