title: Prognostic relevance of dynamic hyperinflation during cardiopulmonary exercise testing in adult patients with cystic fibrosis.
abstract: BACKGROUND
  Dynamic hyperinflation during cardiopulmonary exercise testing (CPET) in cystic fibrosis (CF) has not been well characterized, and little is known regarding its prevalence, risk factors and clinical associations.
  
  
  METHODS
  CPET data from 109 adult patients with mild-to-moderate CF was used, in this retrospective study, to characterize and determine the prevalence of dynamic hyperinflation, and evaluate its relationship with lung function and exercise tolerance, clinical symptoms, and prognosis over a two-year period.
  
  
  RESULTS
  58% of patients responded to CPET with dynamic hyperinflation. These patients had significantly lower lung function (FEV1 66±19 versus 79±18%pred., p<0.01) and exercise tolerance (peak oxygen uptake 28.7±8.1 versus 32.9±6.1 mL·kg(-1)·min(-1), p=0.02), and experienced greater shortness of breath at peak exercise (7±3 versus 5±2 Modified Borg scale, p=0.04) compared to patients who responded without dynamic hyperinflation. Significant relationships between FEV1, FVC, FEV1/FVC, FEF(25-75) and dynamic hyperinflation were shown (p<0.01; p=0.02; p<0.01; p<0.01, respectively). Dynamic hyperinflation was also significantly correlated with oxygen uptake, tidal volume, work-rate and shortness of breath at peak exercise (p=0.03; p<0.01; p<0.01; p=0.04, respectively). Responding to CPET with or without dynamic hyperinflation did not significantly predict FEV1 at 2 years beyond the FEV1 at baseline (p=0.06), or increase the likelihood of experiencing a pulmonary exacerbation over a two-year period (p=0.24).
  
  
  CONCLUSIONS
  The prevalence of dynamic hyperinflation during CPET in adult patients with mild-to-moderate CF is high, and is associated with reduced lung function and exercise tolerance, and increased exertional dyspnea. However, identifying dynamic hyperinflation during CPET had limited prognostic value for lung function and pulmonary exacerbation.
authors.affiliation: School of Physiotherapy, Faculty of Health Professions, Dalhousie University, Forrest Building, 5869 University Avenue, Halifax, NS B3H 4R2, Canada; Division of Respirology, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada. Electronic address: D.Stevens@dal.ca.
authors.forename: D
authors.initials: D
authors.lastname: Stevens
authors.forename: A
authors.initials: A
authors.lastname: Stephenson
authors.forename: M E
authors.initials: ME
authors.lastname: Faughnan
authors.forename: E
authors.initials: E
authors.lastname: Leek
authors.forename: E
authors.initials: E
authors.lastname: Tullis
mesh_terms: D000328:Adult; D003550:Cystic Fibrosis / Q000503:physiopathology* / Q000628:therapy*; D004417:Dyspnea / Q000628:therapy; D015444:Exercise / Q000502:physiology; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance; D005541:Forced Expiratory Volume; D006801:Humans; D010101:Oxygen Consumption / Q000502:physiology; D011379:Prognosis; D012129:Respiratory Function Tests; D012189:Retrospective Studies; D055815:Young Adult
keywords: Cardiopulmonary exercise testing; Clinical utility; Dynamic hyperinflation; Prevalence; Prognosis