Ehtezazi Touraj, Horsfield Mark A, Barry Peter W, Goodenough Paul, O'callaghan Christopher
Department of Child Health and Institute of Lung Health, University of Leicester, Leicester LE2 7LX, United Kingdom.
J Pharm Sci. 2005 Jul;94(7):1418-26. doi: 10.1002/jps.20356.
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.
干粉吸入器（DPI）中气溶胶颗粒的夹带和解聚是通过患者从装置中用力吸气以及装置内置的气流阻力来实现的。上呼吸道施加的空气动力学剪切应力在解聚过程中也起着重要作用。在本研究中，确定了装置气流阻力对上呼吸道形状的影响。七名健康受试者通过不同阻力（0.2×10⁵至2.2×10⁵N⁰.⁵.s.m⁻⁴）的测试吸入器进行吸入，同时使用磁共振成像对上呼吸道进行成像。降低测试吸入器的阻力会导致口腔、口咽和喉部上呼吸道的横截面积增加，而上气管的横截面积保持相对恒定。通过将装置气流阻力从2.2×10⁵N⁰.⁵.s.m⁻⁴降低到0.2×10⁵N⁰.⁵.s.m⁻⁴，上呼吸道的平均体积也从72（22）cm³（平均值（标准差））增加到101（25）cm³。总之，本研究表明，通过不同阻力的装置进行吸入时，上呼吸道的形状存在显著差异。这可能有助于理解干粉吸入器中药物在肺部的沉积情况。
