Effects of hyperoxia on the dynamics of skeletal muscle oxygenation at the onset of heavy-intensity exercise in patients with COPD.
Respir Physiol Neurobiol
; 172(1-2): 8-14, 2010 Jun 30.
Article
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| MEDLINE
| ID: mdl-20417729
ABSTRACT
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.
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1
Banco de datos:
MEDLINE
Asunto principal:
Consumo de Oxígeno
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Resistencia Física
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Músculo Esquelético
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Enfermedad Pulmonar Obstructiva Crónica
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Terapia por Ejercicio
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Oxigenoterapia Hiperbárica
Límite:
Aged
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Humans
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Male
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Middle aged
Idioma:
En
Revista:
Respir Physiol Neurobiol
Año:
2010
Tipo del documento:
Article
País de afiliación:
Brasil