Precision medication dispensing system and method

• US 4,557,726 A
• Filed: 09/28/1984
• Issued: 12/10/1985
• Est. Priority Date: 12/27/1982
• Status: Expired due to Fees

• Current Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Original Assignee: Consolidated Controls Corporation
• Inventors: Reinicke, Robert H.
• Primary Examiner(s): Coven, Edward M.
• Application Number:
  US06/656,085
• Time in Patent Office: 438 Days
• Field of Search: 128/DIG. 12, 604/151, 604/153, 604/131, 604/132, 604/133, 604/134, 604/136, 604/890, 604/891, 604/66, 604/67, 417/412, 417/413
• US Class Current: 604/67
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: G05D 7/0676 by action on flow sources G05D7/0688, G05D7/0694 take precedence
• CPC Class Codes: Y10S 128/12 Pressure infusion

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.

Claims

1. In a system for infusing medication into a body, the combination of, a medication reservoir, a pumping chamber, a medication outlet connected to said pumping chamber, an inlet valve between said reservoir and said pumping chamber and including a fixed valve seat and a movable valve element, a movable member forming a wall portion of said pumping chamber and positioned adjacent said movable valve element, an armature connected to said movable member, means for biasing said armature in the direction to urge said movable member into engagement with said movable valve element and said movable valve element into engagement with said valve seat, thereby normally to provide a substantial closing force for said inlet valve, and electromagnetic means for attracting said armature and moving said movable element away from said movable valve element and in the direction to increase the volume of said pumping chamber thereby to remove said closing force from said inlet valve and permit medication to flow from said reservoir into said pumping chamber.

2. The combination of claim 1, wherein said armature is a flat disc and said biasing means comprises a spring positioned between said disc and a fixed support member.

3. The combination of claim 1, which includes a housing within which said reservior and pumping chamber are located, said armature comprising a flat disc which is mounted in said housing for movement in said direction, and said biasing means comprising a spring positioned between said disc and said housing.

4. The combination of claim 1, wherein said armature is a flat disc, said movable member comprises a pin connected to said disc at the center thereof and having a head portion positioned within said pumping chamber, and a flexible member connected between said head portion and the adjacent wall of said pumping chamber so that said head portion forms a movable wall portion of said pumping chamber.

5. The combination of claim 4, wherein said flexible member is a metal bellows.

6. The combination of claim 1, wherein said electromagnetic means comprises a magnetic core, a coil mounted on said core, said armature being mounted to complete a magnetic flux path with said core, and being moved in response to energization of said coil.

7. In a system for infusing medication into a body, the combination of, means defining a pumping chamber including a movable wall portion, means for biasing said movable wall portion to an initial position, a movably mounted armature connected to said movable wall portion, electromagnetic means including a coil for moving said armature so that the volume of said pumping chamber is altered, a reservoir of medication, conduit means interconnecting said reservoir and said pumping chamber and including a check valve operative when open to permit flow of medication from said reservoir to said pumping chamber and blocking such flow when closed, said check valve being responsive to the differential pressure thereacross and moving to a closed position when the differential of the pressure across said check valve falls below a predetermined value, means for applying a pulse of current to said coil so thast said armature is moved in a direction to increase the volume of said pumping chamber by moving said movable wall portion away from said initial position against the force of said biasing means, the resultant drop in pressure in said pumping chamber when said armature is moved in said direction being sufficient to cause said check valve to open, a medication outlet, and flow restriction means for connecting said pumping chamber to said medication outlet, said biasing means acting after said check valve is closed to force medication through said flow restriction means to said outlet.

8. The system of claim 7, which includes pressure transducer means for developing an electrical signal which varies in accordance with the pressure within said pumping chamber, and means controlled by said electrical signal for varying the rate at which pulses are applied to said coil so as to maintain a predetermined rate of flow of medication to said outlet.

9. In a system for infusing medication into a body, the combination of, means defining a pumping chamber including a movable wall portion biased to an initial position, a coil, means for applying pulses of current to said coil, electromagnetic means for moving said wall portion in the direction to increase the volume of said pumping chamber when said current pulses are applied to said coil, a medication reservior, a check valve positioned between said pumping chamber and said reservoir, said check valve opening in response to a predetermined differential pressure thereacross to permit flow of medication to said pumping chamber and blocking such flow when closed, a medication outlet for infusing medication into the body, a flow restrictor connected between said pumping chamber and said outlet for restricting the flow of medication to 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 said current pulses, said biasing means acting when the differential pressure across said check valve falls below said predetermined value and said check valve closes to increase the pressure in said pumping chamber and force medication through said flow restrictor to said outlet, pressure transducer means for developing an electrical signal which varies in accordance with the pressure within said pumping chamber, and means controlled by said electrical signal for controlling the rate at which said current pulses are applied to said coil so as to maintain a predetermined average flow of medication to said outlet.