A percutaneous device as model to study the in vivo performance of implantable amperometric glucose sensors

Glucose kinetics were investigated in subcutaneous tissue of rabbits, in wh ich a percutaneous device was implanted. The device was used for collection of tissue fluid and as carrier of an amperometric glucose sensor. Changes in glycaemia were reflected in subcutaneous tissue fluid. However, a limite d number of responses of the implanted sensors were observed. Histologic ev aluation showed thin fibrous capsules surrounding the implants. Accumulatio ns of inflammatory cells were observed inside the subcutaneous chamber. The experiments again showed that changes in blood glucose concentration can b e measured in subcutaneous tissue fluid collected with a percutaneous devic e. Nevertheless, implanted glucose sensors could not reliably monitor these changes. Supported by our histological observations and sufficient in vitr o performance, we suppose that the cellular reaction to the sensor plays an important role in this poor in vivo performance. In combination with adsor ption of tissue fluid proteins, this results in a reversible deactivation o f implanted sensors. The exact mechanisms involved in this process are curr ently unknown and need further investigation. (C) 2001 Kluwer Academic Publ ishers.