Parenchymal, bronchiolar, and bronchial measurements in centrilobular emphysema: Relation to weight of right ventricle

Measurements of lung parenchyma, membranous bronchioles, and bronchial mucous gland hyperplasia were made on lungs from eight cases of pure centrilobular emphysema (CLE) and on five normal lungs. The lungs were fixed in formalin and inflated under partial vacuum at a standard transpulmonary pressure of +30 cm. H₂O. The results obtained from the upper halves and the lower halves of the lungs were compared. The circulatory effects of the disease were measured by weighing the heart ventricles, by studying the small pulmonary arteries in microscopical sections, and by post-mortem arteriography. Whereas the parenchymal and internal surface areas destroyed by the emphysematous spaces were relatively moderate and localized, right ventricular hypertrophy was noted in most of the cases. In these cases bronchiolar stenoses were found scattered throughout the whole lung and there was a reduction in the number of these bronchioles, mainly in the upper halves of the lungs. In CLE ventilatory disturbances were caused not only by the centriacinar dilated spaces delaying gas diffusion, but also by scattered bronchiolar stenoses situated at the termination of the conducting air passages. The stenoses seemed the more important cause. It was shown statistically that chronic arterial pulmonary hypertension and right ventricular hypertrophy were mainly the result of functional disturbances, especially hypoxia and abnormalities of VA/Q produced by the two structural changes situated at the end of the small airways.