Performance of a multi-profile critical care testing analyzer

BACKGROUND: Modern blood gas analyzers are often coupled to electrolyte and metabolite analyzers. We evaluated a Stat Profile Critical Care Xpress analyzer (STP CCX) for the rapid point-of-care measurement of blood gases (pH, pCO2, pO2, sO2), hematocrit (Hct), total hemoglobin (tHb), sodium (Na+), potassium (K+), chloride (Cl-), glucose (Glu), lactate (Lac), urea (BUN), ionized calcium (iCa) and ionized magnesium (iMg). METHODS: The analyzer was evaluated in terms of imprecision and recovery using the STP CCX control. Fresh blood samples were also measured to determine the between-day imprecision. Correlation was assessed by clinical sample comparison with the Nova Stat Profile Ultra C and Dimension RxL systems for Cl- and BUN. We used Deming regression, correlation coefficients, mean differences, and the Wilcoxon signed-rank test for data analysis. RESULTS: The coefficients of variation for all analytes were within desirable limits, ranging from 0.1% to 4.3%, and the recovery was 100%+/-3%. Between-day imprecision using fresh blood samples showed good results, ranging from 0.2% to 3.4%. The comparison results showed high to very high correlation. However, statistically significant mean differences with large bias were found for pCO2, pO2 and Cl-. CONCLUSIONS: This analyzer is suitable as a simple and fast diagnostic tool in the laboratory and the critical care unit. However, users should be aware of biases that may lead to clinically significant errors in the assessment of acid-base status.