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, ∼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.