Glucose microdialysis with continuous on-board probe performance monitoring

Tightly controlling blood glucose in selected patients has been shown to significantly decrease complications such as infection, neurologic injury, and respiratory failure. Intravenous microdialysis has been used to continuously monitor glucose levels yet variable recovery may occur due to probe fouling, osmosis, and ultrafiltration. A portable microdialysis system is presented that: (1) uses retrodialysis with fluorescein to monitor probe fouling, (2) measures downstream flow rate to gauge fluid losses from ultrafiltration/osmosis, and (3) employs a wireless microcontroller to sequence the above events and record/transmit the data. In vitro glucose microdialysis is performed with a CMA Microdialysis IView catheter and Medtronic CGMS^reg iProtrade glucose sensor. Providing self-diagnostics can eventually lead to a medical embedded system with calibration, safety alarms, and wireless communication of blood glucose readings to a drug delivery system for closed loop control.