Purposes:

1. To investigate whether patients with severe obstructive sleep apnea syndrome (OSAS) are at higher risk for exercised-induced bronchoconstriction (EIB) due to baseline airway inflammation compared with age, gender, and body mass index (BMI)-matched controls.
2. To investigate the effect of 3-month continuous positive airway pressure (CPAP) therapy on EIB for patients with severe OSAS.

Obstructive sleep apnea syndrome (OSAS) is characterized by repeated episodes of upper airway obstruction during sleep. Recent studies have found evidence of airway inflammation in patients with OSAS. Individuals with chronic airway inflammation are at higher risk for exercise-induced bronchoconstriction (EIB). We hypothesized patients with OSAS are at higher risk for EIB due to baseline airway inflammation. Continuous positive airway pressure (CPAP) is a known standard treatment for OSAS, thus the second aim of the study will be investigating the effect of 3-month CPAP therapy on EIB for patients with OSAS. Twenty severe OSAS patients and 20 control individuals matched for age, gender, and body mass index (BMI) will be recruited. All participants will come to the laboratory on 2 separate days (5~14 days interval). On the 1st visit, baseline pulmonary function test (PFT) and airway inflammation assess by induced sputum will be performed. On the 2nd visit, an exercise challenge test will be performed using standard testing protocol and post-exercise forced expiratory volume in one second (FEV1) will be measured at 2.5, 5, 10, 15,20, and 30 minutes. For patients with severe OSAS, all measurements will be repeated after 3-month CPAP therapy.

Inclusion Criteria:

1. Age ranged 18-65 y/o
2. Severe OSA (AHI≧30/hr)
3. BMI<35 kg/m2

Exclusion Criteria:

1. Clinical asthma

2. Chronic lung disease (FEV1<70% predicted or FEV1/FVC<70%)

3. Exercise contraindication:

   • Stroke or heart attack in last 3 months
   • Major cardiovascular disease
   • Unstable angina
   • Unable to perform cycle ergometry due to musculoskeletal problems

4. Respiratory tract infection in the past 2 weeks

5. Inability to perform acceptable-quality spirometry

6. Refuse to participate