Wd. Bennett et al., ENHANCED DEPOSITION OF FINE PARTICLES IN COPD PATIENTS SPONTANEOUSLY BREATHING AT REST, Inhalation toxicology, 9(1), 1997, pp. 1-14
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.