• Jae Seung Lee, Jin Won Huh, Eun Jin Chae, Joon Beom Seo, Seung Won Ra, Ji-Hyun Lee, Eun-Kyung Kim, Young Kyung Lee, Tae-Hyung Kim, Woo Jin Kim, Jin Hwa Lee, Sang-Min Lee, Sangyeub Lee, Seong Yong Lim, Tae Rim Shin, Ho Il Yoon, Seung Soo Sheen, Yeon-Mok Oh, and Sang-Do Lee.
• Department of Pulmonary and Critical Care Medicine, Asthma Center and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
• Clin Physiol Funct Imaging. 2012 Jan 1;32(1):12-8.

BackgroundPatients with chronic obstructive pulmonary disease (COPD) show different spirometric response patterns to bronchodilator, such that some patients show improvement principally in expiratory flow (forced expiratory volume in 1 s; FEV(1)), whereas others respond by improvement of lung volume (forced vital capacity; FVC). The mechanisms of these different response patterns to bronchodilator remain unclear. We investigated the associations between bronchodilator responsiveness and quantitative computed tomography (CT) indices in patients with COPD.MethodsData on a total of 101 patients with stable COPD were retrospectively analysed. Volume and flow responses to bronchodilator were assessed by FVC and FEV(1) changes before and after inhalation of salbutamol (400 μg). Volumetric CT was performed to quantify emphysema, air trapping and large airway thickness. Emphysema was assessed by the volume fraction of the lung under -950 Hounsfield units (HU; V(950)) at full inspiration and air trapping by the ratio of mean lung density (MLD) at full expiration and inspiration. Airway wall thickness and wall area percentage (WA%; defined as wall area/[wall area + lumen area] × 100), were measured near the origin of right apical and left apico-posterior bronchus.ResultsAmong quantitative CT indices, the CT emphysema index (V(950 insp)) showed a significant negative correlation with postbronchodilator FEV(1) change (R = -0·213, P = 0·004), and the CT air-trapping index correlated positively with postbronchodilator FVC change(R = 0·286, P≤0·001). Multiple linear regression analysis showed that CT emphysema index had independent association with postbronchodilator FEV(1) change and CT air-trapping index with postbronchodilator FVC change.ConclusionThe degrees of emphysema and air trapping may contribute to the different response patterns to bronchodilator in patients with COPD.© 2011 The Authors. Clinical Physiology and Functional Imaging © 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine.

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