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 treatments of aerosolized papain (3 ml of a 4% solution), and measurements were repeated during a 28-wk follow-up period. EAD and AD were measured with boluses of 0.7-micrometer particles of di-2-ethylhexl sebacate, with Pen (i.e., volumetric bolus penetration/total lung capacity) between 0.1 and 0.4. After papain 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 18. There was no evidence of disease progression between weeks 18 and 28, whereas some of the data for individual dogs suggested partial recovery from lung injury at week 28. The results show that aerosol probes can detect and characterize mild lung injury in experimental emphysema.