Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-06-01
2003-05-06
Walberg, Teresa (Department: 3742)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S522000
Reexamination Certificate
active
06558351
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to closed loop drug delivery systems and more specifically to systems for controlling the infusion rate of insulin based on continuously monitored body glucose levels.
BACKGROUND OF THE INVENTION
The pancreas of a normal healthy person produces and releases insulin into the blood stream in response to elevated blood plasma glucose levels. Bata cells (&bgr;-cells), which reside in the pancreas, produce and secrete the insulin into the blood stream, as it is needed. If &bgr;-cells become incapacitated or die, a condition known as Type I diabetes mellitus (or in some cases if &bgr;-cells produce insufficient quantities of insulin, Type II diabetes), then insulin must be provided to the body from another source.
Traditionally, since insulin cannot be taken orally, insulin has been injected with a syringe. More recently, use of infusion pump therapy has been increasing, especially for delivering insulin for diabetics. For example, external infusion pumps are worn on a belt, in a pocket, or the like, and deliver insulin into the body via an infusion tube with a percutaneous needle or a cannula placed in the subcutaneous tissue. As of 1995, less than 5% of Type I diabetics in the United States were using infusion pump therapy. Presently over 7% of the more than 900,000 Type I diabetics in the U.S. are using infusion pump therapy. And the percentage of Type I diabetics that use an infusion pump is growing at an absolute rate of over 2% each year. Moreover, the number of Type I diabetics is growing at 3% or more per year. In addition, growing numbers of insulin using Type II diabetics are also using infusion pumps. Physicians have recognized that continuous infusion provides greater control of a diabetic's condition, and are also increasingly prescribing it for patients. Although offering control, pump therapy can suffer from several complications that make use of traditional external infusion pumps less desirable for the user.
SUMMARY OF THE DISCLOSURE
According to an embodiment of the invention, a closed loop infusion system is for controlling blood glucose concentration in the body of a user. Embodiments of the present invention include a sensor system that measures a glucose level in the body of the user, a controller that uses the measured glucose level to generate commands, and an insulin infusion system that infuses insulin into the body of the user in response to the commands.
According to another embodiment of the invention, a closed loop infusion system is for infusing a fluid into a user. The closed loop infusion system includes a sensor system, a controller, and a delivery system. The sensor system includes a sensor for monitoring a condition of the user. The sensor produces a sensor signal, which is representative of the condition of the user, and is used to generate a controller input. The controller uses the controller input to generate commands that affect the operation of the delivery system. Accordingly, the delivery system infuses a liquid into the user. In particular embodiments, glucose concentration is monitored by the sensor system, and the liquid delivered to the user includes insulin. In preferred embodiments, the sensor system sends a message, generated using the sensor signal, to the delivery system. The message is used to generate the controller input. In particular embodiments, the sensor is a subcutaneous sensor in contact with interstitial fluid. In further particular embodiments, two or more sensors are included in the sensor system.
In preferred embodiments, the sensor system is predominately external to the user's body. And the delivery system is predominately external to the user's body. In alternative embodiments, the sensor system is predominately internal to the user's body. In other alternative embodiments, the delivery system is predominately internal to the user's body.
In preferred embodiments, the sensor signal is used to generate digital sensor values, and the digital sensor values are processed through at least one of a group of components that includes one or more pre-filters, one or more filters, one or more calibrators and one or more post-calibration filters to generate the controller input. In particular embodiments, the one or more pre-filters uses a group of digital sensor values, calculates a parameter using at least a subset of the group of digital sensor values, establishes one or more thresholds relative to the parameter, compares each digital sensor value within the group to the one or more thresholds, and changes the value of any digital sensor value that is outside of the one or more thresholds. In further particular embodiments, the one or more pre-filters compares the digital sensor values to one or more thresholds, and a flag is set when one or more digital sensor values are outside of at least one threshold.
In preferred embodiments, the digital sensor values are processed through at least one FIR filter, preferably at least a 7
th
order FIR filter. In addition, a preferred FIR filter has a pass band for frequencies from zero up to between about 2 cycles/hour and 5 cycles/hour and a stop band beginning at 1.2 to three times the selected pass band frequency. In particular embodiments, the FIR filter has a pass band for frequencies from zero up to between about 2 cycles/hour and 10 cycles/hour and a stop band beginning at 1.2 to three times the selected pass band frequency. In other particular embodiments, the FIR filter has a pass band for frequencies from zero up to less than or equal to 10 cycles/hour. Preferred embodiments include a FIR filter that compensates for time delays of between zero and 30 minutes. In particular embodiments, the FIR filter compensates for time delays of between 3 and 10 minutes.
In preferred embodiments, the controller uses a first set of one or more controller gains when the glucose concentration is higher than a desired basal glucose concentration and the controller uses a second set of one or more controller gains when the glucose concentration is lower than a desired basal glucose concentration. In alternative embodiments, the controller uses a first set of one or more controller gains when the glucose concentration is increasing and a second set of one or more controller gains when the glucose concentration is decreasing. In further alternative embodiments, the controller uses a first set of one or more controller gains when the glucose concentration is higher than a desired basal glucose concentration and the glucose concentration is increasing; and the controller uses a second set of one or more controller gains when the glucose concentration is higher than a desired basal glucose concentration and the glucose concentration is decreasing; and the controller uses a third set of one or more controller gains when the glucose concentration is lower than a desired basal glucose concentration and the glucose concentration is increasing; and the controller uses a fourth set of one or more controller gains when the glucose concentration is lower than a desired basal glucose concentration and the glucose concentration is decreasing.
In preferred embodiments, one or more controller gains are selected such that the commands generated by the controller cause the delivery system to infuse insulin into the body of the user in response to a glucose concentration at a rate similar to the rate that beta cells would release insulin in an individual with a healthy normally functioning pancreas. Alternatively, one or more controller gains are selected so that the commands generated by the controller cause the delivery system to infuse insulin into the body of the user in response to a glucose concentration at a rate such that the insulin concentration profile in the user's blood stream is similar to the insulin concentration profile that would be generated by the release of insulin beta cells in an individual with a healthy normally functioning pancreas. In other alternative embodiments, a post-controller lead/lag compensator is use
Goode, Jr. Paul V.
Mastrototaro John J.
Purvis Richard E.
Rebrin Kerstin
Shin John J.
Medtronic MiniMed, Inc.
Medtronic MiniMed, Inc.
Robinson Daniel
LandOfFree
Closed loop system for controlling insulin infusion does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Closed loop system for controlling insulin infusion, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Closed loop system for controlling insulin infusion will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3085628