Oxygen uptake efficiency slope: a new index of cardiorespiratory functional reserve derived from the relation between oxygen uptake and minute ventilation during incremental exercise.
J Am Coll Cardiol
; 28(6): 1567-72, 1996 Nov 15.
Article
em En
| MEDLINE
| ID: mdl-8917273
ABSTRACT
OBJECTIVES:
We investigated the usefulness of a new variable, oxygen uptake efficiency slope (OUES), as a submaximal measure of cardiorespiratory functional reserve. The OUES is derived from the relation between oxygen uptake (Vo2 [ml/min]) and minute ventilation (VE [liters/min]) during incremental exercise and is determined by VO2 = a log VE + b, where a = OUES, which shows the effectiveness of Vo2.BACKGROUND:
Maximal oxygen uptake (VO2max) is effort dependent. There is no standard submaximal measurement of cardiorespiratory reserve that provides generally acceptable results.METHODS:
Exercise tests, following a standard Bruce protocol, were performed on a treadmill by 108 patients with heart disease and 36 normal volunteers. Expired gas was continuously analyzed. The OUES was calculated from data of the first 75%, 90% and 100% of exercise duration. We also determined the following submaximal variables the ventilatory anaerobic threshold (VAT), the slope of the regression line of the minute ventilation-carbon dioxide production relation (VE-VCO2 slope) and the extrapolated maximal oxygen consumption (EMOC). We analyzed the relation of OUES and other submaximal variables against VO2max and examined the effects of submaximal exercise on OUES.RESULTS:
The correlation coefficient of the logarithmic curve-fitting model was 0.978 +/- 0.016 (mean +/- SD). The OUES and VO2max had a significant correlation (r = 0.941, p < 0.0001). The correlation between VO2max and OUES was stronger than that between VO2max and VAT, the VE-VCO2 slope or EMOC. The OUES values for 100% and 90% of exercise were not different from each other (at an alpha value of 0.05 and treatment effect of 170, the power of the test [1-beta] was 0.90); OUES for 75% of exercise was slightly lower (3.5%).CONCLUSIONS:
Our results suggest that OUES may provide an objective, effort-independent estimation of cardiorespiratory functional reserve that is related both to pulmonary dead space and to metabolic acidosis.
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Base de dados:
MEDLINE
Assunto principal:
Oxigênio
/
Respiração
/
Fenômenos Fisiológicos Cardiovasculares
/
Exercício Físico
Tipo de estudo:
Guideline
/
Prognostic_studies
Limite:
Adolescent
/
Adult
/
Child
/
Female
/
Humans
/
Male
Idioma:
En
Ano de publicação:
1996
Tipo de documento:
Article