Abstract This study numerically investigates the effect of hygroscopicity on transport and deposition of particles in severe asthmatic lungs with distinct airway structures. The study human subjects were selected from two imaging-based severe asthmatic clusters with one characterized by non-constricted airways and the other by constricted airways in the lower left lobe (LLL). We compared the deposition fractions of sodium chloride (NaCl) particles with a range of aerodynamic diameters (1–8 μm) in cluster archetypes under conditions with and without hygroscopic growth. The temperature and water vapor distributions in the airways were simulated with an airway wall boundary condition that accounts for variable temperature and water vapor evaporation at the interface between the lumen and the airway surface liquid layer. On average, the deposition fraction increased by about 6% due to hygroscopic particle growth in the cluster subjects with constricted airways, while it increased by only about 0.5% in those with non-constricted airways. The effect of particle growth was most significant for particles with an initial diameter of 2 μm in the cluster subjects with constricted airways. The effect diminished with increasing particle size, especially for particles with an initial diameter larger than 4 μm. This suggests the necessity to differentiate asthmatic subjects by cluster in engineering the aerosol size for tailored treatment. Specifically, the treatment of severe asthmatic subjects who have constricted airways with inhalation aerosols may need submicron-sized hygroscopic particles to compensate for particle growth, if one targets for delivering to the peripheral region. These results could potentially inform the choice of particle size for inhalational drug delivery in a cluster-specific manner.

中文翻译：

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有和没有气道狭窄的哮喘患者吸湿性颗粒的运输和沉积

摘要 本研究数值研究了吸湿性对具有不同气道结构的重度哮喘肺中颗粒运输和沉积的影响。研究人类受试者选自两个基于成像的严重哮喘群，一个以非收缩气道为特征，另一个以左下叶 (LLL) 的收缩气道为特征。我们比较了在具有和不具有吸湿性生长的条件下簇原型中氯化钠 (NaCl) 颗粒的沉积分数与一系列空气动力学直径 (1-8 μm)。气道中的温度和水蒸气分布使用气道壁边界条件进行模拟，该边界条件考虑了管腔和气道表面液体层之间界面处的可变温度和水蒸气蒸发。一般，在气道狭窄的集群受试者中，由于吸湿性颗粒生长，沉积比例增加了约 6%，而在非狭窄气道的人群中，沉积比例仅增加了约 0.5%。在气道狭窄的簇状受试者中，对于初始直径为 2 μm 的颗粒，颗粒生长的影响最为显着。这种影响随着粒径的增加而减弱，特别是对于初始直径大于 4 μm 的颗粒。这表明在设计气雾剂大小以进行定制治疗时，有必要通过集群来区分哮喘患者。具体而言，如果目标是递送至外周区域，则用吸入气雾剂治疗气道狭窄的严重哮喘患者可能需要亚微米尺寸的吸湿性颗粒来补偿颗粒生长。