Continuous intravascular monitoring of pO2 and pCO2. A comparative in vitro-in vivo study

Two electrodes placed at the tip of catheters for in vivo determinations of PCO2 and PO2 respectively, were tested in dogs. Results were satisfactory when compared to a highly accurate reference method, correlation coefficients were close to 1 (P less than 10(-9)). Means of the differences were respectively --1.74 +/- 1.14 toor for the PO2 probe (P less than 0.01) and --1.62 +/- 0.72 torr for the PCO2 sensor (P less than 0.0001). While no drift was detected in the PCO2 electrode, that of the PO2 was significant but negligible compared to the variability of measurements. Thus, for PCO2 values between 20 and 85 torr, and PO2 values between 20 and 140 torr, in vivo monitoring is sufficiently reliable for clinical use.