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2017/12/10.
概述


肺位于横膈膜上方胸腔内,是人体呼吸系统的重要组成部分。肺组织呈海绵状、有弹性,其生理功能为吸入氧气,呼出二氧化碳。

吸气时,氧气经直径逐渐变细的支气管树(也称为支气管和细支气管)分布至全肺。在支气管树末端的肺泡中,吸入的氧气由肺进入血流,机体新陈代谢产生的二氧化碳由血液进入肺,呼出体外。经血液运送至全身的氧气维持机体细胞正常功能;呼出的二氧化碳作为机体酸碱平衡系统的组成部分,调节血液pH在正常水平,维持机体酸碱平衡

肺具有防御功能,可抵抗外界环境中存在的灰尘、花粉、细菌、病毒、烟和挥发性化学物品等潜在有害物质呼吸时经呼吸道侵入。肺部防御系统包括免疫细胞和黏膜分泌物,可清除肺部有害物质。

Accordion Title
About 肺部疾病
  • 肺部疾病

    肺部疾病在某些肺功能受累时发生,如肺泡和血液间的膜异常使气体交换时氧气摄入和二氧化碳排出受阻;在某些情况下,由于支气管树堵塞或胸部肌肉收缩和舒张功能受损,导致支气管系统不能有效地将空气运输到肺泡;有时由于肺部疾患或者有毒物质数量超过肺防御系统的安全负荷,肺不能够去除外来物质或使其解毒。

    常见肺部疾病:

    哮喘是以支气管和细支气管炎症以及间断气道阻塞为特征的慢性肺病。哮喘患者常对某些物质产生不同于正常人的过敏反应。香烟烟雾、空气中的颗粒、灰尘、霉菌、变应原、运动、冷空气等因素都可诱发哮喘发作。诱因存在个体差异。发作时,气道肺肿胀、环绕支气管的肌肉收缩使气道变窄,而黏液分泌物进一步阻碍气体流动,使呼吸更为困难,导致患者喘息。大多数发作性哮喘不会出现永久性肺损伤,但频繁发作时因O2缺乏和CO2堆积而威胁生命,常需及时处理。美国肺病协会(the American Lung Association,ACA)研究显示,哮喘是儿童时期最常见的慢性疾病,美国有超过600万儿童和1500万成人患者。

    慢性阻塞性肺炎肺气肿和慢性支气管炎的总称。ACA统计,COPD是美国第四位死因。慢性支气管炎是支气管壁的慢性炎症和瘢痕,肺气肿是肺泡的慢性损坏,以上两种疾病同时发生时,患者呼吸更加困难,需吸氧。约80%-90%的COPD患者死亡与吸烟有关,其他危险因素包括反复暴露于空气污染。

    肺纤维化是一种间质性肺病,以肺泡间组织损伤和瘢痕化、肺泡炎症和肺纤维组织增生为特征。病因包括:

    • 反复暴露于职业/环境中的微粒,包括石棉、煤、铍和矽等无机物;
    • 反复暴露于有机物如霉变干草、动物粪便、谷物粉尘等,导致过敏性肺炎,最终形成肺纤维化;
    • 肺毒性化学物质和药物;
    • 放射性治疗;
    • 结节病
    • 系统性硬化病及其他自身免疫性疾病
    • 特发性间质性肺纤维化。

    感染可以原发于肺,累及全身,包括肺或胸膜(包绕于肺表面的膜)。表现为急性或慢性,多因细菌病毒所致,极少数由真菌引起。肺炎是由多种微生物引起的急性肺组织炎症。流行性感冒是由病毒引起的包括呼吸道症状的急性全身性疾病。肺结核非结核分枝杆菌是慢性感染,常见于免疫功能低下患者(如HIV/AIDS患者)。分枝杆菌感染后病程缓慢,可累及全身或局限于肺部。

    肺癌恶性肿瘤细胞在肺中无节制过度生长,主要包括小细胞型肺癌和非小细胞型肺癌两类。其他组织的癌细胞可扩散到肺组织,称为转移癌。近年来,女性肺癌死亡人数上升,男性则下降。美国国家妇女健康信息中心(National Women's Health Information Center)数据显示,目前,肺癌死亡居美国女性癌症死因之首,多于卵巢癌乳腺癌宫颈癌死亡人数之和。肺癌的危险因素包括吸烟和氡暴露。

    肺动脉高压是因肺血管狭窄导致肺动脉高压以及心脏难以将血液运送入肺为特征的疾病。该疾病可合并其他肺部疾病,并使后者加重,亦可诱发心衰。

    肺栓塞通常由腿部或骨盆静脉的血栓移行至肺部,堵塞肺部血管而致胸痛、气促和咳嗽。常危及生命,需紧急治疗。

    支气管肺发育不良常发生于长时间氧疗和(或)机械通气的早产儿,也可见于氧中毒或肺炎患者。表现为气道炎症、不能正常发育并出现损伤。

    呼吸窘迫综合症(RDS)对于提前六周出生的新生儿而言,呼吸窘迫综合症是一种危及生命的呼吸性疾病。由于肺组织发育不良,不能产生足够量的保护性液体,称之为肺表面活性剂,肺组织不能充分扩张或膨胀,难以吸入足够的氧气。多发生于早产后几小时。

