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|Title:||Effects of hyperoxia on the dynamics of skeletal muscle oxygenation at the onset of heavy-intensity exercise in patients with COPD|
|Authors:||Siqueira, Ana Cristina B. [UNIFESP]|
Borghi-Silva, Audrey [UNIFESP]
Bravo, Daniela M. [UNIFESP]
Ferreira, Eloara M. V. [UNIFESP]
Chiappa, Gaspar R. [UNIFESP]
Neder, J. Alberto [UNIFESP]
Universidade Federal de São Paulo (UNIFESP)
Universidade Federal de São Carlos (UFSCar)
|Citation:||Respiratory Physiology & Neurobiology. Amsterdam: Elsevier B.V., v. 172, n. 1-2, p. 8-14, 2010.|
|Abstract:||This study addressed whether hyperoxia (HiOX = 50% O(2)), 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 O(2) uptake kinetics ((V) over dot(o2)p). Surprisingly, however, HiOX was associated with faster fractional O(2) extraction (similar to 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 O(2) delivery (Q(O2)' mv)-to-utilization. These data indicate that, despite improved central O(2) delivery, Q(O2)' mv adapted at a slower rate than muscle (V) over dot(O2) under HiOX in non-hypoxaemic patients with COPD. Our results question the rationale of using supplemental O(2) to improve muscle oxygenation during the transition to high-intensity exercise in this patient sub-population. (C) 2010 Elsevier B.V. All rights reserved.|
|Appears in Collections:||Em verificação - Geral|
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