Volume monitoring for implantable fluid delivery devices

Patent metadata

Field	Value
Publication number	US-9687603-B2
Application number	US-76206410-A
Country	US
Kind code	B2
Filing date	Apr 16, 2010
Priority date	Apr 16, 2010
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

Unexpected changes in the volume of therapeutic fluid in the reservoir of a fluid delivery device are detected based on changes in the pressure of the reservoir measured over a period of time by a pressure sensor. Additionally, an ambulatory reservoir fluid volume gauge is provided to indicate an actual volume of therapeutic fluid in a fluid delivery device reservoir. The actual volume of therapeutic fluid in the reservoir indicated by the ambulatory reservoir fluid volume gauge is determined based on changes in the pressure in the reservoir measured over a period of time by a pressure sensor.

First claim

The invention claimed is:

1. A therapeutic fluid delivery system comprising:
a reservoir configured to house a therapeutic fluid;
a pressure sensor configured to measure a pressure of the reservoir; and
a processor configured to determine at least one of a difference between an actual rate at which the therapeutic fluid is delivered from the reservoir and a rate at which the therapeutic fluid is expected to be delivered from the reservoir or a difference between an actual volume and an expected volume of therapeutic fluid in the reservoir based on changes in the pressure of the reservoir measured by the pressure sensor over time and detect an unexpected change in a volume of the therapeutic fluid in the reservoir when at least one of the difference between the actual rate at which the therapeutic fluid is delivered from the reservoir and the rate at which the therapeutic fluid is expected to be delivered from the reservoir is greater than a first threshold or the difference between the actual volume and the expected volume of therapeutic fluid in the reservoir is greater than a second threshold,
wherein the first and second thresholds decrease as a time period over which the changes in the pressure of the reservoir are measured by the pressure sensor increases.

2. The system of claim 1 , wherein the processor is configured to determine the actual rate at which the therapeutic fluid is delivered from the reservoir at least by dividing a change in the pressure of the reservoir measured by the pressure sensor over a time period by a constant representing the sensitivity of the pressure of the reservoir to changes in the volume of therapeutic fluid in the reservoir.

3. The system of claim 2 , wherein the processor is configured to perform a linear regression of the change in the pressure measured by the pressure sensor to normalize the change in the pressure of the reservoir measured by the pressure sensor over the time period for temperature changes in the reservoir.

4. The system of claim 3 , wherein the linear regression comprises a least squares linear regression.

5. The system of claim 2 , further comprising a temperature sensor configured to measure a temperature of the reservoir, wherein the processor is configured to normalize the change in the pressure of the reservoir measured by the pressure sensor over the time period for temperature changes based on changes in the temperature of the reservoir measured by the temperature sensor over the time period.

6. The system of claim 1 , wherein the expected rate at which the therapeutic fluid is delivered from the reservoir corresponds to a rate at which the processor is programmed to control a pump to deliver the therapeutic fluid from the reservoir.

7. The system of claim 6 , further comprising a memory configured to store the rate at which the processor is programmed to control the pump to deliver the therapeutic fluid from the reservoir.

8. The system of claim 1 , wherein the processor is configured to generate an alert when the difference between the actual rate and the expected rate is greater than the first threshold.

9. The system of claim 1 , wherein the processor is configured to determine the actual volume of therapeutic fluid in the reservoir at least by:
determining the actual rate at which the therapeutic fluid is delivered from the reservoir based on the changes in the pressure of the reservoir measured by the pressure sensor over time;
multiplying the actual rate by a time period over which the changes in the pressure of the reservoir are measured by the pressure sensor to determine an actual volume of therapeutic fluid delivered from the reservoir over the time period; and
subtracting the actual volume of therapeutic fluid delivered from the reservoir over the time period from a starting volume of therapeutic fluid in the reservoir.

10. The system of claim 9 , wherein the processor is configured to determine the actual rate at which the therapeutic fluid is delivered from the reservoir at least by dividing a change in the pressure of the reservoir measured by the pressure sensor over a time period by a constant representing the sensitivity of the pressure of the reservoir to changes in the volume of therapeutic fluid in the reservoir.

11. The system of claim 9 , wherein the processor is configured to perform a linear regression of the change in the pressure measured by the pressure sensor to normalize the change in the pressure of the reservoir measured by the pressure sensor over the time period for temperature changes in the reservoir.

12. The system of claim 1 , wherein the processor is configured to determine the expected volume of therapeutic fluid in the reservoir at least by subtracting a volume of therapeutic fluid expected to be delivered from the reservoir over a time period over which the changes in the pressure of the reservoir are measured by the pressure sensor from a starting volume of therapeutic fluid in the reservoir.

13. The system of claim 12 , wherein the processor is configured to determine the expected volume of therapeutic fluid delivered from the reservoir at least by multiplying a rate at which the therapeutic fluid is expected to be delivered from the reservoir over the time period by the time period.

14. The system of claim 12 , wherein the processor is configured to determine the expected volume of therapeutic fluid delivered from the reservoir at least by multiplying a number of strokes of a pump configured to deliver the therapeutic fluid from the reservoir by a volume of fluid pumped per stroke.

15. The system of claim 1 , wherein the processor is configured to generate an alert when the difference between the actual volume and the expected volume is greater than the second threshold.

16. The system of claim 1 , wherein the processor is configured to generate an alert when the unexpected change in the volume of therapeutic fluid in the reservoir is detected.

17. The system of claim 16 , wherein the alert comprises at least one of an audible, visual, or tactile alert.

18. The system of claim 1 further comprising a fluid delivery device comprising the reservoir, and wherein the processor is configured to cause the fluid delivery device to at least one of vibrate or issue an audible sound when the unexpected change in the volume of therapeutic fluid in the reservoir is detected.

19. The system of claim 18 , wherein the fluid delivery device comprises the processor.

20. The system of claim 1 further comprising a programmer, wherein the processor is configured to cause the programmer to at least one of vibrate, issue an audible sound, or display a visual message when the unexpected change in the volume of therapeutic fluid in the reservoir is detected.

21. The system of claim 20 , wherein the programmer comprises the processor.

22. The system of claim 1 further comprising a memory configured to store one or more pressures of the reservoir measured by the pressure sensor.

23. The system of claim 1 , wherein the first threshold comprises a percentage deviation between the actual rate at which the therapeutic fluid is delivered from the reservoir and the rate at which the therapeutic fluid is expected to be delivered from the reservoir.

24. The system of claim 23 , wherein the time period over which the changes in the pressure of the reservoir are measured by the pressure sensor is less than or equal to 24 hours and wherein the first threshold comprises a

Assignees

• Nelson Konen Cynthia R
• Ali Irfan Z
• Miesel Keith A
• Kalpin Scott L
• Medtronic Inc

Inventors

• Nelson Konen Cynthia R
• Ali Irfan Z
• Miesel Keith A
• Kalpin Scott L

Classifications

• A61M5/1684 Primary

  by detecting the amount of infusate remaining, e.g. signalling end of infusion · CPC title

• A61M2205/3389

  Continuous level detection (A61M2205/3393 takes precedence) · CPC title

• A61M2005/14264

  with means for compensating influence from the environment · CPC title

• A61M5/16854

  by monitoring line pressure · CPC title

• A61M2205/3331

  Pressure; Flow · CPC title