title: Computed tomography assessment of pharmacological lung volume reduction induced by bronchodilators in COPD.
abstract: Pharmacological lung volume reduction in COPD is an important goal in treatment with long-acting bronchodilators because in addition to airflow limitation, lung hyperinflation considerably affects COPD symptoms. Quantitative computed tomography (CT) simultaneously provides structural information about airway dimensions, emphysematous changes, and lung volumes, some of which are difficult to be evaluated by pulmonary function. Here, we evaluated changes in CT parameters and pulmonary function in 30 patients with COPD who underwent CT scans before and one year after starting tiotropium treatment and in 12 patients with COPD who were not treated with long-acting bronchodilators. Baseline pulmonary function and CT parameters did not differ between the two groups. One-year tiotropium therapy improved physiological-indices including residual volume (RV) and ratio of RV to total lung capacity (RV/TLC) (-235 mL, p = 0.005, and -2.9%, p = 0.0001, respectively), and CT-indices including wall area percent (WA%) and inner luminal area in right upper lobe apical and lower lobe basal segmental bronchi (-1.59%, p = 0.01, 2.27 mm(2), p = 0.0005; and -1.33%, p = 0.0008, 3.42 mm(2), p < 0.0001, respectively), low attenuation volume (LAV) and total lung volume (CT-TLV) (-92 mL, p = 0.0003, and -211 mL, p = 0.002, respectively). Changes in LAV, CT-TLV, RV, and RV/TLC were significantly greater in the tiotropium, than the non-bronchodilator group. The tiotropium-induced reduction in LAV correlated with the decrease in RV (ρ = 0.45, p = 0.01). Our findings not only indicate the value of the comprehensive CT measurements in assessing the effects of bronchodilators, including pharmacological lung volume reduction, but also further understanding of the structural changes underlying physiological improvements induced by bronchodilators.
authors.affiliation: Department of Respiratory Medicine, Graduate School of Medicine, Kyoto University, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Tanabe
authors.forename: Shigeo
authors.initials: S
authors.lastname: Muro
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Oguma
authors.forename: Susumu
authors.initials: S
authors.lastname: Sato
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kiyokawa
authors.forename: Tamaki
authors.initials: T
authors.lastname: Takahashi
authors.forename: Megumi
authors.initials: M
authors.lastname: Kudo
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kinose
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kubo
authors.forename: Yuma
authors.initials: Y
authors.lastname: Hoshino
authors.forename: Emiko
authors.initials: E
authors.lastname: Ogawa
authors.forename: Toyohiro
authors.initials: T
authors.lastname: Hirai
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
mesh_terms: D000368:Aged; D001993:Bronchodilator Agents / Q000494:pharmacology* / Q000627:therapeutic use; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000503:physiopathology; D012602:Scopolamine Derivatives / Q000494:pharmacology* / Q000627:therapeutic use; D000069447:Tiotropium Bromide; D014057:Tomography, X-Ray Computed; D014109:Total Lung Capacity / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D001993:Bronchodilator Agents; D012602:Scopolamine Derivatives; D000069447:Tiotropium Bromide