The purpose of this study is to evaluate the effects of CPAP treatment on airway and systemic inflammation in obstructive sleep apnea.

Obstructive sleep apnea (OSA) is characterised by repetitive episodes of upper airway obstruction during sleep. Systemic and airway inflammation has been recently shown to be associated with OSA and is hypothesized to contribute to the clinical manifestation and the complications of OSA patients.

Continuous positive airway pressure (CPAP) is a first-line treatment for OSA and improves diurnal and nocturnal symptoms. However, the effectiveness of CPAP in reversing airway inflammation is less compelling in comparison to systemic inflammation.

This study will assess NO in exhaled breath, inflammatory biomarkers in induced sputum and blood of OSA patients and other clinical measurements before and after 3 months of CPAP treatment.

Inclusion Criteria:

• Subjects on admission for sleep study under the Respiratory Care and Sleep Control Medicine, Kyoto University Hospital.
• Subjects diagnosed with OSA (apnea hypopnea index >=20/hour) by overnight polysomnography.

Exclusion Criteria:

• Known history of respiratory diseases that will affect airway inflammatory markers like asthma, chronic obstructive pulmonary disease and bronchiectasis.
• Treatments with corticosteroids or other immunosuppressive drugs.