Application of chronic intravascular blood glucose sensor in dogs

An intravenous glucose sensor was implanted in six dogs for 1-15 wk. The glucose sensor is a flexible cylinder, approximately 0.2 cm diam and 30 cm long, with a tip containing immobilized glucose oxidase and catalase coupled to a potentiostatic O2 sensor. The sensor and a similar O2 reference sensor were implanted in the superior vena cava near the entrance of the right atrium. The sensor response was conveyed externally either by a telemetry system implanted nearby, surgically accessed leads, or chronically maintained percutaneous leads. Summing over the six implants, there was a total implantation period of 333 days during which glucose sensors were functional on demand. The sensor response showed agreement with conventionally assayed blood samples after accounting for a response lag. Sensor response to glucose showed little change over the implant period. Biocompatibility, enzyme lifetime, O2 availability, O2 sensor stability, and biochemical interference were not limitations. Results demonstrated that this sensor can function effectively as an implant in dogs for a period of months and has the potential for long-term operation.