Clinical, functional and pathological correspondence in early stage idiopathic pulmonary fibrosis: evidence for small airway obstruction 1-2.

We describe the clinical, physiological and pathological features of 23 subjects with early stage idiopathic pulmonary fibrosis. Thirteen subjects who had no symptoms had been fortuitously recruited by a routine chest radiograph, whereas the 10 other subjects complained of dyspnea. Twenty-one subjects showed only light to moderate extent of abnormalities on the chest radiograph. Fourteen subjects had a reduced vital capacity whereas 16 and 17 showed a reduced pulmonary compliance and an increase in lung elastic recoil, respectively. Transfer factor was significantly reduced in 18 subjects. Evidence for significant airway obstruction, mainly located at the peripheral level, was demonstrated by a reduced specific lung conductance and upstream conductance in 13 subjects. Airway obstruction was not associated with smoking habits. Bronchial hyperresponsiveness was noted in 50% of the 18 subjects studied. Although fibrosis was mild to moderate in 15 instances, it was only focal, i.e. at least one zone of normal parenchyma in the lung specimen in 17 subjects. Peribronchial fibrosis was established in 8/11 satisfactory biopsy specimens. Significant correlations were observed between rales, the radiological score, some functional indices and the characteristics of fibrosis. We conclude that small airway obstruction documented by physiological and pathological means is frequent in early stage idiopathic pulmonary fibrosis.