Aerosol probes of lung injury in a 28-wk longitudinal study of mild experimental emphysema in dogs

After baseline measurements of lung mechanics, effective air space diameter (EAD), and aerosol dispersion (AD), three dogs were exposed to two treatme nts of aerosolized papain (3 mi of a 4%;, solution), and measurements were repeated during a 28-wk follow-up period. EAD and AD were measured with bol uses of 0.7-mu m particles of di-2-ethylhexl sebacate, with Pen (i.e., volu metric bolus penetration/total lung capacity) between 0.1 and 0.4. After pa pain exposure, EAD increased a mean of 28% (P < 0.0001) and AD (Pen = 0.3, 0.4) increased 4-7% (P < 0.03). The progression of injury was indicated by increasing trends in total lung capacity (P < 0.05), residual volume (P < 0 .05), and EAD (P = 0.06) through week 28. There was no evidence of disease progression between weeks 18 and 28, whereas some of the data for individua l dogs suggested partial recovery from lung injury at week 28. The results show that aerosol probes can detect and characterize mild lung injury in ex perimental emphysema.