Preliminary performance evaluation of blood gas analyzers.

Background: We evaluated the imprecision and bias of three instruments for the determination of blood gases, pH and ionized calcium (Ca 2q ) in human arterial blood samples, in comparison with the performance of an established methodology. Methods: The ABL 735, Omni S and Rapidpoint 405 blood gas analyzers were evaluated and compared to the ABL 620 analyzer. Imprecision was determined according to the NCCLS EP10-A2 evaluation protocol. The NCCLS EP9-A2 evaluation protocol was used to determine bias relative to the ABL 620 system. Experimental data were compared against preset quality specifications. Results: The three new instruments showed excellent imprecision for the measurement of pH, but only the ABL 620 met the preset imprecision goals for all analytes tested. All new instruments showed good correlation with the comparative instrument. The slope of the regression equation was significantly different from 1.0 in six out of the 12 comparisons, indicating systematic differences between the instruments. Nevertheless, the predicted bias values relative to the comparative instrument did not exceed the preset quality specifications for two out of the three new instruments. Conclusions: Preliminary evaluation using the NCCLS evaluation protocols EP10-A2 and EP9-A2, may provide valuable information on performance characteristics of blood gas analyzers. Clin Chem Lab Med 2006;44:1030–4.