【作者】 于驰；

【导师】 刘迎曦； 孙秀珍；

【作者基本信息】 大连理工大学 ， 生物医学工程， 2007， 博士

【摘要】 咽腔是执行机体和外界进行气体交换的器官之一，咽腔与鼻腔、喉构成上呼吸道，是人呼吸系统中的一个门户性器官和前端通道。近年来人们已经开始注意到咽腔解剖结构形态异常是导致以打鼾、呼吸暂停为主要表征的阻塞性睡眠呼吸暂停低通气综合症等相关疾患发生发展的重要因素之一，然而对于咽腔解剖结构异常发展到功能异常继而发生疾病的过程，由于缺少生物、数学模型和数值量化的计算模型，无法深入细致了解和掌握，限制了咽腔相关疾病的深入研究，影响了疾病的临床预测、诊断、治疗方案优选与手术疗效的估计。从生物力学角度出发，将计算机仿真技术、三维图形重构、计算流体力学、近代医学理论与动物实验等相融合，发挥多学科交叉的优势，进行咽腔三维重建与生物力学特性研究，对于耳鼻咽喉科临床上疾病诊断、手术方案制定以及术后疗效评估都具有一定的指导意义。为更加准确分析人体咽腔流场特性，基于志愿者CT图像，采用表面重建方法，将鼻、咽腔和喉等统一考虑，建立上气道解剖结构数值量化的仿真模型，对人呼吸时气体流场进行数值分析与上气道结构几何形态的定量数值模拟。所建模型真实的反映了上呼吸道实际解剖结构形态，在此模型中施加不同的边界条件，得到的数值模拟结果与临床资料相符合。对比志愿者鼻／咽声反射曲线与上呼吸道三维模型，认证了曲线上典型切迹所对应的上呼吸道的解剖部位，丰富二维曲线的信息量，同时也丰富了三维上呼吸道模型的信息。应用有限元和有限体积两种数值方法对志愿者吸气过程中咽腔气流场进行数值模拟及分析，得到咽腔内气体压力与速度的分布规律，并统计咽腔压力梯度，可以看出咽腔中压力梯度和速度的变化主要集中在鼻咽和口咽位置。建立健康成人与OSAHS患者及健康儿童与OSAHS患儿不同形态的上呼吸道模型，应用这些模型进行对比计算。数值模拟结果显示，健康人的咽腔压力梯度变化比较均匀，在软腭与舌后根附近有一定波动，但波动比较平缓。OSAHS患者在软腭与舌后根附近会产生较高的压差，呼吸时气流强烈冲击咽腔后壁，增加了气道的坍塌性，此处解剖结构的改变是产生OSAHS阻塞的主要原因。对于OSAHS患儿，由于狭窄处的顺应性的增加，使得这部分的气体压力和速度梯度较正常儿童变化快，从而导致气道阻力的增加，增加咽气道的可塌陷性，引起打鼾、呼吸暂停等疾病。应用鼻／咽声反射仪对大量健康人和OSAHS患者进行测试，总结出了某些耳鼻咽喉科临床病症和曲线走势之间的关系。建立健康成人和OSAHS患者上呼吸道与软腭三维有限元模型，采用流固耦合方法进行数值模拟及分析。结果表明，健康人呼吸道前后的压力差较小，气流分布较均匀，呼吸时气流通畅，而OSAHS患者由于软腭肥大，导致呼吸道狭窄，产生较高压差，气流对呼吸道有强烈的冲击，在呼吸过程中，软腭产生较大位移，进而导致上气道内压降低和跨壁压增高，最终发生上气道的不完全和完全闭合，从而加重上气道狭窄与塌陷，产生鼾声和呼吸暂停。呼吸过程中，OSAHS患者在呼吸时软腭的运动姿态与健康人不同，且不同力学性能的软腭运动的姿态不同。通过实验测定一雄性幼猪的软腭、舌及腺样体组织的力学性能，并对实验数据进行处理与分析，推断了软腭与空气流动间流固耦合特性研究中材料参数选取是合理的。最后对本文的工作进行了总结，并指出了进一步的工作。更多还原

【Abstract】 The pharyngeal cavity is one of the organs for the gas exchange between human body and environment. The pharyngeal cavity and the nose cavity, the throat constitute upper respiratory tract, it is portal of human respiratory system. The pharyngeal cavity biomechanics model establishment is in the human body biomechanics model one of the most important tasks. Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) has been realized that the periodic intermittent cessations of breathing or reductions in airflow resulted from OSAHS is closely related to the developed pathological change in shape of pharyngeal cavity of the patients. The abnormal structure of pharyngeal cavity and the anatomical change of the pharyngeal cavity may lead to many diseases, among which the DNS is regular and is widely found in the world. But because of the lack of proper biomechanical model and its numerical description for the course of adaptation, it is difficult to deeply explor and explains this process.In this paper, airflow distribution in pharyngeal cavity was investigated based on 3-dimensional reconstruction model to try to find the correlation between the pharyngeal cavity structure and the airflow characters. Knowledge of airflow in human pharyngeal is important for understanding many aspects of the biology and pathology in the respiratory tract. Through this research, we can more profoundly explore the outbreak, treatment and prevention of nasal diseases.Based on CT medical images of ten volunteers, the 3D FE model of the upper airway was reconstructed by using the method of surface rendering. The reconstruction three-dimensional models precisely preserve original configuration of upper airways. From the results of the numerical simulation, the airflow distribution in the whole cavity in the course of respiration can be obtained. The accuracy of reconstructed model in geometry structure was proved by acoustic rhinometry test, since it can quantify upper airway condition by drawing a graph plotting the distance vs. the cross-sectional area witch is corresponds to the typical anatomic structures of human upper airway.Numerical simulation was performed for the airflow in those pharyngeal cavities using the FEM and FVM. It is comparatively true that the established model reflect s t he real anatomical configuration. The Computed result obtained with the FEM was similar to the computed result obtained with the FVM. From the results of the numerical simulation, the airflow distribution in the pharyngeal cavity in the course of inspiration was obtained. Based on the data which came from the spiral computerized tomography images of the healthy person and patient with Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS), the three-dimensional models of upper airway cavity were reconstructed by the method of surface rendering. From the results of the numerical simulation, the airflow distribution uniformity in the health pharyngeal cavity and higher pressure difference and velocity gradient in the OSAHS patient was obtained.The surface reconstruction is adopted to build a three-dimensional finite element model in the upper airway and the soft palate for a healthy person and an OSAHS patient, respectively. The FE model correctly preserves anatomical configurations of the upper airway and the soft palate thus can be applied to compute the interaction of fluid-structure. With the result comparison between the healthy person and the OSAHS patient, it is found out that the pressure difference between the front and back of the airway is lower in the healthy person; the airflow distribution is uniform with free breath. However, the soft palate of the OSAHS patient is hypertrophic and the airflow channel around the soft palate is narrow with rapid increase in pressure and velocity gradients during the breathing. This leads to the resistance incensement in the airflow channels of the upper airway. On the other hand, higher pressure difference and velocity gradient of the airflow field not only excite larger displacement of the soft palate but also induce decreasing inner pressure as well as increasing transmural pressure in the upper airway.The mechanical properties of the soft palate, tongue and adenoid s were tested by experiments. The experimental data was analyzed, and the choosing of material parameter was reasonable in the Fluid-structure interaction study between airflow and soft palate.The main contributions were summarized and further works were suggested at the end of this dissertation.The research work in this paper is a part of National Natural Science foundation of China (fund number: 10472025; 10672036) and Natural Science Foundation of Liaoning Province, China (fund number: 20032109).更多还原