Transcutaneous measurement of PCO2 at high ambient pressure (41 bar).

The accuracy of transcutaneous CO2 monitoring with the Kontron CO2 sensor was studied during compression to 41 bar and subsequent decompression. The PCO2 was stable and accurate during the test of the sensor in the pressure chamber, although an increase of 0.1-0.2 kPa during compression was found. The function of the transcutaneous sensor was tested in rats at 1 bar for the correlation between transcutaneous PCO2 (PtcCO2) and arterial PCO2 (PaCO2). The correlation coefficient between PtcCO2 and PaCO2 in the rat was found to be 0.93. The time difference between the 90% transcutaneous and 90% arterial response time was 4.6 +/- 0.6 min (mean +/- SEM). Finally, the use of the sensor in rats ventilated at constant minute volume during compression to 41 bar was examined. An increase in PtcCO2 of 0.2-0.4 kPa was found. The present results of transcutaneous PCO2 measurements indicate that this method may be useful in hyperbaric research and treatment.