title: Effect of device inhalational resistance on the three-dimensional configuration of the upper airway.
abstract: Entrainment and de-aggregation of aerosol particles from dry powder inhalers (DPIs) is achieved by a forceful inhalation from the device by the patient and by the airflow resistance built into the device. The aerodynamic shear stress imposed by the upper airway also plays an important role in the de-aggregation process. In this study the effect of device airflow resistance on the upper airway shape is determined. Seven healthy subjects inhaled via a test inhaler of different resistances (0.2 x 10(5) to 2.2 x 10(5) N(0.5).s.m(-4)) while the upper airway was imaged using magnetic resonance imaging. Decreasing the test inhaler resistance led to an increase in the cross-sectional areas of the upper airway at the oral cavity, oropharynx and larynx, while the cross-sectional areas of the upper trachea remained rather constant. The mean volume of the upper airway also increased from 72 (22) cm3 (mean (SD)) to 101 (25) cm3 by decreasing device airflow resistance from 2.2 x 10(5) to 0.2 x 10(5) N(0.5).s.m(-4). In conclusion, this study shows a significant variation in the shape of the upper airway during inhalation via devices with different resistances. This may aid understanding of drug deposition in the lungs from DPIs.
authors.affiliation: Department of Child Health and Institute of Lung Health, University of Leicester, Leicester LE2 7LX, United Kingdom. t.ehtezazi@livjm.ac.uk
authors.forename: Touraj
authors.initials: T
authors.lastname: Ehtezazi
authors.forename: Mark A
authors.initials: MA
authors.lastname: Horsfield
authors.forename: Peter W
authors.initials: PW
authors.lastname: Barry
authors.forename: Paul
authors.initials: P
authors.lastname: Goodenough
authors.forename: Christopher
authors.initials: C
authors.lastname: O'callaghan
mesh_terms: D000328:Adult; D000403:Airway Resistance / Q000502:physiology*; D003761:Dental Impression Technique; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D009330:Nebulizers and Vaporizers; D011208:Powders / Q000008:administration & dosage*; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000033:anatomy & histology; D014070:Tooth / Q000033:anatomy & histology
chemical_list: D011208:Powders