Exercise-Induced Bronchoconstriction in Patients with Severe Obstructive Sleep Apnea Syndrome
Date Issued
2010
Date
2010
Author(s)
Lin, Pei-Chun
Abstract
Background and purpose: 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) during exercise. The main purpose of this study was to evaluate EIB during exercise challenge test in patients with severe OSAS. The effect of a 3-month continuous positive airway pressure (CPAP) therapy on EIB was also explored. Methods: Twenty-two patients with severe OSAS and 9 control subjects matched for age, gender, and body mass index (BMI) were recruited from sleep clinic. All participants came to the laboratory on 2 separate days. On the 1st visit, baseline pulmonary function test (PFT) and airway inflammation assessed by induced sputum were performed. On the 2nd visit, an exercise challenge was performed using standard testing protocol and post-exercise forced expiratory volume in one second (FEV1) were measured at 2.5, 5, 10, 15, 20, and 30 minutes. For patients with severe OSAS, all measurements were repeated after a 3-month CPAP therapy. Results: The FEV1/FVC ratio (p<0.01) and FEF25-75 (p=0.03) were significantly lower in the OSAS group than those in the control group. None of the subjects in the OSAS group demonstrated EIB attack after exercise challenge test. The percentages of macrophage in the induced sputum were significantly lower in the OSAS group both at baseline and post-exercise (p=0.03). Compared with baseline, the percentages of bronchial epithelial cells were significantly higher after exercise challenge test in both groups. The percentage of neutrophil at baseline was negatively correlated with the maximal FEV1 drop post exercise challenge test. Conclusions: The study confirmed airway inflammation exists in patients with severe OSAS. Although no EIB attack was found in patients with OSAS in this study, the correlation between airway inflammation and FEV1 changes post exercise challenge test suggests that the degree of airway inflammation plays a role in how airways would respond to exercise.
Subjects
Obstructive sleep apnea
Airway inflammation
Exercise-induced bronchoconstriction
Continuous positive airway pressure
Type
thesis
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