Mormile F, Ciappi G
Servizio di Fisiopatologia Respiratoria, Università Cattolica del S. Cuore, Policlinico A. Gemelli, Roma, Italy.
Rays. 1997 Jan-Mar;22(1):107-26.
Airways represent a serial and parallel branched system, through which the alveoli are connected with the external air. They participate in the mechanical and immune defense against noxious agents, regional flow regulation to optimize the perfusion/ventilation ratio and provide lung mechanical support. Functional exploration of central airways is based on resistance measurement, flow-volume curve or spirometry, while peripheral airways influence parameters as the upstream resistance, the slope of phase III nitrogen washout and the residual volume. Bronchodynamic tests supply important information on airway reversibility and nonspecific reactivity. Anatomopathologic alterations of obstructive chronic bronchitis, pulmonary emphysema and bronchial asthma account for their specific functional and bronchodynamic alterations. There is a growing interest for bronchiolitis in the clinical, radiologic and functional field. This type of lesion, always present in COPD, asthma and interstitial disease, becomes relevant when isolated or predominant. The most useful anatomofunctional classification separates the "constrictive" forms, the cause of obstruction and hyperinflation, from "proliferative" forms where an intraluminal proliferation more or less extended to alveolar air spaces as in BOOP (bronchiolitis obliterans organizing pneumonia) results in restrictive dysfunction. Constrictive bronchiolitis obliterans represents a severe and frequent complication of lung and bone marrow transplantation. Idiopathic BOOP may occur with cough or flue-like symptoms. In other cases, constrictive and proliferative forms may have a toxic (gases or drugs), postinfective or immune etiology (rheumatoid arthritis, LES, etc). Respiratory bronchiolitis or smokers' bronchiolitis, an often asymptomatic lesion, rarely associated to an interstitial lung disease, should be considered separately. The relationships between respiratory bronchiolitis, COPD and initial centriacinar emphysema is still to be elucidated. The diagnostic combination of the more sensitive functional tests with HRCT will allow a better understanding of the natural history of the various forms of bronchiolitis.
气道是一个串联和并联的分支系统，通过该系统肺泡与外界空气相连。它们参与对有害物质的机械和免疫防御，进行区域血流调节以优化灌注/通气比，并为肺提供机械支持。对中央气道的功能探索基于阻力测量、流量-容积曲线或肺量计，而外周气道则影响诸如上游阻力、氮洗脱第三阶段斜率和残气量等参数。支气管动力学测试提供有关气道可逆性和非特异性反应性的重要信息。阻塞性慢性支气管炎、肺气肿和支气管哮喘的解剖病理学改变导致了它们特定的功能和支气管动力学改变。在临床、放射学和功能领域，对细支气管炎的关注日益增加。这种病变在慢性阻塞性肺疾病、哮喘和间质性疾病中总是存在，当它单独出现或占主导时就变得很重要。最有用的解剖功能分类将导致阻塞和肺过度充气的“狭窄性”形式与“增殖性”形式区分开来，在增殖性形式中，管腔内增殖或多或少扩展到肺泡气腔，如在闭塞性细支气管炎伴机化性肺炎（BOOP）中，会导致限制性功能障碍。闭塞性细支气管炎是肺和骨髓移植的一种严重且常见的并发症。特发性BOOP可能伴有咳嗽或流感样症状。在其他情况下，狭窄性和增殖性形式可能有毒性（气体或药物）、感染后或免疫病因（类风湿性关节炎、狼疮等）。呼吸性细支气管炎或吸烟者细支气管炎是一种通常无症状的病变，很少与间质性肺病相关，应单独考虑。呼吸性细支气管炎、慢性阻塞性肺疾病和初始小叶中心型肺气肿之间的关系仍有待阐明。更敏感的功能测试与高分辨率计算机断层扫描（HRCT）的联合诊断将有助于更好地了解各种形式细支气管炎的自然病程。
