Evaluation of automatic mixing versus manual mixing for point of care hemoglobin measurement

OBJECTIVE: We compared hemoglobin results from manually mixed blood gas (BG) Portex syringes (Smiths Medical) and automatically mixed safePICO BG syringes (Radiometer Medical) measured on the ABL90 FLEX blood gas analyzer at the Point of Care with a laboratory hematology analyzer (XN-series, Sysmex) to determine whether automatic mixing improved the accuracy and precision of hemoglobin measurement relative to the standardized method. METHODS: Ninety-nine lithium heparin tubes and EDTA tubes were collected simultaneously from selected patients at five participating institutions. The lithium heparin tubes were then split between the Portex ABG syringe and the safePICO aspirator. The Portex syringe was mixed manually according to routine procedures, while the safePICO syringe was mixed automatically on the ABL90 FLEX using the automatic mixing ball. The two syringes were mixed and run on the ABL90 FLEX analyzer by the same lab personnel. Total hemoglobin results obtained from the EDTA tubes on the Sysmex XN hematology analyzer were used as the reference values. RESULTS: Manual mixing demonstrated a larger scatter of hemoglobin values (R(2) ​= ​0.515 and Mean diff.: -0.9 ​g/dL) while automatic mixing at the point of care yielded a significantly better correlation (R(2) ​= ​0.986 and Mean diff.: -0.2 ​g/dL) when compared to a reference hematology analyzer. CONCLUSION: Using the safePICO syringe with automatic mixing at the point of care results in a significantly better correlation of hemoglobin with the standardized method.