Document Detail

Effects of hyperoxia on the dynamics of skeletal muscle oxygenation at the onset of heavy-intensity exercise in patients with COPD.
MedLine Citation:
PMID:  20417729     Owner:  NLM     Status:  MEDLINE    
This study addressed whether hyperoxia (HiOX=50% O2), compared to normoxia, would improve peripheral muscle oxygenation at the onset of supra-gas exchange threshold exercise in patients with chronic obstructive pulmonary disease (COPD) who were not overtly hypoxemic (resting Pa O₂> 60 mmHg ). Despite faster cardiac output and improved blood oxygenation, HiOX did not significantly change pulmonary O2 uptake kinetics ( VO₂p ). Surprisingly, however, HiOX was associated with faster fractional O2 extraction ( approximately Delta[deoxy-Hb+Mb] by near-infrared spectroscopy) (p<0.05). In addition, an "overshoot" in Delta[deoxy-Hb+Mb] was found after the initial fast response only in HiOX (7/11 patients) thereby suggesting impaired intra-muscular O2 delivery ( Q'O ₂mv)-to-utilization. These data indicate that, despite improved "central" O2 delivery, Q'O₂mv adapted at a slower rate than muscle VO₂ under HiOX in non-hypoxaemic patients with COPD. Our results question the rationale of using supplemental O2 to improve muscle oxygenation during the transition to high-intensity exercise in this patient sub-population.
Ana Cristina B Siqueira; Audrey Borghi-Silva; Daniela M Bravo; Eloara M V Ferreira; Gaspar R Chiappa; J Alberto Neder
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-04-24
Journal Detail:
Title:  Respiratory physiology & neurobiology     Volume:  172     ISSN:  1878-1519     ISO Abbreviation:  Respir Physiol Neurobiol     Publication Date:  2010 Jun 
Date Detail:
Created Date:  2010-06-14     Completed Date:  2010-09-17     Revised Date:  2010-10-25    
Medline Journal Info:
Nlm Unique ID:  101140022     Medline TA:  Respir Physiol Neurobiol     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  8-14     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier B.V. All rights reserved.
Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Division of Respiratory Diseases, Department of Medicine, Federal University of Sao Paulo (UNIFESP), Rua Professor Francisco de Castro 54, Vila Clementino, CEP: 04020-050 São Paulo, SP, Brazil.
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MeSH Terms
Cardiac Output / physiology
Exercise Therapy / methods*
Hemodynamics / physiology
Hyperbaric Oxygenation*
Middle Aged
Muscle, Skeletal / physiopathology*
Oxygen Consumption / physiology*
Physical Endurance / physiology*
Pulmonary Disease, Chronic Obstructive / physiopathology,  therapy*
Pulmonary Gas Exchange
Respiratory Function Tests
Spectroscopy, Near-Infrared

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