Lizal Frantisek, Elcner Jakub, Jedelsky Jan, Maly Milan, Jicha Miroslav, Farkas Árpád, Belka Miloslav, Rehak Zdenek, Adam Jan, Brinek Adam, Laznovsky Jakub, Zikmund Tomas, Kaiser Jozef
Brno University of Technology, Faculty of Mechanical Engineering, Energy Institute, Technicka 2896/2, Brno, 616 69, Czech Republic.
Centre for Energy Research, Konkoly-Thege Miklós u. 29-33, 1121, Budapest, Hungary.
J Aerosol Sci. 2020 Dec;150:105649. doi: 10.1016/j.jaerosci.2020.105649. Epub 2020 Aug 28.
The inhalation route has a substantial influence on the fate of inhaled particles. An outbreak of infectious diseases such as COVID-19, influenza or tuberculosis depends on the site of deposition of the inhaled pathogens. But the knowledge of respiratory deposition is important also for occupational safety or targeted delivery of inhaled pharmaceuticals. Simulations utilizing computational fluid dynamics are becoming available to a wide spectrum of users and they can undoubtedly bring detailed predictions of regional deposition of particles. However, if those simulations are to be trusted, they must be validated by experimental data. This article presents simulations and experiments performed on a geometry of airways which is available to other users and thus those results can be used for intercomparison between different research groups. In particular, three hypotheses were tested. First: Oral breathing and combined breathing are equivalent in terms of particle deposition in TB airways, as the pressure resistance of the nasal cavity is so high that the inhaled aerosol flows mostly through the oral cavity in both cases. Second: The influence of the inhalation route (nasal, oral or combined) on the regional distribution of the deposited particles downstream of the trachea is negligible. Third: Simulations can accurately and credibly predict deposition hotspots. The maximum spatial resolution of predicted deposition achievable by current methods was searched for. The simulations were performed using large-eddy simulation, the flow measurements were done by laser Doppler anemometry and the deposition has been measured by positron emission tomography in a realistic replica of human airways. Limitations and sources of uncertainties of the experimental methods were identified. The results confirmed that the high-pressure resistance of the nasal cavity leads to practically identical velocity profiles, even above the glottis for the mouth, and combined mouth and nose breathing. The distribution of deposited particles downstream of the trachea was not influenced by the inhalation route. The carina of the first bifurcation was not among the main deposition hotspots regardless of the inhalation route or flow rate. On the other hand, the deposition hotspots were identified by both CFD and experiments in the second bifurcation in both lungs, and to a lesser extent also in both the third bifurcations in the left lung.
吸入途径对吸入颗粒的归宿有重大影响。诸如新冠病毒、流感或结核病等传染病的爆发取决于吸入病原体的沉积部位。但呼吸沉积知识对于职业安全或吸入药物的靶向递送也很重要。利用计算流体动力学的模拟已可供广泛用户使用，并且它们无疑可以带来颗粒区域沉积的详细预测。然而，如果要相信这些模拟，就必须通过实验数据进行验证。本文介绍了在一种气道几何结构上进行的模拟和实验，该气道几何结构可供其他用户使用，因此这些结果可用于不同研究小组之间的相互比较。具体而言，测试了三个假设。第一：就结核气道中的颗粒沉积而言，口呼吸和口鼻联合呼吸是等效的，因为鼻腔的阻力很高，以至于在这两种情况下吸入的气溶胶大多通过口腔流动。第二：吸入途径（鼻、口或联合）对气管下游沉积颗粒的区域分布影响可忽略不计。第三：模拟可以准确且可靠地预测沉积热点。探索了当前方法可实现的预测沉积的最大空间分辨率。使用大涡模拟进行模拟，通过激光多普勒测速仪进行流动测量，并通过正电子发射断层扫描在真实的人体气道模型中测量沉积。确定了实验方法的局限性和不确定性来源。结果证实，鼻腔的高阻力导致速度分布几乎相同，即使在口腔声门上方以及口鼻联合呼吸时也是如此。气管下游沉积颗粒的分布不受吸入途径的影响。无论吸入途径或流速如何，第一分叉处的隆突都不是主要的沉积热点。另一方面，通过计算流体动力学和实验都在双肺的第二分叉处确定了沉积热点，在左肺的第三分叉处也有较小程度的确定。
