[Monitoring of respiratory exchange during ergometric test in patients with heart failure: current aspects and prospects].

The current techniques of respiratory gas-exchange monitoring during stress testing in patients with congestive heart failure have provided new physiopathologic and clinical data. The "breath-by-breath" measurement of oxygen consumption and carbon dioxide production and the evaluation of the relationship between these parameters and respiratory volumes, allow to determine both ventilatory and metabolic responses during exercise, thus giving a precise estimate of the effective cardiopulmonary functional capacity. The demonstration of peripheral vascular and metabolic abnormalities by these techniques have provided new insights into the mechanism of dyspnea and fatigue in patients with heart failure. Although the relationship between respiratory and metabolic parameters and hemodynamics has been extensively studied, its mechanisms are still unclear. Moreover, controversy still exists as to the link between functional capacity and prognosis. Finally, recent studies on the cardiopulmonary adaptations to exercise training in patients with left ventricular dysfunction, have clearly demonstrated clinical and hemodynamic improvement after conditioning. These data, if confirmed, may provide a new approach in the management of patients with this disorder.