title: The effects of helium-hyperoxia on 6-min walking distance in COPD: a randomized, controlled trial.
abstract: BACKGROUND
  We hypothesized that breathing helium-hyperoxia (HeO2) would significantly improve 6-min walking test (6MWT) distance in COPD subjects.
  
  
  METHODS
  This was a blinded, randomized crossover study. At visit 1, we assessed pulmonary function, exercise capacity, and 6MWT distance. Visits 2 and 3 consisted of four 6MWTs in which the following different inspired gases were used: room air (RA) by mask; 100% O2 by mask (mask O2); 100% O2 by nasal prongs (nasal O2); and 70% He/30% O2 by mask (HeO2). Walking distance, shortness of breath, leg fatigue, O2 saturation, and heart rate (HR) were assessed.
  
  
  RESULTS
  Sixteen COPD subjects participated (mean FEV(1)/FVC ratio [+/- SD], 48 +/- 8%; mean FEV1, 55 +/- 13% predicted). Subjects walked farther when breathing HeO2 (564 m) compared to RA (497 m; p < 0.001), mask O2 (520 m; p < 0.001), or nasal O2 (528 m; p < 0.001). Despite the increased distance walked while breathing HeO2, there was no increase in shortness of breath or leg fatigue. There was desaturation when breathing RA (8%; p < 0.001) and nasal O2 (5%; p < 0.001), which was reduced when breathing HeO2 (3%; difference not significant) and mask O(2) (0%; difference not significant). There were no significant differences in HR in the four 6MWTs.
  
  
  CONCLUSIONS
  The use of HeO2 increased 6MWT distance in COPD subjects more than either mask O2 or nasal O2 compared to RA. The increased walking distance was not associated with increased shortness of breath or leg fatigue. The results suggest that clinical benefit would be obtained by administering HeO2 during exercise, which may have significant clinical implications for the management of COPD patients.
authors.affiliation: Department of Medicine, University of Saskatchewan, SK, Canada. darcy.marciniuk@usask.ca
authors.forename: Darcy D
authors.initials: DD
authors.lastname: Marciniuk
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Butcher
authors.forename: John K
authors.initials: JK
authors.lastname: Reid
authors.forename: G Fred
authors.initials: GF
authors.lastname: MacDonald
authors.forename: Neil D
authors.initials: ND
authors.lastname: Eves
authors.forename: Ron
authors.initials: R
authors.lastname: Clemens
authors.forename: Richard L
authors.initials: RL
authors.lastname: Jones
mesh_terms: D000368:Aged; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006371:Helium / Q000627:therapeutic use*; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology / Q000628:therapy*; D012129:Respiratory Function Tests; D016896:Treatment Outcome; D014797:Vital Capacity / Q000502:physiology; D016138:Walking / Q000502:physiology*
chemical_list: D006371:Helium