A practical approach to assess leg muscle oxygenation during ramp-incremental cycle ergometry in heart failure
Data
2017
Autores
Barroco, Adriano Candido 
Sperandio, Priscila Abreu
Almeida, Dirceu Rodrigues de
Neder, Jose Alberto
Tipo
Artigo
Título da Revista
ISSN da Revista
Título de Volume
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 rampincremental cardiopulmonary exercise test in 10 patients (left ventricular ejection fraction o35%) 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 (Po0.05). 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; Po0.05), 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.
Descrição
Citação
Brazilian Journal Of Medical And Biological Research. Sao Paulo, v. 50, n. 12, p. -, 2017.