Effect of Lung Parenchyma on Bronchial Collapsibility during Maximum Expiratory Flow in Dogs

Abstract

Effect of peribronchial lung parenchyma on bronchial collapsibility during the maximum expiration was studied in the dog lung. Maximum expiratory flow volume curve (MEFVC) was obtained from dogs with intact parenchyma (I), parenchyma being dissected away from main lobar bronchi 1.5cm in depth (II) and the dissected parenchyma glued to the bronchi with adhesive substance (III). Lung elastic pressure-volume curve and airway resistance were almost unchanged in the three conditions. Maximum expiratory flow (V_max) in condition II was considerably decreased and the ratio of decrease to the control value was high at the lower lung volumes. V_max in condition III was significantly higher than the control values except at the very low lung volumes. It was proved that even if the airway down to segmental bronchi was dissected from peribronchial lung parenchyma, V_max was significantly limited. It was concluded that the radial traction of peribronchial parenchyma to the bronchi reduced bronchial collapsibility considerably, and in the dissected bronchi of condition II dynamic airway collapse would occur very easily.