Original Article

On-Line Arterial PO₂ Measurements During Cardiopulmonary Bypass

Surgical Clinic A and Institute of Anesthesiology, University Hospital, Zurich, Switzerland

^* Address correspondence to: D. Demierre, Reusslistr. 17 B, CH-8172 Niederglatt, Switzerland.

Abstract

A modified intra-arterial PO₂ sensor (O.D. 0.55 mm) and associated automatic temperature correction module (Roche) were evaluated as on-line monitoring devices during extracorporal circulation (ECC) in six dogs as well as in four patients undergoing open-heart surgery.

Performance of the equipment was assessed by comparing the PO₂ values determined by the sensor with those measured by a blood gas analyzer (AVL). In addition, the reliability of the PO₂ sensor calibration factor and the accuracy of the automatic temperature correction module were determined.

The correlation coefficient between sensor and blood gas analyser was r = 0.97 (n=14) for laboratory and r = 0.98 (n=14) for clinical values with blood temperature ranging from 38°C to 22.5°C.

The calibration factor determined in vivo correlated with the value provided by the manufacturer (r=0.97, n=4).

The correlation factor between calculated and automatic temperature correction was r=0.97 (n=21). On line PO₂ monitoring is feasible with this equipment and early clinical experience was satisfying.