A novel method for indirectly monitoring arterial pO(2) during cardiopulmonary bypass

Arterial blood oxygen tension (P(a)O(2)) is a vital variable that has to be monitored during cardiopulmonary bypass (CPB). The aim of this study was to develop an alternative method for continuously P(a)O(2) monitoring during CPB, based on measurements of exhaust-gas from an oxygenator. A total of 15 adult patients undergoing CPB (n = 81 samples) were included in a study in order to develop an appropriate algorithm for P(a)O(2) estimation based on exhaust gas monitoring of the oxygen tension (P(ex)O(2)). The acquired data was used as a basis for developing a statistical prediction algorithm designed for continuously estimating the P(a)O(2)-level based on exhaust gas data in combination with data from the surrounding medical equipment. A new instrument was developed in order to implement this P(a)O(2) prediction algorithm and was tested on five patients (n = 39 samples). When the first sample was used for calibrating the instrument, the mean (SD) error was 8.7% (7.3%) with a 95% CI of 6.1-11.3%. Our results indicate that a pO(2)-exhaust monitoring device with adequate precision is obtainable, but further studies are required.