title: Relationship between spontaneous expiratory flow-volume curve pattern and air-flow obstruction in elderly COPD patients.
abstract: BACKGROUND
  Assessment of the degree of air-flow obstruction is important for determining the treatment strategy in COPD patients. However, in some elderly COPD patients, measuring FVC is impossible because of cognitive dysfunction or severe dyspnea. In such patients a simple test of airways obstruction requiring only a short run of tidal breathing would be useful. We studied whether the spontaneous expiratory flow-volume (SEFV) curve pattern reflects the degree of air-flow obstruction in elderly COPD patients.
  
  
  METHODS
  In 34 elderly subjects (mean ± SD age 80 ± 7 y) with stable COPD (percent-of-predicted FEV(1) 39.0 ± 18.5%), and 12 age-matched healthy subjects, we measured FVC and recorded flow-volume curves during quiet breathing. We studied the SEFV curve patterns (concavity/convexity), spirometry results, breathing patterns, and demographics. The SEFV curve concavity/convexity prediction accuracy was examined by calculating the receiver operating characteristic curves, cutoff values, area under the curve, sensitivity, and specificity.
  
  
  RESULTS
  Fourteen subjects with COPD had a concave SEFV curve. All the healthy subjects had convex SEFV curves. The COPD subjects who had concave SEFV curves often had very severe airway obstruction. The percent-of-predicted FEV(1)% (32.4%) was the most powerful SEFV curve concavity predictor (area under the curve 0.92, 95% CI 0.83-1.00), and had the highest sensitivity (0.93) and specificity (0.88).
  
  
  CONCLUSIONS
  Concavity of the SEFV curve obtained during tidal breathing may be a useful test for determining the presence of very severe obstruction in elderly patients unable to perform a satisfactory FVC maneuver.
authors.affiliation: Department of Rehabilitation.
authors.forename: Masafumi
authors.initials: M
authors.lastname: Nozoe
authors.forename: Kyoshi
authors.initials: K
authors.lastname: Mase
authors.forename: Shigefumi
authors.initials: S
authors.lastname: Murakami
authors.forename: Makoto
authors.initials: M
authors.lastname: Okada
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Ogino
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Matsushita
authors.forename: Sachie
authors.initials: S
authors.lastname: Takashima
authors.forename: Noriyasu
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Fukuda
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Domen
mesh_terms: D000369:Aged, 80 and over; D000402:Airway Obstruction / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology*; D045853:Exhalation; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000175:diagnosis / Q000503:physiopathology*; D012372:ROC Curve; D015203:Reproducibility of Results; D013147:Spirometry
keywords: COPD; air-flow obstruction; flow-volume curve; respiratory function test