title: Mouthpiece diameter affects deposition efficiency in cast models of the human oral airways.
abstract: We examined the effect of altering mouthpiece diameter to 1.5, 2.0, and 2.7 cm on the deposition efficiency of inertial size particles (2, 4, and 8 microm) in adult human oral-pharyngeal-laryngeal (OPL) airway cast models at various inspiratory flow rates (30, 60, 90, and 120 L/min). Deposition efficiency of 2-microm particles was unaffected by changes in mouthpiece diameter at all flow rates. Deposition of 4-microm particles decreased significantly with the 2.0- and 2.7-cm mouthpieces compared to the 1.5 cm mouthpiece at 60, 90, and 120 L/min (p < 0.01). Deposition of 4-microm particles was significantly reduced with the 2.7-cm mouthpiece compared to the 2.0-cm mouthpiece at 90 and 120 L/min (p < 0.05). Deposition efficiency of 8 microm particles decreased significantly with the 2.0- and 2.7-cm mouthpieces compared to the 1.5-cm mouthpiece at 60 L/min (p < 0.05), and with the 2.7-cm mouthpiece compared to the 1.5-cm mouthpiece at 120 L/min (p < 0.05). These results suggest that the effect of mouthpiece diameter varies with particle size, with 2- and 8-microm particles least affected. However, our findings may have important implications for improving the future design of mouthpieces of devices that deliver particles with 4-microm diameters and require inspiratory flow rates of > or = 60 L/min (i.e., DPIs) for adequate drug delivery.
authors.affiliation: Department of Environmental Health Sciences, School of Hygiene and Public Health, The Johns Hopkins University, Baltimore, Maryland, USA. tlin@inhale.com
authors.forename: T C
authors.initials: TC
authors.lastname: Lin
authors.forename: P N
authors.initials: PN
authors.lastname: Breysse
authors.forename: B L
authors.initials: BL
authors.lastname: Laube
authors.forename: D L
authors.initials: DL
authors.lastname: Swift
mesh_terms: D000336:Aerosols / Q000008:administration & dosage*; D016503:Drug Delivery Systems; D004867:Equipment Design; D006801:Humans; D008297:Male; D009330:Nebulizers and Vaporizers; D010316:Particle Size
chemical_list: D000336:Aerosols