阻塞性睡眠呼吸暂停低通气综合征患者上气道流体动力学模型的建立

 背景：对阻塞性睡眠呼吸暂停低通气综合征患者上呼吸道内气体流动情况进行分析有助于进一步了解上呼吸道解剖结构与功能间的相互关系,从而认识阻塞性睡眠呼吸暂停低通气综合征的发病机制。 目的：建立阻塞性睡眠呼吸暂停低通气综合征患者上气道三维形态及流体动力学模型,为研究阻塞性睡眠呼吸暂停低通气综合征患者上气道气流动力学特征,探讨其发病机制奠定基础。 方法：对1名男性中度阻塞性睡眠呼吸暂停低通气综合征患者的上气道行CT扫描,将以DICOM格式存储的扫描数据导入Mimics 10.01软件中进行处理,得到上气道三维模型。通过ANSYS ICEM CFD14.0对三维模型进行网格划分后,用 ANSYS 14.0-Fluid Dynamics对上呼吸道内部流场进行数值模拟,获得上气道气流场相关信息。 结果与结论：建立了完整的上气道三维形态及流体动力学模型,共得到上气道网格数为1 751 940个单元,节点数为303 981个节点,上呼吸道内最大流速为11.087 m/s位于咽腔狭窄区域腭咽下界处。上气道流体动力学模型符合人体的生物力学特点,为以后进一步研究阻塞性睡眠呼吸暂停低通气综合征患者上呼吸道气流动力学特征奠定了基础。     

扁桃体切除后伤口缝合方式对睡眠呼吸暂停患者咽腔结构影响的有限元方法研究

目的腭咽是阻塞性睡眠呼吸暂停(obstructive sleep apnea,OSA)患者中最为常见的阻塞部位,该类患者手术治疗多采用保留悬雍垂腭咽成形术(Han-uvulopalatopharyngoplasty,H-UPPP),切除扁桃体是该手术的重要组成部分,其目的是扩大咽腔,改善气道通气性能。手术后切口缝合时会引起组织中应力重新分布,从而直接影响术后咽腔壁的几何形态和手术效果。但目前尚无有效方法评估切口缝合方式对手术效果的影响。本研究提出利用有限元分析模型探究扁桃体窝不同缝合方式对咽腔结构的影响,以此对H-UPPP术式操作的选择提供理论依据。方法基于OSA患者头颈部磁共振图像,构建具有真实解剖结构的气道及周边组织的三维有限元模型。通过收缩扁桃体组织体积和限定其组织表面位移来模拟扁桃体切除手术及三种缝合方式。利用ADINA软件进行数值模拟,通过观察气道最小横截面面积和咽腔空间的变化等探讨不同缝合方式对咽腔尺度的影响。结果利用三维有限元模型模拟了对位、前拉、后拉三种缝合方式。数值模拟结果显示,前拉缝合扁桃体窝时气道最狭窄处横截面积变化最为显著,扩大了27.82%。而对位缝合和后拉缝合扁桃体窝的情况,该处横截面积增加量分别为24.76%和27.11%。对于对位和后拉缝合,悬雍垂游离端附近的咽腔横截面积变化更为明显,其平均值约为手术前的5倍。相比之下,前拉缝合后相同区域平均咽腔横截面积值约为手术前的4.3倍。结论腭咽成形术改良术式的伤口缝合方式会对周边软组织中应力分布和气道截面几何形态产生重要影响。本研究建立的方法可用于针对不同患者的个性化模拟,对于本研究所涉的患者上气道解剖结构类型,模型显示前拉缝合对改善患者咽腔最狭窄部位结构更为有利。     

一种检测呼吸暂停阻塞部位方法的研究

介绍一种新的检测呼吸暂停的方法。此法采用改进的三通道阻抗测量检测胸部、鼻部、喉部的组织运动的情况。利用各通道不同的阻抗信息判定呼吸暂停的发生。并通过不同通道中的阻抗变化特征区分呼吸暂停的类型。经人体模拟实验表明，三通道阻抗变化可反映不同部位组织运动的信息。检测喉部阻抗，发现喉部气道阻塞时，阻抗信号发生特征性变化；测量鼻及舌咽部的阻抗，如果舌、咽、软腭阻塞了气道，此通道的阻抗显著减小；胸部通道呼吸运动停止时，阻抗随呼吸的变化基本消失。通过人体实验测试，三通道阻抗法能够判定呼吸暂停的发生并能区分呼吸暂停的类型，进一步分析各通道的阻抗变化特征，确定阻塞部位。     

