1D network simulations for evaluating regional flow and pressure distributions in healthy and asthmatic human lungs
1D network simulations for evaluating regional flow and pressure distributions in healthy and asthmatic human lungs
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DOI：
10.1152/japplphysiol.00016.2019
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发表时间：
2019-07-01
影响因子：
3.3
通讯作者：
Lin, Ching-Long
中科院分区：
文献类型：
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作者：
Choi, Sanghun;Yoon, Sujin;Lin, Ching-Long
本研究旨在引入一维(1D)计算流体动力学(CFD)模型来研究气道阻力和肺顺应性之间的关系，以研究气道阻力、压力和区域血流分布之间的关系。我们使用了5名健康受试者和5名哮喘受试者，他们进行了动态CT扫描(4DCT)，同时进行了两次静态扫描，分别测定了总肺活量和功能残气量。用来自四维CT的风量变化分数(Delta V-air(F))对一维CFD模型进行验证。我们从61名健康受试者的现有数据集中提取直径比，用于计算CT解析的气道收缩/扩张的平均值和标准差(SD)。用气道收缩/扩张的肺叶平均值(SD)测定CT未分辨气道的直径。求解一维等温能量平衡方程，在胸腺区(模型A)或胸膜区(模型B)施加压力边界条件。静态顺应性模型仅适用于模型B以连接腺泡和胸膜区域。模型B的1DCFD导出的Delta V-air(F)与4DCT的Delta V-air(F)的相关性比模型A更好。在吸气和呼气时，有气道狭窄的哮喘患者的压降均明显大于无气道收缩的健康受试者。这增加了哮喘受试者的跨肺压力，导致工作负荷增加(滞后)。一维CFD模型可用于研究健康受试者和哮喘受试者的流动结构、肺滞后和压力分布。导出的流量分布可用于施加3DCFD的边界条件。新和值得注意的是，引入了一维(1D)计算流体动力学(CFD)模型来研究气道阻力、压力和区域流量分布之间的关系。一维CFD模型研究了健康受试者和哮喘受试者的血流结构、肺滞后和压力分布的差异。得到的流量分布可用于施加三维CFD的边界条件。
This study aimed to introduce a one-dimensional (1D) computational fluid dynamics (CFD) model for airway resistance and lung compliance to examine the relationship between airway resistance, pressure, and regional flow distribution. We employed five healthy and five asthmatic subjects who had dynamic computed tomography (CT) scans (4D CT) along with two static scans at total lung capacity and functional residual capacity. Fractional air-volume change (Delta V-air(f)) from 4D CT was used for a validation of the 1D CFD model. We extracted the diameter ratio from existing data sets of 61 healthy subjects for computing mean and standard deviation (SD) of airway constriction/dilation in CT-resolved airways. The lobar mean (SD) of airway constriction/dilation was used to determine diameters of CT-unresolved airways. A 1D isothermal energy balance equation was solved, and pressure boundary conditions were imposed at the acinar region (model A) or at the pleural region (model B). A static compliance model was only applied for model B to link acinar and pleural regions. The values of 1D CFD-derived Delta V-air(f) for model B demonstrated better correlation with 4D CT-derived Delta V-air(f) than model A. In both inspiration and expiration, asthmatic subjects with airway constriction show much greater pressure drop than healthy subjects without airway constriction. This increased transpulmonary pressures in the asthmatic subjects, leading to an increased workload (hysteresis). The 1D CFD model was found to be useful in investigating flow structure, lung hysteresis, and pressure distribution for healthy and asthmatic subjects. The derived flow distribution could be used for imposing boundary conditions of 3D CFD.NEW & NOTEWORTHY A one-dimensional (1D) computational fluid dynamics (CFD) model for airway resistance and lung compliance was introduced to examine the relationship between airway resistance, pressure, and regional flow distribution. The 1D CFD model investigated differences of flow structure, lung hysteresis, and pressure distribution for healthy and asthmatic subjects. The derived flow distribution could be used for imposing boundary conditions of three-dimensional CFD.