Chest
Volume 101, Issue 3, March 1992, Pages 800-809
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The Senile Lung: Comparison with Normal and Emphysematous Lungs 2. Functional Aspects

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Senile lungs are characterized by a homogeneous enlargement of the alveolar airspaces, without fibrosis or destruction of their walls. Study of the functional characteristics of excised senile lungs showed an increase in minimal air and a shift to the left of the elastic recoil pressure-volume curves, less pronounced than in emphysematous lungs. Maximal expiratory volumes and flows were normal. Total lung capacity was not significantly increased, but this may be a consequence of preagonal edema. Comparison of normal, senile, and emphysematous lungs showed a close relationship between recoil pressures and mean linear intercept, Lm, and between forced expiratory volume in 1 s and diameter and density of the membranous bronchioles. It is concluded that airspace enlargement may precede emphysema and may be responsible for changes in lung elasticity. In this respect, senile lungs are an example of the functional changes caused by an isolated airspace enlargement.

Section snippets

MATERIAL AND METHODS

Studies were performed on 17 right and 12 left human lungs and one isolated left lower lobe (V50), obtained at autopsy. Lungs with leaks, gross parenchymal consolidations, and generalized fibrosis were excluded from the study. Functional investigations were started within 24 h after death. Prior to the investigations, the lungs were kept at +4°C. The main bronchus was tied to a cannula of fitting size by which the lung was suspended in an airtight box. To expand atelectatic regions, the lung

RESULTS

The investigated lungs were separated into three groups on the basis of their morphologic characteristics: normal lungs with values of mean linear intercept (Lm) within normal range (A), senile lungs, with uniformly increased Lm without destruction (B), and emphysematous lungs with an irregular increase of Lm and signs of destruction (C). The emphysematous lungs are of the centrilobular type (CLE). The static lung volumes, the pressure-volume characteristics, and some relevant data of the

DISCUSSION

We will discuss first the validity of functional indices measured in excised lungs, second, compare the values recorded in the three groups of lungs, with the purpose of relating the functional to the structural characteristics of senile with respect to normal and emphysematous lungs.

As compared with the expected in vivo values, static lung volumes (TLC, VC, MA/TLC) and shape constant k are rather low in our group of normal lungs. In contrast, the values of FEV1/VC are too large, and elastic

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    Reprint requests: Dr. Verbeken, Laboratorium voor Histopathologie, Kapucijnenvoer 33, B-3000 Leuven, Belgium

    Supported by a grant of the Fonds voor Geneeskundig Wetenschappelijk Onderzoek.

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