镍钛合金网状气道支架置入术的计算机数值模拟分析

气道狭窄已成为一种较为常见的呼吸系统疾病,临床上往往需要进行气道支架置入术以实现气道的快速扩张,缓解患者的呼吸困难。但支架置入后常会出现肉芽组织过度增生的现象,严重的会造成气道的再狭窄。基于"应力-生长"关系的理论,肉芽组织的过度增生可能与局部力学环境的改变相关,特别是支架对气道壁的应力刺激。为此,研究将针对镍钛合金网状气道支架置入术展开计算机数值模拟,以分析支架置入前后局部力学环境的改变。结果显示气道支架置入后,狭窄处壁面的局部应力环境发生了显著的改变,其壁面的扩张应力明显升高且应力集中的现象较为严重。我们认为显著改变的局部应力环境可能是造成气道肉芽组织过度增生的因素之一。     

脱细胞真皮基质联合镍钛合金支架修复犬喉腔缺损

背景:镍钛合金支架可制作成甲状软骨的"V"型,有效修复其空间三维结构,最大程度保证喉通气及发声功能的恢复。目的:评估脱细胞真皮基质联合镍钛合金支架修复喉腔缺损的可行性。方法:将6只健康杂种犬分成两组,每组3只。均行喉次全切除术,实验组行脱细胞真皮基质联合镍钛合金支架修复,对照组用镍钛合金支架同期修复。分别于术后1,6个月行X射线检查及喉内窥镜检查,并于术后6个月处死动物,取出标本,分别行大体标本观察及组织学检查。结果与结论:X射线显示镍钛合金支架无移位及变形,大体标本观察可见实验组喉黏膜修复良好,除1例少量瘢痕生成外,余2例基本无瘢痕生成,喉腔通畅,均无喉腔狭窄,犬术后呼吸、吞咽功能恢复良好。对照组3例支架表面肉芽及瘢痕组织增生,其中1例于术后第63天死于呼吸困难。组织学观察显示实验组上皮基本为复层鳞状上皮,间质内可见血管组织及少量淋巴细胞。对照组肉芽组织及纤维组织增生明显,基本无复层鳞状上皮覆盖,间质内大量淋巴细胞及浆细胞。结果表明,脱细胞真皮基质联合镍钛合金支架可有效修复犬喉腔缺损,既可提供良好的支架作用,又可减少喉腔肉芽组织及瘢痕形成。     

基于ABAQUS的升主动脉置换术术后血流数值模拟

目的:为研究人工升主动脉置换术治疗Stanford A型主动脉夹层后的血流动力学规律,采集临床CT图像,构建术后个性化主动脉流场几何模型。基于计算流体动力学对其进行数值模拟,得到术后流域壁面压力分布和流速分布两个力学指标,从而分析术后流域规律。方法:采集术后CT图像DICOM文件并应用影像后处理软件MIMICS进行三维重构及优化获得几何模型,再将该流域模型导入网格划分软件进行CFD网格划分,最后将网格文件导入ABAQUS/CFD模块进行多周期瞬态模拟。结果:通过模拟计算,得到术后主动脉在心动周期不同时刻的血流动力学参数。结论:血流动力学参数与边界条件密切相关。主动脉内复杂流场环境与心血管疾病存在一定联系。数值模拟可为人工血管置换术后病情发展提供参考。     

