Oxygen consumption

It gets more and more frequent to use oxygen consumption (VO2) to evaluate exercise capacity and response to treatment in heart failure patients. The amount of VO2 is due to ventilation, oxygen transport and muscle activity. No one of these single steps can define by itself VO2, but all these physiological functions are integrated each other. In this paper we examine the modifications of cardiac output, arteriovenous oxygen content difference, and the temporal behavior of their variations during exercise in heart failure. We specifically describe changes in VO2 during simulated altitude; we also contemplate mechanisms governing oxygen diffusion from capillary bed to mitochondria and critical capillary PO2 concept.