title: Bronchodilator response in patients with normal baseline spirometry.
abstract: BACKGROUND
  Spirometry before and after bronchodilator is performed to assess air flow-limitation reversibility. In patients with normal baseline spirometry the frequency of a positive bronchodilator response, as defined by American Thoracic Society/European Respiratory Society criteria,  has not been described.
  
  
  METHODS
  We retrospectively analyzed adult patients tested in 2 academic pulmonary function testing laboratories over a 7-year period, with specific attention to patients who underwent bronchodilator testing after a normal baseline spirometry (FEV(1), FVC,  and FEV(1)/FVC within normal limits). The frequency of a positive response to bronchodilator, defined as a 12% and 200 mL increase in either FEV(1) or FVC, was calculated and associated with demographic factors.
  
  
  RESULTS
  Of the 1,394 patients with normal spirometry who were  administered bronchodilator, 43 (3.1%) had a positive response. The percent of patients responding to bronchodilator were grouped according to pre-bronchodilator FEV(1): > lower limit of normal to 90% of predicted = 6.9%, 90-100% of predicted = 1.9%, and > 100% of predicted  = 0%. An FEV(1)/FVC in the lowest 2 quartiles was associated with a higher frequency of bronchodilator response. Older patients were more likely to respond to bronchodilator, but no other demographic factors were associated with a positive bronchodilator response.
  
  
  CONCLUSIONS
  In  our study population the frequency of a positive bronchodilator response in patients with normal baseline spirometry is 3.1%. None of the patients with a pre-bronchodilator FEV(1) > 100% of predicted and only 1.9% of patients with an FEV(1) between 90% and 100% of predicted  responded. Bronchodilator testing can be omitted in patients with normal spirometry and an FEV(1) above 90% of predicted, as they have a low probability of a positive response.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA. mhegewald@scmc.org
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Hegewald
authors.forename: Ryan G
authors.initials: RG
authors.lastname: Townsend
authors.forename: Jaron T
authors.initials: JT
authors.lastname: Abbott
authors.forename: Robert O
authors.initials: RO
authors.lastname: Crapo
mesh_terms: D000367:Age Factors; D000368:Aged; D000403:Airway Resistance; D000420:Albuterol / Q000494:pharmacology*; D001993:Bronchodilator Agents / Q000494:pharmacology*; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013147:Spirometry; D014797:Vital Capacity / Q000187:drug effects*
chemical_list: D001993:Bronchodilator Agents; D000420:Albuterol