急性呼吸窘迫综合征患者下呼吸道内气流运动特性

目的应用计算流体动力学(computational fluid dynamics,CFD)技术对急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)患者不同程度呼吸窘迫状态时下呼吸道内气流运动特性进行模拟研究。方法基于CT影像数据建立真实健康人体下呼吸道三维模型。采用标准k-ε湍流模型对下呼吸道内的气体流动进行数值模拟,分析下呼吸道内气流的速度、流量、压力以及壁面剪切应力等参数分布特点。结果拟合下呼吸道空气流动阻力与呼吸强度的函数关系;得到下呼吸道内空气流速、压力、壁面剪切应力的分布特点以及空气流量在各肺及各叶支气管的分配情况。结论通过CFD模拟分析可以获得更为详细的下呼吸道流场相关数据,为ARDS患者的临床治疗提供理论依据。     

解剖暴露喉上神经的体会

近年来随着甲状腺疾病患者数量逐年增加,喉上神经解剖学基础显得尤为重要。喉上神经内支双侧受损会导致患者喉部声门裂以上粘膜感觉丧失,在进食尤其是喝水的时候会因误咽而呛咳;喉上神经外支双侧受损则会导致患者环甲肌群瘫痪,引起声带松弛而成波浪状,音调降低,不能发高音,音质变粗而弱,易疲乏。本文就术中显露喉上神经体会,报告如下。     

中央气道阻塞的气管镜处理

目的　中央气道阻塞是频临窒息 ,威胁患者生命的急危重症。系良性和恶性疾病阻塞气道导致解剖变异或功能缺失所致。本文复习此类患者的气管镜处理经验 ,并探讨其适应证 ,处理技巧及治疗效果。方法　回顾性复习 1992 .0 7～ 1996 .0 4月因中央气道阻塞行气管镜处理的 97例患者资料。结果　本组男性 48例 ,女性 49例 ,年龄 13～ 85岁。良性疾病 48例 ,恶性疾病 49例 ,计 10 8处狭窄。诊断包括肺癌 ,原发性气管支气管肿瘤 ,气道内或纵隔的转移性肿瘤和各种良性阻塞。处理方法包括气管镜下用器械挖除肿瘤 ,扩张术 ,激光消融 ,腔内近距离放疗 ,放…     

上气道及部分支气管生物力学模型的数值研究

目的建立上气道、气管及部分支气管的生物力学模型,研究不同呼吸模式对气道内气流特性以及气道阻力的影响。方法根据CT扫描资料,建立包括鼻腔、口腔、咽、喉、气管和部分支气管在内的具有真实解剖结构形态的三维有限元呼吸道模型,针对现实中几种典型情况,数值模拟流经鼻、口的气流不同比例情况下气道内的气流特性。结果当仅有少量气流经由口腔吸入时,呼吸道内气流的分布规律以及各部位气道阻力的大小与完全经由鼻腔呼吸的情况相似。当口腔吸入或呼出大量气体,气流主要经由口腔与外界进行交换时,呼吸道内气流场、压力场和剪应力场分布规律明显不同,主要区别体现在鼻腔、口腔气道内。结论建立上气道与气管、支气管生物力学模型,可以从整体上了解呼吸过程中整个上气道至部分支气管中气流的分布情况,为了解与上气道结构相关疾病的发病机制建立数值研究平台。     

喉全切除术后二期发音功能重建术的临床应用

目的 探讨喉全切除术后失声病人重新恢复喉功能的手术法。方法 对36例病人行喉二期发音功能重建术。喉全切除术后时间为2－43个月，平均15个月，采用颈部肌皮瓣连结咽和气管，同时用皮瓣制做会厌，达到能发音，呼吸，吞咽保护功能的目的。结果 全部患者能发，用于指堵管可以口头交谈，1例已拔除气管套管，3例可完全堵管，并发症为误吸较重3例，其中1例并发严重肺内感染后死亡，2例再次封闭喉口失音。术后气管造口复发癌2例。结论 喉全切除术后二期发音重建术能恢复喉发音功能。     

