title: Exercise tolerance with helium-hyperoxia versus hyperoxia in hypoxaemic patients with COPD.
abstract: The purpose of this study was to investigate whether helium-hyperoxia (HeHOx) would allow greater tolerance to maximal and submaximal exercise compared to hyperoxia (HOx) on isolation in hypoxaemic chronic obstructive pulmonary disease (COPD) patients under long-term oxygen therapy. In a double-blind study, 24 males in the Global Initiative for Chronic Obstructive Lung Disease functional class IV (forced expiratory volume in 1 s 35.2±10.1% predicted and arterial oxygen tension 56.2±7.5 mmHg) were submitted to incremental and constant load cycling at 70-80% peak work rate while breathing HOx (60% nitrogen and 40% oxygen) or HeHOx (60% helium and 40% oxygen). HeHOx improved resting airflow obstruction and lung hyperinflation in all but two patients (p<0.05). Peak work rate and time to exercise intolerance were higher with HeHOx than HOx in 17 (70.8%) out of 24 patients and 14 (66.6%) out of 21 patients, respectively (p<0.05). End-expiratory lung volumes were lower with HeHOx, despite a higher ventilatory response (p<0.05). HeHOx speeded on-exercise oxygen uptake kinetics by ∼30%, especially in more disabled and hyperinflated patients. Fat-free mass was the only independent predictor of higher peak work rate with HeHOx (r(2) = 0.66, p<0.001); in contrast, none of the resting characteristics or exercise responses were related to improvements in time to exercise intolerance (p>0.05). Helium is a valuable ergogenic aid when added to HOx for most long-term oxygen therapy-dependent patients with advanced COPD.
authors.affiliation: Division of Respiratory Diseases, Dept of Medicine, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.
authors.forename: Fernando
authors.initials: F
authors.lastname: Queiroga
authors.forename: Marcos
authors.initials: M
authors.lastname: Nunes
authors.forename: Ethiane
authors.initials: E
authors.lastname: Meda
authors.forename: Gaspar
authors.initials: G
authors.lastname: Chiappa
authors.forename: Maria Christina
authors.initials: MC
authors.lastname: Machado
authors.forename: Luiz Eduardo
authors.initials: LE
authors.lastname: Nery
authors.forename: J Alberto
authors.initials: JA
authors.lastname: Neder
mesh_terms: D000368:Aged; D001823:Body Composition; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise; D017079:Exercise Tolerance; D006371:Helium / Q000737:chemistry*; D006439:Hemodynamics; D006801:Humans; D018496:Hyperoxia / Q000378:metabolism*; D000860:Hypoxia / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000627:therapeutic use; D010102:Oxygen Inhalation Therapy / Q000379:methods; D029424:Pulmonary Disease, Chronic Obstructive / Q000378:metabolism / Q000503:physiopathology*; D012129:Respiratory Function Tests; D013147:Spirometry
chemical_list: D006371:Helium; D010100:Oxygen