You are here:
ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD
Citation:
Brown, J. S., K. L. Zeman, W. D. Bennett, AND C S. Kim. ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD. Presented at American Thoracic Society Annual Meeting, San Francisco, CA, May 18-23, 2001.
Description:
Individuals affected with chronic obstructive pulmonary disease (COPD) have increased susceptibility to adverse health effects from exposure to particulate air pollution. The dosimetry of ultrafine aerosols (diameter # 0.1 :m) is not well characterized in the healthy or diseased lung. We measured the deposition and 24-hour retention (Ret24) of Tc-99m labeled carbon particles (0.06 :m diameter) in a group of 7 COPD patients with moderate airways obstruction (FEV1, 65"16 %predicted; Age, 57"11 yrs) and 9 healthy age-matched volunteers (FEV1, 103"16 %predicted; Age, 53"11 yrs). Aerosol was inhaled by subjects at their spontaneous sedentary breathing pattern measured by respiratory inductance plethysmography. The aerosol total deposition fraction (DF) was measured using a filter technique. Planar gamma scintigraphy was used to quantify regional particle deposition (RDep), Ret24 , and regional ventilation (RVent) from a multiple-breath Xe-133 washout. Regions of interest (ROI) were established by dividing the lungs into thirds by height and half by width. RDep was computed as the fraction of aerosol deposited in a ROI normalized to volume. RVent was computed as the xenon washout rate for a ROI divided by the combined washout rate for all ROI. A strong linear relationship, which did not differ significantly between groups, was found between RDep and RVent (Slope'1.0, p<0.001). Ret24 was also quite similar between COPD patients (81"9%, Mean"SD) and healthy subjects (83"9%). However, DF was significantly increased in the COPD patients (64"9%) relative to the healthy subjects (51"8%) (p'0.01, two-tailed t-test). Across all subjects, DF increased with decreased %predicted FEV1(r'!0.82, p<0.001). Results suggest moderate airways obstruction may cause an average 25% increase in tissue doses from ultrafine aerosol exposures relative to the healthy lung. Severe airways obstruction might further augment tissue doses and contribute to the susceptibility of this population. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.