Efficacy of CPAP therapy on pulmonary function test in patients with COPD-OSA overlap syndrome

<bold>Background:</bold> Both COPD and OSA can cause nocturnal hypoxia. COPD-OSA overlap syndrome (OVS) has been shown to increase morbidity and mortality compared to each condition alone. A few nights of CPAP therapy in OVS patients showed improvement of exercise capacity in prior study. However, there has been no research examining the impact of longer-duration CPAP treatment in this population. <bold>Objective:</bold> To evaluate the efficacy of 2-month CPAP therapy on exercise capacity measured by 6-minute walk distance and oxygen consumption. <bold>Methods:</bold> A single-center open label randomized control trial was conducted at a university hospital in Bangkok, Thailand from January 2023 to January 2024. Participants with stable COPD underwent polysomnography to diagnose OSA. OVS patients were then randomized into control and CPAP treatment groups. Baseline and 2-month follow-up assessments consisted of spirometry, lung volume study, 6MWD, mobile device cardiopulmonary exercise test, and questionnaires. <bold>Results:</bold> 10 male patients were included in the intention-to-treat analysis, with the majority classified as GOLD stage 1 and 2. Severe OSA was present in 90%. A significant difference was found in 6MWD (372.8±19.87m. vs. 436.64±20.10m., mean difference:63.84 m(8.44–119.24),p=0.024). Peak oxygen consumption during 6-minute walk test also differed (825.8±44.05 ml/min vs. 1052.47±46.81 ml/min, mean difference:226.7ml/min(100.68–352.66),p<0.0001). The CPAP group exhibited lower CAT score, St George’s respiratory questionnaire, and Pittsburg sleep quality index. No spirometry or lung volumetry differences were found. <bold>Conclusion:</bold> CPAP improved exercise capacity as defined by 6MWD and oxygen consumption in OVS patients.