DIFFUSE PULMONARY GRANULOMATOUS DISEASE IN DOG - RELATION BETWEEN PRESSURE-VOLUME BEHAVIOR AND MORPHOLOGIC FEATURES

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Abstract
Diffuse pulmonary granulomatous disease is an animal model of interstitial lung disease that is produced by i.v. injection of complete Freund''s adjuvant. The disease is characterized by granulomas interspersed with normal parenchyma. Diffuse pulmonary granulomatous disease was induced in dogs; the animals were killed, and the lungs were excised for physiologic and morphologic studies. The pressure-volume characteristics of excised lungs were determined during inflation and deflation with air, and during inflation with saline. The extent of the disease was assessed from a morphologic score and from the ratio of lung weight to body weight. In diffuse pulmonary granulomatous disease the morphologic score correlated well with the ratio of lung weight to body weight. The observed total lung capacity was decreased by the disease, and was correlated inversely with the morphologic score. The compliance of lungs with diffuse pulmonary granulomatous disease was lower than normal when expressed as ml per cm H2O per predicted total lung capacity, and it correlated inversely with the morphologic score. When compliance was expressed as ml per cm H2O per l of observed total lung capacity, it was the same in normal and diseased lungs. On the average, diffuse pulmonary granulomatous disease increased the pressure required to initiate inflation with air but not with saline. The disease reduces total lung capacity, primarily by replacing normal tissue with granulomas. The distensibility of the lung is decreased, but it is normal when corrected for volume. Lung distensibility appears to be determined primarily by the normal parenchyma between the granulomas. The increased difficulty of initiating inflation with air may result from distortion of small airways by adjacent granulomas.