An intravascular microdialysis sampling system suitable for application in continuous biochemical monitoring of glucose and lactate

Direct sensor implantation for continuous biochemical monitoring has proved disappointing, but microdialysis sampling devices can serve as a biocompatible patient-sensor interface. We propose a novel “MiniShunt” extracorporeal microdialysis sampling circuit designed to sample core blood, and report the performance of different microdialysis probe membrane types and sizes with pumped and non-pumped blood flow in anaesthetised dogs. Discrete microdialysate and plasma samples collected during glucose and lactate monitoring were analysed with a YSI analyzer and showed microdialysis efficiency (% relative recovery) in excess of 95% for both analytes using fibres of greater than 70 mm² internal surface area. Pumped veno-venous extracorporeal blood microdialysis sampling of this type could provide a suitable interface for future multi-analyte on-line biosensor applications in critically ill patients.