| Effect of hyperoxia on gas exchange and lactate kinetics following exercise onset in nonhypoxemic COPD patients. | |
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MedLine Citation:
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PMID: 11834648 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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STUDY OBJECTIVES: The slow oxygen uptake (VO(2)) kinetics observed in COPD patients is a manifestation of skeletal muscle dysfunction of multifactorial origin. We determined whether oxygen supplementation during exercise makes the dynamic VO(2) response faster and reduces transient lactate increase. DESIGN: Ten patients with severe COPD (ie, mean [+/- SD] FEV(1), 31 +/- 10% predicted) and 7 healthy subjects of similar age performed four repetitions of the transition between rest and 10 min of moderate-intensity, constant-work rate exercise while breathing air or 40% oxygen in random order. Minute ventilation (VE), gas exchange, and heart rate (HR) were recorded breath-by-breath, and arterialized venous pH, PCO(2), and lactate levels were measured serially. RESULTS: Compared to healthy subjects, the time constants (tau) for VO(2), HR, carbon dioxide output (VCO(2)), and VE kinetic responses were significantly slower in COPD patients than in healthy subjects (70 +/- 8 vs 44 +/- 3 s, 98 +/- 14 vs 44 +/- 8 s, 86 +/- 8 vs 61 +/- 4 s, and 81 +/- 7 vs 62 +/- 4 s, respectively; p < 0.05). Hyperoxia decreased end-exercise E in the COPD group but not the healthy group. Hyperoxia did not increase the speed of VO(2) kinetics but significantly slowed VCO(2) and E response dynamics in both groups. Only small increases in lactate occurred with exercise, and this increase did not correlate with the tau for VO(2). CONCLUSION: In nonhypoxemic COPD patients performing moderate exercise, the lower ventilatory requirement induced by oxygen supplementation is not related to improved muscle function but likely stems from direct chemoreceptor inhibition. |
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Authors:
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Attila Somfay; János Pórszász; Sang-Moo Lee; Richard Casaburi |
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Publication Detail:
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Type: Clinical Trial; Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Chest Volume: 121 ISSN: 0012-3692 ISO Abbreviation: Chest Publication Date: 2002 Feb |
Date Detail:
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Created Date: 2002-02-08 Completed Date: 2002-03-22 Revised Date: 2008-11-21 |
Medline Journal Info:
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Nlm Unique ID: 0231335 Medline TA: Chest Country: United States |
Other Details:
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Languages: eng Pagination: 393-400 Citation Subset: AIM; IM |
Affiliation:
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Rehabilitation Clinical Trials Center, Harbor-UCLA Research and Education Institute, Torrance, CA 90502, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Aged Carbon Dioxide / analysis Female Heart Rate / physiology Humans Lactates / metabolism* Male Muscles / metabolism Oxygen Consumption Physical Exertion / physiology* Pulmonary Disease, Chronic Obstructive / physiopathology* Pulmonary Gas Exchange / physiology* Respiratory Physiological Phenomena |
| Chemical | |
Reg. No./Substance:
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0/Lactates; 124-38-9/Carbon Dioxide |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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