The relationship between oxygen demand, oxygen uptake, and oxygen supply. 
Results of the relationships between oxygen supply, demand, and uptake can be used to interpret cardiac output values, identify types of acute circulatory failure, guide attempts to improve cellular function, and thus prevent the development of multiple organ failure and death.  Five steps in the interpretation of cardiac output values are recommended: (1) relate cardiac output to the patient's size; (2) determine the presence of anemia or hypoxemia; (3) measure mixed venous O2 saturation and (4) blood lactate levels; and (5) evaluate O2 uptake before and after a transient increase in cardiac output.