title: Response patterns to bronchodilator and quantitative computed tomography in chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Patients 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.
  
  
  METHODS
  Data 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.
  
  
  RESULTS
  Among 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.
  
  
  CONCLUSIONS
  The degrees of emphysema and air trapping may contribute to the different response patterns to bronchodilator in patients with COPD.
authors.affiliation: 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.
authors.forename: Jae Seung
authors.initials: JS
authors.lastname: Lee
authors.forename: Jin Won
authors.initials: JW
authors.lastname: Huh
authors.forename: Eun Jin
authors.initials: EJ
authors.lastname: Chae
authors.forename: Joon Beom
authors.initials: JB
authors.lastname: Seo
authors.forename: Seung Won
authors.initials: SW
authors.lastname: Ra
authors.forename: Ji-Hyun
authors.initials: JH
authors.lastname: Lee
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
authors.forename: Young Kyung
authors.initials: YK
authors.lastname: Lee
authors.forename: Tae-Hyung
authors.initials: TH
authors.lastname: Kim
authors.forename: Woo Jin
authors.initials: WJ
authors.lastname: Kim
authors.forename: Jin Hwa
authors.initials: JH
authors.lastname: Lee
authors.forename: Sang-Min
authors.initials: SM
authors.lastname: Lee
authors.forename: Sangyeub
authors.initials: S
authors.lastname: Lee
authors.forename: Seong Yong
authors.initials: SY
authors.lastname: Lim
authors.forename: Tae Rim
authors.initials: TR
authors.lastname: Shin
authors.forename: Ho Il
authors.initials: HI
authors.lastname: Yoon
authors.forename: Seung Soo
authors.initials: SS
authors.lastname: Sheen
authors.forename: Yeon-Mok
authors.initials: YM
authors.lastname: Oh
authors.forename: Sang-Do
authors.initials: SD
authors.lastname: Lee
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D000420:Albuterol / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D016014:Linear Models; D008168:Lung / Q000000981:diagnostic imaging* / Q000187:drug effects* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000503:physiopathology; D011656:Pulmonary Emphysema / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000503:physiopathology; D056910:Republic of Korea; D012189:Retrospective Studies; D013147:Spirometry; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol