【作者】 于申；

【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， 2008， 博士

【摘要】 鼻腔是给人体提供氧气来源的主要通道,除了承担呼吸的主要功能外,还有对吸入气流进行加温、加湿、滤过清洁等作用,以保护下呼吸道粘膜;同时又是防止呼吸系统疾病入侵人体的第一道防线。临床医疗实践和研究工作证明:鼻腔结构几何形态与鼻腔能否保持正常功能以及鼻腔疾病有着密切关系。近年来人们已经开始注意到鼻腔结构异常是导致鼻腔某些常见病的原发因素之一,然而鼻腔结构复杂,由于缺少生物模型和数值量化的计算模型,无法深入细致了解和掌握,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。根据CT扫描获取的鼻腔结构数据,构建鼻腔的数值模型对鼻腔内的气流场进行研究。通过大量鼻腔模型的建立与数值模拟,对鼻腔结构几何形态与鼻腔内气流流场的关系进行研究;进而模拟鼻腔某部位结构变化导致整个鼻腔气流场的变化。在此基础上设计两个临床应用的医疗器件,用以减轻医生的工作量和患者的痛苦。论文工作分为以下五个部分:第一部分介绍了一种重建鼻腔模型的有效方法,根据一名健康志愿者的CT图像,用表面重建的方法对该患者的鼻腔结构进行三维重建,用有限元的方法对鼻腔域中的气体流动进行了数值模拟及分析,并把得到的结果与医学文献中记载的数据相比较,证明重建鼻腔模型与气体流场数值模拟的可行性。第二部分主要研究鼻腔结构的几何形态与鼻腔内气体流场的关系,应用三维重建和数值模拟的方法对24例健康成年人鼻腔的气流流场进行了分析和比较,总结健康成年人鼻腔气体流场的特点并对其按照一定规律进行分类。通过数值模拟方法分析鼻腔在鼻甲部分切除后的气流流场,并与原始模型的模拟结果进行比较,研究鼻腔结构的变化对鼻腔内气流分布的影响。第三部分主要研究正常成年人的鼻腔气道几何尺寸和鼻腔阻塞程度的关系,对17个志愿者进行鼻阻力测试,得到鼻腔的阻塞系数与气流量的关系。对测试数据进行函数拟合,确定鼻腔的阻塞系数。根据每个志愿者的鼻腔的CT扫描图像,提取鼻腔结构的几何数据。对鼻腔阻塞系数和鼻腔结构几何数据进行分析对比,建立气道几何尺寸与鼻腔阻塞系数的关系式,并确定其中的待定系数。结果表明,可以通过鼻腔气道的截面积、气道长度、湿周长等几何尺寸大致的确定鼻腔的阻塞程度。第四部分设计一种应用于功能性内窥镜鼻窦手术后的引流器,在术后放入窦口鼻道复合体处,防止窦口的粘连,保证鼻腔通气,通过鼻腔呼吸气流自动将上颌窦内的积液引出,将液体药剂输送到上颌窦,方便术后的管理。根据重建的三维鼻腔模型进行数值模拟的结果和鼻阻力仪测量的结果得到窦口鼻道复合体处的气流流动情况。通过两相流理论和建立的引流器计算模型,对于“引流和注药过程”进行数值模拟和定量分析。在数值模拟过程中,改变引流器的管径以及引流物质的粘性系数,分别计算并比较结果,对引流器形状进行优选,确保本文设计的引流器可以完成通气、引流,注药和保持上颌窦窦口不粘连的功能。第五部分设计一种鼻用塞固器,在鼻中隔粘骨膜下矫正术后,放入鼻腔替代传统的填塞材料,起到固定鼻中隔、压迫止血和保持鼻腔通气的作用。通过有限单元法模拟塞固器和膨胀海绵在鼻腔中的工作情况,分析两者的模拟结果,比较鼻中隔粘骨膜的压应力和第一主应力。由模拟结果可知,鼻用塞固器可以起到固定鼻中隔、压迫止血和保持鼻腔通气的作用,同时不会导致鼻腔粘膜的破裂。更多还原

