Am. J. Respir. Crit. Care Med., Vol 152, No. 1, Jul 1995, 32-37.
Added external resistance reduces oropharyngeal deposition and increases lung deposition of aerosol particles in asthmatics
K Svartengren, P Lindestad, M Svartengren, K Philipson, G Bylin and P Camner
Department of Respiratory and Allergic Diseases, Karolinska Institute, Huddinge University Hospital, Sweden.
Mouth and throat, and regional lung deposition was estimated in fifteen
asthmatic subjects for 3.6-microns (aerodynamic diameter) radiolabeled
polytetrafluoroethylene (Teflon) particles inhaled at 0.5 L/s with and
without added external resistance. Radioactivity was measured by a profile
scanner. Behavior of the pharynx and larynx was assessed by fiberoptic
laryngoscopy. Mean mouth and throat deposition was 22% (range, 13 to 47%)
and 33% (range, 12 to 84%) with and without resistance (p < 0.05),
respectively. A marked reduction in mouth and throat deposition (range, 20
to 44%), with a corresponding increase in lung deposition, was observed
especially in the six subjects with mouth and throat deposition values >
30% at inhalation without resistance. Furthermore, a small (mean 8%) but
significant (p < 0.05) increase in peripheral lung deposition, estimated
as retention at 24 h, was found at inhalation with increased resistance.
The fiberoptic examination showed wide intersubject variability in the
pharynx and larynx, with tendencies toward higher mouth and throat
deposition with pharyngeal narrowing, and significantly (p < 0.05) lower
lung retention with laryngeal narrowing. Our results show that an external
resistance reduces mouth and throat deposition and increases deposition and
retention of aerosol particles in the lungs in asthmatic individuals.
