The Estimation of oxygen avallability in arterial blood and the derivation of its reference range from venous blood

We have developed a new parameter to describe the amount of oxygen in arterial blood which is available for release at tissue level. We have called it "Maximum Available Oxygen". It is calculated using a model of the oxygen dissociation curve described by Siggaard-Andersen and associates. The traditional parameters which describe the capacity of arterial blood to transport oxygen are oxygen tension ( p O2) and haemoglobin oxygen saturation ( s O2). These parameters, even In combination, may give misleading information about the ability of the patient's arterial blood to deliver oxygen to the tissues. A further problem for arterial blood gas analysis has been the difficulty in establishing accurate reference ranges, as normal individuals are infrequently tested. Our new parameter describes the amount of oxygen which is released from the arterial blood specimen when its p O2 falls to a value of 30 mmHg (4.0 kPa). We believe that this single term provides an integrated assessment of all the relevant variables which influence the oxygen status of blood. It is also a simpler concept than other new parameters recently described in the literature. We have determined reference ranges for Maximum Available Oxygen. This was done using a calculation based on the above model applied to data from normal venous blood.