title: Assessment of acute bronchodilator effects from specific airway resistance changes in stable COPD patients.
abstract: BACKGROUND
  In COPD patients, reversibility is currently evaluated from the changes of forced expiratory volume at 1s (ΔFEV1) and forced vital capacity (ΔFVC). By lowering peripheral airway smooth muscle tone, bronchodilators should decrease dynamic hyperinflation, gas trapping, and possibly dyspnea at rest. Hence, we hypothesize that specific airway resistance changes (ΔsRAW) should better characterize the acute response to bronchodilators.
  
  
  METHODS
  On two days, 60 COPD patients underwent dyspnea evaluation (VAS score) and pulmonary function testing at baseline and one hour after placebo or 300μg indacaterol administration.
  
  
  RESULTS
  Spirographic and ΔsRAW-based criteria identified as responders 24 and 45 patients, respectively. ΔsRAW correlated with changes of intrathoracic gas volume (ΔITGV) (r=0.61; p<0.001), residual volume (ΔRV) (r=0.60; p<0.001), ΔFVC (r=0.44; p=0.001), and ΔVAS (r=0.73; p<0.001), while ΔFEV1 correlated only with ΔFVC (r=0.34; p=0.008). Significant differences in terms of ΔITGV (p=0.002), ΔRV (p=0.023), and ΔVAS (p<0.001) occurred only if patients were stratified according to ΔsRAW.
  
  
  CONCLUSIONS
  In assessing the acute functional effect of bronchodilators, ΔsRAW-based criterion is preferable to FEV1-FVC-based criteria, being more closely related to bronchodilator-induced improvements of lung mechanics and dyspnea at rest.
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Pneumologia Riabilitativa Fondazione Salvatore Maugeri-IRCCS, Milan, Italy. Electronic address: pierachille.santus@unimi.it.
authors.forename: Pierachille
authors.initials: P
authors.lastname: Santus
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Pneumologia Riabilitativa Fondazione Salvatore Maugeri-IRCCS, Milan, Italy. Electronic address: danko86@hotmail.com.
authors.forename: Dejan
authors.initials: D
authors.lastname: Radovanovic
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Pneumologia Riabilitativa Fondazione Salvatore Maugeri-IRCCS, Milan, Italy. Electronic address: soniaponga85@yahoo.it.
authors.forename: Sonia
authors.initials: S
authors.lastname: Henchi
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy. Electronic address: fabiano.dimarco@unimi.it.
authors.forename: Fabiano
authors.initials: F
authors.lastname: Di Marco
authors.affiliation: Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy. Electronic address: stefano.centanni@unimi.it.
authors.forename: Stefano
authors.initials: S
authors.lastname: Centanni
authors.affiliation: Dipartimento di Fisiopatologia e dei Trapianti, Università degli Studi di Milano, Milan, Italy. Electronic address: edgardo.dangelo@unimi.it.
authors.forename: Edgardo
authors.initials: E
authors.lastname: D'Angelo
authors.affiliation: Dipartimento di Fisiopatologia e dei Trapianti, Università degli Studi di Milano, Milan, Italy. Electronic address: matteo.pecchiari@unimi.it.
authors.forename: Matteo
authors.initials: M
authors.lastname: Pecchiari
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use; D000368:Aged; D000403:Airway Resistance / Q000187:drug effects*; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004417:Dyspnea / Q000188:drug therapy / Q000503:physiopathology; D005260:Female; D006801:Humans; D007189:Indans / Q000627:therapeutic use*; D008176:Lung Volume Measurements; D008297:Male; D010991:Plethysmography; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy* / Q000503:physiopathology*; D015363:Quinolones / Q000627:therapeutic use*; D012129:Respiratory Function Tests; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents; D007189:Indans; D015363:Quinolones; C510790:indacaterol
keywords: Adrenergic beta-agonists; Dyspnea; Plethysmography; Respiratory function tests; Reversibility; Short-term variability