Harmonizing POCT and Central Core Laboratory analyzers

Anne-Charlotte Wicktorsson1,*, Maria Thornemo1

1Clinical Chemistry, Sahlgrenska University Hospital, Göteborg, Sweden

Introduction: Sahlgrenska University Hospital is a part of Västra Götalands regionen. In 2010 a public procurement of blood gas analyzers started, one of the goals was to harmonize the POCT equipment and Central Core Laboratory analyzers. Before the procurement, blood gas analyzers from 4 different suppliers were used and distributed on 25 clinical departments.

Objectives: The main objective of this evaluation was to compare the new procured blood gas analyzer intendended for POCT against the existing instruments used in the Central Core Laboratory.

Methods: Electrolytes, Glucose, Lactate, and total hemoglobine (tHb) were compared with the Central Core Laboratory instruments which served as references. These analytes as well as  pH, pCO2, pO2 and iCa were also measured against the blood gas equipment used in the Central Core Laboratory.

Results: No significant bias were found between the new POCT analyser and the instruments used in Central Core Laboratory regarding  Na, K, Cl, Glucoce, Lactate, pH, pCO2 and pO2.  For iCa we observed a bias between the two models of blood gas analyzers. The same bias was noticed in the external quality control program. The parameter with the largest bias was tHb, mean bias was 8-11 g/L all over the measurement range between the two blood gaz analysers. This was not acceptable for clinical use. The new POCT blood gas analyzer was also compared with the manual reference method (traceable to ICSH) and the same bias was found here. New studies made by the supplier confirmed our observations and therefore they introduced a correlation coefficient to harmonize with the Central Core Laboratory. 

Conclusion: The correlation have shown acceptable agreement for most of the analytes. Anyhow iCa showed a bias difficult to conclude which instrument is correct therefore we will be using  a  verification/linearity test to be able to valuate the results. For tHb the introduction of correlation coefficients  will cause extra work and demands on the central laboratory in the control of POCT.


Keywords: Method