Regional deposition of 2.5–7.5 μm diameter inhaled particles in healthy male non-smokers

ABSTRACT. Oral and nas al airways are entryways to the respiratory tract. Most people breathe through the nasal airway during rest or light exercise, then switch to oral r r r r r nasal breathing during heavy exercise or work. Resistance through the oral airways is much lower than through the n asal airways , so fewer aerosol particles are deposited in the oral airways. Aerosol drugs are usually delivered by inhalation to the lung via the oral route for that reason. Oral deposition data from humans are limited, and those available show great intersubject variability. The purpose of this study was to investigate the effects of particle size and breathing rate on the deposition pattern in a human or al airway cast with a de® ned geometry. The airway replica included the oral cavity, ph arynx, larynx, trachea, an d 3 generations of bronchi. The oral portion of the cast was molded from a dental impression of the oral cavity in a hum an volunteer, while the other airway portions of the cast were made from a cadaver. Nine different sizes of polystyrene latex¯uorescent particles in the size ran ge of 0.93± 30 m m were used in the study. Regional deposition was measured at a constant inspiratory¯ow rate of 15, 30, and 60 L min I 1 . Deposition in the oral airway appeared to increase with an increasinḡ ow rate an d particle diameter. Deposition at the highest¯ow rate of 60 L min I 1 was close to 90% for particles ) 20 m m. Particles ) about 10 m m deposited mainly in the oral cavity. Deposition ef® ciency has been found to be a unique function of the Stokes number, suggesting that impaction is the dominant deposition mech anism. Oral deposition can be approximated by a theoretical deposition model of inertial impaction in a 1808 curved tube, assuming perfect mixing in a turbulent ow. Our model suggests th at the minimum dimension near the larynx and the average cross-sectional area are important parameters for oral airway deposition; however, addition al data from the oral airway replica are needed to ascertain wh ether these are indeed the critical dimensions. Information from the present study will add to our knowledge of the deposition mech anism, the correlation of particle deposition with airway geometry, and eventually the best way to deliver aerosol drugs.

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“…However, for particles ) 10 m m, a higher deposition was observed in the oral cavity, which is similar to the ® nds . ing of Foord et al 1978 .…”

Section: Deposition Experimentsmentioning

confidence: 99%

“…Regional deposition in the oral airway of human volunteers has been me asured using monodisperse particles tagged with radios label Lippmann and Albert 1969;Foord et al 1978;Chan and Lippmann 1980;Stahlhofen et al 1980Stahlhofen et al , 1983Emmett et al . 1982;Bowes and Swift 1989 .…”

Section: Deposition Mechanismmentioning

confidence: 99%

Particle Deposition in a Cast of Human Oral Airways

Cheng¹,

Zhou²,

Chen³

1999

Aerosol Science and Technology

285

218

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“…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).…”

Section: Introductionmentioning

confidence: 99%

Direct numerical simulations of flow in realistic mouth–throat geometries

Nicolaou

Zaki

2013

Journal of Aerosol Science

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“…Oral deposition is usually overlooked because of its relatively low deposition efficiency as well as the varying geometries that occur from tongue movement. In vivo studies concerning geometry specific oral deposition are 1998 reported by Foord et al (1978) and Heyder et al (1986).…”

Section: Researchmentioning

confidence: 99%