Predictive value of ventilatory and metabolic variables for risk of death in patients with cardiac failure

• Published in: Arquivos brasileiros de cardiologia Vol. 86; no. 6; pp. 451 - 458
• Main Authors: Braga, Ana Maria F Wanderley, Rondon, Maria Urbana P B, Negrão, Carlos Eduardo, Wajngarten, Maurício
• Format: Journal Article
• Language: Portuguese
• Published: Brazil 01.06.2006
• Subjects: Carbon Dioxide - physiology; Cardiac Output, Low - mortality; Cardiac Output, Low - physiopathology; Echocardiography, Doppler; Exercise Test; Female; Humans; Male; Middle Aged; Oxygen Consumption - physiology; Predictive Value of Tests; Prognosis; Pulmonary Gas Exchange - physiology; Risk Assessment; Severity of Illness Index
• ISSN: 0066-782X

To analyze the predictive value of respiratory, metabolic, and hemodynamic variables obtained during the cardiopulmonary stress test for the risk of death in patients with heart failure. Eighty-seven NYHA Functional Class II and III patients were analyzed, ages 51 +/- 0.5 years, 26 of them with Chagas' disease, 30 with coronary ischemia, and 31 with idiopathic etiology. The cardiopulmonary stress test consisted of a ramp-protocol with 5 to 15 W/min workload increments performed on a bicycle-ergonometer until exhaustion. In this study, the multiple Cox regression analysis of age, height, weight, body surface, and gender showed that these parameters were not statistically significant control factors. Oxygen uptake, ventilatory equivalent of oxygen, ventilatory equivalent of carbon dioxide production, oxygen pulse, and end-tidal partial pressure of carbon dioxide at the anaerobic threshold, respiratory compensation point, and peak exercise proved to be important death predictors in heart failure patients. The relationship between the increase in carbon dioxide output as a function of the increase in minute ventilation, and the association between the oxygen uptake increase and the elevation of the workload from the beginning of exercise to the anaerobic threshold were statistically significant predictors of death in heart failure patients (p<0.05). The cardiopulmonary stress test makes it possible to evaluate ventilatory, metabolic, and hemodynamic variables that may be utilized as important markers of life prognosis in these patients.