Litonjua A A, Sparrow D, Weiss S T
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, and VA Outpatient Clinic, Boston, Massachusetts, USA.
Am J Respir Crit Care Med. 1999 May;159(5 Pt 1):1574-9. doi: 10.1164/ajrccm.159.5.9803063.
Airway responsiveness is known to be partly explained by geometric and anatomic factors. This cross-sectional investigation was undertaken to determine whether FEF25-75/FVC as a surrogate measure of airway size relative to lung size is associated with airway responsiveness to methacholine. Posteroanterior chest radiographs and spirometry were performed on a group of 929 middle aged and older men from an ongoing longitudinal study, the Normative Aging Study, who returned for their regularly scheduled examination between 1984 and 1989. Subjects had a mean age of 60.5 +/- 7.7 yr. FEV1, FEF25-75, and FVC were taken from spirometric results and FEF25-75/FVC ratios were obtained. Main bronchus (MB) and tracheal (TR) diameters and lung area (LA) were obtained from chest radiographs, and ratios of MB/LA and TR/LA were calculated for each subject and compared with FEF25-75/ FVC as measures of airway size relative to lung size. In a multiple linear regression model adjusting for age, height, initial FEV1, smoking, eosinophil count, and IgE level, FEF25-75/FVC was significantly related to the degree of methacholine airway responsiveness as measured by Log10 dose response slope (beta = -0.37, p < 0.001). Controlling for the same variables, both MB/LA (beta = -149.07, p < 0.001) and TR/LA (beta = -125.87, p < 0.001) were significant predictors of the degree of bronchial responsiveness in separate regression models; however, their effects were greatly attenuated when FEF25-75/ FVC was present in the same model. Similar results were obtained after excluding subjects with FEV1/ FVC </= 0.70 and subjects who had any smoking history. We conclude that FEF25-75/FVC as a surrogate measure of airway size relative to lung size is significantly associated with airway responsiveness.
气道反应性部分可由几何和解剖学因素来解释。开展这项横断面研究旨在确定，作为气道大小相对于肺大小的替代指标，用力呼气流量25%-75%与用力肺活量之比（FEF25-75/FVC）是否与对乙酰甲胆碱的气道反应性相关。对一组来自正在进行的纵向研究“标准老龄化研究”的929名中老年男性进行了后前位胸部X光片检查和肺功能测定，这些男性在1984年至1989年期间返回进行定期检查。受试者的平均年龄为60.5±7.7岁。从肺功能测定结果中获取第一秒用力呼气容积（FEV1）、用力呼气流量25%-75%（FEF25-75）和用力肺活量（FVC），并计算FEF25-75/FVC比值。从胸部X光片中获取主支气管（MB）和气管（TR）直径以及肺面积（LA），为每个受试者计算MB/LA和TR/LA比值，并与FEF25-75/FVC进行比较，作为气道大小相对于肺大小的指标。在一个对年龄、身高、初始FEV1、吸烟情况、嗜酸性粒细胞计数和免疫球蛋白E水平进行校正的多元线性回归模型中，FEF25-75/FVC与通过对数剂量反应斜率测量的乙酰甲胆碱气道反应程度显著相关（β=-0.37，p<0.001）。在控制相同变量的情况下，在单独的回归模型中，MB/LA（β=-149.07，p<0.001）和TR/LA（β=-125.87，p<0.001）都是支气管反应程度的显著预测指标；然而，当FEF25-75/FVC存在于同一模型中时，它们的作用会大大减弱。在排除FEV1/FVC≤0.70的受试者和有任何吸烟史的受试者后，得到了类似的结果。我们得出结论，FEF25-75/FVC作为气道大小相对于肺大小的替代指标，与气道反应性显著相关。
