Julia-Serda G, Molfino N A, Chapman K R, McClean P A, Zamel N, Slutsky A S, Hoffstein V
Department of Medicine, University of Toronto, Ontario, Canada.
J Appl Physiol (1985). 1992 Dec;73(6):2328-32. doi: 10.1152/jappl.1992.73.6.2328.
We examined the effect of volume history on the dynamic relationship between airways and lung parenchyma (relative hysteresis) in 20 asthmatic subjects. The acoustic reflection technique was employed to evaluate changes in airway cross-sectional areas during a slow continuous expiration from total lung capacity to residual volume and inspiration back to total lung capacity. Lung volume was measured continuously during this quasi-static maneuver. We studied three anatomic airway segments: extra- and intrathoracic tracheal and main bronchial segments. Plots of airway area vs. lung volume were obtained for each segment to assess the relative magnitude and direction of the airway and parenchymal hysteresis. We also performed maximal expiratory flow-volume and partial expiratory flow-volume curves and calculated the ratio of maximal to partial flow rates (M/P) at 30% of the vital capacity. We found that 10 subjects (group I) showed a significant predominance of airway over parenchymal hysteresis (P < 0.005) at the extra- and intrathoracic tracheal and main bronchial segments; these subjects had high M/P ratios [1.53 +/- 0.27 (SD)]. The other 10 subjects (group II) showed similar airway and parenchymal hysteresis for all three segments and significantly lower M/P ratios (1.16 +/- 0.20, P < 0.01). We conclude that the effect of volume history on the relative hysteresis of airway and lung parenchyma and M/P ratio at 30% of vital capacity in nonprovoked asthmatic subjects is variable. We suggest that our findings may result from heterogeneous airway tone in asthmatic subjects.
我们研究了容量变化史对20名哮喘患者气道与肺实质之间动态关系（相对滞后现象）的影响。采用声学反射技术评估从肺总量缓慢持续呼气至残气量以及吸气回到肺总量过程中气道横截面积的变化。在这个准静态操作过程中持续测量肺容量。我们研究了三个解剖学气道节段：胸外和胸内气管以及主支气管节段。获取每个节段的气道面积与肺容量的关系图，以评估气道和实质滞后现象的相对大小和方向。我们还进行了最大呼气流量-容积曲线和部分呼气流量-容积曲线的测定，并计算了肺活量30%时最大流量与部分流量的比值（M/P）。我们发现，10名受试者（第一组）在胸外和胸内气管以及主支气管节段显示出气道滞后现象显著强于实质滞后现象（P < 0.005）；这些受试者的M/P比值较高[1.53 ± 0.27（标准差）]。另外10名受试者（第二组）在所有三个节段均显示出相似的气道和实质滞后现象，且M/P比值显著较低（1.16 ± 0.20，P < 0.01）。我们得出结论，在未激发的哮喘患者中，容量变化史对气道与肺实质相对滞后现象以及肺活量30%时的M/P比值的影响是可变的。我们认为我们的研究结果可能源于哮喘患者气道张力的异质性。