同种异体犬分期喉移植再造的可行性

背景：控制感染是保证喉移植成功的关键。在实践中应探索如何最低限度地减少感染,使重建血运后的供体喉在免疫抑制状态下先成活,之后再恢复喉的呼吸、吞咽、发音功能。 目的：为减少感染,探讨采用分期移植方法进行同种异体喉移植的可行性。 方法：根据体质量、喉体大小将10只雄性同种比格犬配对成5组供受体,采用异体喉移植方式,埋置在受体犬颈部皮下,每日应用免疫抑制剂抗机体免疫排斥,待喉体成活后再将供体喉与受体分别行咽部、气管对位吻合,建立Ⅱ期喉移植动物模型。 结果与结论：Ⅰ期喉植入后,供喉生存良好,血运可。颈部纵切口的1号和颈部横切口的4,5号犬伤口生长良好,4,5号供喉未发生感染现象,最长可至4周后行Ⅱ期再植;U形切口的2,3号犬皮瓣坏死,供喉不同程度发生感染,2号喉坏死,3号经处理后喉存活。供喉在受体内生存最长可达4周。提示将喉移植分期进行,供喉摘除后预埋置法模式可以避免、减少移植后的喉体感染,受体犬耐受,供喉易成活,可以进行Ⅱ期的喉再造。移植后的主要组织学变化是黏膜上皮的改变,可以此作为观察免疫抑制反应的指标。需要处理的是埋置喉的腺体分泌问题,免疫抑制剂必须连续长期应用。     

Studies on laryngeal calibre during stimulation of peripheral and central chemoreceptors, pneumothorax and increased respiratory loads

1. The effects of asphyxia, hypoxia, hypercapnia, stimulation of peripheral chemoreceptors, pneumothorax and breathing through resistances have been investigated on laryngeal resistance to airflow in anaesthetized cats, with and without bilateral vagotomy below the origin of the recurrent laryngeal nerves.2. Resistance to airflow of the innervated larynx was usually measured with the larynx isolated in situ with constant flow from the trachea to a pharyngeal opening, and expressed by the relationship between translaryngeal pressure and airflow.3. Asphyxia, hypoxia and hypercapnia each stimulated breathing and decreased laryngeal resistance to airflow, in both the inspiratory and expiratory phases. After vagotomy the effect was reduced, abolished or (usually) reversed to a laryngeal constriction, especially in expiration.4. Intra-arterial injections of potassium cyanide (to stimulate carotid body chemoreceptors) caused a short apnoea or an augmented breath followed by hyperpnoea, concurrently with expiratory constrictions of the larynx. The responses were usually stronger after bilateral vagotomy.5. Pneumothorax caused tachypnoea, inspiratory dilatations and expiratory constrictions of the larynx. The responses were abolished by vagotomy.6. Imposition of respiratory resistances dilated the larynx, in inspiration and expiration, while complete closure of trachea caused expiratory constrictions of the larynx. These changes did not depend on intact vagal pathways.7. The results are discussed in terms of nervous control of the larynx in the different conditions.     

Functional Morphology of the Hyolaryngeal Complex of the Harbor Porpoise (Phocoena phocoena): Implications for its Role in Sound Production and Respiration

In several publications, it was shown that echolocation sound generation in the nasal (epicranial) complex of toothed whales (Odontoceti) is pneumatically driven. Modern hypotheses consider the larynx and its surrounding musculature to produce the initial air pressure: (a) contraction of the strong pipelike palatopharyngeal sphincter muscle complex, which connects the choanae with the epiglottic spout of the larynx, should provide much of the power for this process and (b) muscles suspending the larynx/hyoid complex from the skull base and the mandibles may support these pistonlike laryngeal movements. Here, we describe the morphology and topography of the larynx, the hyoid apparatus, and the relevant musculature in the harbor porpoise (Phocoena phocoena) with respect to odontocete vocalization and respiration. We demonstrate that the hyoid apparatus, reminiscent of a “swinging cage,” may not only be a stable framework in which the larynx can move but should support laryngeal actions by its own movements. Rostrocaudal relocations of the hyoid apparatus may thus support pistonlike actions of the larynx creating air flow into the nasal complex for sound production. The lift of the hyoid apparatus with the thick larynx in the direction of the skull base may squeeze the pharynx in the region of the piriform recesses and thus help to secure the (waterproof) tracheochoanal connection during respiration when the palatopharyngeal sphincter cannot be contracted maximally, because the air passage must remain open at the epiglottic spout. Anat Rec, 291:1262–1270, 2008. © 2008 Wiley‐Liss, Inc.     

