Continuous, simultaneous measurement of arterial oxygen tension and arterial blood pressure.

This is an investigation of a technique for simultaneously measuring arterial oxygen tension (PaO2) and blood pressure continuously during and after surgical anesthesia. In 27 patients, a special T attachment was placed on the end of an indwelling arterial catheter so that pressurized dilute heparin could be flushed through continuously while blood pressure was being recorded by means of a transducer-oscilloscope system and PaO2 was being recorded through an indwelling polarograph oxygen tension (PO2) readout device. The electrode was left in the artery for an average of 16 hours; the average PaO2 during mechanical ventilation with the patient breathing 50 per cent oxygen was approximately 200 torr at the beginning of anesthesia; it dropped to 158 torr 6 hours later. The average PaO2 in the recovery room 1 hour postoperatively, with the patient spontaneously breathing approximately 30 per cent oxygen, was 122 torr. No significant complications were encountered during this investigation. We believe this dual technique to be a valuable monitoring tandem in the anesthetized and surgical intensive care patient.