Air tolerant implantable piston pump

Patent metadata

Field	Value
Publication number	US-9968733-B2
Application number	US-68443610-A
Country	US
Kind code	B2
Filing date	Jan 8, 2010
Priority date	Dec 15, 2008
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

An implantable infusion device includes a reservoir for housing an infusion medium and a drive mechanism having an inlet chamber, a piston and a piston channel. The inlet chamber is in fluid communication with the reservoir. The piston channel is in fluid communication with the inlet chamber, and has a distal end and a proximal end, the proximal end being closer to the inlet channel than the distal end. The piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel. The clearance between the piston and the channel is sufficiently small to prevent undissolved gas in the inlet chamber from passing through the clearance. The inlet chamber may be sufficiently large to allow undissolved gas to accumulate without adversely affecting the performance of the infusion device.

First claim

What is claimed is:

1. An implantable infusion device, comprising:
a reservoir for housing an infusion medium;
a drive mechanism having an inlet chamber, a piston and a piston channel,
wherein the inlet chamber is in fluid communication with the reservoir,
wherein the piston channel is in fluid communication with the inlet chamber, the piston channel having a distal end and a proximal end, the proximal end being closer to the inlet chamber than the distal end,
wherein the piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel,
wherein the piston is positioned and moveable within the piston channel such that a clearance between the piston and the piston channel is sufficiently small to prevent undissolved gas in the inlet chamber from passing through the clearance;

a filter disposed between the inlet chamber and the reservoir, wherein the filter is hydrophilic and is configured to prevent microorganisms from entering the inlet chamber from the reservoir, wherein the filter is configured to allow dissolved gas to pass from the reservoir to the inlet chamber such that over time, the dissolved gas comes out of solution as undissolved gas in the inlet chamber, and wherein the filter is configured to prevent the undissolved gas from passing from the inlet chamber to the reservoir;
an outlet in fluid communication with the piston channel, the outlet being closer to the distal end of the piston channel than the proximal end of the piston channel; and
a valve in fluid communication with, and disposed between, the outlet and the piston channel,
wherein the piston has a valve facing end and a diameter, and wherein the valve facing end of the piston is spaced from the valve by a distance of about 10% of the piston diameter when the piston is in a forward position.

2. The implantable infusion device of claim 1 , wherein the clearance between the piston and the piston channel is sufficiently small such that the infusion medium is retained in the piston channel via capillary action.

3. The implantable infusion device of claim 1 , wherein the clearance between the piston and the piston channel is between 3 micrometers and 10 micrometers.

4. The implantable infusion device of claim 1 , wherein the filter is configured to filter particles larger than 0.22 microns in diameter.

5. The implantable infusion device of claim 1 , wherein a volume of the inlet chamber is between 100 microliters and 300 microliters.

6. The implantable infusion device of claim 1 , wherein the reservoir is maintained at a pressure of greater than 5 psia.

7. The implantable infusion device of claim 1 , wherein the reservoir is maintained at a pressure of greater than 10 psia.

8. The implantable infusion device of claim 1 , wherein the reservoir is maintained at a pressure of between 15 psia and 16 psia.

9. The implantable infusion device of claim 1 ,
wherein the valve has a cracking pressure that is between 5 psi less than a pressure of the reservoir and 5 psi more than the pressure of the reservoir.

10. The implantable infusion device of claim 1 , wherein the valve has a cracking pressure that is at least 2 psi greater than a difference of a reservoir pressure minus an outlet pressure at a lowest ambient atmospheric pressure that the device is designed to be subjected.

11. The implantable infusion device of claim 1 , wherein the valve has a cracking pressure that is equal to or greater than a reservoir pressure minus 6.3 psia.

12. The implantable infusion device of claim 1 , wherein the drive mechanism is capable of continued operation without undissolved gas exiting the distal end of the piston channel when 70% of a volume of the inlet chamber is occupied by undissolved gas.

13. An implantable infusion device, comprising:
a reservoir for housing an infusion medium, the reservoir being maintained at a pressure of greater than 8 psia;
a drive mechanism having an inlet chamber, a piston and a piston channel,
wherein the inlet chamber is in fluid communication with the reservoir, the inlet chamber having a volume of between 100 microliters and 300 microliters,
wherein the piston channel is in fluid communication with the inlet chamber, the piston channel having a distal end and a proximal end, the proximal end being closer to the inlet chamber than the distal end,
wherein the piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel,
wherein the piston is positioned and moveable within the piston channel such that an average clearance between the piston and the piston channel is between 3 micrometers and 10 micrometers;

a filter disposed between the inlet chamber and the reservoir, wherein the filter is hydrophilic and is configured to prevent microorganisms from entering the inlet chamber from the reservoir, wherein the filter is configured to allow dissolved gas to pass from the reservoir to the inlet chamber such that over time, the dissolved gas comes out of solution as undissolved gas in the inlet chamber, and wherein the filter is configured to prevent the undissolved gas from passing from the inlet chamber to the reservoir;
an outlet in fluid communication with the piston channel, the outlet being closer to the distal end of the piston channel than the proximal end of the piston channel; and
a valve in fluid communication with, and disposed between, the outlet and the piston channel,
wherein the piston has a valve facing end and a diameter, and wherein the valve facing end of the piston is spaced from the valve by a distance of about 10% of the piston diameter when the piston is in a forward position.

14. The implantable infusion device of claim 13 , wherein the reservoir is maintained at a pressure of greater than 10 psia.

15. The implantable infusion device of claim 13 , wherein the reservoir is maintained at a pressure of between 14 psia and 19 psia.

16. The implantable infusion device of claim 13 ,
wherein the valve has a cracking pressure that is between 5 psi less than the pressure of the reservoir and 5 psi more than the pressure of the reservoir.

17. The implantable infusion device of claim 13 , wherein the valve has a cracking pressure that is at least 2 psi greater than a difference of the reservoir pressure minus an outlet pressure at a lowest ambient atmospheric pressure that the device is designed to be subjected.

18. The implantable infusion device of claim 13 , wherein the valve has a cracking pressure that is equal to or greater than the reservoir pressure minus 6.3 psia.

19. The implantable infusion device of claim 13 , wherein the drive mechanism is capable of continued operation without undissolved gas exiting the distal end of the piston channel when 70% of the volume of the inlet chamber is occupied by undissolved gas.

20. An implantable infusion device, comprising:
a reservoir for housing an infusion medium wherein the reservoir being maintained at a pressure;
a drive mechanism having an inlet chamber, a piston and a piston channel,
wherein the inlet chamber is in fluid communication with the reservoir,
wherein the piston channel is in fluid communication with the inlet chamber, the piston channel having a distal end and a proximal end, the proximal end being closer to the inlet chamber than the distal end,
wherein the piston is axially moveable within the piston channel to drive infusion medium out of the distal end of the piston channel,

wherein the piston is positioned and

Assignees

• Haase James M
• Whitehead Nicholas R
• Mezera Ronald L
• Medtronic Inc

Inventors

• Haase James M
• Whitehead Nicholas R
• Mezera Ronald L

Classifications

• A61M5/14276 Primary

  specially adapted for implantation · CPC title

• F04B19/006

  Micropumps (F04B43/043 and F04B43/095 take precedence) · CPC title

• A61M2205/7518

  bacterial · CPC title

• F04B53/1032

  Spring-actuated disc valves (F04B53/1022, F04B53/103 take precedence) · CPC title

• F04B35/045

  using solenoids · CPC title