Method and apparatus for estimating a paco2 value for a patient subject to extra corporeal circulation

摘要

The invention relates to a method and an apparatus for estimating a P_aCO₂ value for a patient subject to extracorporeal circulation by means of an oxygenator. The method comprises the steps of measuring a P_exCO₂ value in the exhaust gas of the oxygenator and the patient's arterial blood temperature value T_a, using a temperature sensor arranged in the oxygenator. The estimated P_aCO₂ value is then calculated, based on the measured P_exCO₂ value and the arterial temperature measurement. Advantageously, an average value determined from a predetermined number of recent P_exCO₂ values is used in the calculation. The calculation is performed by adding a correction term to the P_exCO₂ value, which is composed of a temperature dependent component and an offset component. The correction term may be adjusted by a user. The estimated P_aCO₂ value is presented on a display. A switch provides easy alteration between pH-stat mode and alpha-stat mode.