Effects of experimental emphysema and bronchiolitis on lung mechanics and morphometry

The effects of experimental emphysema and bronchiolitis on lung mechanics and morphology were studied in excised hamster lungs. The four study groups consisted of controls, bronchiolitis, emphysema, and combined lesions. The emphysema was induced by a single 6 hr exposure to an aerosol of papain solution. Bronchiolitis lesions were produced by a continuous 7 to 10 day exposure to 30-35 ppm nitrogen dioxide. Static elastic recoil pressures were greatly reduced in the emphysema lungs. There was a close correlation between the loss of elastic recoil and the decrease in internal surface area. Frequency dependent changes in dynamic compliance were observed in the lungs with emphysema but not those with bronchiolitis. Maximal expiratory flow rates were significantly decreased by emphysema and to a lesser extent by bronchiolitis. The determination of upstream resistance at small lung volumes was the most sensitive indicator of the mild bronchiolitis lesion. Mild bronchiolitis lesions may produce accentuated effects in the presence of emphysema.