DEVICES AND METHODS FOR DETECTING CATHETER COMPLICATIONS

• US 20110257593A1
• Filed: 06/27/2011
• Published: 10/20/2011
• Est. Priority Date: 03/30/2007
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Solefack, Lucien Bell, Miesel, Keith A., Kalpin, Scott L.
• Granted Patent: US 9,044,537 B2
• Time in Patent Office: Days
• US Class Current: 604/111
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• CPC Class Codes: A61M 2025/0003 having an additional lumen transmitting fluid pressure to the outside for measurement
• CPC Class Codes: A61M 2202/0464 Cerebrospinal fluid
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3344 Measuring or controlling pressure at the body treatment site
• CPC Class Codes: A61M 2205/3355 Controlling downstream pump pressure
• CPC Class Codes: A61M 2210/0693 Brain, cerebrum
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/04 Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 2230/06 Heartbeat rate only
• CPC Class Codes: A61M 2230/40 Respiratory characteristics
• CPC Class Codes: A61M 2230/42 Rate
• CPC Class Codes: A61M 2230/63 Motion, e.g. physical activity
• CPC Class Codes: A61M 27/006 Cerebrospinal drainage; Accessories therefor, e.g. valves
• CPC Class Codes: A61M 5/14276 specially adapted for implantation
• CPC Class Codes: A61M 5/16854 by monitoring line pressure
• CPC Class Codes: A61M 5/16859 Evaluation of pressure response, e.g. to an applied pulse
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00

Abstract

A method for determining status of an implanted catheter includes acquiring raw pressure data from a pressure sensor of in an implantable infusion device. The pressure sensor is in communication with a lumen of the catheter operably coupled to the infusion device. The catheter has a delivery region, in communication with the lumen, intended to be positioned in a fluid-filled target location of a patient. The method further includes filtering the raw pressure data to remove the DC component, leaving the AC component within a relevant physiological frequency range; rectifying the AC component to produce a rectified pressure signal; calculating a mean magnitude of the rectified signal; and determining whether the mean magnitude is below a predetermined threshold. If the mean magnitude is below the threshold, the catheter is determined to be in a state other than a normal state.

Claims

1. A method for determining status of an implanted catheter, the method comprising:

acquiring raw pressure data from a pressure sensor of an implantable infusion device, wherein the pressure sensor is in communication with a lumen of the catheter configured to be coupled to the infusion device, wherein the catheter has a delivery region intended to be positioned in a fluid-filled target location of a patient, the delivery region being in communication with the lumen;

filtering the raw pressure data to remove the DC component, leaving the AC component within a relevant physiological frequency range;

rectifying the AC component to produce a rectified pressure signal;

calculating a mean magnitude of the integrated rectified signal;

determining whether the mean magnitude is below a predetermined threshold, wherein if the mean magnitude is below the threshold, the catheter is determined to be in a state other than a normal state.

2. The method of claim 1, wherein calculating the mean magnitude comprises integrating the rectified pressure signal and dividing by the number of samples within the integrated time period.

3. The method of claim 1, wherein filtering the raw pressure data comprises filtering the data with a band pass filter that has a lower frequency cutoff between 0.1 Hz and 1 Hz and has an upper frequency cutoff of between 2 Hz and 5 Hz.

4. The method of claim 1, wherein filtering the raw pressure data comprises filtering the data with a band pass filter that has a lower frequency cutoff of between 0.2 Hz and 0.5 Hz and has an upper frequency cutoff of between 2 Hz and 3 Hz.

5. The method of claim 1, wherein filtering the raw pressure data comprises filtering the data with a band pass filter that leaves AC data within the frequency range of between 0.5 Hz and 2 Hz.

6. The method of claim 1, further comprising sampling the raw pressure data prior to the filtering to obtain a pressure reading and obtaining a compensation factor related to sensor gain for the pressure reading, wherein calculating the mean magnitude comprises applying the compensation factor.

7. The method of claim 1, further comprising determining whether the mean magnitude remains below the predetermined threshold for a predetermined amount of time.

8. The method of claim 7, further comprising determining whether the mean magnitude remains below the predetermined threshold for a predetermined amount of time for a predetermined number of testing cycles.

9. The method of claim 8, further comprising providing an alarm if the mean magnitude is determined to remain below the predetermined threshold for a predetermined amount of time for a predetermined number of testing cycles.

10. The method of claim 1, further comprising providing an alarm if the mean magnitude is determined to be below the predetermined threshold.

11. The method of claim 1, further comprising determining whether a sampling frequency period of time has elapsed, wherein the acquiring, filtering, rectifying and calculating steps are commenced if the sampling frequency period of time has elapsed, and wherein the acquiring, filtering, rectifying and calculating steps are not commenced until the sampling frequency period of time has elapsed.

12. The method of claim 11, wherein the sampling frequency is between 3 and 96 times per day.

13. The method of claim 11, wherein the sampling frequency is between 6 and 24 times per day.

14. The method of claim 11, further comprising determining whether a sampling window duration has elapsed, wherein if the sample period window has elapsed, the acquiring, filtering, rectifying and calculating steps are stopped.

15. The method of claim 14, wherein the sampling window duration is between 10 and 60 seconds.

16. The method of claim 14, wherein the sampling window duration is between 15 and 30 seconds.

17. The method of claim 1, further comprising acquiring patient activity data via an activity sensor and determining whether the patient activity data is indicative of patient activity below a predetermined threshold prior to performing the acquiring, filtering, rectifying and calculating steps.

18. A computer readable medium comprising instructions that, when executed by an implantable infusion device, cause the device to carry out a process according to claim 1.

19. An implantable infusion device comprising:

a pressure sensor configured and positioned to be in communication with a lumen of a catheter configured to be coupled to the infusion device;

an analog-to-digital converter for converting raw analog data from the pressure sensor to raw digital data;

a band-pass filter for filtering the raw digital data;

a rectifier for rectifying the filtered pressure data;

an integrator for integrating the filtered pressure data over time;

the computer readable medium of claim 18; and

a processor operably coupled to the pressure sensor, the analog-to-digital converter, the band-pass filter, the rectifier, and the integrator, wherein the processor is configured to execute the instructions of the computer readable medium.

20. An implantable infusion device comprising:

a pressure sensor configured and positioned to be in communication with a lumen of a catheter operably couplable to the infusion device;

an analog-to-digital converter for converting raw analog data from the pressure sensor to raw digital data;

a band-pass filter for filtering the raw digital data;

a rectifier for rectifying the filtered pressure data;

an integrator for integrating the filtered pressure data over time;

electronics configured to calculate a mean magnitude of the integrated pressure data and configured to determine whether the mean magnitude is below a predetermined threshold for identifying a catheter complication or potential catheter complication.