Regional deposition of aerosols in health and in airways obstruction: a comparison with krypton-81m ventilation scanning

In order to explore means of providing a convenient and simple method of assessing regional lung ventilation, we characterized a commercially available polydispersed aerosol of human albumin microspheres. The mass median particle diameter was 1.20 μm and nebulization of particles >2.0 μm diameter was prevented. After labelling this aerosol with technetium-99m, a quantitative comparison of regional particle deposition with regional lung ventilation, as assessed by krypton-81m, was made in eight normal subjects and twenty patients with varying degrees of chronic airflow obstruction. There was a strong correlation between the depth of particle penetration and the degree of airflow obstruction as indicated by the FEV1 (r=0.91 p<0.001) and also the degree of lung hyperinflation as indicated by the RV (r=-0.88; p<0.001). This aerosol preparation provides useful information about regional lung ventilation in normal subjects and patients with mild airflow obstruction, but patchy, primarily central areas of hyperdeposition can restrict its use in patients with severe airflow obstruction.