Method and apparatus for infusing liquids using a chemical reaction in an implanted infusion device

• US 6,520,936 B1
• Filed: 06/08/2000
• Issued: 02/18/2003
• Est. Priority Date: 06/08/1999
• Status: Expired due to Fees

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Mann, Alfred E.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): Fastovsky, Leonid M
• Application Number:
  US09/590,482
• Time in Patent Office: 985 Days
• Field of Search: 604/141, 604/93, 604/131, 604/140, 604/19, 128/899
• US Class Current: 604/141
• CPC Class Codes: A61M 2005/14204 with gas-producing electrochemical cell
• CPC Class Codes: A61M 2005/14513 with secondary fluid driving or regulating the infusion
• CPC Class Codes: A61M 2205/8243 by induction
• CPC Class Codes: A61M 2209/045 for filling, e.g. for filling reservoirs
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/14593 the diaphragm being actuated by fluid pressure

Abstract

Embodiments of implantable infusion pumps are provided that use a process of converting a first substance to a second gaseous substance (e.g. by electrolysis) to provide a motivating force to expel a desired fluid (e.g. drug or medication) from the pump into the body of a patient. An expandable sack may be provided around a gas producing electrolytic cell, such that as the gas expands it displaces a portion of the volume originally allocated to the desired fluid, and thereby forces the fluid from the pump. Pumps may be provided with a double septum to allow refilling of the desired fluid while simultaneously allowing removal of the generated gas from the system while using a single needle. Recharging of pump batteries may occur by direct electrical conduction through one or more needles and/or by r.f. energy transfer. Programming of the pump may occur by way of conductive paths provided by one or more needles or by means of r.f. transfer. A pressure regulator may be provided in vicinity to an outlet port of the pump so as to enable more reliable operation of the pump when subjected to changes in ambient pressure. A one-way valve may also be provided to reduce risk of back flow into the pump.

Claims

1. An implantable infusion pump for dispensing a fluid to a patent, comprising:

a pump housing capable of being implanted in a body of a patient;

an inlet in the housing for receiving the fluid to be dispensed, the inlet in the housing including a first septum and a second septum;

an outlet in the housing from which fluid is dispensed;

a first reservoir of variable size for holding the fluid, wherein the inlet and first reservoir are connected at least periodically by a flow path so as to allow fluid supplied to the inlet to flow to the first reservoir, and wherein the outlet and first reservoir are at least periodically connected by a flow path so as to allow fluid in the first reservoir to be dispensed through the outlet;

a second reservoir of variable size for holding a gas;

a volume comprising the first reservoir and the second reservoir, such that as the second reservoir expands in size the first reservoir diminishes in size; and

a gas generating source for controllably and variably producing quantities of gas that expand the size of the second reservoir, thereby decreasing the size of the first reservoir to cause dispensing of fluid through the outlet to the patient.

2. The pump of claim 1 wherein the source for generating gas comprises a controllable reaction trigger for causing at least a first chemical substance to change into at least one secondary chemical substance wherein at least one of the secondary substances comprises a gas.

3. The pump of claim 2 wherein the reaction trigger comprises an electric current.

4. The pump of claim 3 wherein the at least first chemical substance comprises a conducting solution that comprises water.

5. The pump of claim 4 wherein the conducting solution comprises NaCl.

6. The pump of claim 4 wherein the at least one secondary chemical substance is a gas of hydrogen and a gas of oxygen.

7. The pump of claim 6 wherein the reaction trigger converts water to gases of hydrogen and oxygen by electrolysis.

8. The pump of claim 2 wherein the reaction trigger causes a liquid substance within a reaction chamber to create a gas, and wherein the reaction chamber is separated from the second reservoir by a membrane that is permeable to a generated gas but is relatively impermeable to the liquid from which the gas is generated.

9. The pump of claim 8 wherein the reaction chamber is contained within a volume of variable size, such that as gas is created and passes through the membrane the chamber reduces in size so that the reaction chamber contains primarily liquid.

10. The pump of claim 2 wherein the reaction trigger causes a liquid substance to create a gas.

11. The pump of claim 1 additionally comprising a pressure regulator located along the flow path between the first reservoir and the outlet.

12. The pump of claim 11 wherein the pressure regulator inhibits flow of fluid to the outlet when a pressure of the gas in the second reservoir is less than a preset amount.

13. The pump of claim 12 wherein the preset amount is at least 1.1 standard atmospheres.

14. The pump of claim 13 wherein the preset amount is at least 1.2 standard atmospheres.

15. The pump of claim 11 wherein the pressure regulator comprises:

a sealed chamber filled with a gas, the sealed chamber having an end surface; and

a seating surface to which the end surface of the sealed chamber is pressed by the gas in the sealed chamber when the pressure in the second reservoir is less than the pressure in the sealed chamber when the sealed chamber is in contact with the seat;

wherein the end surface is dislodged from the seat, and fluid is allowed to flow through the outlet, when the pressure within the second reservoir exceeds the pressure within the sealed chamber.