【Abstract】 Nasal cavity is the main passage of oxygen airflow. Except the main function of respiration nasal cavity provides the functions to filters, warms, and humidifies inspired air and protects the delicate structure of the lower respiratory system. The nasal cavity places itself at risk from the respiratory system sickness. Clinical medical treatment and research work demonstrate that nasal functions and nasal diseases are related to the structure of nasal cavity. In recent years it has been proved that the abnormal nasal structure will lead to some nasal diseases. The complex nasal structure and the lack of biomechanical model and numerical model make it is difficult to deeply explore. It has influenced the clinical forecast, diagnose, selection of treatment project and estimation of curative effect for the disease.In this paper, the nasal cavity structure is reconstructed based on the CT images and the numerical simulation for nasal airflow is performed. The relationship between nasal cavity structure and distribution of nasal airflow is investigated based on many reconstructed nasal cavity models. Then the change of distribution of nasal airflow is investigated that caused by the partly change of nasal structure. Based on these works two medical wares are designed to help the doctors and the patients. Five parts of this paper are summarized as follows:In the first part an efficient method for building nasal model is introduced. The nasal cavity structure of a healthy volunteer is reconstructed by the method of surface rendering based on his CT images. The numerical simulation and the analysis for the airflow in the nasal cavity was made by the finite element method and the results are compared with the data from the literature. The comparison indicates that the result is believable and this method is feasible.In the second part the relationship between nasal structure and distribution of nasal airflow is investigated. Numerical simulation for the airflow in 24 nasal models is performed. The characters of airflow distribution in all nasal models are investigated and classified. The numerical simulation and analysis for airflow field in the nasal models with turbinate removed partly are performed by the numerical simulation method. The simulation results from new models are compared with that from the original model to study the influence of change of nasal structure on the distribution of nasal airflow.In the third part the relationship between nasal airway dimension of normal adults and the degree of nasal obstruction will be investigated. The nasal airway resistance of 17 volunteers is measured through active anterior rhinomanomety. Curve fitting for the rhinomanometer data is performed to find the obstruction coefficient of nasal airway. We obtain the geometry dimensions of the nasal cavities from the CT images of volunteers. Nasal obstruction coefficient is considered as a function of the nasal airway dimensions. The undetermined coefficient is identified by curves fitting for the data of geometry dimensions and obstruction coefficients. It can be concluded that the nasal obstruction coefficient can be identified closely by geometry dimensions of nasal cavity such as nasal coronal section area, length of nasal airway and perimeter of coronal section of nasal airway.In the fourth part the drainage ware is designed for postoperative care after functional endoscopic sinus surgery. It can prevent the ostium of maxillary sinus from closing, drain the empyemata from maxillary sinus and send the medicament to the field of ostiomeatal complex. Based on the results of numerical simulation of airflow in nasal cavity and the data obtained from Rhinomanometry the characters of airflow in the middle nasal meatus are acquired. The numerical model of drainage ware is generated. Based on the tow-phase flow theory numerical simulation for the liquid in the drainage ware is performed to explain how the drainage ware dose its work. Changing the tube diameter or viscosity parameters of liquid-phase flow different results of numerical simulation are acquired. Comparing the computational results the fit diameter of drainage tube is obtained. The drainage ware designed in this study can accomplish the work of keeping ventilation, draining the empyemata, sending medicament and preventing the ostium of maxillary sinus from closing.In the fifth part the packing-fixer is designed as packing material for nasal that can keep breathing, fix the nasal septum and arrest bleeding after nasal septum mucous membrane surgery. Numerical simulation is performed to study the function of packing-fixer and expansive sponge in nasal cavity by means of finite element method. The compression stress and the first principal stress are compared between tow conditions. From the simulation results it can be demonstrated that the packing-fixer designed in this study can keep breathing, fix the nasal septum and arrest bleeding after nasal septum mucous membrane surgery and would not break the nasal septum mucous membrane.The study would contribute to nasal clinical application in clinical diagnose, design of treatment project and estimation of curative effect for the disease.更多还原