The Ventilatory Cost of Exercise Compared in Chronic Heart Failure and Chronic Renal Anaemia

The cardiorespiratory responses to maximal treadmill exercisewere compared in matched groups of patients with chronic renalanaemia or treated chronic heart failure, and in normal controls.Exercise capacity was similarly reduced in both patient groupscompared to normal controls, the raised respiratory exchangeratio at peak exercise implying anaerobic metabolism due tolimited oxygen delivery in heart failure and limited oxygencarrying capacity in anaemia. Minute ventilation (V_F) was relatedlinearly to minute CO₂ production (VCO₂) in all subjects (eachr>0.92) from all three groups. The slope of the V_E/VCO₂ relationshipwas normal in anaemia but steeper in heart failure, reflectingventilation/perfusion mismatching in chronic heart failure.