Comparison of blood gas analyzer biases in measuring tonometered blood and a fluorocarbon-containing, proficiency-testing material.

This study was designed to test whether the interinstrument differences (biases) in analyses of the PO2 and PCO2 of the commercial fluorocarbon-containing emulsion (FCE) proficiency-testing material abc were similar in magnitude and direction to analyses of the PO2 and PCO2 at four similar partial pressures in tonometered blood. There were large differences among the 13 individual instrumental mean values for both blood and FCE at the four levels: for PO2 (average range, 10.3 mm Hg for blood and 17.0 mm Hg for FCE) and PCO2 (average range, 9.4 mm Hg for blood and 6.2 mm Hg for FCE). Although the instrumental biases for blood and FCE were approximately the same, the biases were slightly higher for FCE in measuring PO2 and slightly higher for blood in measuring PCO2. Accuracy and precision in blood measurement and precision in FCE measurement were significantly correlated among instruments for PO2 and PCO2. The biases of the nine instrument models evaluated significantly correlated with those of the same models participating in national surveys. We suggest that differences in technique, maintenance, and instrumental design rather than inherent differences in PO2 and PCO2 electrodes probably account for the demonstrable differences between instruments. The fluorocarbon-containing emulsion used is of value in proficiency testing for PO2 and PCO2.