Problems of continuous Pa, O2 monitoring by means of indwelling intra-arterial electrodes.

Continuous monitoring of intra-arterial PO2 has many advantages in intensive care. However, there are some problems which have prevented the routine use of this method until now. A commercially available polarographic oxygen electrode was tested in vitro. Continuous PO2 monitoring was performed in vivo in 63 adult patients. The electrode is suitable for intensive care with regard to handling, dimensions, biocompatibility, mechanical stability, electrical safety, sensitivity, flow dependency, response time and costs. It should be improved with regard to the instability of the measuring properties and its non-linearity in hyperoxia. Serious complications of continuous PO2 monitoring were not observed. In view of the specific properties of the polarographic electrode and the contraindications of arterial cannulation, the continuous intra-arterial PO2 measurement has proved to be a valuable, safe and simple technique of monitoring, especially for short-term changes of arterial PO2.