ENHANCED DEPOSITION OF FINE PARTICLES IN COPD PATIENTS SPONTANEOUSLY BREATHING AT REST

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Abstract
Particulate air pollution has been linked to acute increases in mortality among individuals with preexisting cardiorespiratory disease. While these individuals may be predisposed to acute toxic effects, they may also receive an increased dose of particles to their lungs compared to healthy subjects. We measured fractional deposition (DF) of inhaled, fine particles in subjects with moderate-severe chronic obstructive pulmonary disease (COPD; n = 13) and an age-matched group of subjects (n = 11) with normal pulmonary function, mean age = 62 versus 67 yr, and FEV1 (% pred) = 33 versus 90, respectively. Each subject inhaled 2- m monodisperse, Carnauba wax particles while following a breathing pattern previously determined by respiratory inductance plethysmography (RIP) for that subject (i.e., that subject's spontaneous pattern at rest). Breath-by-breath DF (ratio of particles not exhaled to total particles inhaled) was determined by photometry at the mouth. The COPD patients had greater DF than normals, 0.40 0.16(SD) versus 0.26 0.06, p < .02. In addition, the COPD patients had an increased resting minute ventilation for DF measurements compared to normals, mean Ve = 11.2 L/min versus 7.4 L/min. As a result, deposition rate, Drate, directly proportional to particles depositing/time, was nearly 2.5 times greater in the COPD subjects relative to normal, Drate = 4.6 2.5 and 1.9 0.8 respectively, p < .005. Among the COPD subjects, Drate increased with increasing specific airway resistance, sRaw (r = .70, p < .01). These data indicate that at rest COPD patients receive an increasing dose of inhaled, fine particles with increased severity of their airways disease.