Bronchial Pressure Measurements in Emphysema and Bronchitis*

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Abstract
Bronchial pressures were measured in a segmental and main-stem bronchus in 9 patients with chronic airway obstruction, simultaneously with lung volume, flow at the mouth, and esophageal pressure during a series of vital capacity breaths in which the subject attempted to increase flow rate with each breath. Subsequently, radiopaque material was instilled into the tracheo bronchial tree, and cinefluorographic films were taken during forced expiration and cough. The technique permitted identification of the flow-limiting airways, location of the obstruction, and measurement of the caliber changes in the airways. The results showed that there are 2 levels of obstruction in emphysema and bronchitis. One is in the small airways, is relatively fixed, present on both inspiration and expiration, and little affected by changes in lung volume, and the other obstruction is in the large airways, is highly variable, present only on expiration, and markedly affected by changes in lung volume. In 5 patients expiratory flow limitation was due to the large airway obstruction; in 2 patients it was due to obstruction in the small airways; and in 2 others both large and small airways appeared to limit flow simultaneously. The relative severity of the 2 lesions apparently determined which obstruction is flow limiting. In those patients in whom collapse of the large airways limited flow, there was significantly less narrowing of the segmental bronchi during forced expiration compared to the other patients. The cough mechanism is therefore more seriously impaired in the former group.