Assessment of blood lactate: practical evaluation of the Biosen 5030 lactate analyzer

Purpose: The aim of this study was to assess the validity and reliability o f the Biosen 5030 lactate analyzer compared with a YSI 2300 lactate analyze r and a Kodak Ektachem DTII in a practical laboratory study context. Method s: To assess validity, 144 triplicate capillarized blood samples, across a range of values, were analyzed using the three analyzers. To assess reliabi lity a further 665 samples were repeat analyzed. Temporal stability was det ermined by the reanalysis of resting and maximal exercise blood samples, af ter a period of storage ranging from 7 to 20 h, at room temperature. To mea sure inter- and intra-investigator reliability, 20 resting samples were tak en from three different subjects by different investigators and a coefficie nt of variation was determined. Results: There were strong relationships be tween the Biosen, the YSI (r(2) = 0.97), and che Kodak Ektachem (r(2) = 0.9 1). An analysis of Biosen compared with YSI revealed a positive bias of 0.3 7 mmol.L-1 (95% limits of agreement, -0.85 to 1.59 mmol.L-1). The test-rete st reliability correlation was significant (r(2) = 0.99, P < 0.05), but a p aired t-test revealed a small (0.03 mmol.L-1, P < 0.05) significant differe nce. The coefficient of variation from the three investigators across the 2 0 samples ranged from 1.3 to 3%. Blood lactate concentration in resting blo od samples did significantly increase in value (0.2 mmol.L-1, P < 0.05) aft er 7-h exposure to the air, whereas there was no change in maximal exercise blood lactate values after 20-h exposure to the air. Conclusions: In a pra ctical context, the Biosen 5030 lactate analyzer was comparable to the othe r analyzers giving fast reliable measures of blood lactate concentrations o ver the full range of values, which remained stable over extended periods a t room temperature.