Multiple vector fluid localization

• US 8,900,140 B2
• Filed: 10/26/2010
• Issued: 12/02/2014
• Est. Priority Date: 10/27/2009
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Thakur, Pramodsingh Hirasingh, Patangay, Abhilash, Lee, Kent
• Primary Examiner(s): Patel, Niketa
• Assistant Examiner(s): Flory, Christopher A
• Application Number:
  US12/912,219
• Publication Number:
  US 20110098771A1
• Time in Patent Office: 1,498 Days
• Field of Search: 600/300, 600/301, 600/345, 600/483, 600/484, 600/506, 600/528, 600/529, 607/5, 607/9, 607/17, 607/27
• US Class Current: 600/300
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/0538 invasively, e.g. using a catheter
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61B 5/6869 Heart
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/74 Details of notification to user or communication with user or patient indicating measured values G01D7/00; user input means input or output arrangements for computers G06F3/00
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371

Abstract

A differential or relative measurement between an orthogonal measurement vector and another measurement vector can be used to determine the location where fluid accumulation is occurring or the local change in such fluid accumulation. This can help diagnose or treat infection or hematoma or seroma at a pocket of an implanted cardiac rhythm management device, other implanted medical device, or prosthesis. It can also help diagnose or treat pulmonary edema, pneumonia, pulmonary congestion, pericardial effusion, pericarditis, pleural effusion, hemodilution, or another physiological condition.

Claims

1. An apparatus comprising:

a first interface, adapted to be coupled to implantable first electrodes adapted to define a first measurement vector, within a subject, the first measurement vector comprising a first excitation vector for providing a first excitation signal and a first response vector for sensing a first response to the first excitation signal, wherein the first excitation vector is non-orthogonal to the first response vector;

a second interface, adapted to be coupled to implantable second electrodes adapted to define a second measurement vector, within the subject, the second measurement vector comprising a second excitation vector for providing a second excitation signal and a second response vector for sensing a second response to the second excitation signal, wherein the second excitation vector is substantially orthogonal to the second response vector;

a tissue impedance measurement circuit, selectively communicatively coupled to the first electrodes and to the second electrodes, and adapted to repeatedly perform a first tissue impedance measurement using the first measurement vector and to perform a second tissue impedance measurement using the second measurement vector; and

a processor, communicatively coupled to the tissue impedance measurement circuit, the processor configured to;

compute a change in the first tissue impedance measurement over a period of time and a change in the second tissue impedance measurement over a period of time;

generate an indication associated with how much fluid is present at a first location in the subject relative to how much fluid is present at a second location in the subject using a comparison between the change in the first tissue impedance measurement and the change in the second tissue impedance measurement.

2. The apparatus of claim 1, further comprising the implantable first electrodes and the implantable second electrodes.

3. The apparatus of claim 1, wherein the processor is configured to compare the change in the first tissue impedance measurement over the period of time and the change in the second tissue impedance measurement over the period of time to provide an indication associated with how much fluid is present at the first location, wherein the first location is associated with a pocket about an implantable medical device, relative to how much fluid is present at the second location, wherein the second location is within the subject but separated from the pocket about the implantable medical device.

4. The apparatus of claim 3, wherein the processor is configured to compare the change in the first tissue impedance measurement over the period of time and the change in the second tissue impedance measurement over the period of time to provide an indication of whether infection is present at the first location associated with the pocket about the implantable medical device.

5. The apparatus of claim 4, further comprising a first temperature sensor configured to be associated with the subject, and wherein the processor is configured to be communicatively coupled to the first temperature sensor to receive information about a first temperature at a location of the subject associated with the first temperature sensor, and to use the information about the first temperature to provide the indication of whether infection is present at the first location associated with the pocket about the implantable medical device.

6. The apparatus of claim 5, further comprising a second temperature sensor configured to be associated with the subject at a different location than the first temperature sensor, and wherein the processor is configured to be communicatively coupled to the second temperature sensor to receive information about a second temperature at a location of the subject associated with the second temperature sensor, and to use the information about a difference between the second temperature and the first temperature to provide the indication of whether infection is present at the first location associated with the pocket about the implantable medical device.

