Data/hora: 10/06/2024 00:56:36

Provedor de dados: 	56	
País: 	Brazil	
Título: 	A practical approach to assess leg muscle oxygenation during ramp-incremental cycle ergometry in heart failure	
Autores: 	Barroco,A.C.; Sperandio,P.A.; Reis,M.; Almeida,D.R.; Neder,J.A.	
Data: 	2017-01-01	
Ano: 	2017	
Palavras-chave: 	Heart failure; Exercise; Oxygen; Muscle; Near-infrared spectroscopy.	
Resumo: 	Heart failure is characterized by the inability of the cardiovascular system to maintain oxygen (O2) delivery (i.e., muscle blood flow in non-hypoxemic patients) to meet O2 demands. The resulting increase in fractional O2 extraction can be non-invasively tracked by deoxygenated hemoglobin concentration (deoxi-Hb) as measured by near-infrared spectroscopy (NIRS). We aimed to establish a simplified approach to extract deoxi-Hb-based indices of impaired muscle O2 delivery during rapidly-incrementing exercise in heart failure. We continuously probed the right vastus lateralis muscle with continuous-wave NIRS during a ramp-incremental cardiopulmonary exercise test in 10 patients (left ventricular ejection fraction &lt;35%) and 10 age-matched healthy males. Deoxi-Hb is reported as % of total response (onset to peak exercise) in relation to work rate. Patients showed lower maximum exercise capacity and O2 uptake-work rate than controls (P&lt;0.05). The deoxi-Hb response profile as a function of work rate was S-shaped in all subjects, i.e., it presented three distinct phases. Increased muscle deoxygenation in patients compared to controls was demonstrated by: i) a steeper mid-exercise deoxi-Hb-work rate slope (2.2±1.3 vs 1.0±0.3% peak/W, respectively; P&lt;0.05), and ii) late-exercise increase in deoxi-Hb, which contrasted with stable or decreasing deoxi-Hb in all controls. Steeper deoxi-Hb-work rate slope was associated with lower peak work rate in patients (r=–0.73; P=0.01). This simplified approach to deoxi-Hb interpretation might prove useful in clinical settings to quantify impairments in O2 delivery by NIRS during ramp-incremental exercise in individual heart failure patients.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-879X2017001200603	
Editor: 	Associação Brasileira de Divulgação Científica	
Relação: 	10.1590/1414-431x20176327	
Formato: 	text/html	
Fonte: 	Brazilian Journal of Medical and Biological Research  v.50 n.12 2017	
Fonte: 	info:eu-repo/semantics/openAccess