In a typical blood gas analyser
Oxygen tension falls with hypothermia. The pH electrode directly measure pH. The standard bicarbonate measured in sample titrated to pCO2 of 5.3 kPa, which eliminates respiratory component.
Oxygen tension will be overstimulated in hypothermia
pH is a derived measurement
Standard bicarbonate can be used to indicate the respiratory component
The oxygen tension can be measured using Clarke electrode.