Implantable medication infusion system

A medical infusion system intermittently switchable at selected times between an open loop system without feedback and a closed loop system with feedback, said system comprising an implantable unit including means for controllably dispensing medication into a body, an external controller, and an extra-corporeal sensor;

• wherein said implantable unit comprises an implantable transceiver means for communicating with a similar external transceiver means in said external controller to provide a telemetry link between said controller and said implantable unit, a first reservoir means for holding medication liquid, a liquid dispensing device, a pump connected between said reservoir means and said liquid dispensing device, and a first electronic control circuit means connected to said implantable transceiver means and to said pump to operate said pump;
• wherein said external controller comprises a second electronic control circuit means connected with said external transceiver means, a transducer means for reading said sensor, said transducer means having an output connected to said second electronic control circuit means, and a manually operable electric input device connected to said second electronic control circuit means;
• wherein said pump is operable by said first electonic control circuit means to pump said medication liquid from said first reservoir means to said liquid-dispensing deive at a first predetermined rate independent of the output of said extra-corporeal sensor, and wherein said input device or said transducer means include means which selectively operable at intermittent times to respectively convey commands or output of said transducer representing the reading of said sensor to said second control circuit to instruct said first control circuit via said telemetry link to modify the operation of said pump.