Minimal-Fouling enzyme electrode for continuous flow measurement of whole blood lactate

A new membrane system evaluated in an enzyme electrode for monitoring of whole blood lactate under continuous flow conditions has been developed. The membrane confers functional haemocompatibility and has been coupled to an electrode based on amperometric detection of hydrogen peroxide with lactate oxidase interposed between the haemocompatible membrane acting as diffusion barrier and an inner membrane excluding interfering electroactive species. Here, the enzyme electrode is combined with a flow-through measuring chamber and a double lumen catheter permitting continuous sampling and heparinization of blood. The blood contacting membranes have unique haemocompatibility properties and were produced through modification of poly(vinyl chloride), with the nonionic surfactant Pluronic F-68. On-line monitoring of whole blood samples with different amounts of added lactate was carried out to simulate fluctuations in blood lactate levels during extracorporeal monitoring and results were compared with a standard lactate analyser.