[Changes in blood gases with temperature: implications for clinical practice].

Annales francaises d'anesthesie et de reanimation

PubMedID: 15158238

Tremey B, Vigué B. [Changes in blood gases with temperature: implications for clinical practice]. Ann Fr Anesth Reanim. 2004;23(5):474-81.
OBJECTIVE
To understand changes in blood gases results with core temperature.

METHODS
Analysis from two case reports.

RESULTS
Hypothermia induces a decrease in PaCO(2) with a related increase in pH, thus a physiologic alkalosis. Decrease in PaCO(2) is due to an increase of gas solubility and a decrease of peripheral consumption that can be estimated from comparison between corrected and non-corrected for temperature blood gases. For O(2), variations of temperature induce variations of solubility but also of haemoglobin affinity for O(2). During hyperthermia, haemoglobin affinity for O(2) is decreased with a decreased SvO(2) for a same PvO(2). SvO(2) ischemic or therapeutic thresholds are thus modified with core temperature.

CONCLUSION
Blood gases cannot be understood without patient core temperature. Physiologic variations of PaCO(2) and pH must probably be tolerated. Ischemic threshold should be estimated on PvO(2), not only on PvO(2).