Effects of respiratory muscle unloading on leg muscle oxygenation and blood volume during high-intensity exercise in chronic heart failure

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dc.contributor.author Borghi-Silva, Audrey [UNIFESP]
dc.contributor.author Carrascosa, Claudia [UNIFESP]
dc.contributor.author Oliveira, Cristino Carneiro [UNIFESP]
dc.contributor.author Barroco, Adriano C. [UNIFESP]
dc.contributor.author Berton, Danilo C. [UNIFESP]
dc.contributor.author Vilaca, Debora [UNIFESP]
dc.contributor.author Lira-Filho, Edgar B. [UNIFESP]
dc.contributor.author Ribeiro, Dirceu [UNIFESP]
dc.contributor.author Nery, Luiz Eduardo [UNIFESP]
dc.contributor.author Neder, J. Alberto [UNIFESP]
dc.date.accessioned 2016-01-24T13:51:24Z
dc.date.available 2016-01-24T13:51:24Z
dc.date.issued 2008-06-01
dc.identifier http://dx.doi.org/10.1152/ajpheart.91520.2007
dc.identifier.citation American Journal of Physiology-heart and Circulatory Physiology. Bethesda: Amer Physiological Soc, v. 294, n. 6, p. H2465-H2472, 2008.
dc.identifier.issn 0363-6135
dc.identifier.uri http://repositorio.unifesp.br/handle/11600/30678
dc.description.abstract Blood flow requirements of the respiratory muscles (RM) increase markedly during exercise in chronic heart failure (CHF). We reasoned that if the RM could subtract a fraction of the limited cardiac output (QT) from the peripheral muscles, RM unloading would improve locomotor muscle perfusion. Nine patients with CHF ( left ventricle ejection fraction = 26 +/- 7%) undertook constant-work rate tests (70-80% peak) receiving proportional assisted ventilation (PAV) or sham ventilation. Relative changes (Delta%) in deoxy-hemoglobyn, oxi-Hb ([O(2)Hb]), tissue oxygenation index, and total Hb ([Hb(TOT)], an index of local blood volume) in the vastus lateralis were measured by near infrared spectroscopy. in addition, QT was monitored by impedance cardiography and arterial O-2 saturation by pulse oximetry (SpO(2)). There were significant improvements in exercise tolerance (Tlim) with PAV. Blood lactate, leg effort/Tlim and dyspnea/Tlim were lower with PAV compared with sham ventilation (P < 0.05). There were no significant effects of RM unloading on systemic O-2 delivery as QT and SpO2 at submaximal exercise and at Tlim did not differ between PAV and sham ventilation (P > 0.05). Unloaded breathing, however, was related to enhanced leg muscle oxygenation and local blood volume compared with sham, i.e., higher Delta[O(2)Hb]% and Delta[Hb(TOT)]%, respectively (P < 0.05). We conclude that RM unloading had beneficial effects on the oxygenation status and blood volume of the exercising muscles at similar systemic O-2 delivery in patients with advanced CHF. These data suggest that blood flow was redistributed from respiratory to locomotor muscles during unloaded breathing. en
dc.format.extent H2465-H2472
dc.language.iso eng
dc.publisher Amer Physiological Soc
dc.relation.ispartof American Journal of Physiology-heart and Circulatory Physiology
dc.rights Acesso aberto
dc.subject blood flow en
dc.subject cardiac failure en
dc.subject cardiovascular physiology en
dc.subject hemodynamics en
dc.subject muscle en
dc.subject oxygen consumption en
dc.title Effects of respiratory muscle unloading on leg muscle oxygenation and blood volume during high-intensity exercise in chronic heart failure en
dc.type Artigo
dc.contributor.institution Universidade Federal de São Paulo (UNIFESP)
dc.description.affiliation Universidade Federal de São Paulo, Paulista Sch Med UNIFESP EPM, Pulm Funct & Clin Exercise Physiol Unit, Div Resp Dis, BR-04020050 São Paulo, Brazil
dc.description.affiliation Universidade Federal de São Paulo, Dept Med, Div Cardiol, BR-04020050 São Paulo, Brazil
dc.description.affiliation Universidade Federal de São Paulo, Cardiopulm Lab, Nucleus Res Phys Exercise, BR-04020050 São Paulo, Brazil
dc.description.affiliationUnifesp Universidade Federal de São Paulo, Paulista Sch Med UNIFESP EPM, Pulm Funct & Clin Exercise Physiol Unit, Div Resp Dis, BR-04020050 São Paulo, Brazil
dc.description.affiliationUnifesp Universidade Federal de São Paulo, Dept Med, Div Cardiol, BR-04020050 São Paulo, Brazil
dc.description.affiliationUnifesp Universidade Federal de São Paulo, Cardiopulm Lab, Nucleus Res Phys Exercise, BR-04020050 São Paulo, Brazil
dc.identifier.doi 10.1152/ajpheart.91520.2007
dc.description.source Web of Science
dc.identifier.wos WOS:000256497300007



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