肺腺泡內(nèi)顆粒物的沉積及阻塞影響的數(shù)值模擬研究
發(fā)布時間：2018-07-14 12:23
【摘要】：近年來,隨著經(jīng)濟發(fā)展帶來的空氣污染日益嚴重,由此引起的各類呼吸系統(tǒng)疾病和發(fā)病率和死亡率隨之上升。大氣中的可吸入顆粒物尤其是PM2.5(可入肺顆粒物)被吸入后,在人體呼吸系統(tǒng)的肺腺泡區(qū)沉積,甚至?xí)M入人體的血液循環(huán)系統(tǒng),對人體的健康造成危害。兒童的呼吸系統(tǒng)還處于發(fā)育階段,自身的抵抗力較差,對大氣中的可吸入顆粒物更加敏感。因此,研究成人和兒童肺腺泡區(qū)的氣流特性以及可吸入顆粒物的沉積,對理解氣體和顆粒物的輸運機理,評價可入肺顆粒物對不同年齡人群的影響具有重要意義,將有助于肺部物質(zhì)輸運及相關(guān)領(lǐng)域的深入研究。并且,研究藥物顆粒在肺腺泡病變部位的沉積,可以評價藥物的靶向作用,為進一步改善和優(yōu)化藥物靶向治療提供可靠的理論基礎(chǔ)。由于人體肺腺泡部位的真實生理結(jié)構(gòu)尺度小、肺泡數(shù)量多、結(jié)構(gòu)復(fù)雜,目前僅有組織學(xué)上的平面切片圖形。實驗中一般利用相似原則建模,開展大尺度下的流動顯示與顆粒沉積實驗。與之相比,數(shù)值模擬方法則不受實驗手段的制約,能夠揭示流動中的細節(jié)。本文基于Weibel-A模型數(shù)據(jù)的基礎(chǔ),通過假設(shè)簡化建立三維0~8級正常肺腺泡模型和二維阻塞肺腺泡模型,并通過引入動壁面邊界條件反映肺部節(jié)律收縮/擴張的動力學(xué)機制,采用數(shù)值模擬手段研究成人與兒童肺腺泡氣流與顆粒的沉積特性,肺腺泡的阻塞產(chǎn)生的影響,以及藥物顆粒在阻塞部位的靶向作用。本文數(shù)值模擬采用多物理場耦合軟件COMSOL Multiphysics 4.3a,分別采用歐拉法和拉格朗日法對肺腺泡區(qū)氣流流動和顆粒運動進行研究。正常肺腺泡的模擬結(jié)果表明:隨著肺腺泡級數(shù)的增加,氣流速度逐漸減小,壓力值逐漸增大,顆粒物的分級沉積率逐漸增大;模型的三維結(jié)構(gòu)是肺腺泡流動特性的研究中不可忽視的問題,顆粒的沉積率整體高于二維模型;與固定肺泡壁條件相比,動肺泡壁條件可以增強肺泡內(nèi)流場的對流流動,使顆粒沉積率增大;不同呼吸狀態(tài)下,顆粒的沉積有所不同,主要受呼吸時間的影響;年齡越小的個體,肺腺泡各級的氣流速度和壓力值相對越大,顆粒的沉積率也越大。阻塞肺腺泡的模擬結(jié)果表明:阻塞主要影響阻塞處的上下游流速,以及和阻塞處具有相同上級的另一側(cè)流速;阻塞處附近壓降較大,且距離肺腺泡終端越遠的區(qū)域發(fā)生阻塞,其壓降值越大;管段的阻塞對有相同上級的正常一側(cè)區(qū)域的顆粒沉積幾乎沒有影響;阻塞主要影響阻塞處下一分叉處的顆粒沉積;概括性地找出藥物的最佳靶向粒徑不太可能,藥物的靶向性和阻塞發(fā)生的部位以及阻塞處的數(shù)量等復(fù)雜因素有關(guān)。
[Abstract]:In recent years, air pollution caused by economic development is becoming more and more serious. After inhalable particulate matter (PM2.5) in the atmosphere is inhaled, it deposits in the pulmonary acinar area of the human respiratory system, and even enters the human blood circulatory system, which is harmful to human health. The respiratory system of children is still in the developmental stage, their own resistance is poor, and they are more sensitive to respirable particles in the atmosphere. Therefore, it is of great significance to study the airflow characteristics of pulmonary acinar area and the deposition of inhalable particles in adults and children, in order to understand the transport mechanism of gas and particulate matter, and to evaluate the effect of particulate matter on people of different ages. It will be helpful for the further study of lung transport and related fields. Furthermore, the study of the deposition of drug particles in the lesion of pulmonary acinus can evaluate the targeting effect of drugs and provide a reliable theoretical basis for further improvement and optimization of drug targeting therapy. Due to the small size of the real structure of the human pulmonary acinar, the large number of alveoli and the complex structure, there are only histologically planar slices. In the experiments, the principle of similarity is generally used to model the flow display and particle deposition in large scale. In contrast, the numerical simulation method is not restricted by experimental means and can reveal the details of the flow. On the basis of Weibel-A model data, a 3-dimensional normal pulmonary acinar model of grade 8 and a two-dimensional model of obstructive pulmonary acinus were established by hypothetical simplification, and the dynamic mechanism of pulmonary rhythm contraction / dilation was reflected by introducing the moving wall boundary condition. The characteristics of airflow and particle deposition of pulmonary acinar in adults and children, the effects of pulmonary acinar obstruction and the targeting effect of drug particles on the blocking site were studied by numerical simulation. In this paper, the multi-physical field coupling software COMSOL Multiphysics 4.3a is used to simulate the airflow and particle motion in the pulmonary acinar region by Euler method and Lagrangian method, respectively. The simulation results of normal pulmonary acinar show that with the increase of pulmonary acinar progression, the airflow velocity decreases gradually, the pressure value increases, and the graded deposition rate of particulate matter increases. The three-dimensional structure of the model can not be ignored in the study of the characteristics of pulmonary acinar flow, the deposition rate of particles is higher than that of the two-dimensional model, compared with the fixed alveolar wall condition, the dynamic alveolar wall condition can enhance the convective flow in the alveolar flow field. The deposition rate of particles is different in different breathing states, which is mainly affected by respiration time. The younger the age is, the greater the airflow velocity and pressure at all levels of pulmonary acinus are, and the higher the deposition rate of particles is. The simulation results of obstructive pulmonary acinar show that blockage mainly affects the upstream and downstream velocity of the blockage and the flow velocity on the other side with the same superior level as the obstruction place, and the pressure drop near the obstruction place is larger, and the area farther away from the pulmonary acinar terminal is blocked. The greater the pressure drop value, the less likely the blockage of the tube segment has any effect on the particle deposition in the normal side of the area with the same upper level; the blockage mainly affects the particle deposition at the next branch of the blockage; and it is unlikely that the optimal target particle size of the drug will be found. Drug targeting is related to complex factors such as the location and number of blockages occurring.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：R56;X51
