Differences in particle deposition between the two lungs

Certain inhalational diseases show a predilection for a particular region of one or the other lung that may be related to the site of deposition of inhaled particles. We conducted inhalation studies with monodispersed aerosol particles in 22 healthy student volunteers to determine how deposition varied between the two lungs. Ventilation lung scans were obtained with the subjects seated in front of a gamma camera while breathing radiolabelled particles. Subsequently we made paired comparisons of the radioactivity deposited in corresponding regions of the right and left lungs. Although regional differences in deposition between the left and right lung were often statistically significant, they were not always consistent between individuals. Particle deposition and the degree of penetration differed between the two lungs with there being generally more deposition in the perihilar region of the right lung. We suggest that the anatomy of the central airways may influence the pattern of deposition, thereby introducing disparities in particle deposition between the two lungs. The present findings lend support to experimental lung cast data and to the concept that anatomical differences between the two lungs influence the site of deposition.