Importance

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Abstract

An implantable measuring instrument for a body substance for use in controlling an implantable infusion device has a housing with a recess covered by a semi-permeable membrane which permits transfer of molecules of a selected size therethrough. The volume defined by the recess and the membrane is in communication with an expandable chamber in the housing and a channel leading directly or indirectly via an additional membrane to a sensor for the body substances to interest. The channel is also in communication with a pump. There is also provided another recess covered by a pierceable, resealable septum. A conduit leads from the septum to the sensor. For calibrating the instrument, a cannula is introduced through the septum, and all of the fluid in the conduit leading to the sensor is withdrawn by suction. A known calibrating substance is then introduced by the cannula through the septum until the conduit leading to the sensor is filled. Data can then be acquired from the sensor, and if necessary one or more operating parameters of the instrument can be re-set. This procedure can also be used for rinsing and/or reactivating the sensor.

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First Claim