title: Residual Volume and Total Lung Capacity to Assess Reversibility in Obstructive Lung Disease.
abstract: BACKGROUND
  Reversibility of obstructive lung disease is traditionally defined by changes in FEV1or FVC in response to bronchodilators. These may not fully reflect changes due to a reduction in hyperinflation or air-trapping, which have important clinical implications. To date, only a handful of studies have examined bronchodilators' effect on lung volumes. The authors sought to better characterize the response of residual volume and total lung capacity to bronchodilators.
  
  
  METHODS
  Responsiveness of residual volume and total lung capacity to bronchodilators was assessed with a retrospective analysis of pulmonary function tests of 965 subjects with obstructive lung disease as defined by the lower limit of normal based on National Health and Nutritional Examination Survey III prediction equations.
  
  
  RESULTS
  A statistically significant number of subjects demonstrated response to bronchodilators in their residual volume independent of response defined by FEV1or FVC, the American Thoracic Society and European Respiratory Society criteria. Reduced residual volume weakly correlated with response to FEV1and to FVC. No statistically significant correlation was found between total lung capacity and either FEV1or FVC.
  
  
  CONCLUSIONS
  A significant number of subjects classified as being nonresponsive based on spirometry have reversible residual volumes. Subjects whose residual volumes improve in response to bronchodilators represent an important subgroup of those with obstructive lung disease. The identification of this subgroup better characterizes the heterogeneity of obstructive lung disease. The clinical importance of these findings is unclear but warrants further study.
authors.affiliation: Department of Internal Medicine as St. Louis University, St. Louis, MO.
authors.forename: Conor T
authors.initials: CT
authors.lastname: McCartney
authors.affiliation: Department of Internal Medicine, The Division of Pulmonary, Critical Care and Sleep Medicine, St. Louis, MO.
authors.forename: Melissa N
authors.initials: MN
authors.lastname: Weis
authors.affiliation: Department of Internal Medicine, The Division of Pulmonary, Critical Care and Sleep Medicine, St. Louis, MO.
authors.forename: Gregg L
authors.initials: GL
authors.lastname: Ruppel
authors.affiliation: Department of Internal Medicine, The Division of Pulmonary, Critical Care and Sleep Medicine, St. Louis, MO. nayakrp@slu.edu.
authors.forename: Ravi P
authors.initials: RP
authors.lastname: Nayak
mesh_terms: D000280:Administration, Inhalation; D000368:Aged; D000420:Albuterol / Q000008:administration & dosage*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012115:Residual Volume / Q000187:drug effects*; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D014109:Total Lung Capacity / Q000187:drug effects*; D016896:Treatment Outcome
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol
keywords: bronchodilator agent; chronic obstructive; lung diseases; obstructive; pulmonary disease