Respiratory muscle unloading improves leg muscle oxygenation during exercise in patients with COPD

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dc.contributor.authorBorghi-Silva, Audrey [UNIFESP]
dc.contributor.authorOliveira, Cristino Carneiro [UNIFESP]
dc.contributor.authorCarrascosa, Claudia Regina [UNIFESP]
dc.contributor.authorMaia, Joyce [UNIFESP]
dc.contributor.authorBerton, Danilo Cortozi [UNIFESP]
dc.contributor.authorQueiroga, Fernando [UNIFESP]
dc.contributor.authorFerreira, Eloara Vieira Machado [UNIFESP]
dc.contributor.authorAlmeida, Dirceu Rodrigues de [UNIFESP]
dc.contributor.authorNery, Luiz Eduardo [UNIFESP]
dc.contributor.authorNeder, Jose Alberto [UNIFESP]
dc.contributor.institutionUniversidade Federal de São Paulo (UNIFESP)
dc.date.accessioned2016-01-24T13:51:43Z
dc.date.available2016-01-24T13:51:43Z
dc.date.issued2008-10-01
dc.description.abstractBackground: Respiratory muscle unloading during exercise could improve locomotor muscle oxygenation by increasing oxygen delivery (higher cardiac output and/or arterial oxygen content) in patients with chronic obstructive pulmonary disease (COPD).Methods: Sixteen non-hypoxaemic men (forced expiratory volume in 1 s 42.2 (13.9)% predicted) undertook, on different days, two constant work rate (70-80% peak) exercise tests receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (Delta%) in deoxyhaemoglobin (HHb), oxyhaemoglobin (O(2)Hb), tissue oxygenation index (TOI) and total haemoglobin (Hb(tot)) in the vastus lateralis muscle were measured by near-infrared spectroscopy. in order to estimate oxygen delivery (DO(2)est, l/min), cardiac output and oxygen saturation (SpO(2)) were continuously monitored by impedance cardiography and pulse oximetry, respectively.Results: Exercise tolerance (Tlim) and oxygen uptake were increased with PAV compared with sham ventilation. in contrast, end-exercise blood lactate/Tlim and leg effort/Tlim ratios were lower with PAV (p<0.05). There were no between-treatment differences in cardiac output and SpO(2) either at submaximal exercise or at Tlim (ie, DO(2)est remained unchanged with PAV; p>0.05). Leg muscle oxygenation, however, was significantly enhanced with PAV as the exercise-related decrease in Delta(O(2)Hb)% was lessened and TOI was improved; moreover, Delta(Hb(tot))%, an index of local blood volume, was increased compared with sham ventilation (p<0.01).Conclusions: Respiratory muscle unloading during high-intensity exercise can improve peripheral muscle oxygenation despite unaltered systemic DO(2) in patients with advanced COPD. These findings might indicate that a fraction of the available cardiac output had been redirected from ventilatory to appendicular muscles as a consequence of respiratory muscle unloading.en
dc.description.affiliationUniversidade Federal de São Paulo, Dept Med, Div Resp Dis, Pulm Funct & Clin Exercise Physiol Unit,UNIFESP, BR-04020050 São Paulo, Brazil
dc.description.affiliationUniversidade Federal de São Paulo, Dept Med, Div Cardiol, BR-04020050 São Paulo, Brazil
dc.description.affiliationUnifespUniversidade Federal de São Paulo, Dept Med, Div Resp Dis, Pulm Funct & Clin Exercise Physiol Unit,UNIFESP, BR-04020050 São Paulo, Brazil
dc.description.affiliationUnifespUniversidade Federal de São Paulo, Dept Med, Div Cardiol, BR-04020050 São Paulo, Brazil
dc.description.provenanceMade available in DSpace on 2016-01-24T13:51:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-10-01en
dc.description.sourceWeb of Science
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)pt
dc.description.sponsorshipIDFAPESP: 05/00722-0pt
dc.format.extent910-915
dc.identifierhttps://dx.doi.org/10.1136/thx.2007.090167
dc.identifier.citationThorax. London: B M J Publishing Group, v. 63, n. 10, p. 910-915, 2008.
dc.identifier.doi10.1136/thx.2007.090167
dc.identifier.issn0040-6376
dc.identifier.urihttps://repositorio.unifesp.br/handle/11600/30922
dc.identifier.wosWOS:000259586300016
dc.language.isoeng
dc.publisherB M J Publishing Group
dc.relation.ispartofThorax
dc.rightsAcesso aberto
dc.titleRespiratory muscle unloading improves leg muscle oxygenation during exercise in patients with COPDen
dc.typeArtigo
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