Medication infusion device using negatively biased ambient pressure medication chamber

• US 20060089620A1
• Filed: 12/06/2005
• Published: 04/27/2006
• Est. Priority Date: 06/25/2003
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Lord, Peter C., Gibson, Scott R.
• Granted Patent: US 8,070,745 B2
• Time in Patent Office: Days
• US Class Current: 604/891.100
• CPC Class Codes: A61M 2005/14264 with means for compensating influence from the environment
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/14586 pressurised by means of a flexible diaphragm

Abstract

A method and apparatus for infusing medication into a patient'"'"'s body using a medication chamber referenced to ambient pressure. The apparatus includes a medication chamber enclosed by a peripheral wall which includes a movable portion configured to transfer exterior ambient pressure into the chamber. Means are provided for exerting a negative bias force acting on the movable portion in a direction opposed to the ambient pressure force. Thus, the resultant pressure in the chamber will be negative with respect to ambient pressure, reducing the risk that the chamber can be overpressurized and produce an unintended medication discharge.

Claims

1. A device for storing medication and for selectively discharging medication for application to a patient'"'"'s body, said device including:

a peripheral member enclosing a chamber suitable for storing medication;

said peripheral member including a wall portion configured for transferring exterior ambient pressure into said chamber;

bias means for exerting a force on said wall portion acting in opposition to the force produced by said ambient pressure to produce a resultant pressure in said chamber which is negative with respect to said ambient pressure; and

an actuatable pump coupled to said chamber for extracting medication from said chamber for infusion into a patient'"'"'s body.

2. The device of claim 1 wherein said wall portion is configured for movement to vary the volume of said chamber.

3. The device of claim 1 further including a support plate and wherein said wall portion comprises a flexible membrane mounted on said support plate to define said chamber therebetween.

4. The device of claim 3 wherein said flexible membrane exhibits resiliency characterized by a restoration force acting in opposition to the force produced by said ambient pressure on said wall portion.

5. The device of claim 3 wherein said flexible membrane comprises a substantially planar elastic sheet.

6. The device of claim 3 wherein said flexible membrane comprises a bellows.

7. The device of claim 1 wherein said bias means includes a spring bearing against said wall portion.

8. The device of claim 1 wherein said bias means includes spaced magnets oriented to repel.

9. The device of claim 1 wherein said actuatable pump is electrically powered.

10. A method of storing fluid medication for selective infusion into a patient'"'"'s body, said method comprising:

providing a peripheral wall for enclosing a chamber suitable for storing medication;

exposing an exterior surface of a portion of said wall to ambient pressure for transferring said ambient pressure into said chamber; and

applying a bias force to said wall portion acting to oppose the force produced by said ambient pressure for creating a resultant pressure in said chamber which is negative with respect to said ambient pressure.

11. The method of claim 10 further including pumping medication from said chamber for infusion into a patient'"'"'s body.

12. A medication infusion device suitable for implantation in a patient'"'"'s body, said device comprising:

a medication chamber including an interior volume bounded by a peripheral wall;

a pump coupled to said interior volume actuatable to extract medication therefrom for delivery to a patient'"'"'s body site;

said peripheral wall including a portion configured for exposure to exterior ambient pressure for producing an interiorly directed ambient pressure force component against said wall portion; and

means for exerting a bias force component on said wall portion directed oppositely to said inwardly directed force component for producing a resultant pressure in said interior volume which is negative with respect to said ambient pressure

13. The device of claim 12 wherein said means for exerting a bias force includes a spring.

14. The device of claim 12 wherein said medication chamber includes an inlet port for supplying medication to said interior volume.

15. The device of claim 12 further including an inlet valve through which medication can be introduced into said interior volume.

16. The device of claim 15 wherein said inlet valve comprises a self healing septum

17. The device of claim 12 wherein said wall portion is configured for movement to vary the magnitude of said interior volume.

18. The device of claim 12 wherein said chamber peripheral wall includes a support plate and wherein said peripheral wall portion comprises a flexible membrane mounted on said support plate.

19. The device of claim 18 wherein said flexible membrane exhibits resiliency characterized by a restoration force acting in opposition to the force produced on said membrane by said ambient pressure.

20. The device of claim 19 wherein said flexible membrane comprises a substantially planar elastic sheet.