Evoked response and impedance measures for monitoring heart failure and respiration

• US 7,430,447 B2
• Filed: 06/06/2005
• Issued: 09/30/2008
• Est. Priority Date: 06/06/2005
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Min, Xiaoyi, Park, Euljoon, Öhlander, Malin
• Primary Examiner(s): Layno; Carl
• Assistant Examiner(s): Gedeon; Brian T
• Application Number:
  US11/149,058
• Publication Number:
  US 20060276848A1
• Time in Patent Office: 1,212 Days
• Field of Search: 607/17, 600/508, 600/529, 600/538
• US Class Current: 607/17
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61N 1/3601 of respiratory organs
• CPC Class Codes: A61N 1/365 controlled by a physiological parameter, e.g. heart potential evoked response A61N1/371
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/371 Capture, i.e. successful stimulation

Abstract

An exemplary method includes acquiring impedance values over one or more respiratory cycles, determining an impedance span based on the impedance values and, based at least in part on the impedance span, determining cardiac condition or respiratory condition. Another exemplary method includes acquiring IEGMs over one or more respiratory cycles, determining evoked response measure values based on the IEGMs, determining an evoked response span based on the evoked response measure values and, based at least in part on the evoked response span, determining cardiac condition or respiratory condition. Other exemplary methods, devices, systems, etc., are also disclosed.

Claims

1. A method comprising:

acquiring impedance values over one or more respiratory cycles;

determining an impedance span based on the impedance values;

acquiring IEGMs over one or more respiratory cycles;

determining evoked response measure values based on the IEGMs;

determining an evoked response span based on the evoked response measure values;

based on the impedance span and the evoked response span, determining one or more indexes;

determining a respiratory condition based on the one or more indexes;

wherein the respiratory condition is apnea and wherein apnea is characterized by a small impedance span;

or the respiratory condition is Cheyne-Stokes Respiration (CSR) and wherein CSR is characterized by a progressively diminishing impedance span; and

adjusting patient therapy if the one or more indexes indicates need for respiratory improvement.

2. The method of claim 1 wherein the impedance span comprises a difference between a minimum impedance value and a maximum impedance value of the acquired impedance values.

3. The method of claim 1 wherein the acquiring comprises acquiring intrathoracic impedance values.

4. The method of claim 1 wherein the acquiring comprises acquiring impedance values using an implantable device.

5. The method of claim 1 wherein patient posture is substantially constant over the one or more respiratory cycles.

6. The method of claim 1 wherein patient activity is substantially constant over the one or more respiratory cycles.

7. The method of claim 1 further comprising determining a cardiac condition based on the one or more indexes and wherein determining the cardiac condition comprises determining whether heart failure exists.

8. The method of claim 7 wherein the determining a cardiac condition determines whether heart failure has worsened.

9. The method of claim 7 wherein the determining a cardiac condition determines whether heart failure has improved.

10. The method of claim 1 wherein the determining a cardiac condition comprises comparing the one or more indexes to a previously determined one or more indexes.

11. The method of claim 1 wherein the evoked response measures comprise post depolarization integrals.

12. The method of claim 1 wherein the evoked response span comprises a difference between a minimum evoked response measure value and a maximum evoked response measure value of the determined evoked response measure values.

13. The method of claim 1 wherein the acquiring comprises acquiring IEGMs using an implantable device.

14. The method of claim 1 wherein patient posture is substantially constant over the one or more respiratory cycles.

15. The method of claim 1 wherein patient activity is substantially constant over the one or more respiratory cycles.

16. The method of claim 1 wherein the determining one or more indexes comprises a product of the impedance span and the evoked response span.

17. The method of claim 1 wherein the determining one or more indexes comprises dividing the evoked response span by the impedance span.

18. A system comprising:

means for acquiring impedance values over one or more respiratory cycles;

means for determining an impedance span based on the impedance values;

means for acquiring IEGMs over one or more respiratory cycles;

means for determining evoked response measure values based on the IEGMs;

means for determining an evoked response span based on the evoked response measure values;

means for determining one or more indexes based on the impedance span and the evoked response span;

means for determining a respiratory condition based on the one or more indexes;

wherein the respiratory condition is apnea and wherein apnea is characterized by a small impedance span;

or the respiratory condition is Cheyne-Stokes Respiration (CSR) and wherein CSR is characterized by a progressively diminishing impedance span; and

means for adjusting patient therapy if the one or more indexes indicates need for respiratory improvement.

19. The system of claim 18 wherein the means for determining one or more indexes comprises a product of the impedance span and the evoked response span.

20. The system of claim 18 wherein the means for determining one or more indexes comprises dividing the evoked response span by the impedance span.