，
本文編號：2121634
[Abstract]:In recent years, air pollution caused by economic development is becoming more and more serious. After inhalable particulate matter (PM2.5) in the atmosphere is inhaled, it deposits in the pulmonary acinar area of the human respiratory system, and even enters the human blood circulatory system, which is harmful to human health. The respiratory system of children is still in the developmental stage, their own resistance is poor, and they are more sensitive to respirable particles in the atmosphere. Therefore, it is of great significance to study the airflow characteristics of pulmonary acinar area and the deposition of inhalable particles in adults and children, in order to understand the transport mechanism of gas and particulate matter, and to evaluate the effect of particulate matter on people of different ages. It will be helpful for the further study of lung transport and related fields. Furthermore, the study of the deposition of drug particles in the lesion of pulmonary acinus can evaluate the targeting effect of drugs and provide a reliable theoretical basis for further improvement and optimization of drug targeting therapy. Due to the small size of the real structure of the human pulmonary acinar, the large number of alveoli and the complex structure, there are only histologically planar slices. In the experiments, the principle of similarity is generally used to model the flow display and particle deposition in large scale. In contrast, the numerical simulation method is not restricted by experimental means and can reveal the details of the flow. On the basis of Weibel-A model data, a 3-dimensional normal pulmonary acinar model of grade 8 and a two-dimensional model of obstructive pulmonary acinus were established by hypothetical simplification, and the dynamic mechanism of pulmonary rhythm contraction / dilation was reflected by introducing the moving wall boundary condition. The characteristics of airflow and particle deposition of pulmonary acinar in adults and children, the effects of pulmonary acinar obstruction and the targeting effect of drug particles on the blocking site were studied by numerical simulation. In this paper, the multi-physical field coupling software COMSOL Multiphysics 4.3a is used to simulate the airflow and particle motion in the pulmonary acinar region by Euler method and Lagrangian method, respectively. The simulation results of normal pulmonary acinar show that with the increase of pulmonary acinar progression, the airflow velocity decreases gradually, the pressure value increases, and the graded deposition rate of particulate matter increases. The three-dimensional structure of the model can not be ignored in the study of the characteristics of pulmonary acinar flow, the deposition rate of particles is higher than that of the two-dimensional model, compared with the fixed alveolar wall condition, the dynamic alveolar wall condition can enhance the convective flow in the alveolar flow field. The deposition rate of particles is different in different breathing states, which is mainly affected by respiration time. The younger the age is, the greater the airflow velocity and pressure at all levels of pulmonary acinus are, and the higher the deposition rate of particles is. The simulation results of obstructive pulmonary acinar show that blockage mainly affects the upstream and downstream velocity of the blockage and the flow velocity on the other side with the same superior level as the obstruction place, and the pressure drop near the obstruction place is larger, and the area farther away from the pulmonary acinar terminal is blocked. The greater the pressure drop value, the less likely the blockage of the tube segment has any effect on the particle deposition in the normal side of the area with the same upper level; the blockage mainly affects the particle deposition at the next branch of the blockage; and it is unlikely that the optimal target particle size of the drug will be found. Drug targeting is related to complex factors such as the location and number of blockages occurring.
【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：R56;X51
，
本文編號：2121634
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