Increased arterial oxygen content -- an important compensatory mechanism in chronic moderate heart failure

Abstract

The aim was to determine whether there is a compensatory increase in arterial oxygen content to a hypokinetic circulation in ambulant patients with chronic moderate heart failure caused by dilated cardiomyopathy. DESIGN - Central haemodynamics, arterial oxygen content, arterial haemoglobin concentration, arterial oxygen saturation, and blood gases were measured during a 6 min supine exercise test on a symptom related submaximal workload. At rest, total body haemoglobin was determined. 19 patients with chronic stable moderate heart failure caused by dilated cardiomyopathy, treated with diuretics and digoxin, were studied. During exercise arterial oxygen content correlated inversely with the cardiac index (r = 0.66, p less than 0.01). The two determinants of arterial oxygen content, arterial haemoglobin concentration and arterial oxygen saturation, also correlated inversely with the cardiac index (r = 0.60, p less than 0.01 and r = 0.70, p less than 0.001 respectively). Cardiac index during exercise correlated inversely with total body haemoglobin (r = 0.73, p less than 0.001). A hypokinetic circulation during daily living induces an increase in arterial oxygen content in patients with chronic stable moderate heart failure caused by dilated cardiomyopathy. Renal hypoperfusion may play a role in stimulating the erythropoiesis and exertional hyperventilation in raising arterial oxygen saturation.