title: Spirometric correlates of dyspnea improvement among emergency department patients with chronic obstructive pulmonary disease exacerbation.
abstract: OBJECTIVE
  To examine whether change in slow vital capacity (SVC) correlates to dyspnea improvement during emergency department (ED) treatment of chronic obstructive pulmonary disease (COPD) exacerbation.
  
  
  METHODS
  We performed a prospective cohort study and enrolled consecutive patients during a 3-week period. ED patients > or = 55 years old with COPD exacerbation were asked to perform bedside spirometry shortly after ED arrival and again at discharge. SVC was measured first, then forced expiratory volume in the first second (FEV1), peak expiratory flow (PEF), and forced vital capacity (FVC). Concurrent with spirometry, patients rated their dyspnea on a 10-cm visual analogue scale.
  
  
  RESULTS
  Thirty-six patients were enrolled. The median ED stay was 271 min (interquartile range 219-370 min). Seventy-one percent of the patients reported dyspnea improvement during their ED stay. Change in SVC was significantly higher among the patients whose dyspnea improved than among those whose did not (median increase of 0.15 L vs median decrease of 0.25 L, respectively, p < 0.01). By contrast, the change in spirometry values were similar for FEV1, PEF, and FVC (all p > 0.30). Spearman correlation supported these findings: SVC r = 0.45 (p = 0.02) versus nonsignificant correlation with FEV(1) (r = 0.33), PEF (r = -0.22), and FVC (r = 0.35).
  
  
  CONCLUSIONS
  Increase in SVC significantly correlated with dyspnea improvement among ED patients with moderate-to-severe COPD exacerbation. Change in SVC merits consideration when evaluating therapeutic response during COPD exacerbation.
authors.affiliation: Department of Emergency Medicine, Massachusetts General Hospital, 326 Cambridge Street, Suite 410, Boston MA 02114, USA. ccamargo@partners.org
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
authors.forename: Chu-Lin
authors.initials: CL
authors.lastname: Tsai
authors.forename: Sunday
authors.initials: S
authors.lastname: Clark
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Kenney
authors.forename: Michael S
authors.initials: MS
authors.lastname: Radeos
mesh_terms: D000368:Aged; D018450:Disease Progression; D004417:Dyspnea / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D004636:Emergency Service, Hospital; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D012720:Severity of Illness Index; D013147:Spirometry / Q000379:methods*; D014797:Vital Capacity / Q000502:physiology*