7. The apparatus of claim 1, further comprising the implantable first electrodes and the implantable second electrodes,

wherein the second measurement vector comprises a second excitation vector for providing a second excitation signal between a left ventricular electrode configured to be associated with a left ventricle and a pectoral electrode configured to be associated with a pectoral region, and a second response vector for sensing a second response to the second excitation signal between a left ventricular electrode configured to be associated with a left ventricle and a right atrial electrode configured to be associated with a right atrium, wherein the second excitation vector is substantially orthogonal to the second response vector.

8. The apparatus of claim 7, wherein at least one of:

the first measurement vector comprises a first excitation vector for providing a first excitation signal between a right ventricular electrode configured to be associated with a right ventricle and a pectoral electrode configured to be associated with a pectoral region, and a first response vector for sensing a first response to the first excitation signal, the sensing the first response using a right ventricular electrode configured to be associated with a right ventricle and a pectoral electrode configured to be associated with a pectoral region;

the first measurement vector comprises a first excitation vector for providing a first excitation signal between a right atrial electrode configured to be associated with a right atrium and a pectoral electrode configured to be associated with a pectoral region, and a first response vector for sensing a first response to the first excitation signal, the sensing the first response using a right atrial electrode configured to be associated with a right atrium and a pectoral. electrode configured to be associated with a pectoral region;

or

the first measurement vector comprises a first excitation vector for providing a first excitation signal between a left ventricular electrode configured to be associated with a left ventricle and a pectoral electrode configured to be associated with a pectoral region, and a first response vector for sensing a first response to the first excitation signal, the sensing the first response using a left ventricular electrode configured to be associated with a left ventricle and a pectoral electrode configured to be associated with a pectoral region.

9. The apparatus of claim 1, wherein the processor is configured to compare the change in the first tissue impedance measurement over the period of time and the change in the second tissue impedance measurement over the period of time to provide an indication associated with how much fluid is present at the first location, wherein the first location is associated with a localized lung region, relative to how much fluid is present at the second location, wherein the second location is within the subject and associated with a global region that extends beyond the localized lung region.

21. The apparatus of claim 1, further comprising the implantable first electrodes and the implantable second electrodes,

wherein the first measurement vector is defined by one of the following electrode combinations:

1) right ventricle (RV) electrode-Can electrode;

     2) right atrium (RA) electrode-Can electrode; and

     3) left ventricle (LV) electrode-Can electrode, and wherein the second measurement vector is defined by the following electrode combination;

RA electrode-LV electrode-Can electrode.

22. The apparatus of claim 1, further comprising the implantable first electrodes and the implantable second electrodes,

wherein the second measurement vector is defined by one of the following electrode combinations:

1) left ventricle (LV) electrode-Can electrode-right atrium (RA) electrode;

     2) right ventricle (RV) electrode-Can electrode-RA electrode;

     3) LV electrode-Can electrode-RV electrode.

23. The apparatus of claim 1, further comprising the implantable first electrodes and the implantable second electrodes, wherein the second measurement vector is defined by one of the following electrode combinations:

1) Can electrode-right ventricle (RV) electrode-right atrium (RA) electrode;

     2) Can electrode-left ventricle (LV) electrode-RA electrode;

     3) Can electrode-RV electrode-LV electrode; and

(4) Can electrode-LV electrode-RV electrode.

10. A method comprising:

providing a first measurement vector, within a subject, comprising a first excitation vector for providing a first excitation signal and a first response vector for sensing a first response to the first excitation signal, wherein the first excitation vector is non-orthogonal to the first response vector;

providing a second measurement vector, within the subject, comprising a second excitation vector for providing a second excitation signal and a second response vector for sensing a second response to the second excitation signal, wherein the second excitation vector is substantially orthogonal to the second response vector;

repeatedly performing a first tissue impedance measurement using the first measurement vector and to perform a second tissue impedance measurement using the second measurement vector;

computing a change in the first tissue impedance measurement over a period of time and a change in the second tissue impedance measurement over the period of time; and

generating an indication associated with how much fluid is present at an first location in the subject relative to how much fluid is present at a second location in the subject using a comparison between the change in the first tissue impedance measurement and the change in the second tissue impedance measurement.

