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VARIATION OF LUNG DEPOSITION OF MICRON SIZE PARTICLES WITH LUNG VOLUME AND BREATHING PATTERN
Citation:
KIM, C. S. AND S. Hu. VARIATION OF LUNG DEPOSITION OF MICRON SIZE PARTICLES WITH LUNG VOLUME AND BREATHING PATTERN. Presented at International Society for Aerosols in Medicine Biennial meeting, Rotterdam, NETHERLANDS, June 18 - 22, 2011.
Impact/Purpose:
In the present study we measured total lung deposition fraction (TDF) in healthy subjects (n=10) with varying lung volume (LV) from near residual volume (RV) to total lung capacity (TLC).
Description:
Lung volume and breathing pattern are the source of inter-and intra-subject variability of lung deposition of inhaled particles. Controlling these factors may help optimize delivery of aerosol medicine to the target site within the lung. In the present study we measured total lung deposition fraction (TDF) in healthy subjects (n=10) with varying lung volume (LV) from near residual volume (RV) to total lung capacity (TLC). The subject inhaled monodisperse aerosols (dp= 1, 3 and 5 urn) via a laser aerosol photometer with two tidal volumes (Vt=500 and 1000 ml) and a constant flow rate of 250 ml/s. Mathematical model was used to analyze regional deposition distribution at the inhalation conditions used in the experiment. TDF showed no or minimal changes with LV within +/-500 ml from FRC. Compared with values at FRC, TDF increased by 21,10 and 6% at RV and decreased by 13,5, and 4% at near TLC for Dp= 1, 3 and 5 um, respectively. Model analyses showed deposition did not change with LV for Dp=1 urn but was variable with Dp=3 and 5 urn in the tracheobronchial region. Variation was greater in the alveolar deposition, particularly with Vt=500 ml (-20% ~ +80%). Surface dose was found markedly increased (150-400%) at near RV and decreased (20-60%) at near TLC: changes were greater in the alveolar region and with smaller Vt. The results show that enhancement of local dose may be achieved by inhaling at low LV. A large Vt, however, tends to neutralize the effects of LV. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.