Ambulatory infusion devices and methods with blockage detection

• US 7,867,192 B2
• Filed: 02/29/2008
• Issued: 01/11/2011
• Est. Priority Date: 02/29/2008
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: D'Brot, John Paul, Gibson, Scott R., Ong, Lawrence Eric, Shelton, Brian Michael, Bowman, Sam W.
• Primary Examiner(s): Lucchesi; Nicholas D
• Assistant Examiner(s): STOHR, LEAH C
• Application Number:
  US12/040,468
• Publication Number:
  US 20090221957A1
• Time in Patent Office: 1,047 Days
• Field of Search: 604/67, 604/31, 604/505, 604/28, 604/500
• US Class Current: 604/67
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/16854 by monitoring line pressure

Abstract

Infusion devices with blockage detection capability and methods of monitoring infusion devices.

Claims

1. A method of operating an infusion device including a fluid transfer device and a catheter, the method comprising the steps of:

transferring fluid to the catheter with the fluid transfer device a plurality of times during a measurement window;

sensing catheter pressure a plurality of times during the measurement window;

storing a plurality of sensed pressures in a queue in the order that the pressures were sensed;

computing the pressure differences between time adjacent pairs of sensed pressures; and

determining whether an increase in sensed pressure during the measurement window corresponds to an increase in sensed pressure that would result from a catheter blockage.

2. A method as claimed in claim 1, wherein the sensing step comprises sensing catheter pressure immediately after a transfer by the fluid transfer device.

3. A method as claimed in claim 1, wherein the determining step comprises:

determining whether each of the pressure differences is within a predetermined range; and

determining whether the sum of the pressure differences is greater than a predetermined sum threshold.

4. A method as claimed in claim 3, wherein the predetermined range is between the largest decrease that would be associated with the weather and a value that is slightly larger than the pressure increase that would result from a blockage.

5. A method as claimed in claim 1, wherein the measurement window is a first-in first-out measurement window, the method further comprising the step of:

deleting the oldest sensed pressure from the queue after the queue becomes full.

6. A method of operating an infusion device including a fluid transfer device and a catheter, the method comprising the steps of:

transferring fluid to the catheter with the fluid transfer device a plurality of times during a measurement window of a plurality of hours;

sensing catheter pressure a plurality of times during the measurement window;

storing a plurality of sensed pressures in a queue in the order that the pressures were sensed;

computing the pressure differences between time adjacent pairs of sensed pressures; and

determining whether there are consistent blockage-based additions to catheter pressure during the measurement window that correspond to a catheter blockage.

22. A method as claimed in claim 6, wherein the sensing step comprises sensing catheter pressure immediately after a transfer by the fluid transfer device.

23. A method as claimed in claim 6, wherein the measurement window is a first-in first-out measurement window, the method further comprising the step of:

deleting the oldest sensed pressure from the queue after the queue becomes full.

7. A method of operating an infusion device including a fluid transfer device and an outlet, the method comprising the step of:

signaling that a blockage has been detected in response to consistent blockage-based additions to outlet pressure that are within a predetermined range and persist over a plurality of hours.

8. A method as claimed in claim 7, wherein the predetermined range is between the largest decrease that would be associated with the weather and a value that is slightly larger than the pressure increase that would result from a blockage.

9. A method as claimed in claim 7, wherein the predetermined range is between the largest decrease that would be associated with the weather and a value that is 10% to 20% greater than the pressure increase that would result from a blockage.

19. A method as claimed in claim 7, wherein

the fluid transfer device comprises a pump;

and

the consistent blockage-based additions to outlet pressure that are within a predetermined range comprises blockage-based additions to outlet pressure within the predetermined range that occur after each pump stroke.

10. An infusion device for use with a catheter, comprising:

an outlet port configured to be secured to the catheter;

a fluid transfer device operably connected to the outlet port;

a pressure sensor located between the fluid transfer device and the outlet port; and

a controller that differentiates between increases in sensed pressure that are the result of changes in environmental pressure and increases in sensed pressure that are the result of a catheter blockage by calculating a plurality of individual pressure differences, calculating the sum of the plurality of individual pressure differences only if each of the pressure differences is within a predetermined range, and comparing the sum to a predetermined sum threshold.

11. An infusion device as claimed in claim 10, wherein the fluid transfer device comprises an electromagnet pump.

12. An infusion device as claimed in claim 10, wherein

the controller is configured to determine whether a plurality of pressures sensed periodically throughout a predetermined measurement window correspond to consistent blockage-based additions to pressure.

20. An infusion device as claimed in claim 10, wherein the changes in environmental pressure comprise changes in altitude.

21. An infusion device as claimed in claim 10, wherein the changes in environmental pressure comprise changes in weather.

13. An infusion device for use with a catheter, comprising:

an outlet port configured to be secured to the catheter;

a fluid transfer device operably connected to the outlet port;

a pressure sensor located between the fluid transfer device and the outlet port; and

a controller configured to

store a plurality of sensed pressures in a queue,

compute the pressure differences between time adjacent pairs of sensed pressures in the queue,

determine whether each of the pressure differences is within a predetermined range, and

determine whether the sum of the pressure differences is greater than a predetermined sum threshold.

14. An infusion device as claimed in claim 13, wherein the predetermined range is between the largest decrease that would be associated with the weather and a value that is slightly larger than the pressure increase that would result from a blockage.

15. An infusion device as claimed in claim 13, wherein the predetermined range is between the largest decrease that would be associated with the weather and a value that is 10% to 20% greater than the pressure increase that would result from a blockage.

16. An infusion device as claimed in claim 13, wherein the controller is further configured to

delete the oldest sensed pressure from the queue after the queue is full.

17. An infusion device for use with a catheter, comprising:

an outlet port configured to be secured to the catheter;

a fluid transfer device operably connected to the outlet port;

a pressure sensor located between the fluid transfer device and the outlet port; and

means for storing a plurality of pressures sensed during a measurement window; and

means for calculating a plurality of individual pressure differences between pairs of sensed pressures, calculating the sum of the plurality of individual pressure differences only if each of the pressure differences is within a predetermined range, and comparing the sum to a predetermined sum threshold to determine whether an increase in sensed pressure during the measurement window corresponds to an increase in sensed pressure that would result from a catheter blockage.

18. An infusion device as claimed in claim 17, wherein the fluid transfer device comprises an electromagnet pump.