Further observations on luminal deformity and stenosis of nonrespiratory bronchioles in pulmonary emphysema

In an endeavour to elucidate the anatomical basis for the increased resistance to airflow which characterises the most peripheral conducting air passages in pulmonary emphysema, lumina of nonrespiratory bronchioles of lungs with mainly centrilobular disease were assessed for two- and three-dimensional features by: (1) determination of percentage conformity of the lumina of individual bronchioles in histological sections to hypothetical planes through cylinders (ie, ellipses with the same areas and circumferences), and (2) comparison of luminal areas at regular intervals along bronchiolar longitudinal axes. The lumina of most nonrespiratory bronchioles from normal lungs conformed closely to their respective ellipses, thus corroborating previous observations that they are normally cylindroid. In contrast, there was a substantial excess of plane section deformities in the lumina of nonrespiratory bronchioles from the emphysematous specimens. The incidence of stenotic bronchioles (by both diameter and area determinations) was also greatly increased in emphysema. Since there was a strong positive association between such stenotic lesions and bronchiolar deformity, the latter was concluded to be a major factor in bronchiolar restriction. Furthermore, these characteristics seemed to have three-dimensional expression, for the lumina of stenotic bronchioles in emphysema were irregular in a longitudinal fashion.