title: Dynamic hyperinflation during treadmill exercise testing in patients with moderate to severe COPD.
abstract: OBJECTIVE
  To characterize the presence, extent, and patterns of dynamic hyperinflation (DH) during treadmill exercise testing in patients with moderate to severe COPD.
  
  
  METHODS
  This was a cross-sectional study involving 30 non-hypoxemic patients (FEV1= 43 ± 14% of predicted) who were submitted to a cardiopulmonary exercise test on a treadmill at a constant speed (70-80% of maximum speed) to the tolerance limit (Tlim). Serial inspiratory capacity (IC) maneuvers were used in order to assess DH.
  
  
  RESULTS
  Of the 30 patients studied, 19 (63.3%) presented with DH (DH+ group), having greater pulmonary function impairment at rest than did those without DH (DH- group). None of the variables studied correlated with exercise tolerance in the DH- group, whereas Tlim, IC, and perception of dyspnea during exercise did so correlate in the DH+ group (p < 0.05). In the DH+ group, 7 and 12 patients, respectively, presented with a progressive and a stable pattern of DH (ΔIC Tlim,2min = -0.28 ± 0.11 L vs. 0.04 ± 0.10 L; p < 0.01). Patients with a progressive pattern of DH presented with higher perception of dyspnea/Tlim rate and lower exercise tolerance than did those with a stable pattern (354 ± 118 s and 465 ± 178 s, respectively; p < 0.05).
  
  
  CONCLUSIONS
  The presence of DH is not a universal phenomenon during walking in COPD patients, even in those with moderate to severe airflow limitation. In the patients who presented DH, a progressive pattern of DH had a greater impact on exercise tolerance than did a stable pattern of DH.
authors.affiliation: Department of Pulmonology, ABC School of Medicine, Santo André, Brazil.
authors.forename: Priscila Kessar
authors.initials: PK
authors.lastname: Cordoni
authors.forename: Danilo Cortozi
authors.initials: DC
authors.lastname: Berton
authors.forename: Selma Denis
authors.initials: SD
authors.lastname: Squassoni
authors.forename: Maria Enedina Aquino
authors.initials: ME
authors.lastname: Scuarcialupi
authors.forename: José Alberto
authors.initials: JA
authors.lastname: Neder
authors.forename: Elie
authors.initials: E
authors.lastname: Fiss
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000503:physiopathology*; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology; D008168:Lung / Q000503:physiopathology; D008297:Male; D029424:Pulmonary Disease, Chronic Obstructive / Q000145:classification / Q000503:physiopathology*; D018709:Statistics, Nonparametric