COMPUTED TOMOGRAPHY-GUIDED BRONCHOALVEOLAR LAVAGE IN IDIOPATHIC PULMONARY FIBROSIS

Background - High resolution computed tomography (HRCT) is now recogni sed as a sensitive tool for predicting the histological characteristic s of the lung parenchymal abnormalities in patients with idiopathic pu lmonary fibrosis (IPF). A reticular pattern on HRCT scanning is indica tive of fibrotic histology while a ground glass pattern has been assoc iated with inflammatory disease. The purpose of the present study was to investigate whether the cell population in the bronchoalveolar lava ge (BAL) fluid from different lobes differs according to HRCT characte ristics in patients with IPF. Methods - Twenty six patients with IPF ( 18 men) of mean (SE) age 67 (2) years were included in the study. A se miquantitative analysis of the extent of the abnormalities on the HRCT scan was applied by summing the proportion of both reticular and grou nd glass patterns in each lobe (expressed as percentage of total area evaluated) and 100 ml double BAL was then randomly performed in the lo be with the most extensive involvement (lobe A) and that with the leas t extensive involvement (lobe B). Results - Twenty three of the 26 pat ients (88%) had an abnormal cell count in the BAL fluid from lobe A co mpared with 18 patients (69%) with abnormalities in the BAL fluid from lobe B. The median (range) percentage of 8.5% (0-34%) and the absolut e numbers of neutrophils (1.3 x 10(4)/ml, 0-14.6 x 10(4)/ml) in lobe A were significantly higher than those in lobe B (5% (0-26%) and 1.2 x 10(4)/ml (0-5 x 10(4)/ml), respectively). The percentage (3%, 0-19%) a nd absolute numbers (0.65 x 10(4)/ml, 0-4 x 10(4)/ml) of eosinophils w ere also higher in lobe A than in lobe B (1% (0-12%) and 0.1 x 10(4)/m l (0-4.8 x 10(4)/ml), respectively). For the group as a whole a correl ation was found between the percentage and absolute numbers of neutrop hils in the BAL fluid and the total score of abnormalities on the HRCT scan in the most involved lobe (lobe A). Multiple regression analysis indicated that both the percentage and absolute numbers of neutrophil s were significantly and independently related to the extent of ground glass pattern. Conclusions - In patients with IPF the cell population in the BAL fluid is not homogeneous and seems to be related to the ch aracteristics of the abnormalities on the HRCT scan present in the lav aged lobe.