Roberts H R, Wells A U, Milne D G, Rubens M B, Kolbe J, Cole P J, Hansell D M
Royal Brompton Hospital, Sydney Street, London SW3 6NP, UK.
Thorax. 2000 Mar;55(3):198-204. doi: 10.1136/thorax.55.3.198.
An obstructive defect is usual in bronchiectasis, but the pathophysiological basis of airflow obstruction remains uncertain. High resolution computed tomographic (CT) scanning now allows quantitation of static morphological abnormalities, as well as dynamic changes shown on expiratory CT scans. The aim of this study was to determine which static and dynamic structural abnormalities on the CT scan are associated with airflow obstruction in bronchiectasis.
The inspiratory and expiratory features on the CT scan of 100 patients with bronchiectasis undergoing concurrent lung function tests were scored semi-quantitatively by three observers.
On univariate analysis the extent and severity of bronchiectasis, the severity of bronchial wall thickening, and the extent of decreased attenuation on the expiratory CT scan correlated strongly with the severity of airflow obstruction; the closest relationship was seen between decreased forced expiratory volume in one second (FEV(1)) and the extent of decreased attenuation on the expiratory CT scan (R(s) = -0.55, p<0. 00005). On multivariate analysis bronchial wall thickness and decreased attenuation were consistently the strongest independent determinants of airflow obstruction. The extent of decreased attenuation was positively associated with the severity of bronchial wall thickness, but was not independently linked to gas transfer levels. Endobronchial secretions seen on CT scanning had no functional significance; the severity of bronchial dilatation was negatively associated with airflow obstruction after adjustment for other morphological features.
These findings indicate that airflow obstruction in bronchiectasis is primarily linked to evidence of intrinsic disease of small and medium airways on CT scanning and not to bronchiectatic abnormalities in large airways, emphysema, or retained endobronchial secretions.
阻塞性缺陷在支气管扩张中较为常见，但气流阻塞的病理生理基础仍不明确。高分辨率计算机断层扫描（CT）现在能够对静态形态异常以及呼气CT扫描显示的动态变化进行定量分析。本研究的目的是确定CT扫描上哪些静态和动态结构异常与支气管扩张中的气流阻塞相关。
100例同时进行肺功能测试的支气管扩张患者的CT扫描吸气和呼气特征由三名观察者进行半定量评分。
单因素分析显示，支气管扩张的范围和严重程度、支气管壁增厚的严重程度以及呼气CT扫描上衰减降低的范围与气流阻塞的严重程度密切相关；一秒用力呼气量（FEV(1)）降低与呼气CT扫描上衰减降低的范围之间的关系最为密切（R(s)=-0.55，p<0.00005）。多因素分析显示，支气管壁厚度和衰减降低始终是气流阻塞最强的独立决定因素。衰减降低的范围与支气管壁厚度的严重程度呈正相关，但与气体交换水平无独立关联。CT扫描上可见的支气管内分泌物无功能意义；在对其他形态学特征进行校正后，支气管扩张的严重程度与气流阻塞呈负相关。
这些发现表明，支气管扩张中的气流阻塞主要与CT扫描显示的中小气道内在疾病证据相关，而与大气道的支气管扩张异常、肺气肿或残留的支气管内分泌物无关。
