Exhaled nitric oxide in interstitial lung diseases

Nitric oxide (NO) is a biomarker of nitrosative stress, which is involved in the pathogenesis of idiopathic interstitial pneumonias (IIP). This study evaluates exhaled NO levels in IIP patients and relates alveolar concentrations of NO (Calv(NO)) to pulmonary function test (PFT) and 6-minute walking test (6MWT) parameters. We measured fractional exhaled nitric oxide (FeNO), Calv(NO) and maximum conducting airway wall flux (J'aw(NO)) in 30 healthy subjects and 30 patients with IIP (22 idiopathic pulmonary fibrosis and 8 idiopathic non-specific interstitial pneumonias). IIP patients had higher FeNO at flow rates of 50-100-150 ml/s and higher Calv(NO) levels than healthy controls (p < 0.0001). Calv(NO) was significantly correlated with 6-minute walking distance (p < 0.0001), recovery time (p < 0.0005), TLC (p < 0.001), PVC (p = 0.01) and TLCO (p < 0.01). IIP patients showed abnormal nitric oxide production, probably due to lung fibrosis and oxidative-mediated lung injury. Calv(NO) was correlated with PFT and 6MWT parameters and is proposed as a potential biomarker of lung fibrosis and exercise tolerance. (C) 2014 Elsevier B.V. All rights reserved.