Portable system for on-line continuous ex vivo monitoring of subcutaneous tissue glucose using open tissue perfusion

CONTINUOUS MEASUREMENT O[ glucose by a relatively noninvasive technique would greatly facilitate therapy in patients with diabetes millitus. The potential use of devices for subcutaneous tissue glucose (SG) monitoring includes the detection of hypoglycaemic episodes and the development of an artificial pancreas in which the subcutaneous tissue is also used as a site for insulin infusion. Recently, microdialysis (HASHIGUCH1 et al., 1994), miniaturised implanted glucose sensors (POITOt~-r et al., 1993); and the suction effusion fluid collection technique (ITO et al., 1994) have been used to measure SG concentration. However, the disadvantage of the first two methods is that the glucose sensor, which only gives a relative glucose output, must be calibrated/n vivo according to the current blood glucose (HAsHIGUCH! et al., 1994; POITOUT et al., 1993). On the other hand, the sampling rate of the suction effusion fluid collection technique is limited (ITO et al., 1994), and the problems arising from long-term application have not yet been investigated. The aim of this study was to develop and evaluate a portable system for continuous on-line ex viva SG monitoring by combining open tissue perfusion, an enzyme-based glucose sensor and conductivity measuremenL