Analytical and pre-analytical performance characteristics of a novel cartridge-type blood gas analyzer for point-of-care and laboratory testing

Abstract

Background: Point-of-care blood gas test results may benefit therapeutic decision making by their immediate impact on patient care. We evaluated the (pre-)analytical performance of a novel cartridge-type blood gas analyzer, the GEM Premier 5000 (Werfen), for the determination of pH, partial carbon dioxide pressure (pCO₂), partial oxygen pressure (pO₂), sodium (Na⁺), potassium (K⁺), chloride (Cl^-), ionized calcium (_iCa²⁺), glucose, lactate, and total hemoglobin (tHb).

Methods: Total imprecision was estimated according to the CLSI EP5-A2 protocol. The estimated total error was calculated based on the mean of the range claimed by the manufacturer. Based on the CLSI EP9-A2 evaluation protocol, a method comparison with the Siemens RapidPoint 500 and Abbott i-STAT CG8+ was performed. Obtained data were compared against preset quality specifications. Interference of potential pre-analytical confounders on co-oximetry and electrolyte concentrations were studied.

Results: The analytical performance was acceptable for all parameters tested. Method comparison demonstrated good agreement to the RapidPoint 500 and i-STAT CG8+, except for some parameters (RapidPoint 500: pCO₂, K⁺, lactate and tHb; i-STAT CG8+: pO₂, Na⁺, _iCa²⁺ and tHb) for which significant differences between analyzers were recorded. No interference of lipemia or methylene blue on CO-oximetry results was found. On the contrary, significant interference for benzalkonium and hemolysis on electrolyte measurements were found, for which the user is notified by an interferent specific flag.

Conclusion: Identification of sample errors from pre-analytical sources, such as interferences and automatic corrective actions, along with the analytical performance, ease of use and low maintenance time of the instrument, makes the evaluated instrument a suitable blood gas analyzer for both POCT and laboratory use.

Keywords: Analytical quality specifications; Blood gas analyses; Imprecision; Method comparison; Point-of-care.