    急性呼吸窘迫综合症(ARDS)是因广泛的肺部炎症和肺水肿引起的急性进行性的严重呼吸困难。该疾病常由多种病因导致肺损伤,如严重的病毒或细菌感染、败血症、创伤、大量输血、药物过量或吸入物质,如盐水或吸烟。

    囊性纤维变性是一种遗传性疾病,累及肺、胰腺以及其他组织。特点为咸汗,汗水中存在高浓度的钠和氯离子;分泌稠性粘液阻碍呼吸,脂肪和蛋白质消化能力降低,导致吸收不良和营养不良。该疾病多见于白种人,且常在婴儿期即被诊断。ALA数据显示,美国每年大约确诊1000多个新病例。

    α - 1抗胰蛋白酶缺乏症是一种肺组织保护性蛋白质遗传性缺乏。缺乏该蛋白质时,肺进行性受损,患者发生早发性肺气肿和肝脏疾病的风险显著增加。据ALA估计,大约100,000名美国人存在这种缺陷,约25,000,000名基因携带者

    其他疾病不直接累及肺部,但可影响机体的正常呼吸功能。这些外因可影响胸腔、肌肉、神经和心脏的正常功能,主要包括神经肌肉疾病如肌肉萎缩症、脊髓灰质炎、重症肌无力、格林巴利综合症、肌萎缩侧索硬化症(ALS,鲁盖瑞氏症),以及造成脊柱结构或肋架活动异常的限制肺扩张的疾病。 [注:具体检测和治疗在本文中未提及。]

  • Signs and Symptoms

    体征症状肺病的症状与体征因人因时而异。慢性肺部疾病的症状往往呈进行性加重,而急性肺部疾病可为轻度到重度,有些病例若不及时治疗,甚至威胁生命。尽管疾病有其自身特点,但大多数肺部疾病患者有相似的症状与体征,包括持续咳嗽和气喘,亦出现气喘、喘息、咯血、咳痰或伴随胸痛。慢性阻塞性肺疾病等梗阻性肺病患者,可能出现呼吸困难,常被描述为“似用吸管呼吸”。缺氧使患者肤色偏蓝。长期缺氧者出现杵状指,即指尖膨大、指甲异常生长。

  • 试验

    肺部疾病检查目的在于诊断、确定可能的病因、评估疾病的严重程度。多数医生通过血气分析评估血液中O2和CO2水平;肺功能试验(PFTs)有助于诊断或监测肺功能;胸部x线或计算机断层成像(CT)扫描检查肺部结构。其他检查根据疾病种类选择。

    实验室检查

    肺功能检查(PFT)
    以下列出常用的检测方法。如果需要详细信息请访问乔恩•霍普金医学肺功能实验室检测网站

    • 呼吸量测定法– 测定病人用力呼出气体的量和比例。用于评价气道狭窄和梗阻程度。
    • 空气流量最大流速–测定呼出气体的比率。哮喘患者可在家中自行检测用以监测病情。
    • 肺容积– t测定深吸气量和呼气后功能残气量。有助于评价肺弹性活度、胸廓张力和呼吸肌功能。
    • 肺扩散功能检查– 评估肺泡中氧气扩散到血液的容量,通过吸入少量一氧化碳(不足以致病)来计算血液中CO的量。

    影像学检查

    • 胸部x线– 检查肺部结构和胸腔
    • 计算机断层成像(CT) – 更准确评价肺部结构
    • 核磁共振成像(MRI) – 检查胸腔内血管和器官的细微结构
    • 超声波检查– 检查胸膜腔内液体量
    • 肺核扫描– 有助于识别肺栓塞,较少用于评价肺癌治疗效果
    • 电子发射断层扫描(PET) – 有助于肺癌诊断

    其他检查

    • 心电图 (EKG, ECG) – 测定心脏节律,确定心脏疾病是否影响呼吸功能
    • 睡眠试验– 判断患者睡眠时呼吸状况(通常在指定的睡眠中心检测)
  • 治疗


    肺部疾病的治疗重在预防,治疗感染,避免传播,缓解炎症,阻止或延缓进行性肺部损害,减轻症状,呼吸通畅,减小治疗副作用,确保患者氧气充足。

    肺部疾病可通过戒烟、氡检测、减少暴露如含有石棉、碳、铍、硅、霉菌、灰尘、污染空气,以及肺毒性药物和化学物品获得有效预防。免疫功能低下者、肺部基础疾病患者、儿童和老年人通过咨询医生后注射流感和肺炎疫苗防流感和肺炎。

    肺部疾病治疗新方法不断出现,病人治疗方案需要调整。患者需要定期向医生咨询以获得最适的治疗方案。

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