Objective: To review the concept of a possible link between asthma and obstructive sleep apnea syndrome (OSAS) and the impact on asthma symptoms of treatment of OSAS with continuous positive airway pressure (CPAP) in patients with both conditions.
Data sources: The Ovid, MEDLINE, and PubMed databases from 1950 to the present were searched for relevant articles regarding a possible relationship between asthma and OSAS and the effectiveness of CPAP in treating OSAS.
Study selection: Articles describing pathophysiologic conditions occurring in OSAS that may be linked to asthma pathogenesis were used for this review.
Results: The data suggest that OSAS is an independent risk factor for asthma exacerbations. CPAP has been shown in prospective clinical studies to have a positive impact on asthma outcome in patients with concomitant OSAS. Ameliorative mechanisms of treatment with CPAP include mechanical and neuromechanical effects, gastroesophageal acid reflux suppression, local and systemic anti-inflammatory effects (including suppression of increased serum levels of inflammatory cytokines, chemokines, and vascular endothelial growth factor), cardiac function improvements, leptin level suppression, weight reduction, and sleep restoration.
Conclusions: Asthma and OSAS are increasingly troublesome public health issues. Mounting evidence implicates OSAS as a risk factor for asthma exacerbations, thereby linking these 2 major epidemics. We describe potential mechanisms whereby CPAP, the first line of therapy for OSAS, might modify airway smooth muscle function and asthma control in patients with both disorders. Despite the ever-increasing population of patients with both disorders, large, prospective, randomized controlled studies are necessary to more fully evaluate CPAP and asthma outcomes.