arteriovenous (A-V) difference

arteriovenous (A-V) difference

the difference between the arterial and the venous concentration of a substance in the blood, for the whole body (when 'venous' refers to mixed venous blood in the pulmonary artery) or for an organ or region (e.g. for the tissues of the leg if 'venous' refers to blood in the femoral vein). Together with the blood flow, allows calculation of the amount removed in a given time during circulation around the whole body or region. The arteriovenous difference for oxygen is often of interest in exercise physiology. For the whole body, cardiac output (m L.min-1)×arteriovenous difference for oxygen (L.L-1) = oxygen uptake (L.min-1) or regional blood flow×arteriovenous difference for oxygen = regional oxygen uptake. See also oxyhaemoglobin dissociation curve.