[Time integral of oxygen pulse for exercise submaximal levels in patients with heart insufficiency--correlation with maximal oxygen consumption].
Maximal oxygen consumption (VO2max) has an important prognostic value in patients with congestive heart failure (CHF). However, it requires a maximal exercise test, not often available for these patients. To overcome this limitation, we examined whether a simple time integral of oxygen pulse (OP) to submaximal exercise levels correlates with VO2max.


METHODS
We performed a maximal symptom-limited treadmill exercise test, while measuring breath-by-breath oxygen consumption, using the CAEP protocol, in 24 patients with CHF (51 +/- 11 years, 18 males, sinus rhythm). No exercise was terminated due to ischemia or arrhythmias. All patients attained anaerobic threshold. Besides standard parameters, OP (ml) and time integral of OP (OPTI) were calculated at 2 minutes (OP-2 min and OPTI-2 min) and at 4 minutes (OP-4 min and OPTI-4 min) of exercise. Patients were divided in two groups according to VO2max: group I--VO2max > or = 16 ml/kg/min (14 patients) and group II--VO2max < 16 (10 patients).


RESULTS
Age, sex, body surface and CHF etiology were similar in both groups. Exercise duration, maximal OP, time to anaerobic there shold, VO2 and OP at anaerobic there shold were higher in group I (p < 0.05). Comparing group I vs group II--OP-2 min: 6.2 +/- 1.5 vs 5.0 +/- 1.2 ml (p = 0.026); OP-4 min: 7.6 +/- 1.9 vs 5.4 +/- 1.2 (p = 0.001); OPTI-2 min: 3.1 +/- 1.1 vs 2.2 +/- 0.9 (p = 0.021) and OPTI-4 min: 15.2 +/- 4.4 vs 9.3 +/- 3.1 (p = 0.0007). The best correlation with VO2max was obtained for OPTI-4 min (r = 0.696). An OPTI-4 min value > or = 10 occurred in 13 patients of group I and in two patients of group II (p = 0.00013), with a predictive value of 87% for VO2max > 16 (sensitivity = 93%, specificity = 80%)--kappa index = 0.739.


CONCLUSIONS
OPTI-4 min can be a useful tool for assessing cardiocirculatory functional status in patients with CHF and unable to perform a maximal exercise test.
Martins
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Serviço de Cardiologia do Hospital de Santa Marta, Lisboa.
Cotrim
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Soares
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Silveira
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do Rosário
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Rasteiro
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Ferreira
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Antunes
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D000328:Adult; D000368:Aged; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D006334:Heart Function Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D013997:Time Factors
Integral tempo do pulso de oxigénio para níveis submáximos de exercício em doentes com insuficiência cardíaca--correlação com o consumo máximo de oxigénio.