Increased exhaled nitric oxide in chronic bronchitis - Comparison with asthma and COPD

Study objectives: To test the hypothesis that exhaled nitric oxide (NO) is increased in patients with chronic bronchitis, and to compare the results w ith exhaled NO in patients with asthma and COPD. Study design: Cross-sectional survey, Setting and patients: Veterans Administration pulmonary function laboratory . Patients (n = 179) were recruited from 234 consecutive patients. Two nons moking control groups of similar age, with normal spirometry measurements a nd no lung disease, were used (18 patient control subjects and 20 volunteer s), Measurements: Participants completed questionnaires and spirometry testing. Exhaled NO was measured by chemiluminescence using a single-breath exhalat ion technique. Results: Current smoking status was associated with reduced le, els of exha led NO (smokers, 9.2 +/- 0.9 parts per billion [ppb]; never and ex-smokers, 14.3 +/- 0.6 ppb; p < 0.0001). Current smokers (n = 97) were excluded from further analysis. Among nonsmokers, the levels of exhaled NO were signific antly higher in patients with chronic bronchitis (17.0 +/- 1.1 ppb; p = 0.0 35) and asthma (16.4 +/- 1.3 ppb; p = 0.05) but not in those with COPD (14. 7 +/- 1.0 ppb; p = 0.17) when compared with either control group (patient c ontrol subjects, 11.1 +/- 1.6 ppb; outside control subjects, 11.5 +/- 1.5 p pb), The highest mean exhaled NO concentration occurred in patients with bo th chronic bronchitis and asthma (20.2 +/- 1.6 ppb; p = 0.005 vs control su bjects). Conclusions: Exhaled NO is increased in patients with chronic bronchitis. T he increase of exhaled NO in patients with chronic bronchitis was similar t o that seen in patients with asthma, The highest mean exhaled NO occurred i n patients with both chronic bronchitis and asthma, Exhaled NO was not incr eased in patients with COPD, Although chronic bronchitis and asthma have di stinct histopathologic features, increased exhaled NO in patients with both diseases suggests common features of inflammation.