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

Particulate air pollution has been linked to acute increases in mortal ity among individuals with preexisting cardiorespiratory disease. Whil e these individuals may be predisposed to acute toxic effects, they ma y 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 = I ii with normal pulmonary function, mean age = 62 versus 67 yr, and FEV, (%pred) = 33 versus 90, respectively. Each subject inhaled 2- mu m monodisperse, Carnauba wax particles while following a breathing pattern previously determined by respiratory inductance plethysmograph y (RIP) for that subject (i.e., that subject's spontaneous pattern at rest). Breath-by-breath DF (ratio of particles not exhaled to total pa rticles inhaled) was determined by photometry at the mouth. The COPD p atients 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 V-e = 11.2 L/min versus 7.4 L/min. As a result, deposition rate, D-rate, d irectly proportional to particles depositing/time, was nearly 2.5 time s greater in the COPD subjects relative to normal, D-rate = 4.6 +/- 2. 5 and 1.9 +/- 0.8 respectively, p < .005. Among the COPD subjects, D-r ate increased with increasing specific airway resistance, sRaw (r = .7 0, 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.