Temperature correction of blood gas results

Measurements of pH, pCO₂ and pO₂ of arterial blood during blood gas analysis are all made at normal body temperature, 37 °C. The sample is warmed to that temperature prior to analysis. Blood gas analyzers provide the option for these primary measurements to be automatically "corrected" to the patient’s actual body temperature, using validated correction formulae. 

Controversy has surrounded the use of "temperature-corrected" blood gas results, so that there has been lack of consistency in their adoption. This inconsistency is reported in a recently published study that revisits the controversy. The authors begin with a review of the conditions and treatments associated with hypothermia, as it is usually in the context of clinically significant hypothermia that the question of whether or not to apply the temperature correction arises. 

There follows a review of the undisputed knowledge surrounding the effect that temperature has on the solubility of gases in solution, the oxygen dissociation curve and the affinity of hemoglobin for oxygen. This background physiology informs discussion of the main controversy, which the authors describe as hanging on two alternative hypotheses: the pH-stat hypothesis and the alpha-stat hypothesis. 

Those who ascribe to the pH-stat hypothesis correct for abnormal temperature, whereas the alpha-stat approach is never to correct blood gas results for patient temperature. Some of the arguments for and against the two approaches are presented, although no firm conclusion concerning which should be adopted is made; the authors suggest that more research is needed to make this judgment.

However, they are clear that what is possible and needed now is a standardization of approach, so that within each unit there is a clear policy of whether or not to apply temperature correction.