Continuous positive airway pressure treatment increases bronchial reactivity in obstructive sleep apnea patients

The effects of continuous positive airway pressure (CPAP) treatment on the function of the lower airways are poorly understood. One of the methods used to determine the influence of positive pressure breathing on lower airways is the bronchial hyperreactivity test. Some authors report that CPAP increases bronchial hyperreactivity, while others report decreases.

To assess the influence of CPAP treatment on bronchial reactivity and the effects of bronchial hyperreactivity on compliance to CPAP treatment.

The study group consisted of 101 obstructive sleep apnea syndrome patients (88 men and 13 women) with a mean age of 51 ± 11 years, mean apnea-hypopnea index of 53 ± 20 and mean body mass index of 32.6 ± 5.4. Patients were randomly assigned to a treatment group that received 3 weeks of CPAP therapy (group 1) or to a nontreatment control group (group 2). Pulmonary function tests and the methacholine bronchial provocation test were performed at baseline and 3 weeks later.

There were no statistically significant differences between treated and control groups in anthropometry and polysomnography variables. At baseline, bronchial hyperreactivity was found in 6 patients from group 1 and 5 patients from group 2. A significant increase in bronchial reactivity was observed after CPAP treatment. Log PC20M decreased from 1.38 ± 0.30 at baseline to 1.26 ± 0.50 (p < 0.05). In group 2, changes were statistically insignificant. Patients with bronchial hyperreactivity during CPAP treatment were characterized by significantly lower FEV1, FVC and MEF50 values.

CPAP produces statistically significant bronchial hyperreactivity. However, there were no clinical symptoms and it is not necessary to withdraw previous therapies.