Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran.
Department of Mechanical Engineering, Razi University, Kermanshah, Iran.
Int J Pharm. 2020 Sep 25;587:119599. doi: 10.1016/j.ijpharm.2020.119599. Epub 2020 Jul 11.
Effective drug delivery into the lungs plays an important role in management of pulmonary diseases that affect millions all around the world. The main objective of this investigation is to study airflow structure, as well as transport and deposition of micron-size particles at different inhalation flow rates in a realistic model of human tracheobronchial airways. The airway model was developed based on computed tomography (CT) images of a healthy 48-years-old female, which includes extrathoracic, trachea, and bronchial airways up to fourth generations. Computational fluid dynamics (CFD) simulations were performed to predict transport and deposition of inhaled particles and the results were compared to our previous in vitro experiments. Airflow structure was studied through velocity contours and streamlines in the extrathoracic region, where the onset of turbulence, reverse flow and subsequently vortex formation, and laryngeal jet are found to be critical phenomenons in the formation of airflow and deposition patterns. The deposition data was presented by deposition efficiency (DE) and deposition fraction (DF) against impaction parameter and Stokes number. At all of the inhalation flow rates, highest values of deposition fractions were devoted to the mouth-throat (MT), tracheobronchial tree (TB), and trachea (Tra), respectively (At 60 L/min: MT = 6.7%, TB = 5.3%, Tra = 1.9%). The numerical deposition data showed a good agreement with the experimental deposition data in most of the airway regions (e.g. less than 10% difference between the deposition fractions in the tracheobronchial region). Enhancing inhalation flow rate in all of the airway regions led to an uptrend in deposition rate due to the increase of particles inertia and turbulence level. In addition, the increase of particle deposition with enhancing inhalation flow rate in all of the sections including extrathoracic, trachea, and tracheobronchial tree suggesting that inertial impaction is the dominant deposition mechanism due to the increase of inertial force. In conclusion, the validated CFD model provided an opportunity to cover the limitations of our previous experimental investigation on aerosol deposition of commercial inhalers and became an efficient method for further studies.
有效将药物递送至肺部对于管理影响全球数百万人的肺部疾病至关重要。本研究的主要目的是研究在真实人体气管支气管气道模型中，不同吸气流量下微米级颗粒的气流结构、输运和沉积。气道模型是基于一位 48 岁健康女性的计算机断层扫描（CT）图像开发的，其中包括胸外、气管和支气管气道的前四代。进行了计算流体动力学（CFD）模拟以预测吸入颗粒的输运和沉积，结果与我们之前的体外实验进行了比较。通过在胸外区域的速度轮廓和流线研究气流结构，其中湍流的起始、回流和随后的涡旋形成以及喉喷流被发现是气流形成和沉积模式的关键现象。沉积数据通过撞击参数和斯托克斯数的沉积效率（DE）和沉积分数（DF）呈现。在所有吸气流量下，沉积分数的最高值都分配给了口咽（MT）、气管支气管树（TB）和气管（Tra）（在 60 L/min 时：MT = 6.7%，TB = 5.3%，Tra = 1.9%）。在大多数气道区域，数值沉积数据与实验沉积数据吻合良好（例如，气管支气管区域的沉积分数差异小于 10%）。在所有气道区域增加吸气流量会由于颗粒惯性和湍流水平的增加而导致沉积率上升。此外，在胸外、气管和气管支气管树的所有部分，随着吸气流量的增加，颗粒沉积增加，这表明由于惯性力的增加，惯性撞击是主要的沉积机制。总之，经过验证的 CFD 模型提供了一个机会，可以弥补我们之前关于商业吸入器气溶胶沉积的实验研究的局限性，并成为进一步研究的有效方法。
