A practical approach to assess leg muscle oxygenation during ramp-incremental cycle ergometry in heart failure
Braz. j. med. biol. res
;
50(12): 6327, 2017. tab, graf
Article
in English
| LILACS, SES-SP, SESSP-IDPCPROD, SES-SP
| ID: biblio-888973
ABSTRACT
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 <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<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<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.
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Oxygen Consumption
/
Hemoglobins
/
Muscle, Skeletal
/
Heart Failure
/
Leg
Type of study:
Observational study
/
Risk factors
Limits:
Humans
/
Male
Language:
English
Journal:
Braz. j. med. biol. res
Year:
2017
Type:
Article
Institution/Affiliation country:
Departamento de Fisioterapia, Faculdade de Medicina, Universidade Federal do Rio de Janeiro/BR
/
Disciplina de Cardiologia, Universidade Federal de São Paulo/BR
/
Laboratory of Clinical Exercise Physiology, Division of Respiratory and Critical Care Medicine, Queen's University/BR
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