Abstract
BackgroundWe have previously shown that the bronchodilatory effect of deep inspiration is attenuated in individuals with COPD. This study was designed to investigate whether the impairment in this effect is associated with loss of alveolar attachments.MethodsWe measured deep inspiration (DI)-induced bronchodilation in 15 individuals with and without COPD (67 ± 2.2 yrs of age, mean ± SEM) undergoing lobar resection for peripheral pulmonary nodule. Prior to surgery, we measured TLCO and determined the bronchodilatory effect of deep inspiration after constricting the airways with methacholine. The number of destroyed alveolar attachments, as well as airway wall area and airway smooth muscle area, were determined in tumor-free, peripheral lung tissue.ResultsThe bronchodilatory effect of deep inspiration correlated inversely with the % destroyed attachments (r = -0.51, p = 0.05) and directly with the airway smooth muscle area (r = 0.59, p = 0.03), but not with the total wall area (r = 0.39, p = 0.15).ConclusionWe postulate that attenuation of airway stretch due to loss of alveolar attachments contributes to the loss of the bronchodilatory effect of lung inflation in COPD.
Highlights
We have previously shown that the bronchodilatory effect of deep inspiration is attenuated in individuals with COPD
We postulate that attenuation of airway stretch due to loss of alveolar attachments contributes to the loss of the bronchodilatory effect of lung inflation in COPD
We have suggested that the lack of deep inspiration-induced bronchodilation may be one of the major factors that contribute to persistent airway narrowing in chronic obstructive pulmonary diseases
Summary
We have previously shown that the bronchodilatory effect of deep inspiration is attenuated in individuals with COPD. We have recently demonstrated that the ability of deep inspirations to dilate constricted airways is impaired in subjects with COPD [1]. The mechanism accounting for the reduction in the bronchodilatory effect of deep inspiration in COPD has not yet been elucidated. When a deep inspiration takes place, radial traction is applied to the outer airway walls by virtue of the forces of interdependence between the airways and the surrounding parenchyma [2], which are sustained by the connective tissue of the lungs. If the airways are constricted, the stretch imposed by airway distension may produce bronchodilation [3,4]
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