Precision medication dispensing system and method
First Claim
1. In a system for infusing medication into a body, the combination of, a medication reservoir, a flow restriction means having an outlet for infusing medication into the body, metering means connected betwen said reservoir and the inlet of said flow restriction means for periodically supplying a small portion of the medication in said reservoir to the inlet of said flow restriction means during successive spaced apart dispensing periods, means for measuring the exact amount of medication supplied to said flow restriction outlet during each dispensing period, said measuring means including a pressure transducer for developing a signal corresponding to the pressure transient developed at said inlet of said flow restriction means during each of said dispensing periods, and means responsive to said measuring means for varying the time between successive dispensing periods so as to maintain the rate of infusion of medication into the body at a desired value.
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Accused Products
Abstract
The implantable device includes a medication reservoir, a pulsatile pump and an absolute pressure transducer. The pumping pressure wave developed in the pumping chamber is measured by the absolute pressure transducer whose output is used to adjust the pulsing rate of the solenoid operated pump so that the programmed time averaged rate of infusion of medication into the body is precisely maintained throughout all operating temperature and pressure conditions.
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Citations
27 Claims
- 1. In a system for infusing medication into a body, the combination of, a medication reservoir, a flow restriction means having an outlet for infusing medication into the body, metering means connected betwen said reservoir and the inlet of said flow restriction means for periodically supplying a small portion of the medication in said reservoir to the inlet of said flow restriction means during successive spaced apart dispensing periods, means for measuring the exact amount of medication supplied to said flow restriction outlet during each dispensing period, said measuring means including a pressure transducer for developing a signal corresponding to the pressure transient developed at said inlet of said flow restriction means during each of said dispensing periods, and means responsive to said measuring means for varying the time between successive dispensing periods so as to maintain the rate of infusion of medication into the body at a desired value.
- 5. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, a flow restrictor positoned between said pumping chamber and said outlet, said flow restrictor allowing the pressure within said pumping chamber to become equal to the pressure at said outlet in the intervals between strokes of said pump element, and a pressure transducer for measuring the absolute pressure within said pumping chamber and developing an electrical signal which varies in accordance with the instantaneous pressure within said pumping chamber, whereby said electrical signal includes a base line portion proportional to the pressure at said outlet during said intervals and a pumping pressure transient portion which varies in accordance with variations in the pressure within said chamber during pumping strokes of said pump element, and means controlled by said electrical signal for varying the rate at which said pump is actuated so as to maintain a predetermined average rate of flow of medication to said outlet.
- 9. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, a pressure transducer for developing an electrical signal corresponding to the pressure transient developed within said pumping chamber during one stroke of said pump element, means for generating successive signals corresponding to the flow of medication to said outlet during successive portions of said pressure transient, means responsive to said successive signals for developing an output signal corresponding to the total volume of medication supplied to said outlet during said one stroke of said pump element, and means controlled at least in part by said output signal by varying the rate at which said pump element is stroked to maintain the volume of medication supplied to said outlet per unit of time at a predetermined value.
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11. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, a flow restrictor connected between said pumping chamber and said outlet, said flow restrictor allowing the pressure within said pumping chamber to become equal to the pressure at said outlet in the intervals between strokes of said pump element, means for measuring the precise volume of medication pumped to said outlet on each stroke of said pump element, and means controlled at least in part by said measuring means for varying the rate at which said pump element is stroked to maintain the volume of medication supplied to said outlet per unit of time at a predetermined value.
- 12. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, a flow restrictor connected between said pumping chamber and said outlet, said flow restrictor allowing the pressure within said pumping chamber to become equal to the pressure at said outlet in the intervals between strokes of said pump element, a pressure transducer for developing an electrical signal corresponding to the pressure transient developed within said pumping chamber during one stroke of said pump element, means for generating a series of signals corresponding to the differential pressure across said flow restrictor at different points along said pressure transient, means responsive to each of said series of differential pressure signals for developing a signal representing the corresponding flow of medication through said flow restrictor, means responsive to said series of flow signals for developing an output signal representing the total volume of medication supplied to said outlet during said one stroke of said pump element, and means controlled at least in part by said output signal for varying the rate at which said pump element is stroked to maintain the volume of medication supplied to said outlet per unit of time at a predetermined value.
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14. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, a flow restrictor connected between said pumping chamber and said outlet, said flow restrictor allowing the pressure within said pumping chamber to become equal to the pressure at said outlet in the intervals between strokes of said pump element, a pressure transducer for developing an electrical signal corresponding to the pressure transient developed within said pumping chamber during one stroke of said pump element, means responsive to said electrical signal for generating a differential pressure signal which varies in accordance with the differential pressure across said flow restrictor during said pressure transient, means for converting said different pressure signal into a corresponding flow rate signal whose amplitude varies in accordance with variations in flow through said flow restrictor during said pressure transient, means for integrating said flow rate signal, thereby to provide an output signal representing the total volume of medication supplied to said outlet during said one stroke of said pump element, and means controlled at least in part by said output signal for varying the rate at which said pump element is stroked to maintain the volume of medication supplied to said outlet per unit of time at a predetermined value.
- 16. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, means for actuating said pump element at a variable rate, means for generating a reference signal corresponding to a desired flow of medication to said outlet, means for developing an output signal representing the precise volume of medication pumped to said outlet on each stroke of said pump element, said means for developing an output signal including a pressure transducer for developing an electrical signal corresponding to the pumping pressure transient developed within said pumping chamber during one stroke of said pump element, means for comparing said reference signal and said output signal to develop an error signal corresponding to the difference therebetween, and means controlled by said error signal for varying the rate of actuation of said pump element by said actuating means to maintain said desired flow of medication to said outlet.
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27. In a system for infusing medication into a body, the combination of, a medication reservoir, a medication outlet for infusing medication into the body, positive displacement pump means connected between said reservoir and said outlet and including a pumping chamber and a pump element movable through a predetermined stroke within said chamber to force medication from said reservoir into said medication outlet, means for actuating said pump element at a variable rate, means for generating a reference signal corresponding to a desired flow of medication to said outlet, a flow restrictor connected between said pumping chamber and said outlet, said flow restrictor permitting the pressure within said pumping chamber to become equal to the pressure at said outlet in the intervals between strokes of said pump element, means for developing a first signal corresponding to the pressure in said chamber during said intervals, means for developing a second signal which varies in accordance with variations in the pressure within said chamber during strokes of said pump element, means responsive to said first and second signals for developing a control signal means for comparing said reference signal and said control signal to develop an error signal corresponding to the difference therebetween, and means controlled by said error signal for varying the rate of actuation of said pump element by said actuating means to maintain said desired flow of medication to said outlet.
Specification