THE EVALUATION OF A NEW INTRAVASCULAR BLOOD-GAS MONITORING-SYSTEM IN THE PIG

Objective. Our objective was to investigate the accuracy of a new intravascular blood gas sensor, the Paratrend 7 (P7) (Biomedical Sensors Ltd, Pfizer Hospital Products Group, High Wycombe, England) in a porcine model. Methods. A total of 12 sensors were inserted into 10 animals under total intravenous anesthesia. Changes in blood gas chemistry were produced over a wide range by manipulagting the inspired oxygen and carbon dioxide concentrations and by adjustments in minute ventilation. Blood gas samples (BGA) were taken and analyzed during periods of stability; the results obtained were compared with the readings from the intravascular sensor. Results. A total of 292 blood gas samples were taken and analyzed for pHa, Paco2, and Po2; the results were compared with the readings from the intravascular sensor. Correlation coefficients of r = 0.98 for Pco2 and r = 0.99 for Po2 were obtained. Analysis of bias and precision as mean +/- SD of the difference (P7 - BGA) gave the following results: pH bias = -0.03, precision = +/- 0.04; Pco2 bias = 0.65 mm Hg, precision = +/- 3.1 mm Hg; and Po2 bias = -6.50 mm Hg, precision = +/- 0.6 mm Hg. No problems with clot formation on the sensor were seen, and the sensors did not appear to show the ''wall effect'' seen with other systems. Conclusions. The results obtained were well within the requirements for a clinically useful blood gas monitoring system.