Conducting Airways in Lung Fibrosis

Diffuse Interstitial Pneumonias are a heterogeneous group of chronic respiratory diseases. Idiopathic Pulmonary Fibrosis, one of such diseases, is characterized by lesions of the conducting airways including extension of bronchioles towards the distal lung, or bronchiolization of the distal lung. Such lesions are traditionally referred to as "traction bronchiectasis" although no evidence supports a cause-and-effect relationship between alveolar fibrosis and airway lesions. Another feature of IPF is chronic, invalidating dry cough. Our hypothesis is that IPF is characterized by early increases in the volume of conducting airways, that such changes correlate with cough, and that airway changes are in direct relation with airway fibrosis. The primary aim of this study is to demonstrate increased anatomical dead space (VD), a surrogate for conducting airway volume, in patients with moderate (or early) IPF, in comparison with subjects without any respiratory disease ("non-DIP controls"). The secondary aims are : To show that VD is increased in patients with IPF in comparison with patients with other DIPs ("DIP controls"), to show that in patients with IPF increased VD does not correlate with indices of alveolar fibrosis, and to show associations between increased VD and cough and other respiratory symptoms in patients with IPF.