title: Added external resistance reduces oropharyngeal deposition and increases lung deposition of aerosol particles in asthmatics.
abstract: 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.
authors.affiliation: Department of Respiratory and Allergic Diseases, Karolinska Institute, Huddinge University Hospital, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Svartengren
authors.forename: P
authors.initials: P
authors.lastname: Lindestad
authors.forename: M
authors.initials: M
authors.lastname: Svartengren
authors.forename: K
authors.initials: K
authors.lastname: Philipson
authors.forename: G
authors.initials: G
authors.lastname: Bylin
authors.forename: P
authors.initials: P
authors.lastname: Camner
mesh_terms: D000328:Adult; D000336:Aerosols / Q000493:pharmacokinetics*; D000403:Airway Resistance / Q000502:physiology; D001249:Asthma / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007205:Indium Radioisotopes; D007828:Laryngoscopy; D007830:Larynx / Q000378:metabolism; D008168:Lung / Q000378:metabolism*; D008297:Male; D009330:Nebulizers and Vaporizers; D009960:Oropharynx / Q000378:metabolism*; D010316:Particle Size; D011138:Polytetrafluoroethylene / Q000493:pharmacokinetics; D012129:Respiratory Function Tests
chemical_list: D000336:Aerosols; D007205:Indium Radioisotopes; D011138:Polytetrafluoroethylene