[Nitric oxide in exhaled breath of patients with interstitial lung diseases]

Nitric oxide (NO) in exhaled breath is a marker of inflammation in bronchial asthma. Its role in interstitial lung disease has so far not been established.

The present study investigates exhaled NO in patients with interstitial lung diseases using constant flow and flow independent NO exchange parameters. These parameters were compared with clinical, lung function and BAL data.

83 patients with the following diagnoses were included into the study: 33 patients with sarcoidosis, 14 patients with idiopathic pulmonary fibrosis, 12 patients with connective tissue disease affecting the lungs, 10 with extrinsic allergic alveolitis, 8 patients with cryptogenic organizing pneumonitis, 6 patients with respiratory bronchiolitis with interstitial lung disease and 17 control patients. NO was analysed using a chemiluminescence-analyser. NO-concentration in the exhaled breath was measured at a constant flow of 50 ml/s according the ATS/ERS-standard (FENO50) and additionally at three different flow rates of 30, 100 and 300 ml/s to analyse the following flow independent NO parameters: NO alveolar concentration (CANO), airway wall NO concentration (CAWNO), maximum airway wall NO flux (JAWNO) and airway NO diffusing capacity (DAWNO). BAL was performed during flexible bronchoscopy with an irrigation volume of 100 ml 0.9 % saline solution in 5 aliquots of 20 ml each.

CANO (p = 0.012), CAWNO (p = 0.008) and DAWNO (p = 0.031) varied between the diagnostic groups. CANO was positively correlated with age (p < 0.05) and negatively correlated with inspiratory vital capacity (%pred.; p < 0.01). CAWNO was positively correlated with the relative proportion of CD8 cells in BAL (p < 0.01) and negatively correlated with smoking history (p < 0.05). DAWNO was negatively correlated with the relative proportion of CD8 cells in BAL (p < 0.05). FENO50 was positively correlated with age (p < 0.01) and negatively correlated with smoking history (p < 0.05).

In patients with interstitial lung diseases there were correlations of flow independent NO exchange parameters with diagnoses, lung function parameters and BAL-variables.