Study objectives: To test the hypothesis that exhaled
nitric oxide (NO) is increased in patients with chronic bronchitis, and
to compare the results with exhaled NO in patients with asthma and
Study design: Cross-sectional survey.
Setting and patients: Veterans Administration pulmonary
function laboratory. Patients (n = 179) were recruited from 234
consecutive patients. Two nonsmoking control groups of similar age,
with normal spirometry measurements and no lung disease, were used (18
patient control subjects and 20 volunteers).
Measurements: Participants completed questionnaires and
spirometry testing. Exhaled NO was measured by chemiluminescence using
a single-breath exhalation technique.
smoking status was associated with reduced levels of exhaled 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 = 57) were excluded from further analysis. Among nonsmokers, the
levels of exhaled NO were significantly higher in patients with chronic
bronchitis (17.0 ± 1.1 ppb; p = 0.035) 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 control
subjects, 11.1 ± 1.6 ppb; outside control subjects, 11.5 ± 1.5
ppb). The highest mean exhaled NO concentration occurred in patients
with both chronic bronchitis and asthma (20.2 ± 1.6 ppb; p = 0.005
vs control subjects).
Conclusions: Exhaled NO is
increased in patients with chronic bronchitis. The increase of exhaled
NO in patients with chronic bronchitis was similar to that seen in
patients with asthma. The highest mean exhaled NO occurred in patients
with both chronic bronchitis and asthma. Exhaled NO was not increased
in patients with COPD. Although chronic bronchitis and asthma have
distinct histopathologic features, increased exhaled NO in patients
with both diseases suggests common features of