[Optimisation of the acid-base status in hypothermia]

Abstract

Under laboratory conditions, it can be demonstrated within sufficient clinical accuracy that the base excess (BE, [mmol/l]) is independent of temperature. In any blood gas analyzer with temperature correction, the results are consistent with tonometry when measuring a sample of hypothermic equilibrated blood at 37 degrees C. Under clinical conditions, it is shown that there is practically no difference in the CO(2) partial pressure, irrespective of whether measured directly by capnometry (p(et)CO(2)) or obtained from arterial blood (p(a)CO(2)) in the blood gas analyzer after correction for the patient's temperature. Hence, the clinical recommendations for hypothermia are: correct artificial ventilation, preferably pCO(2) 40+/-5 mmHg, should be established by capnometry and controlled by temperature-corrected p(a)CO(2): metabolic changes should be diagnosed by temperature-independent BE: the temperature-corrected pH, if at all, should be used only for the diagnosis of acidosis or alkalosis.