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Increased exhaled nitric oxide in patients with stable chronic obstructive pulmonary disease
M Corradi1, M Majori, G C Cacciani
1Istituto di Clinica delle Malattie dell'Apparato Respiratorio, Università degli Studi di Parma, Parma, Italy.
Background:
Nitric oxide (NO) plays an important role as an inflammatory mediator in the airways. Since chronic obstructive pulmonary disease (COPD) is characterised by airway inflammation, a study was undertaken to determine NO levels in the exhaled air of patients with COPD.
Methods:
Two groups of patients with clinically stable COPD were studied, 10 current smokers and 10 ex-smokers. Two control groups of healthy subjects consisting of 10 current smokers and 20 non-smokers were also studied. Exhaled NO levels were measured by the collection bag technique and NO chemiluminescence analyser.
Results:
Mean (SE) levels of exhaled NO in ex-smokers and current smokers with COPD (25.7 (3.0) ppb and 10.2 (1.4) ppb, respectively) were significantly higher than in non-smoker and current smoker control subjects (9.4 (0.8) ppb and 4.6 (0.4) ppb, respectively). In current smokers with COPD exhaled levels of NO were significantly lower than in ex-smokers. In this latter group of patients there was a significant negative correlation between smoking history (pack years) and levels of exhaled NO (r = -0.8, p = 0.002). A positive correlation was seen between forced expiratory volume in one second (FEV1) and levels of exhaled NO (r = 0.65, p = 0.001) in patients with COPD.
Conclusions:
These data show that exhaled NO is increased in patients with stable COPD, both current and ex-smokers, compared with healthy control subjects.