CPAP increases bronchial reactivity in OSAS patients

Continuous positive airways pressure (CPAP) is a well known and safe method of treatment patients with obstructive sleep apnoea syndrome (OSAS). The effects of CPAP administration on the upper respiratory tract are known. However its effects on the lower respiratory tract still needs to be determined. Studies on bronchial hyperreactivity in patients treated by CPAP are contradictory. The aim of the study was to assess the influence of a 3-week CPAP treatment in patients with OSAS and to evaluate associations between changes in bronchial reactivity and clinical features of OSAS and lung function tests (LFT). Patients with newly diagnosed OSAS and lack of infection or chronic illness of the respiratory tract or other conditions which could influence bronchial hyperreactivity (BHR) were included. Investigations were performed in 101 patients. There were 88 males and 13 females, mean age 51.5±11.2 years and BMI 32.6±5.4 kg·m–2. Qualified patients were randomly divided into 2 groups: 76 patients to CPAP treatment group, 25 control group. Both groups did not differ in anthropometrics features, severity of OSAS and LFT. Metacholine challenge test (MchCT) was performed at baseline and repeated after 3 weeks. Analysis of the individual results showed that in 11 patients the MchCT was positive (6 in the CPAP and 5 in the control groups). After 3 weeks in the group of CPAP treated patients an increase of BHR was noted. Log PC20M decreased from 1.38±0.3 to 1.26±0.5 (p<0.05). The number of patients with a positive result in the MchCT increased from 6 to 16 patients. There was no significant change in BHR in the control group. It was found that CPAP treated patients with BHR were older, had less severe OSAS and lower FEV1 (p