Air tolerant implantable piston pump

• US 9,968,733 B2
• Filed: 01/08/2010
• Issued: 05/15/2018
• Est. Priority Date: 12/15/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Haase, James M., Whitehead, Nicholas R., Mezera, Ronald L.
• Primary Examiner(s): Mehta, Bhisma
• Assistant Examiner(s): WILSON, LARRY ROSS
• Application Number:
  US12/684,436
• Publication Number:
  US 20100152714A1
• Time in Patent Office: 3,049 Days
• Field of Search: 604151, 604 67, 60428801-28804, 6048901, 6048911, 417417
• CPC Class Codes: A61M 2205/7518 bacterial
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/165 Filtering accessories, e.g. blood filters, filters for infusion liquids A61M1/14 , A61M1/34, A61M1/3627, A61M1/3679, A61M1/3687 take precedence; needle sets with incorporated air inlet filters A61M5/162
• CPC Class Codes: A61M 5/36 with means for eliminating or preventing injection or infusion of air into body dialysis systems, blood oxygenators A61M1/14; haemofiltration equipment A61M1/34; automatic tube cut-off A61M39/281
• CPC Class Codes: F04B 17/042 the solenoid motor being separated from the fluid flow
• CPC Class Codes: F04B 19/006 Micropumps F04B43/043 and F04B43/095 take precedence
• CPC Class Codes: F04B 35/045 using solenoids
• CPC Class Codes: F04B 53/008 Spacing or clearance between cylinder and piston
• CPC Class Codes: F04B 53/1032 Spring-actuated disc valves F04B53/1022, F04B53/103 take precedence

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.

Claims

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 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 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,

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.

21. The implantable infusion device of claim 20, wherein the pressure of the reservoir is maintained at greater than 0 psia.

22. The implantable infusion device of claim 20, wherein the inlet chamber has a volume of between 100 microliters and 300 microliters.

23. 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 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 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,

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.