DETECTING WORSENING HEART FAILURE BASED ON FLUID ACCUMULATION WITH RESPIRATORY CONFIRMATION

• US 20100198097A1
• Filed: 01/30/2009
• Published: 08/05/2010
• Est. Priority Date: 01/30/2009
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Sowelam, Sameh
• Granted Patent: US 8,632,473 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• 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 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/4836 Diagnosis combined with treatment in closed-loop systems or methods A61B5/0036 takes precedence
• CPC Class Codes: A61B 5/4878 Evaluating oedema
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/39622 Pacing therapy
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment

Abstract

A medical device monitors a level of fluid accumulation, e.g., pulmonary edema, and one or more respiratory parameters of the patient to detect worsening heart failure. The medical device may use intrathoracic impedance measurements to monitor both the fluid accumulation and the one or more respiratory parameters. Respiration rate and volume, also referred to as the tidal volume, are examples of respiratory parameters. The medical device examines the one or more respiratory parameters after determining that the fluid accumulation indicates worsening heart failure. In this manner, the medical device uses the one or more respiratory parameters to confirm a determination of worsening heart failure that was made based on the fluid accumulation.

Claims

1. A method comprising:

monitoring, by a medical device, thoracic fluid accumulation in a patient;

determining, by the medical device, that the fluid accumulation indicates worsening heart failure in the patient; and

in response to the determination that the fluid accumulation indicates worsening heart failure;

monitoring, by the medical device, at least one respiratory parameter of the patient, and

determining, by the medical device, whether the respiratory parameter indicates worsening heart failure in the patient.

2. The method of claim 1,

further comprising collecting, with the medical device, intrathoracic impedance measurements from the patient,

wherein monitoring the fluid accumulation comprises monitoring the fluid accumulation based on the impedance measurements, and monitoring the respiratory parameter comprises monitoring the respiratory parameter based on the impedance measurements.

3. The method of claim 1, further comprising, by the medical device, continuing to monitor the respiratory parameter and determine whether the respiratory parameter indicates worsening heart failure so long as the fluid accumulation indicates worsening heart failure.

4. The method of claim 1, wherein the at least one respiratory parameter comprises respiration rate and respiration volume, and wherein determining whether the respiratory parameter indicates worsening heart failure comprises determining whether both of the respiration rate and the respiration volume indicate worsening heart failure.

5. The method of claim 1,

wherein monitoring the fluid accumulation comprises changing a fluid index value that indicates fluid accumulation in the patient over time based on the impedance measurements, and

wherein determining that the fluid accumulation indicates worsening heart failure comprises determining that the fluid index crossed a threshold.

6. The method of claim 1, further comprising monitoring, by the medical device, an activity level of the patient, wherein monitoring the respiratory parameter comprises monitoring the respiratory parameter when the activity level is less than a threshold level.

7. The method of claim 1, further comprising providing, by the medical device, an alert to a user if the respiratory parameter indicates worsening heart failure.

8. The method of claim 1, wherein the user comprises the patient.

9. The method of claim 1, further comprising:

delivering a therapy to the patient by the medical device; and

automatically modifying, by the medical device, the therapy in response to detecting worsening heart failure in the patient.

10. The method of claim 9, wherein the therapy comprises at least one of substance delivery, cardiac resynchronization therapy, refractory period stimulation, or cardiac potentiation therapy.

11. The method of claim 1, wherein the medical device comprises an implantable medical device.

12. The method of claim 11, wherein the implantable medical device comprises at least one of a pacemaker, cardioverter, or defibrillator.

13. A medical system comprising:

a fluid accumulation monitor configured to monitor thoracic fluid accumulation in a patient;

a detection module configured to detect worsening heart failure in the patient, wherein the detection module is configured to determine that the fluid accumulation indicates worsening heart failure in the patient; and

a respiratory monitor configured to monitor at least one respiratory parameter of the patient in response to the determination that the fluid accumulation indicates worsening heart failure,

wherein the detection module is configured to determine whether the respiratory parameter indicates worsening heart failure in the patient in response to the determination that the fluid accumulation indicates worsening heart failure.

14. The system of claim 13,

further comprising an impedance measurement module configured to collect intrathoracic impedance measurements from the patient via a plurality of electrodes,

wherein the fluid accumulation monitor is configured to monitor the fluid accumulation based on the impedance measurements, and the respiratory monitor is configured to monitor the at least one respiratory parameter based on the impedance measurements.

15. The system of claim 13, wherein the respiratory monitor continues to monitor the respiratory parameter and the detection module continues to determine whether the respiratory parameter indicates worsening heart failure so long as the fluid accumulation indicates worsening heart failure.

16. The system of claim 13, wherein the respiratory monitor is configured to monitor respiration rate and respiration volume, and wherein the detection module is configured to determine whether both of the respiration rate and the respiration volume indicate worsening heart failure.

17. The system of claim 13,

wherein the fluid accumulation monitor changes a fluid index value that indicates fluid accumulation in the patient over time based on the impedance measurements, and

wherein the detection module determines that the fluid accumulation indicates worsening heart failure when the fluid index crosses a threshold.

18. The system of claim 13, further comprising an activity monitor that periodically determines an activity level of the patient, wherein the respiratory monitor monitors the respiratory parameter when the activity level is less than a threshold level.

19. The system of claim 13, further comprising an alert module that provides an alert to a user if the respiratory parameter indicates worsening heart failure.

20. The system of claim 13, further comprising an implantable medical device, wherein the implantable medical device comprises the impedance measurement module, fluid accumulation monitor, respiratory monitor, and detection module.

21. The system of claim 20, wherein the implantable medical device comprises at least one of a pacemaker, cardioverter, or defibrillator.

22. A medical system comprising:

means for monitoring thoracic fluid accumulation in a patient;

means for determining that the fluid accumulation indicates worsening heart failure in the patient;

means for monitoring at least one respiratory parameter of the patient in response to the determination that the fluid accumulation indicates worsening heart failure; and

means for determining whether the respiratory parameter indicates worsening heart failure in the patient in response to the determination that the fluid accumulation indicates worsening heart failure.

23. The system of claim 22,

further comprising means for collecting intrathoracic impedance measurements from the patient,

wherein the means for monitoring the fluid accumulation comprises means for monitoring the fluid accumulation based on the impedance measurements, and the means for monitoring the at least one respiratory parameter comprises means for monitoring the at least one respiratory parameter based on the impedance measurements.

24. The system of claim 22, wherein the at least one respiratory parameter comprises respiration rate and respiration volume, and wherein the means for determining whether the respiratory parameter indicates worsening heart failure comprises means for determining whether both of the respiration rate and the respiration volume indicate worsening heart failure.

25. The system of claim 22, further comprising means for monitoring an activity level of the patient, wherein the means for monitoring the respiratory parameter comprises means for monitoring the respiratory parameter when the activity level is less than a threshold level.

26. The system of claim 22, further comprising means for providing an alert to a user if the respiratory parameter indicates worsening heart failure.