Difference in inhaled aerosol deposition patterns in the lungs due to three different sized aerosols.

Deposition patterns of inhaled aerosol in the lungs were studied in five normal subjects and 20 patients with lung disease by inhaling radioaerosols with three different particle size distributions. These aerosols were generated from BARC, UltraVent, and Mistogen-EN-142. Particle size distributions generated by these three nebulizers were 0.84, 1.04 and 1.93 microns in activity median aerodynamic diameter (AMAD) with its geometric standard deviation (sigma g) of 1.73, 1.71 and 1.52, respectively. Deposition patterns of inhaled aerosols were compared qualitatively and quantitatively by studying six different parameters: alveolar deposition ratio (ALDR), Xmax, Xmean, standard deviation (S.D.), skewness and kurtosis of the radioactive distribution in the lungs following inhalation. It has been found that aerosol deposition patterns varied with particle size. The unevenness of aerosol deposition, Xmax, Xmean and the number of 'hot spots' became more prominent with the increase in particle size, whereas values of ALDR and S.D. decreased as particle size increased. Knowing these deposition characteristics would facilitate a judicious application of aerosol inhalation to medical use.