Page 4, O2 Uptake, Exercise & Cor. Circ., Dr. D. Penney

Oxygen Delivery / Utilization

Oxygen delivery, the total amount of oxygen reaching an organ per unit time, whether extracted or not, is equal to blood flow (ml) times blood oxygen content (ml/dl). Content, in turn, is equal to the percent oxygen saturation of the blood times the hemoglobin concentration times the constant for oxygen carriage per g of hemoglobin (1.35 ml/g).

On the other hand, oxygen utilization, the amount of oxygen extracted by an organ per unit time, is equal to the blood flow (ml) times the A-V O2 diff. The total O2 utilization of the whole body can be calculated by multiplying average A-VO2 diff. by cardiac output. Average A-VO2 diff., about 6 ml/dl, is obtained by drawing a mixed venous sample from the right ventricle or the pulmonary artery. During exercise or other activity, whole body O2 utilization is increased. This is achieved by increasing both A-VO2 diff. and cardiac output, an excess over rest which is referred to as "Cardiovascular Reserve". (Figure 3.02)