title: Changes in oscillatory impedance and nitrogen washout with combination fluticasone/salmeterol therapy in COPD.
abstract: BACKGROUND
  Combination inhaled corticosteroid/long-acting bronchodilator (ICS/LABA) therapy reduces the exacerbation rate and improves spirometry and quality of life in COPD. We hypothesized that ICS/LABA therapy also improves small airway function measured by FOT.
  
  
  METHODS
  14 subjects with COPD were commenced on combination fluticasone propionate/salmeterol therapy for 3 months. At baseline, subjects completed the St George Respiratory Questionnaire (SGRQ) and underwent standard pulmonary function tests as well as forced oscillation technique (FOT) and single and multiple breath nitrogen washouts. All tests were repeated at the completion of 3 months of therapy.
  
  
  RESULTS
  Subjects were of mean (SD) age 65.9 years (8.4), BMI 30.0 (5.6), pack years 51.4 (21.1), post-bronchodilator FEV1% predicted 62.7 (20). At baseline, mean SGRQ total was 39.0 (17.7) and FRC% predicted 125.4 (31.3). From FOT, Rrs-total was 5.69 (1.29) cmH2O/L/s, Xrs-total -3.48 (2.16) cmH2O/L/s, EFL Index 3.51 (2.45) cmH2O/L/s. After 3 months of therapy, there were significant improvements in SGRQ score (-13.81, p < 0.0001) despite no change in FEV1 (+40 mL, p = 0.14). From FOT, total resistance (-0.63 cmH2O/L/s, p = 0.0004), reactance (+1.2 cmH2O/L/s, p = 0.013), and expiratory flow limitation (-1.21 cmH2O/L/s, p = 0.02) also improved. There were no significant changes in ventilation heterogeneity indices.
  
  
  CONCLUSIONS
  Combination therapy is associated with improvements in small airways function in COPD, despite an absence of change in FEV1. FOT may be a clinically useful marker of small airway function in COPD that is responsive to treatment.
authors.affiliation: The Woolcock Institute of Medical Research, Glebe, NSW 2037, Australia; Department of Respiratory Medicine Royal North Shore Hospital, St Leonards, NSW 2065, Australia; The Sydney Medical School, The University of Sydney, NSW 2006, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, NSW 2037, Australia. Electronic address: stimmins@med.usyd.edu.au.
authors.forename: Sophie C
authors.initials: SC
authors.lastname: Timmins
authors.affiliation: The Woolcock Institute of Medical Research, Glebe, NSW 2037, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, NSW 2037, Australia. Electronic address: chantale@woolcock.org.au.
authors.forename: Chantale
authors.initials: C
authors.lastname: Diba
authors.affiliation: The Woolcock Institute of Medical Research, Glebe, NSW 2037, Australia; Department of Respiratory Medicine Royal North Shore Hospital, St Leonards, NSW 2065, Australia; The Sydney Medical School, The University of Sydney, NSW 2006, Australia. Electronic address: rschoeff@nssachs.health.nsw.gov.au.
authors.forename: Robin E
authors.initials: RE
authors.lastname: Schoeffel
authors.affiliation: The Woolcock Institute of Medical Research, Glebe, NSW 2037, Australia; The Sydney Medical School, The University of Sydney, NSW 2006, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, NSW 2037, Australia. Electronic address: cms@woolcock.org.au.
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: Salome
authors.affiliation: The Woolcock Institute of Medical Research, Glebe, NSW 2037, Australia; Department of Respiratory Medicine Royal North Shore Hospital, St Leonards, NSW 2065, Australia; The Sydney Medical School, The University of Sydney, NSW 2006, Australia; Cooperative Research Centre for Asthma and Airways, Glebe, NSW 2037, Australia. Electronic address: ggk@woolcock.org.au.
authors.forename: Gregory G
authors.initials: GG
authors.lastname: King
authors.affiliation: The Woolcock Institute of Medical Research, Glebe, NSW 2037, Australia. Electronic address: cindy.thamrin@woolcock.org.au.
authors.forename: Cindy
authors.initials: C
authors.lastname: Thamrin
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D000420:Albuterol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000704:Analysis of Variance; D000730:Androstadienes / Q000008:administration & dosage*; D001980:Bronchi / Q000502:physiology / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D004338:Drug Combinations; D000068297:Fluticasone-Salmeterol Drug Combination; D005938:Glucocorticoids / Q000008:administration & dosage*; D006801:Humans; D008137:Longitudinal Studies; D009584:Nitrogen / Q000032:analysis; D009991:Oscillometry / Q000379:methods; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy*; D012129:Respiratory Function Tests / Q000379:methods
chemical_list: D000730:Androstadienes; D001993:Bronchodilator Agents; D004338:Drug Combinations; D000068297:Fluticasone-Salmeterol Drug Combination; D005938:Glucocorticoids; D009584:Nitrogen; D000420:Albuterol
keywords: COPD; Forced oscillation technique; Physiology; Therapy