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Analyte sensor

The preferred embodiments relate generally to systems and methods for measuring an analyte in a host.

Diabetes mellitus is a disorder in which the pancreas cannot create sufficient insulin (Type I or insulin dependent) and/or in which insulin is not effective (Type 2 or non-insulin dependent). In the diabetic state, the victim suffers from high blood sugar, which can cause an array of physiological derangements associated with the deterioration of small blood vessels, for example, kidney failure, skin ulcers, or bleeding into the vitreous of the eye. A hypoglycemic reaction (low blood sugar) can be induced by an inadvertent overdose of insulin, or after a normal dose of insulin or glucose-lowering agent accompanied by extraordinary exercise or insufficient food intake.

Conventionally, a person with diabetes carries a self-monitoring blood glucose (SMBG) monitor, which typically requires uncomfortable finger pricking methods. Due to the lack of comfort and convenience, a person with diabetes normally only measures his or her glucose levels two to four times per day. Unfortunately, such time intervals are so far spread apart that the person with diabetes likely finds out too late of a hyperglycemic or hypoglycemic condition, sometimes incurring dangerous side effects. It is not only unlikely that a person with diabetes will take a timely SMBG value, it is also likely that he or she will not know if his or her blood glucose value is going up (higher) or down (lower) based on conventional methods. This inhibits the ability to make educated insulin therapy decisions.

A variety of sensors are known that use an electrochemical cell to provide output signals by which the presence or absence of an analyte, such as glucose, in a sample can be determined. For example, in an electrochemical cell, an analyte (or a species derived from it) that is electro-active generates a detectable signal at an electrode, and this signal can be used to detect or measure the presence and/or amount within a biological sample. In some conventional sensors, an enzyme is provided that reacts with the analyte to be measured, and the byproduct of the reaction is qualified or quantified at the electrode. An enzyme has the advantage that it can be very specific to an analyte and also, when the analyte itself is not sufficiently electro-active, can be used to interact with the analyte to generate another species which is electro-active and to which the sensor can produce a desired output. In one conventional amperometric glucose oxidase-based glucose sensor, immobilized glucose oxidase catalyses the oxidation of glucose to form hydrogen peroxide, which is then quantified by amperometric measurement (for example, change in electrical current) through a polarized electrode.

In a first aspect, a system for measuring an analyte is provided, the system comprising a vascular access device in communication with a vascular system of a host; and an analyte sensor configured to extend within the vascular access device, wherein the analyte sensor is configured to measure a concentration of an analyte within the vascular system.

In an embodiment of the first aspect, the analyte sensor is configured to extend through the vascular access device and into a blood stream of the host.

In an embodiment of the first aspect, the vascular access device is a catheter.

In an embodiment of the first aspect, the vascular access device is configured for insertion into a vein of the host.

In an embodiment of the first aspect, the vascular access device is configured for insertion into an artery of the host.

In an embodiment of the first aspect, the vascular access device is configured to operatively couple to a pressure transducer for measurement of a blood pressure of the host.

In an embodiment of the first aspect, the vascular access device is configured to operatively couple to a blood chemistry analysis device for measuring a blood chemistry of the host.

In an embodiment of the first aspect, the analyte sensor is a glucose sensor.

In an embodiment of the first aspect, the system further comprises a sheath configured to protect the analyte sensor during insertion of the analyte sensor into the catheter. The sheath can comprise a slot configured to allow the release of the analyte sensor therefrom.

In an embodiment of the first aspect, the system further comprises a fluid coupler having first end and second end, wherein the fluid coupler is configured to mate with the vascular access device on the first end, and wherein at least a portion of the analyte sensor extends through the fluid coupler or is housed within the fluid coupler. The fluid coupler can comprise sensor electronics formed thereon. The sensor electronics can a potentiostat. The fluid coupler can be configured to mate with a medical device on the second end. The medical device can comprise at least one device selected from the group consisting of a blood pressure monitor, a blood chemistry device, and a dialysis bypass machine.

In an embodiment of the first aspect, the analyte sensor is configured to extend through the vascular access device and into a blood stream of the host by from about 0.010 inches to about 1 inch.

In an embodiment of the first aspect, the vascular access device and the analyte sensor are configured to indwell within a blood stream of the host in vivo.

In an embodiment of the first aspect, further comprising sensor electronics operatively connected to the analyte sensor.

In an embodiment of the first aspect, the analyte sensor comprises at least one working electrode configured to measure a first signal. The first signal can be substantially analyte related.

In an embodiment of the first aspect, the analyte sensor further comprises a second working electrode configured to measure a second signal. The second signal can be substantially non-analyte related.

In an embodiment of the first aspect, the sensor electronics are configured to process the second signal and the first signal to determine a concentration of an analyte.