[Experimental study in the cat on the alveolar density and heterogeneity in the obstructed lung. Comparison with the emphysematous lung in the aged].

An experimental model of lung obstruction has been achieved in the cat reared in our laboratory. 30 young adults (J) and one adult subject (A) had tracheal stenosis from 8 to 15 weeks and were the object of a study of pulmonary airways and were compared with four young controls and seven older controls. The presence of emphysema was revealed by microscopy. The size of the alveoli was measured by the mean linear intercept (MLI). The study was systematized by an image analyser giving the ratio of airway spaces to pulmonary tissue (% of surface). The mean value S represented the alveolar section in the lung. Alveolar heterogeneity was expressed by the dispersion of the point values S around the mean S. The animals had episodes of ventilatory distress. Cytology of the broncho-alveolar lavage performed when the animals were sacrificed did not distinguish between the obstructive and other subjects. Emphysema was found in 10 out of 22 of the young stenosed animals. No control J were abnormal. 5 adults were emphysematous through ageing (5 years or more). The mean linear intercept of the alveoli was increased in the emphysematous (115%) and even more in the obstructive cases without or with emphysema where MIL attained 173%. The obstructive lung, whether emphysematous or not, is heterogeneous. Emphysema, always focal, corresponded to an alveolar section which was weakened (S less than S controls - 2 standard deviations) for 40% of the older subjects and for 50% of the J obstruction, up to two times more often than in obstruction without emphysema.(ABSTRACT TRUNCATED AT 250 WORDS)