Evaluation of lactate measurement in blood and plasma with biosensor technology: a comparison of methods

The introduction of biosensor technology for near bedside measurement of pl asma lactate concentrations has been a promising step for critical care pro filing. However, methodological drawbacks and relevant inaccuracy have been reported. With the advent of a new biosensor (Chiron Diagnostics) and a re vised NOVA Biomedical device,accuracy was expected to be improved. The goal of the present investigation was to evaluate the accuracy of both methods. Methods: Two devices (System 860, Chiron Diagnostics; StatProfile 9, NOVA B iomedical) were simultaneously analysed using 9 biosensors in both fresh fr ozen plasma and citrated whole blood. The results were compared with an est ablished photometric method (Lactat PAP, Analyticon). Measurements were per formed as duplicates (n = 1120) before and after the addition of 1 molar so dium lactate solution (2-24 mmol/L). For the estimation of between-day prec ision commercially available aqueous and serum-based quality controls were analysed daily over a period of 60 days. Results: Reproducibility in blood was 2.6+/-2.8% (Chiron), 4.1+/-4.0% (NOVA ) and 1.5+/-2.1% (Analyticon),in plasma respectively 2.1+/-2.4%, 2.1+/-2.9% and 1.0+/-1.1%. Mean inaccuracy in plasma presented to be -0.2+-16.4% (pla sma) and +7.2+/-13.1% (blood) for Chiron, +9.4+/-18.4% and +18.7+/-16.7% fo r NOVA,and -37.8+/-18.2% and -27.5+/-17.6% for Analyticon. Calculated betwe en-day-precision (variation coefficients mean values) was 11.5+/-4.9% (Chir on) and 14.0+/-5.9% (NOVA). Conclusion: Although accuracy of lactate concentrations obtained with biose nsor technology has improved ((x) over bar 0-18%), the variability of the r esults still poses a problem ((x) over bar 13-18%). Therefore, from the met hodological point of view, interpretation of a single lactate value require s caution when applying to the critically ill, particularly with View to th reshold values, and should be considered vis-a-vis other options.