Objectives: To describe system requirements for determination of the o
xygen status of the blood using the oxygen status algorithm, a compute
r program, To define the oxygen extractivity, a term we propose, of th
e arterial blood and the oxygen extraction tension, To describe the di
fferent causes of tissue hypoxia, and the clinical interpretation of m
ixed venous oxygen tension and oxygen consumption rate, Data Sources:
Previous physiological and clinical studies related to oxygen status o
f the blood. Data Synthesis: The oxygen status algorithm calculates th
e oxygen extraction tension and generates the oxygen graph as an aid i
n interpreting oxygen status of the patient. A cybernetic scheme expla
ins the causes of tissue hypoxia and forms the basis for the interpret
ation of changes in the mixed venous oxygen tension, A diagram with th
e mixed venous oxygen tension on the abscissa and the oxygen consumpti
on rate on the ordinate illustrates the oxygen flux dependent oxygen c
onsumption rate, A graph shows the relationship between mixed venous o
xygen tension and oxygen delivery, Conclusions: The oxygen status of a
rterial blood comprises three groups of quantities related to arterial
oxygen tension, hemoglobin oxygen capacity, and hemoglobin oxygen aff
inity. Disturbances in one of these groups may be compensated by oppos
ite changes in one or both of the other. The oxygen extraction tension
indicates the degree of compensation, and mixed venous oxygen tension
is the key parameter in evaluating the presence of a state of oxygen
flux-dependent oxidative metabolism.