Compact implantable medication infusion device

• US 4,604,090 A
• Filed: 11/22/1983
• Issued: 08/05/1986
• Est. Priority Date: 11/22/1983
• 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): NOT, DEFINED
• Assistant Examiner(s): Kartchner, Gene B.
• Application Number:
  US06/554,197
• Time in Patent Office: 987 Days
• Field of Search: 604/49, 604/131, 604/132, 604/140, 604/141, 604/151, 604/152, 604/153, 604/118, 604/122, 604/891, 604/65-67, 604/245-246, 128/DIG. 12, 128/DIG. 13, 128/419 P
• US Class Current: 604/118
• CPC Class Codes: A61M 2039/0054 Multiple layers
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/14593 the diaphragm being actuated by fluid pressure
• CPC Class Codes: A61M 5/16809 by repeated filling and emptying of an intermediate volume pressure infusion using positive displacement pumps A61M5/142
• CPC Class Codes: F15C 5/00 Manufacture of fluid circuit elements; Manufacture of assemblages of such elements integrated circuits
• CPC Class Codes: Y10S 128/12 Pressure infusion

Abstract

An implantable medication infusion device wherein a generally cylindrical manifold is employed having a shallow recess on one face thereof. A flexible diaphragm is positioned to form with the face of said manifold a medication reservoir. A circular cover member is positioned over the diaphragm to form with said diaphragm a pressure stabilizing chamber within which is positioned a two-phase fluid for maintaining a constant pressure on said diaphragm. A permanent magnet is positioned at the center of said diaphragm and is movable therewith. A Hall effect transducer positioned on said manifold opposite said permanent magnet is employed continuously to measure the position of said diaphragm and provide an indication of the amount of medication in said reservoir.

A method of filling and sealing the pressure stabilizing chamber which insures that a small bubble of two-phase fluid is present in said chamber at all times.

An inlet filter is positioned between the medication reservoir and an inlet check valve to act as a bubble trap during the intake stroke of a pulsatile pumping unit also mounted in the manifold.

Claims

1. An implantable medication infusion unit, comprising a flat generally disc shaped manifold having a shallow recess on one face thereof, a flexible circular diaphragm secured at its periphery to the edge of said recess to form with said one face of said manifold a medication reservoir, means accessible from the exterior of said unit through a first penetrable septum mounted in the other face of said manifold for filling said medication reservoir, said last named means including a fill check valve, a pulsatile pumping unit mounted in said manifold and including an inlet check valve mounted in said manifold, a second penetrable septum mounted in said manifold, means defining a chamber beneath said second penetrable septum, and a passage in said manifold interconnecting said chamber and said reservoir, whereby the space between said fill check valve and said inlet check valve may be evacuated through said penetrable second septum.

2. An implantable medication infusion unit, comprising a flat generally disc shaped manifold having a shallow recess on one face thereof, a flexible circular diaphragm secured at its periphery to the edge of said recess to form with said one face of said manifold a medication reservoir, a pulsatile pumping unit mounted in said manifold and including an inlet check valve mounted in said manifold and connected to said medication reservoir, said pulsatile pumping unit also having an outlet check valve mounted in said manifold, a penetrable septum mounted in said manifold, means defining a chamber beneath said septum, and passage means in said manifold interconnecting said chamber with the space between said inlet check valve and said outlet check valve, whereby said space may be evacuated through said penetrable septum.

3. An implantable medication infusion unit, comprising a flat generally disc shaped manifold having a shallow recess on one face thereof, a flexible circular diaphragm secured at its periphery to the edge of said recess to form with said one face of said manifold a medication reservoir, means defining a pumping chamber in said manifold, an inlet check valve between said medication reservoir and said pumping chamber, a catheter assembly mounted in said manifold and extending to the exterior of said unit, an outlet check valve between said pumping chamber and said catheter assembly, a penetrable septum mounted in said manifold, means defining a chamber beneath said septum, and passage means in said manifold interconnecting said chamber and said pumping chamber so that said pumping chamber may be evacuated through said penetrable septum.

4. In an implantable medication infusion device of the type which includes a pressure stabilizing chamber formed by a flexible member and an opposed rigid cover member, the method of filling and sealing said pressure stabilizing chamber which comprises the steps of heating said chamber and a two-phase fluid to an elevated temperature, introducing said heated fluid into said chamber, forcing said flexible member against said cover to expel heated fluid through an opening in said cover, sealing said opening while it is submerged in heated fluid expelled from said chamber, and removing said force from said flexible member and cooling said chamber so that a small vapor bubble is formed in said chamber due to the increase in volume of said chamber produced by said removal of force and said cooling, said vapor bubble acting as a site to facilitate vaporization of said fluid as said flexible member is moved away from said cover.

5. The method of claim 4 wherein said elevated temperature is just below the boiling point of said two-phase fluid.

6. The method of claim 4 wherein said two-phase fluid is a mixture of 25% Freon 112 and 75% Freon 113, by weight.

7. The method of claim 4, wherein said two-phase fluid has a vapor pressure of approximately 8.5 psia at body temperature.

8. The method of claim 7, wherein said mixture is heated to a temperature of 125°

F.

