Continuous polarographic monitoring of intra-arterial oxygen in the perioperative period.

Intra-arterial PO2 (PiO2) was polarographically monitored in ten critically ill patients during induction of anesthesia, the intraoperative period, extubation, and the immediate postoperative period; 147 PiO2 values were then paired with simultaneous measurements of PaO2. Mean PiO2 closely followed mean PaO2 over a wide range of values (r = .97), and the continuous, online real-time PiO2 readings provided a useful early warning system for hypoxemia during crisis periods. Technical problems included catheter clotting from improper flushing, changes in PiO2 due to changes in body temperature, the need for in vitro and in vivo calibration, and sensor drift. However, these problems were resolved by appropriate catheter management and sensor calibration.