A morphometric study in ordinary lungs of bronchial dimensions throughout the airway tree as a basis for the analysis of COPD
Yaegashi, H.; Ebina, M.; Takahashi, T.
Nihon Kyobu Shikkan Gakkai Zasshi 28(6): 819-827
1990
ISSN/ISBN: 0301-1542 PMID: 2214423 Document Number: 357670
A morphometrical method was established to estimate the initial dimensions of bronchi in the state in which they are strongly deformed due to narrowing or ectasis, and to enable the determination of the grade of deformity. In ordinary lungs from 16 autopsy cases, the dimension of airways were correlated with that of the accompanying pulmonary arteries to establish a standard for the estimation of the former from the latter. In each case, cross-sectioned pairs of an airway and an artery were sampled so as to cover the entire range from segmental bronchi to respiratory bronchioles. The varingly constricted state of airways and ateries was standardized by measuring the perimeter length of L of the epithelial basement membrane (BM) for airways and the internal elastic membrane (IEM) for arteries with a digital image analyzer, and reducing these into a circular state with completely stretched BM and IEM, where D(br), the anatomical diameter of airway, and D(pa), that of artery, were calculated from L. In addition, the sectional area of the epithelium was measured to calculate Rs, the ratio of luminal stenosis by epithelial thickening. In every case, a close correlation was shown to exist between D(br) and D(pa) on bilogarithmic coordinates: When all the measurements from 671 pairs of D(Br) and D(pa) were pooled, the correlation coefficient proved to be as high as 0.91 (p < 0.001). This allows estimation of the deminsion of an airway from that of the accompanying artery, even when the airway is severely deformed like in COPD. The range of D(br) for the bronchi (B), that for the membranous bronchioles (MB) and the respiratory bronchioles (RB), were shown to overlap between the neighboring ranges. At the border between MB and RB,D(br)=0.55 mm and D(pa)=0.33 mm, values apparently very significant from a patho-physiological point of view. Rs had a tendency to rise toward the periphery, normally however not exceeding 10%. Concerning the arterioles running along the respiratory bronchioles, no significant difference in D(pa) was proved to exist between control and COPD lungs, making it possible to estimate the original D(br) upon D(pa) also in these diseases.