16. The pump of claim 11 wherein a one-way valve is located between the regulator and the outlet.

17. The pump of claim 11 wherein a filter is located between the first reservoir and the pressure regulator.

18. The pump of claim 1 additionally comprising a filter located between the first reservoir and the outlet.

19. The pump of claim 1 additionally comprising a one-way valve between the first reservoir and the outlet.

20. The pump of claim 1 wherein the inlet comprises:

a guide region; and

a stop;

wherein the first septum is located between the guide region and the second septum, and the second septum is located between the first septum and the stop;

wherein a first inlet is between the first and second septums and a second inlet is between the second septum and the stop, and

wherein one of the first inlet and the second inlet allows fluid to be added to the first reservoir, while the other inlet allows gas to be exhausted from the second reservoir.

21. The pump of claim 1 wherein the gas generating source comprises an electrical control circuit and a battery.

22. The pump of claim 21 wherein the battery is rechargeable while implanted in the body by one or both of (1) conduction from a source outside the body through at least one lead that is made to contact the pump, and (2) r.f. energy transfer from a source outside the body.

23. The pump of claim 1 wherein a first and second inlet are provided for accepting a first and second syringes that may be used for adding fluid to the first reservoir and for exhausting gas from the second reservoir, respectively.

39. The pump of claim 20, wherein the guide region is conical.

24. A method for infusing a fluid into a body of a patient, comprising:

providing an implantable device in a patient, wherein the implantable device includes a volume that is partitioned into a first reservoir of variable size and a second reservoir of variable size, such that as the second reservoir expands in size the first reservoir diminishes in size;

providing fluid to a first reservoir; and

generating and providing within the implantable device quantities of a gas, on a controllable and variable basis, to the second reservoir to cause expansion of the second reservoir such that a portion of a volume of the first reservoir is diminished and a portion of the fluid supplied to the first reservoir is dispensed through an outlet of the implanted device into the body of the patient;

providing a first septum within the implantable device;

providing a second septum with the implantable device; and

wherein a first inlet is between the first and second septums and a second inlet is between the second septum and a housing of the implantable device, and

wherein one of the first inlet and the second inlet allows fluid to be added to the first reservoir, while the other inlet allows gas to be exhausted from the second reservoir.

25. The method of claim 24 wherein generating a gas comprises causing at least a first chemical substance to change into at least one secondary chemical substance, wherein at least one of the secondary substances is a gas.

26. The method of claim 25 wherein causing comprises applying an electric current to the first chemical substance.

27. The method of claim 26 wherein the first chemical substance comprises water.

28. The method of claim 27 wherein the at least one secondary chemical substance is a gas of hydrogen and a gas of oxygen.

29. The method of claim 24 additionally comprising:

allowing fluid to enter the body of the patient only when a pressure within the second reservoir exceeds a preset amount set by a pressure regulator located along the flow path between the first reservoir and the outlet.

30. The method of claim 29 wherein the preset amount is at least 1.1 standard atmospheres.

31. The method of claim 30 wherein the preset amount is at least 1.2 standard atmospheres.

32. The method of claim 29 wherein a one-way valve is located between the regulator and the outlet.

33. The method of claim 29 wherein a filter is located between the first reservoir and the pressure regulator.

34. The method of claim 24 wherein the generating of a gas comprises utilization of an electrical control circuit and a battery.

35. The method of claim 34 wherein the battery is recharged while implanted in the body by one or both of (1) providing charging current through a conducting element extending from a source outside the body to the pump, and (2) supplying r.f. energy to the implanted device from a source outside the body.

36. An implantable device for dispensing a drug to a patient, comprising:

a means for holding a fluid that may be electrolyzed,

a means for causing a selected amount of the fluid to be electrolyzed to produce a gas;

a means for separating produced gas from the fluid and allowing the gas, but not the fluid, to pass to a volume surrounded by a variable size containment means;

a reservoir means for holding a drug to be dispensed, the reservoir means being of variable size and located in relation to the containment means such that as the containment means increases in size, the reservoir means decreases in size thereby dispensing the drug to the patient;

a means for refilling the reservoir with the drug; and

a means to remove gas from inside the containment means so that refilling of the reservoir means may occur;

a first septum located within the implantable device;

a second septum located within the implantable device; and

wherein a first inlet exists between the first and second septums and a second inlet exists between the second septum and a housing of the implantable device, and

wherein one of the first inlet and the second inlet allows fluid to be added to the first reservoir, while the other inlet allows gas to be exhausted from the second reservoir.

37. The device of claim 36 wherein the means to remove gas comprises an outlet means to exhaust gas from inside the containment means.

38. The device of claim 37 where the outlet means is opened to allow exhaustion of gas when the reservoir means is meaning refilled.

40. An implantable device comprising:

a housing;

a first reservoir located within the housing for holding fluid;

a second reservoir located within the housing for holding gas;

a first septum located within the housing; and

a second septum located within the housing adjacent the first septum,

wherein the first septum and the second septum form a first cavity therebetween for allowing fluid to flow from the first reservoir, and the second septum and the housing form a second cavity therebetween for allowing gas to flow from the second reservoir.