Identification of the tracheal and laryngeal afferent neurones mediating cough in anaesthetized guinea-pigs

We have identified the tracheal and laryngeal afferent nerves regulating cough in anaesthetized guinea-pigs. Cough was evoked by electrical or mechanical stimulation of the tracheal or laryngeal mucosa, or by citric acid applied topically to the trachea or larynx. By contrast, neither capsaicin nor bradykinin challenges to the trachea or larynx evoked cough. Bradykinin and histamine administered intravenously also failed to evoke cough. Electrophysiological studies revealed that the majority of capsaicin-sensitive afferent neurones (both Aδ- and C-fibres) innervating the rostral trachea and larynx have their cell bodies in the jugular ganglia and project to the airways via the superior laryngeal nerves. Capsaicin-insensitive afferent neurones with cell bodies in the nodose ganglia projected to the rostral trachea and larynx via the recurrent laryngeal nerves. Severing the recurrent nerves abolished coughing evoked from the trachea and larynx whereas severing the superior laryngeal nerves was without effect on coughing. The data indicate that the tracheal and laryngeal afferent neurones regulating cough are polymodal Aδ-fibres that arise from the nodose ganglia. These afferent neurones are activated by punctate mechanical stimulation and acid but are unresponsive to capsaicin, bradykinin, smooth muscle contraction, longitudinal or transverse stretching of the airways, or distension. Comparing these physiological properties with those of intrapulmonary mechanoreceptors indicates that the afferent neurones mediating cough are quite distinct from the well-defined rapidly and slowly adapting stretch receptors innervating the airways and lungs. We propose that these airway afferent neurones represent a distinct subtype and that their primary function is regulation of the cough reflex.     

The effects of lung reflexes on laryngeal resistance and motoneurone discharge

1. The reflex action of stimulation of alveolar J-receptors and of airway epithelial irritant receptors has been investigated on laryngeal resistance to airflow and on laryngeal motoneurone discharge in cats and rabbits.2. Resistance to airflow of the innervated larynx was measured (1) with the larynx isolated in situ with constant flow from the trachea to a pharyngeal opening; and (2) with the animal breathing through the larynx and the pharyngeal opening. With both methods resistance was determined from the relationship between translaryngeal pressure and airflow.3. In control conditions the laryngeal resistance was about one tenth of total lung resistance.4. I.V. injections of phenyl diguanide (to stimulate J-receptors) caused apnoea and complete closure of the larynx, followed by rapid shallow breathing with expiratory constrictions of the larynx. Expiratory laryngeal motoneurones were strongly stimulated.5. The laryngeal responses to phenyl diguanide were nearly abolished by bilateral vagotomy in the chest (below the origin of the recurrent laryngeal nerves), and were absent on injection of the drug into the left atrium; the motoneurone responses were abolished by vagotomy and lessened by paralysis and artificial ventilation.6. I.V. injections of histamine acid phosphate or inhalation of an aerosol of the drug in solution (to stimulate lung irritant receptors) caused tachypnoea and expiratory constrictions of the larynx, and increased discharges in expiratory laryngeal motoneurones.7. The laryngeal responses to histamine were more than halved by bilateral intrathoracic vagotomy.8. Phenyl diguanide and histamine increased the frequency of the discharge of inspiratory laryngeal motoneurones, but reduced the number of impulses per inspiratory phase. Laryngeal resistance in inspiration was usually increased.     

Assessment of immunomodulation and regulation of cell cycle in epithelium and stroma after Cidofovir injection in patients with recurrent respiratory papillomatosis—Pilot study

Recurrent respiratory papillomatosis is strictly connected with human papillomavirus (HPV) infection of the epithelium of the upper respiratory tract. The main treatment of lesions located in the larynx or lower pharynx includes microsurgical excision by using a CO₂ laser. To decrease the amount of surgical procedures gain in importance combined therapy with antiviral agents. The aim of this study was to investigate the effect of the intralesional application of Cidofovir on the tissue of laryngeal papillomas. We have shown that simultaneous microsurgery with adjuvant therapy of Cidofovir reduces chronic inflammation (by measuring the expression of CD4 and CD8 in tissue samples), cell proliferation, and regulates the cell cycle of HPV-infected cells by reducing the expression of p53 and p63 proteins. In addition, this strategy reduces the multiple surgical procedures and regrowth of the pathology.     

