Particle transport and deposition correlation with near-wall flow characteristic under inspiratory airflow in lung airways
Particle transport and deposition correlation with near-wall flow characteristic under inspiratory airflow in lung airways
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DOI：
10.1016/j.compbiomed.2020.103703
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发表时间：
2020-05-01
影响因子：
7.7
通讯作者：
Arzani, Amirhossein
中科院分区：
文献类型：
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作者：
Farghadan, Ali;Poorbahrami, Kamran;Arzani, Amirhossein
肺气道暴露于环境中有害的悬浮气溶胶会增加呼吸和心血管系统的脆弱性。此外，治疗吸入装置的最新发展凸显了颗粒传输的重要性。在这份手稿中，研究了上部气管支气管（TB）树中的颗粒传输和沉积模式，其中微粒的惯性力相当大。壁剪切应力发散度 (WSSdiv) 被提议作为基于壁的参数，可以预测颗粒沉积模式。 WSSdiv 与近壁法向速度成正比，可以量化流向和远离壁的强度。通过计算流体动力学 (CFD) 模拟来量化气流速度和 WSS 矢量，以实现 1 个病例对照中的稳定吸入和 6 个特定受试者气道树中的不稳定吸入。采用大涡模拟对稳态工况进行湍流模拟，研究湍流的影响。磁共振测速 (MRV) 测量用于验证病例对照 CFD 模拟。通过在拉格朗日框架中求解 Maxey-Riley 方程来模拟惯性粒子输运。对五种粒径的病例对照模型的沉积百分比 (DP) 进行了量化。发现 DP 与粒径成正比，这与文献中先前的研究一致。定义标准化沉积浓度（DC）来表征局部沉积。对于生理相关的斯托克斯 (St) 数，DC 与正 WSSdiv 之间存在相对较强的相关性（Pearson 值 > 0.7）。此外，将肺部分成更小的区域后进行了区域分析。每个分区的正 WSSdiv 空间积分与累积空间 DC 或区域剂量测定保持非常强的相关性（Pearson 值 > 0.9）。这些结论被推广到更大的人群，其中对两名健康患者和四名哮喘患者进行了调查。这项研究表明，WSSdiv 可用于预测定性表面沉积和相对区域剂量测定，而无需解决粒子传输问题。
Exposure of lung airways to detrimental suspended aerosols in the environment increases the vulnerability of the respiratory and cardiovascular systems. In addition, recent developments in therapeutic inhalation devices magnify the importance of particle transport. In this manuscript, particle transport and deposition patterns in the upper tracheobronchial (TB) tree were studied where the inertial forces are considerable for microparticles. Wall shear stress divergence (WSSdiv) is proposed as a wall-based parameter that can predict particle deposition patterns. WSSdiv is proportional to near-wall normal velocity and can quantify the strength of flow towards and away from the wall. Computational fluid dynamics (CFD) simulations were performed to quantify airflow velocity and WSS vectors for steady inhalation in one case-control and unsteady inhalation in six subject-specific airway trees. Turbulent flow simulation was performed for the steady case using large eddy simulation to study the effect of turbulence. Magnetic resonance velocimetry (MRV) measurements were used to validate the case-control CFD simulation. Inertial particle transport was modeled by solving the Maxey- Riley equation in a Lagrangian framework. Deposition percentage (DP) was quantified for the case-control model over five particle sizes. DP was found to be proportional to particle size in agreement with previous studies in the literature. A normalized deposition concentration (DC) was defined to characterize localized deposition. A relatively strong correlation (Pearson value > 0.7) was found between DC and positive WSSdiv for physiologically relevant Stokes (St) numbers. Additionally, a regional analysis was performed after dividing the lungs into smaller areas. A spatial integral of positive WSSdiv over each division was shown to maintain a very strong correlation (Pearson value > 0.9) with cumulative spatial DC or regional dosimetry. The conclusions were generalized to a larger population in which two healthy and four asthmatic patients were investigated. This study shows that WSSdiv could be used to predict the qualitative surface deposition and relative regional dosimetry without the need to solve a particle transport problem.