Deposition of inhaled particles in the mouth and throat of asthmatic subjects

Abstract

D De ep po os si it ti io on n o of f i in nh ha al le ed d p pa ar rt ti ic cl le es s i in n t th he e m mo ou ut th h a an nd d t th hrABSTRACT: We previously studied the deposition of inhaled particles in the mouth and throat of asthmatic patients, and found large, reproducible differences among subjects. In the present study, we examined whether anatomical and/or functional differences in the pharynx and larynx could underlie this interindividual variation. Deposition in the mouth and throat, and in the lung was estimated in 16 asthmatic subjects after inhalation of 3.6 µm (aerodynamic diameter) monodisperse Teflon particles labelled with 111 In. The particles were inhaled at a flow rate of 0.5 l·s -1 with maximally deep breaths. Radioactivity was measured by external scanning over head and neck, lungs and stomach, immediately after the inhalation. Radioactivity in the lungs was also measured 24 h later. A measure of the total amount of particles deposited in the mouth and throat was obtained from the added activities in mouthwash, head and neck, and stomach, immediately after the inhalation of the test particles. Pharynx and larynx function was examined by fibreoptic laryngoscopy performed during a corresponding inhalation procedure.Deposition in the mouth and throat varied widely among the subjects, ranging 9-76% (median 12%). We found two subpopulations, 13 subjects in the range 9-34%, and 3 subjects with >70% deposition. Deviations in pharyngeal configuration during inhalation were significantly related to high mouth and throat deposition, whereas functional differences in the larynx were not.Our study shows that mouth and throat deposition may be extremely high in some asthmatics, and that pharyngeal configuration affects deposition of particles in the mouth and throat.

Development of the Premature Infant Nose Throat-Model (PrINT-Model)—An Upper Airway Replica of a Premature Neonate for the Study of Aerosol Delivery

“…Furthermore, in a number of in vitro studies (4 -6,22,23) it has been pointed out, that the use of a realistic human upper airway replica would be preferable to the USP throat. The main reason, why anatomically correct upper airway models are of interest is that the upper airways act as an important trap for inhaled aerosols (10,14,16,24,25). Aerosol deposition occurs mostly in the larynx and trachea (26,27), and is determined by pharyngeal and glottal morphologic constrictions and consequent flow jets (28).…”

Direct numerical simulations of flow in realistic mouth–throat geometries

“…A number of in vivo (Walsh et al, 1977;Foord et al, 1978;Chan & Lippmann, 1980;Stahlhofen et al, 1980Stahlhofen et al, , 1981Emmett & Aitken, 1982;Svartengren et al, 1994;Dunbar et al, 2002) and in vitro studies (Cheng et al, 1999(Cheng et al, , 2001Lin et al, 2001;Grgic et al, 2004b;DeHaan & Finlay, 2004;Grgic et al, 2004a;Heenan et al, 2004;Zhang et al, 2007;Zhou et al, 2011;Shinneeb & Pollard, 2012) have been conducted in order to develop an understanding of the flow and particle dynamics in the extrathoracic airways. In vivo experiments are costly and complex to perform, and accurate results are difficult to obtain due to spatial resolution and tissue attenuation limit (Grgic et al, 2004b).…”

Surfactant Driven Post-Deposition Spreading of Aerosols on Complex Aqueous Subphases. 2: Low Deposition Flux Representative of Aerosol Delivery to Small Airways

“…(6) High local drug concentrations are produced in the central airways with little drug reaching the peripheral airways. (7)(8)(9) This hinders full eradication of infections and may lead to antibiotic resistance. (10)(11)(12) We propose the use of surfactants in inhaled drug formulations to improve dosing homogeneity in the lungs by driving surface flows that enhance the post-deposition spreading of medications along the airway surface liquid (ASL).…”