Effects of cartilage rings on airflow and particle deposition in the trachea and main bronchi

In most computational fluid dynamic (CFD) analysis of the human lung, it has been assumed that the trachea and branches of the lung have smooth walls. In order to determine if this is a valid assumption, the effects of cartilage rings on airflow and particle deposition in the lungs was determined through conducting simulations with two CFD packages, Fluent and CFX. A smooth walled model and a ringed model of the trachea and main bronchi were created based on idealized models with realistic characteristics. Turbulent velocity profiles were implemented at the inlet of the trachea to account for the laryngeal jet at 15, 30 and 60 lpm's, while random and uniform distributions of particles were injected into the airways. Deposition of particles through sedimentation and impaction were recorded and compared for each model at each flow rate. The results of this work show that the effects of cartilage rings increase with the size of particles and flow rate.     

The reflex effects on the respiratory regulation of the CO2 at the different flow rate and concentration

PURPOSE: The purpose of this study was to investigate the activation of the respiratory centers during insufflation of the larynx with CO2 at different flow rates and concentrations. MATERIALS AND METHODS: The experiments were carried out in spontaneous air breathing rabbits, anesthetized with thiopental sodium (25 mg kg(-1) i.v.). The larynx was separated from the oropharyngeal cavity and the trachea. The tidal volume (VT) and respiratory frequency (f min(-1)) were recorded from the lower tracheal cannula. The respiratory minute volume (VE) was calculated, the action potentials from the right phrenic nerve were recorded and the inspiratory (TI) and expiratory (TE) periods and the mean inspiratory flow rate (VT/TI) were calculated. The larynx was insufflated at flow rates of 500 mL min(-1) and 750 mL min(-1), with 7 and 12% CO2-Air by means of a respiratory pump. RESULTS: Insufflation of the larynx, with both gas mixtures, decreased the f and VT significantly. The TI and TE were found to increase significantly due to the decreasing in f. There was a significant decrease in VT/TI ratio. Following bilateral midcervical vagotomy, on the passing of both gas mixtures, significant decreases were observed in the VT, and the responses of f, TI and TE were abolished. After cutting the superior laryngeal nerve, the responses of the VT to both gas mixtures were abolished. CONCLUSION: In conclusion, the results of this study purpose that the stimulation of the laryngeal mechanoreceptors by the effect of hypercapnia decreases the activation of the respiratory center.     

Ventilatory and upper-airway resistance responses to upper-airway cooling and CO2 in anaesthetised rats

The effects of upper airway (UA) cool air and CO₂ on breathing and on laryngeal and supraglottic resistances were studied in anaesthetised rats breathing spontaneously through a tracheostomy. Warm, humidified air containing 0, 5 and 9–10% CO₂ and cool, room-humidity air were delivered at constant flow to either the isolated larynx to exit through a pharyngotomy or to the supraglottic UA to exit through the mouth and/or nose (nose open or sealed). Spontaneous tracheal airflow and UA airflows, temperatures and pressures were recorded. CO₂ had no effect on breathing but caused a slight increase in laryngeal resistance which was abolished by cutting the superior laryngeal nerves (SLN). Cool air caused a decrease in respiratory frequency and/or peak inspiratory flow when applied to the isolated larynx or to the supraglottic airway with the nose closed. These effects were abolished by SLN section. With the nose open, the ventilatory inhibition was not abolished by SLN section. Cool air also caused substantial decreases in laryngeal and supraglottic resistances which were attenuated by SLN section and which persisted following recurrent laryngeal nerve section. In conclusion, whilst UA cooling inhibits breathing and decreases UA resistances, UA CO₂ has minimal effects.