A Continuous, Implantable Lactate Sensor

An implantable sensor for continuous monitoring of lactate in the bloodstream or tissues has been made. The sensor includes a lactate electrode based on immobilized L-lactate oxidase coupled to a potentiostatic oxygen electrode and an often reference electrode to account for local oxygen. This design renders the response essentially independent of oxygen concentration. In vitro characterization demonstrated that the sensor can respond specifically to lactate over a broad concentration range. This response is stable for more than 1 week during continuous in vitro operation at body temperature. As an acute implant in the canine right atrium, the sensor produced a continuous recording of lactate that was in good agreement with conventional, discrete blood lactate assays