11. The method of claim 10, further comprising providing implantable first electrodes configured for providing the first measurement vector and providing implantable second electrodes configured for providing the second measurement vector.

12. The method of claim 10, further comprising using the comparison to provide an indication associated with how much fluid is present at the first location, wherein the first location is associated with a pocket about an implantable medical device, relative to how much fluid is present at the second location, wherein the second location is within the subject but separated from the pocket about the implantable medical device.

13. The method of claim 12, further comprising using the comparison to provide an indication of whether infection is present at the first location associated with the pocket about the implantable medical device.

14. The method of claim 13, further comprising using information about a first temperature at a location of the subject to provide the indication of whether infection is present at the first location associated with the pocket about the implantable medical device.

15. The method of claim 10, further comprising using information about a second temperature at a location of the subject that is different from the location associated with the first temperature to provide the indication of whether infection is present at the first location associated with the pocket about the implantable medical device.

16. The method of claim 10, further comprising:

providing the implantable first electrodes and the implantable second electrodes,

wherein the second measurement vector comprises a second excitation vector for providing a second excitation signal between a left ventricle region and a pectoral region, and a second response vector for sensing a second response to the second excitation signal between a left ventricle region and a right region, wherein the second excitation vector is substantially orthogonal to the second response vector.

17. The method of claim 16, wherein at least one of:

the first measurement vector comprises a first excitation vector for providing a first excitation signal between a right ventricular region and a pectoral region, and a first response vector for sensing a first response to the first excitation signal, the sensing the first response between a right ventricular region and a pectoral region;

the first measurement vector comprises a first excitation vector for providing a first excitation signal between a right atrial region and a pectoral region, and a first response vector for sensing a first response to the first excitation signal, the sensing the first response between a right atrial region and a pectoral region;

or

the first measurement vector comprises a first excitation vector for providing a first excitation signal between a left ventricular region and a pectoral region, and a first response vector for sensing a first response to the first excitation signal, the sensing the first response between a left ventricular region and a pectoral region.

18. The method of claim 10, further comprising using the comparison to provide an indication associated with how much fluid is present at the first location, wherein the first location is associated with a localized lung region, relative to how much fluid is present at the second location, wherein the second location is within the subject and associated with a global region that extends beyond the localized lung region.

19. An apparatus comprising:

means for providing a first measurement vector, within a subject, comprising a first excitation vector for providing a first excitation signal and a first response vector for sensing a first response to the first excitation signal, wherein the first excitation vector is non-orthogonal to the first response vector;

means for providing a second measurement vector, within the subject, comprising a second excitation vector for providing a second excitation signal and a second response vector for sensing a second response to the second excitation signal, wherein the second excitation vector is substantially orthogonal to the second response vector;

means for repeatedly performing u first tissue impedance measurement using the first measurement vector and to perform a second tissue impedance measurement using the second measurement vector;

means for computing a change in the first tissue impedance measurement over a period of time and a change in the second tissue impedance measurement over the period of time; and

means for generating an indication associated with how much fluid is present at an first location in the subject relative to how much fluid is present at a second location in the subject using a comparison between the change in the first tissue impedance measurement and the change in the second tissue impedance measurement.

20. The apparatus of claim 19, further comprising:

a processor configured to use the comparison to provide an indication associated with how much fluid is present at the first location, wherein the first location is associated with a pocket about an implantable medical device, relative to how much fluid is present at the second location, wherein the second location is within the subject but separated from the pocket about the implantable medical device; and

wherein the processor is configured to use the comparison to provide an indication of whether infection is present at the first location associated with the pocket about the implantable medical device.