III. Pathological Findings and Radiological Changes in Chronic Bronchitis and Emphysema

Abstract

Chronic bronchitis is primarily concerned with changes in the bronchi, especially hypersecretion of mucus and damage caused by infection. This latter also causes emphysema, which must be included in any discussion of chronic bronchitis, but as it occurs in the respiratory part of the lung it is convenient to discuss it separately. In chronic bronchitis the most constant clinical finding is cough and sputum which, although it may be purulent from the presence of pus, is often mucoid. Normal. Mucous secretion is a normal function of the bronchial tree, mucous glands being concentrated in the trachea, lobar and segmental bronchi and the larger intra-segmental branches. Tracing an axial pathway in the direction of the periphery, the glands are numerous in the proximal five or so divisions and then decrease progressively in the smaller bronchi. Goblet cells, the mucus-secreting cells in the epithelium lining the bronchial tree, extend as far as its final ramifications, the terminal bronchioles, but, although here they are sparse, proximally goblet cells are numerous. Up to 100 ml. of mucoid secretion may be formed in a day but this amount does not give rise to phlegm. Hypersecretion. The earliest clinical finding in chronic bronchitis is cough and mucoid sputum, but it is not known what increase is necessary before sputum is produced nor what percentage of any increase is coughed up. In its earliest stages then chronic bronchitis would seem to be essentially a hypersecretion of mucus.