9. The method of filling and sealing the pressure stabilizing chamber subassembly of an implantable medication infusion device, said device including a generally cylindrical manifold having a shallow recess on one face thereof, said pressure stabilizing chamber subassembly being formed by a flexible diaphragm secured to a cover member which subassembly is adapted to be secured to said manifold so that said diaphragm forms with said face of said manifold a medication reservoir, which comprises the steps of filling said pressure stabilizing chamber with a two-phase fluid which is heated to a temperature just below the boiling point thereof, forcing said diaphragm against said cover member to expel heated fluid through an opening in said cover, sealing said opening while it is submerged in heated fluid expelled from said chamber, and removing said force from said diaphragm and cooling said chamber so that a small vapor bubble is formed in said chamber due to the increase in volume of said chamber produced by said removal of force and said cooling, said vapor bubble acting as a site to facilitate vaporization of said fluid as said diaphragm is moved away from said cover.

10. The method of claim 9 which includes the step of securing said cover member to said manifold after said vapor bubble is formed in said pressure stabilizing chamber.

11. The method of claim 9 which includes the step of securing said subassembly to a fixture having a shallow recess in one face thereof which simulates said shallow recess in said manifold to form a simulated medication reservoir between said diaphragm and said fixture, and filling both said pressure stabilizing chamber and said simulated medication reservoir with said heated two phase liquid.

12. The method of claim 11, which includes the step of evacuating both said pressure stabilizing chamber and said simulated medication reservoir before said two-phase fluid is placed therein.

13. The method of claim 11, which includes the step of supplying gas under pressure through said fixture to the medication reservoir side of said diaphragm, thereby forcing said diaphragm against said cover member and expelling said heated fluid through said opening.

14. The method of claim 13, which includes the step of securing said cover member to said manifold after said vapor bubble is formed in said pressure stabilizing chamber.

15. In an implantable medication infusion unit, the combination of, a medication reservoir, a pumping chamber, a pulsatile pumping unit connected to a movable wall portion of said pumping chamber and adapted to increase the volume of said pumping chamber during the intake stroke thereof, an inlet check valve positioned between said reservoir and said pumping chamber and arranged to open during the intake stroke of said pumping unit, and filter means positioned between said reservoir and said inlet check valve, said filter means including a filter element which flexes toward said inlet check valve during the intake stroke of said pumping unit to permit a predetermined amount of medication which has already passed through said filter element to flow through said inlet check valve into said pumping chamber, wherein said filter element comprises a thin back up plate of titanium having relatively large openings therein, and a porous membrane positioned adjacent said back up plate, both said back up plate and said porous membrane being sufficiently flexible to permit said predetermined amount of medication to flow through said inlet check valve into said pumping chamber.

16. The combination of claim 15, wherein said porous membrane has a filter rating of from 0.22 to 5.0 microns.

17. In an implantable medication infusion unit, the combination of, a medication reservoir, a pumping chamber, a pulsatile pumping unit connected to a movable wall portion of said pumping chamber and adapted to increase the volume of said pumping chamber during the intake stroke thereof, an inlet check valve positioned between said reservoir and said pumping chamber and arranged to open during the intake stroke of said pumping unit, and filter means positioned between said reservoir and said inlet check valve, said filter means including a filter element which flexes toward said inlet check valve during the intake stroke of said pumping unit to permit a predetermined amount of medication which has already passed through said filter element to flow through said inlet check valve into said pumping chamber, the increase in volume of the pumping chamber being greater than the volume of flow through said filter during the pump stroke, the amount of flex being proportional to the difference between the increase in volume of the pumping chamber and the volume of flow through the filter during the pump stroke and selected to limit the pressure drop across the filter to a level insufficient to permit bubbles to be generated.

18. The combination of claim 17, wherein medication passes through said filter element from said reservoir during the periods between the intake strokes of said pumping unit.

20. The combination of claim 17, wherein during the intake stroke of said pumping unit said filter means has a pressure drop there across which is less than the minimum pressure drop required to pass a bubble of medication therethrough.

21. The combination of claim 17, wherein during the intake stroke of said pumping unit said filter means has a pressure drop of less than 0.5 psid thereacross.

19. In an implantable medication infusion unit, the combination of, a medication reservoir, a pumping chamber, a pulsatile pumping unit connected to a movable wall portion of said pumping chamber and adapted to increase the volume of said pumping chamber during the intake stroke thereof, an inlet check valve positioned between said reservoir and said pumping chamber and arranged to open during the intake stroke of said pumping unit, and filter means positioned between said reservoir and said inlet check valve, said filter means including a filter element which flexes toward said inlet check valve during the intake stroke of said pumping unit to permit a predetermined amount of medication which has already passed through said filter element to flow through said inlet check valve into said pumping chamber, wherein said filter element comprises a thin back up plate of titanium having relatively large openings therein, and a woven wire mesh screen positioned adjacent said back up plate both said back up plate and said screen being sufficiently flexible to permit said predetermined amount of medication to flow through said inlet check valve into said pumping chamber.

22. In an implantable medication infusion unit, the combination of, a medication reservoir, a pumping chamber, a pulsatile pumping unit connected to a movable wall portion of said pumping chamber and adapted to increase the volume of said pumping chamber during the intake stroke thereof, an inlet check valve positioned between said reservoir and said pumping chamber and arranged to open during the intake stroke of said pumping unit, and filter means positioned between said reservoir and said inlet check valve to block the flow of bubbles from said reservoir and said inlet check valve to block the flow of bubbles from said reservoir to said pumping chamber, the increase in volume of the pumping chamber being greater than the volume of flow through said filter during the pump stroke, said filter means flexing during the intake stroke of said pumping unit by an amount proportional to the difference between the increase in volume of the pumping chamber and the volume of flow through the filter during the pump stroke and selected to prevent the development of a pressure drop across said filter means which is great enough to force a bubble of medication therethrough.