Nitric oxide has been extensively studied as a noninvasive marker of airway inflammation, especially in asthma. Assuming, bronchoscopy can produced not only systemic but also local inflammatory response we hypothesized that bronchofiberoscopy can be responsible for an increase in nitric oxide synthesis with resulting increase in fractional concentration of exhaled nitric oxide (FE(NO)). Seventeen subjects (10 M, 7 F), at mean age of 53.8+/-14.1 yrs undergoing diagnostic bronchoscopy participated in the study. The indications for bronchoscopy were as follows: lung cancer (n=5; 29%), interstitial lung diseases (n=3; 18%), slowly resolving pneumonia (n=3; 18%), hemoptysis (n=3; 18%), differential diagnosis of asthma/ dyspnea (n=3; 18%). During bronchoscopy bronchial washing (n=7) and bronchoalveolar lavage (BAL) (n=10) has been performed. FE(NO) has been analyzed on-line with chemiluminescence analyzer (NIOX, Aerocrine, Sweden) according to American Thoracic Society guidelines, before and at 1, 2, 3 and 24 hours after bronchoscopy. Mean FE(NO) before bronchoscopy was 19.7+/-4.5 ppb (mean +/- SEM), post - bronchoscopy a decrease with a nadir at second hour (12.1+/-1.5 ppb, p<0.05) was observed, FE(NO) 24 hours after bronchoscopy was not different than baseline (18.4+/-2.5 ppb). There were no differences in the FE(NO) profile in BAL patients when compared to those in whom only the bronchial washing has been performed.
Conclusions: Bronchoscopy leads to a significant decrease in exhaled nitric oxide. The underlying mechanisms are unclear. Future studies including analysis of other inflammatory markers are needed to explain these changes.