Analytical performance evaluation of four cartridge-type blood gas analyzers

The immediate impact of blood gas test results on patient care favors the use of blood gas analyzers as point-of-care-testing (POCT) devices. We performed an analytical performance evaluation of four cartridge-type blood gas analyzers for the determination of pH, partial carbon dioxide pressure (pCO2), partial oxygen pressure (pO2), ionized calcium (iCa2+), potassium (K+), glucose, lactate and total hemoglobin (tHb), in comparison with a traditional blood gas analyzer.

The analyzers included in the study are: RP405, GEM Premier 4000, ABL90 FLEX and Cobas b 123. The ABL700 served as comparator. For each instrument the imprecision was estimated according to the CLSI EP5-A2. Based on the CLSI EP9-A2 evaluation protocol, a method comparison was performed using patient samples. Obtained data were compared against preset quality specifications, based on ABL700 performance and biological variation.

The precision of the RP405 and ABL90 FLEX was remarkably better than the preset criteria based on ABL700 performance. The GEM appears to have the worst precision. The RP405 yielded the best overall performance, with exception for tHb and iCa2+. Noteworthy is the very good performance of the glucose determination on RP405. The ABL90 FLEX showed the best performance for pH, K+ and iCa2+ measurements. For tHb determination the Cobas b123 revealed the best results. Regarding practicability, all instruments were found to be user friendly.

Globally, all four cartridge-type blood gas analyzers produced clinically acceptable results. The analytical performance, together with the ease of use and low maintenance time of the instruments, demonstrate that these analyzers are perfectly suitable for both POCT and laboratory use.