Figure 1.

Illustration of the conflicting effects of emphysema and lung volume on airway dimensions. A, Intact airway with attachments to the lung parenchyma. B, On the top, lung attachments are broken by emphysematous destruction, resulting in a diminished total bronchial area (TBA) (arrows) and increased wall area percent (WA%) (gray area). At the bottom, an increase in lung volume results in increased TBA (arrows) and lower WA%. C, The likely result of these two processes is an airway with lower TBA and an increased WA% compared with a normal airway.