On-line PO2 and PN2O analysis with an in vivo catheter electrode

A technique was developed for the in vivo determination of PO2 and PN2O with a catheter electrode using double-pulse polarography. The method was evaluated in dog studies comparing readings from the electrode with those from a mass spectrometer employing an in vivo probe. The oxygen readings obtained from the catheter electrode were also compared with values obtained by conventional blood-gas analysis. Good agreement was observed between the electrode and the mass spectrometer for both PO2 and PN2O. Similar agreement was found between the electrode readings and blood-gas analysis for PO2. In the presence of halothane, the electrode over-read for both PO2 and PN2O; a remedy is suggested. The in vivo electrode provides an effective, less expensive, alternative to the mass spectrometer for the on-line measurement of PO2 and PN2O in vivo.