Novel system for real-time ex vivo lactate monitoring in human whole blood

The objective of the study was to evaluate the performance of an amperometr ic enzyme based lactate sensor and to investigate the possibility of replac ing a double lumen catheter based blood withdrawal system with a heparin co ated single lumen system. The inner lumen of a double lumen catheter which was placed in a peripheral vein was perfused with heparin solution. The out er lumen was used to collect heparinized blood samples at a defined flow ra te. The single lumen system was attached to a heparinized catheter which wa s also placed in a peripheral vein. The undiluted blood samples were collec ted at a specified flow rate, A sensor flow chamber incorporating an ampero metric thin-film lactate microbiosensor was placed in the sampling line for real-time lactate monitoring. Plasma lactate concentrations were measured during frequently performed hyperlactatemia bicycle ergometer experiments i n six healthy volunteers (age 25.8 +/- 2.8 years, BMI 22.7 +/- 1 kg/m(2)). Additionally, plasma lactate was measured in realtime using the lactate sen sors. The first three experiments were performed with a double lumen based catheter system whereas the following three experiments were performed with a heparin coated catheter system. The correlation coefficients of sensor r eadings and laboratory analyzer results in all six experiments were between 0.93 and 0.99, respectively (P < 0.001). The miniaturized lactate sensors showed a linear range up to 25 mmol/l lactate concentration and 95% respons e times < 30 s in undiluted serum. During the experiments maximum lactate c oncentrations of 14 mmol/l were achieved. Improvements of system performanc e using heparin coated catheter systems could be shown. The overall SD of t he sensor readings compared to laboratory results using three double lumen catheter based systems was 0.91 mmol/l whereas the SD using three heparin c oated systems was 0.65 mmol/l, In summary, real-time monitoring of lactate in human whole blood is feasible with such a device and can be improved by using heparin coated catheter systems. (C) 1998 Elsevier Science S.A. All r ights reserved.