PRESSURE-BASED TEMPERATURE ESTIMATION FOR IMPLANTABLE FLUID DELIVERY DEVICES

• US 20110257907A1
• Filed: 04/16/2010
• Published: 10/20/2011
• Est. Priority Date: 04/16/2010
• Status: Abandoned Application

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Kalpin, Scott L.
• Application Number:
  US12/762,121
• Publication Number:
  US 20110257907A1
• Time in Patent Office: Days
• US Class Current: 702/50
• CPC Class Codes: A61M 2205/33 Controlling, regulating or measuring
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/3379 Masses, volumes, levels of fluids in reservoirs, flow rates
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: G16H 20/17 delivered via infusion or injection

Abstract

A number of parameters related to the operation of a fluid delivery device are determined based on a pressure within the device sensed using a pressure sensor. In one example, the volume of therapeutic fluid added to or removed from a reservoir of a fluid delivery device is determined based on a sensed pressure of the reservoir. In another example, the volume of therapeutic fluid added to or removed from the reservoir is determined based on a sensed pressure of a refill port assembly of the device. In another example, an initial temperature of the reservoir as a therapeutic fluid is removed from the reservoir is estimated based on a sensed pressure within the device. In another example, a temperature of a therapeutic fluid added to the reservoir is estimated based on a sensed pressure within the device.

Claims

1. A method comprising:

sensing a pressure within a fluid delivery device using a pressure sensor; and

estimating a temperature related to adding a therapeutic fluid to or removing the fluid from a reservoir of the fluid delivery device based on the sensed pressure.

2. The method of claim 1, wherein the temperature comprises at least one of an initial temperature of the reservoir as the therapeutic fluid is added or removed or a temperature of the therapeutic fluid.

3. The method of claim 2, wherein estimating the initial temperature of the reservoir comprises:

identifying a pressure at which a first derivative of the sensed pressure with respect to time traverses a first threshold as the therapeutic fluid is added to or removed from the reservoir; and

determining an initial temperature of the reservoir at the identified pressure of the reservoir based on a temperature-pressure characteristic for the fluid delivery device as the therapeutic fluid is added to or removed from the reservoir.

4. The method of claim 3, wherein estimating the temperature of the therapeutic fluid comprises:

identifying a local maximum pressure of the reservoir as the therapeutic fluid is added or removed;

determining a first temperature of the reservoir at the identified local maximum pressure of the reservoir based on a temperature-pressure characteristic for the fluid delivery device as the therapeutic fluid is added to or removed from the reservoir; and

calculating a temperature of the therapeutic fluid based on the initial and first temperatures of the reservoir.

5. The method of claim 4, wherein identifying a local maximum pressure of the reservoir comprises at least one of:

determining that a first derivative of the sensed pressure with respect to time traverses a second threshold as the therapeutic fluid is added to or removed from the reservoir;

determining that a difference between a first pressure of the reservoir and a second pressure of the reservoir sensed using the pressure sensor traverses a third threshold;

or

determining an amount of time since a change in a local maximum pressure of the reservoir sensed using the pressure sensor has traversed a fourth threshold.

6. The method of claim 5, wherein the first threshold is a negative pressure differential and the second threshold is a positive pressure differential.

7. The method of claim 1, wherein sensing a pressure within a fluid delivery device using a pressure sensor comprises sensing a pressure within the reservoir using a pressure sensor.

8. The method of claim 1, wherein sensing a pressure within a fluid delivery device using a pressure sensor comprises sensing a pressure within a refill port assembly of the fluid delivery device using a pressure sensor.

9. A fluid delivery system comprising:

an implantable fluid delivery device comprising;

a reservoir configured to store a therapeutic fluid; and

a pressure sensor configured to sense one or more pressures within the fluid delivery device; and

a processor configured to sense a pressure within the fluid delivery device using the pressure sensor and estimate a temperature related to adding a therapeutic fluid to or removing the fluid from the reservoir based on the sensed pressure.

10. The system of claim 9, wherein the temperature comprises at least one of an initial temperature of the reservoir as the therapeutic fluid is added or removed or a temperature of the therapeutic fluid.

11. The system of claim 10, wherein the processor estimating the initial temperature of the reservoir comprises:

identifying a pressure at which a first derivative of the sensed pressure with respect to time traverses a first threshold as the therapeutic fluid is added to or removed from the reservoir; and

determining an initial temperature of the reservoir at the identified pressure of the reservoir based on a temperature-pressure characteristic for the fluid delivery device as the therapeutic fluid is added to or removed from the reservoir.

12. The system of claim 11, wherein the processor estimating the temperature of the therapeutic fluid comprises:

identifying a local maximum pressure of the reservoir as the therapeutic fluid is added or removed;

determining a first temperature of the reservoir at the identified local maximum pressure of the reservoir based on a temperature-pressure characteristic for the fluid delivery device as the therapeutic fluid is added to or removed from the reservoir; and

calculating a temperature of the therapeutic fluid based on the initial and first temperatures of the reservoir.

13. The system of claim 12, wherein the processor identifying a local maximum pressure of the reservoir comprises at least one of:

determining that a first derivative of the sensed pressure with respect to time traverses a second threshold as the therapeutic fluid is added to or removed from the reservoir;

determining that a difference between a first pressure of the reservoir and a second pressure of the reservoir sensed using the pressure sensor traverses a third threshold;

or

determining an amount of time since a change in a local maximum pressure of the reservoir sensed using the pressure sensor has traversed a fourth threshold.

14. The system of claim 13, wherein the first threshold is a negative pressure differential and the second threshold is a positive pressure differential.

15. The system of claim 9, wherein the processor is configured to sense a pressure within a refill port assembly of the fluid delivery device using the pressure sensor.

16. The system of claim 9, wherein the processor is configured to sense a pressure within the reservoir using the pressure sensor.

17. The system of claim 9, wherein the fluid delivery device comprises the processor.

18. The system of claim 9 further comprising a programmer, wherein the programmer comprises the processor.

19. A computer-readable storage medium comprising instructions for causing a programmable processor in an implantable fluid delivery system to:

sense a pressure within a fluid delivery device using a pressure sensor; and

estimate a temperature related to adding a therapeutic fluid to or removing the fluid from a reservoir of the fluid delivery device based on the sensed pressure.

20. A system comprising:

means for sensing a pressure within a fluid delivery device using a pressure sensor; and

means for estimating a temperature related to adding a therapeutic fluid to or removing the fluid from a reservoir of the fluid delivery device based on the sensed pressure.