Bass Karl, Longest P Worth
Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States.
Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, United States; Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, United States.
Med Eng Phys. 2018 Jun 22. doi: 10.1016/j.medengphy.2018.05.002.
A complete-airway in vitro model would be very useful for toxicological dosimetry testing and for developing targeted inhaled medications in cases where conducting in vivo experiments are exceedingly difficult, as with infants. The objective of this study was to determine whether packed bed in vitro models, which contain spheres as the primary repeating unit, provide a realistic representation of aerosol deposition in the tracheobronchial region of infant lungs based on computational fluid dynamics (CFD) predictions. The packed bed (PB) CFD model contained an inlet consistent with airway bifurcation B3 (∼lobar bronchi) leading to a spherical array with voids between the spheres forming a divided flow pathway. The hydrodynamic diameter of the voids was approximately matched to the diameter of bifurcations in various lung regions. For comparison, a CFD stochastic individual pathway (SIP) geometry with realistic bifurcations extending from B4-B15 (terminal bronchioles) was selected as an anatomically accurate model. The CFD-SIP model predictions were benchmarked with existing algebraic correlations for aerosol deposition in the lungs and found to be reasonable. Unfortunately, the CFD-PB model did not provide a good representation of aerosol deposition in the tracheobronchial region of human lungs. Through careful selection of the PB sphere size and inlet conditions, total deposition in the CFD-PB model matched CFD-SIP deposition within 10% absolute error across a range of relevant aerosol sizes. However, regional deposition within the CFD-PB model was very different from the CFD-SIP case. Therefore, the PB approach cannot be recommended for determining spatial or temporal distribution of aerosol transport and impaction deposition through the lungs.
对于毒理学剂量测定测试以及在进行体内实验极为困难的情况下（如婴儿）开发靶向吸入药物而言，完整气道体外模型会非常有用。本研究的目的是基于计算流体动力学（CFD）预测，确定以球体作为主要重复单元的填充床体外模型是否能真实反映婴儿肺部气管支气管区域的气溶胶沉积情况。填充床（PB）CFD模型包含一个与气道分叉B3（约叶支气管）一致的入口，通向一个球体阵列，球体之间的空隙形成分流路径。空隙的流体动力学直径与不同肺区域的分叉直径大致匹配。为作比较，选择了一个具有从B4 - B15（终末细支气管）延伸的真实分叉的CFD随机个体路径（SIP）几何模型作为解剖学上准确的模型。CFD - SIP模型预测结果与现有的肺部气溶胶沉积代数相关性进行了基准测试，结果合理。不幸的是，CFD - PB模型未能很好地反映人肺气管支气管区域的气溶胶沉积情况。通过仔细选择PB球体尺寸和入口条件，CFD - PB模型中的总沉积在一系列相关气溶胶尺寸范围内与CFD - SIP沉积的绝对误差在10%以内匹配。然而，CFD - PB模型内的区域沉积与CFD - SIP情况非常不同。因此，不建议采用PB方法来确定气溶胶在肺部传输和撞击沉积的空间或时间分布。
