Management of Patients with Asthma, COPD, and OSA in Outpatient Unit: ACOSOU-Global Perspectives and Challenges.

Obstructive sleep apnea (OSA) is increasingly recognized as a major comorbidity in chronic respiratory diseases, particularly asthma and chronic obstructive pulmonary disease (COPD). The coexistence of OSA with asthma or COPD significantly complicates the clinical course, leading to poorer disease control, more frequent exacerbations, reduced lung function, impaired sleep quality, and increased cardiovascular and overall mortality. In asthma, OSA exacerbates airway inflammation, enhances bronchial hyperresponsiveness, and decreases responsiveness to standard therapies. In COPD, the "overlap syndrome" is associated with profound nocturnal hypoxemia, chronic hypercapnia, pulmonary hypertension, and a markedly elevated risk of hospitalization and death. Underlying mechanisms include chronic airway inflammation, oxidative stress induced by intermittent hypoxia, instability of ventilatory control (high loop gain), structural upper-airway alterations, and the burden of obesity and metabolic dysfunction. These interactions highlight the urgent need for integrated and proactive management strategies. Thus, we propose an Asthma-COPD-OSA Outpatient Unit (ACOSOU)-a care-delivery model, not a disease entity-designed to integrate systematic screening, diagnosis, treatment initiation, and long-term follow-up of OSA in patients with asthma and COPD. Optimal care requires systematic screening in respiratory outpatient settings, appropriate diagnostic pathways using polysomnography or home sleep apnea testing, and individualized treatment approaches. Continuous positive airway pressure (CPAP) remains the cornerstone therapy for OSA-asthma and OSA-COPD overlap, improving gas exchange, reducing exacerbations, and enhancing disease control. Comprehensive management also includes optimization of inhaled therapies, pulmonary rehabilitation, weight reduction, sleep hygiene, and multidisciplinary collaboration. This review proposes an integrated ACOSOU model to streamline screening, diagnosis, CPAP titration, and long-term follow-up. However, implementation in low- and middle-income countries faces challenges including limited trained sleep-medicine personnel, unequal access to diagnostic tools, and high CPAP costs without insurance coverage. Strengthening infrastructure, training, and policy support will be essential to improve outcomes for patients with chronic respiratory diseases and OSA comorbidity.