本文選題：全肺　切入點：屏氣呼吸　出處：《西安建筑科技大學(xué)》2017年碩士論文

【摘要】：研究呼吸過程肺部顆粒物的沉積及氣體傳輸特性對于評估人體健康至關(guān)重要。例如,發(fā)生火災(zāi)時,人處于高濃度煙氣環(huán)境中,有毒有害煙氣隨呼吸進(jìn)入人體呼吸道,當(dāng)有害物質(zhì)到達(dá)人體呼吸功能的肺腺泡區(qū),可穿過氣血屏障進(jìn)入血液,嚴(yán)重危害人體健康。有毒有害煙氣進(jìn)入肺部的深度和濃度,直接影響人在火災(zāi)中的存活時間。另一方面,吸入療法是利用藥物顆粒在肺內(nèi)病變區(qū)域沉積的一種新型治療呼吸系統(tǒng)疾病的方法,由于它的高生物利用度和高效率的優(yōu)點,近年來被認(rèn)為是一種很有前途的治療方式。本文基于多級分叉特征的健康成年人肺部模型,通過對模型的合理簡化及邊界條件的改進(jìn),改善了數(shù)值模擬的效率,研究在不同的呼吸狀態(tài),如平靜呼吸、高頻呼吸、深呼吸以及屏氣呼吸狀況下肺內(nèi)顆粒沉積及氣體傳輸特性。本文數(shù)值模擬采用多物理場耦合軟件COMSOL Multiphysics4.3a。首先,利用本課題前人建立的二維八級肺腺泡模型,研究了屏氣狀況下重力方向?qū)Ψ蜗倥輧?nèi)顆粒沉積特性的影響,豎直重力方向和水平重力方向分別代表人處于豎直站立和平躺兩個狀態(tài)。研究表明:不同的重力方向?qū)Ψ蜗倥輧?nèi)的整體沉積率基本沒有影響,但對分級沉積率有影響,相對于人站立時的豎直重力方向,人在平躺狀況下能增加特定區(qū)域的分級沉積率。其次,基于Weibel-A肺部模型,通過對稱簡化原則建立二維4-23級健康成年人全肺模型,研究了全肺內(nèi)不同呼吸方式對氣體傳輸?shù)挠绊�。研究表�?氣體在肺部擴(kuò)散非�？�,在第一個吸氣周期就能到達(dá)具有呼吸功能的肺腺泡區(qū)域;在循環(huán)呼吸狀況下,通過高頻呼吸、平靜呼吸、深呼吸的對比發(fā)現(xiàn),高頻呼吸和平靜呼吸傳輸速度相當(dāng),深呼吸擴(kuò)散更快;通過循環(huán)呼吸和屏氣呼吸的對比發(fā)現(xiàn),屏氣能減緩肺部氣體傳輸,這一現(xiàn)象在平靜呼吸時最明顯;通過對比不同方式的屏氣呼吸發(fā)現(xiàn),平靜屏氣呼吸氣體傳輸最慢,高頻屏氣呼吸次之,深屏氣呼吸傳輸最快。最后,通過全肺模型引出了模擬多級分叉網(wǎng)絡(luò)中粒子沉積計算量巨大的難點,基于此提出粒子加倍算法,改進(jìn)對多級分叉網(wǎng)絡(luò)中粒子傳輸和沉積特性的模擬。并且對所提出的粒子加倍算法進(jìn)行了詳細(xì)分析,首先對加倍前的原始粒子和加倍后產(chǎn)生的次級粒子的速度大小和運動軌跡進(jìn)行分析,然后對粒子加倍算法計算分叉網(wǎng)絡(luò)中顆粒沉積率進(jìn)行研究,證明粒子加倍方法的可行性和有效性。本文所提出的粒子加倍算法,不僅可以簡化全肺內(nèi)顆粒沉積的數(shù)值模擬,而且可以運用到河流或者空調(diào)管路等多級分叉網(wǎng)絡(luò)中的研究中。
[Abstract]:It is important to study the deposition and gas transport characteristics of pulmonary particulate matter in respiratory process. For example, when a fire occurs, a person is in a high concentration of smoke, and the toxic and harmful smoke enters the respiratory tract of the human body with breathing. When the harmful substance reaches the pulmonary acinar area of the human body's respiratory function, it can enter blood through the air and blood barrier and seriously endanger human health. The depth and concentration of toxic and harmful smoke entering the lungs directly affect the survival time of a person in a fire. On the other hand, Inhalation therapy is a new method for the treatment of respiratory diseases, which is deposited in the diseased area of the lung by using drug particles, because of its advantages of high bioavailability and high efficiency. In recent years, it has been considered as a promising treatment method. In this paper, the efficiency of numerical simulation is improved by reasonably simplifying the model and improving the boundary conditions. The characteristics of particle deposition and gas transport in lung under different breathing conditions, such as calm breathing, high frequency breathing, deep breathing and breath-holding, were studied. In this paper, the multi-physical field coupling software COMSOL Multiphysics4.3a was used to simulate the particle deposition and gas transport in the lung. In this paper, the influence of gravity direction on the deposition characteristics of pulmonary acinar particles under breath-holding condition was studied by using the 2-D eight grade pulmonary acinus model established by our predecessors. The direction of vertical gravity and the direction of horizontal gravity represent a person standing vertically and lying flat, respectively. The study shows that different directions of gravity have no effect on the overall deposition rate of pulmonary acinus, but have an effect on the deposition rate of different grades. Compared with the vertical gravity direction of standing, people can increase the graded deposition rate of specific areas in lying on their back. Secondly, based on the Weibel-A lung model, the 2-D 4-23 grade healthy adult whole lung model is established by the principle of symmetry simplification. The effects of different breathing patterns in the whole lung on gas transport were studied. The results show that the gas diffuses very quickly in the lung and reaches the pulmonary acinar region with respiratory function in the first inspiratory cycle, and in the condition of circulatory respiration, By comparing high-frequency breathing, calm breathing, and deep breathing, it was found that high-frequency breathing and calm breathing transmit at the same speed, and deep breathing diffuses faster; by comparing circulatory breathing with breath-holding, holding breath can slow down lung gas transmission. This phenomenon is most obvious when breathing peacefully. By comparing different breathing modes, it is found that the slow transfer of breath-holding gas is the slowest, followed by high-frequency breath-holding, and the fastest transmission of deep breath-holding. Through the whole lung model, the difficulty of particle deposition calculation in simulating multilevel bifurcation network is presented. Based on this, a particle doubling algorithm is proposed. The simulation of particle transport and deposition characteristics in multilevel bifurcation network is improved, and the particle doubling algorithm is analyzed in detail. The velocity and trajectory of the original particles before doubling and the secondary particles after doubling are analyzed, and then the particle doubling algorithm is studied to calculate the deposition rate of particles in the bifurcation network. It is proved that the particle doubling method is feasible and effective. The particle doubling algorithm presented in this paper not only simplifies the numerical simulation of particle deposition in the whole lung, but also can be applied to the study of multi-level bifurcation networks such as rivers or air conditioning pipes.
【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】：2017
【分類號】：R56;TU83

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