Can exhaled nitric oxide differentiate causes of pulmonary fibrosis?

• Published in: Respiratory medicine Vol. 107; no. 11; pp. 1789 - 1796
• Main Authors: Guilleminault, L, Saint-Hilaire, A, Favelle, O, Caille, A, Boissinot, E, Henriet, A.C, Diot, P, Marchand-Adam, S
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-11-2013; Elsevier Limited
• Subjects: Aged; Aged, 80 and over; Alveolitis, Extrinsic Allergic - complications; Alveolitis, Extrinsic Allergic - diagnosis; Biomarkers - metabolism; Breath Tests - methods; Bronchiolar disease; Connective Tissue Diseases - complications; Connective Tissue Diseases - diagnosis; Diagnosis, Differential; Disease; Exhaled nitric oxide; Female; Humans; Hypersensitivity pneumonitis; Idiopathic pulmonary fibrosis; Lungs; Male; Medical imaging; Nitric Oxide - metabolism; Pneumonia; Pneumonia - chemically induced; Pneumonia - complications; Pneumonia - diagnosis; Pulmonary Fibrosis - etiology; Pulmonary Fibrosis - physiopathology; Pulmonary/Respiratory; Respiratory Function Tests - methods; Retrospective Studies; Sensitivity and Specificity; Tomography, X-Ray Computed - methods; CANO; ILD; 25–75% Forced Expiratory Flow; Hypersensitivity pneumonitis; Idiopathic pulmonary fibrosis; HP; J'aw NO; TLC; interquartile range; CTD-ILD; drug induced pneumonia; ground-glass opacities; connective tissue disease-associated ILD disorders; FEF 25–75; systemic sclerosis; vital capacity; interstitial lung disease; Bronchiolar disease; SSC; Exhaled nitric oxide; conducting airway flux; Total Lung Capacity; DIP; IQR; VC; GGO; alveolar concentration of exhaled NO; FEV 1; fractional exhaled nitric oxide; FE NO; Forced Expiratory Volume in 1 s; IPF; FENO; J'awNO; FEV1; FE(NO); J'aw(NO); FEV
• ISSN: 0954-6111; 1532-3064
• DOI: 10.1016/j.rmed.2013.07.007

Summary Background Interstitial lung diseases (ILD) comprise a heterogeneous group of disorders, and when diagnosed at the stage of pulmonary fibrosis, the underlying lung disease can sometimes be difficult to identify. The aim of the present study was to determine whether there are differences in FENO (fraction of exhaled nitric oxide) between different subtypes of fibrotic ILD. Methods Sixty-one patients, with honeycombing on computed tomography (CT) scan, and whose FENO levels had been measured during chronic dyspnoea evaluation, were divided into four groups based on pulmonary fibrosis aetiology: idiopathic pulmonary fibrosis (IPF), chronic hypersensitivity pneumonitis (HP), connective tissue disease-associated ILD disorders (CTD-ILD), drug-induced pneumonia. The FENO values of each group were compared and CT scan features were analysed to identify the mechanisms involved in FENO change. Results The median FENO value of patients with chronic HP was 51 ppb (IQR 36–74), higher than that of the other groups (22 ppb (IQR 17–30) in IPF, 19 ppb (IQR 17–21) in drug-induced pneumonia, and 25 ppb (IQR 17–37) for CTD-ILD; p  = 0.008). At the cut-off value of 41 ppb, the optimal sensitivity and specificity to diagnose HP with FENO were respectively 76.9% and 85.4%. On CT scans, only extensive lobular areas with decreased attenuation, a recognized marker of bronchiolar disease, were associated with high FENO values ( p  = 0.0002). Conclusion FENO could be a tool for differentiating chronic HP from other types of pulmonary fibrosis. The mechanism involved seems to be bronchiolar disease.