SYSTEMS AND METHODS FOR MONITORING PULMONARY EDEMA DYNAMICS

• US 20100022911A1
• Filed: 07/20/2009
• Published: 01/28/2010
• Est. Priority Date: 07/22/2008
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Lewicke, Aaron, Wariar, Ramesh, Hatlestad, John D., Beck, Kenneth C.
• Granted Patent: US 8,417,463 B2
• Time in Patent Office: Days
• US Class Current: 600/561
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/4878 Evaluating oedema

Abstract

This document discusses, among other things, systems and methods for measuring the dynamics of pulmonary congestion in heart failure subjects over time to monitor the subjects susceptibility to pulmonary edema, including sensing and receiving information indicative of a bodily pressure and information indicative of pulmonary fluid, and using the transient responses of these measurements to compute parameters related to the dynamics of thoracic fluid accumulation, such as a critical pressure (P_c), a critical time (T_c), or a filtration index (K_fi).

Claims

1. A system comprising:

a pressure sensor configured to sense information indicative of a bodily pressure;

a fluid sensor configured to sense information indicative of pulmonary fluid; and

a processor, communicatively coupled to the pressure sensor and the fluid sensor, the processor configured to receive pressure information and pulmonary fluid information, and wherein the processor is configured to compute a critical pressure (P_c) using the pressure information and the pulmonary fluid information, wherein the critical pressure (P_c) is the pressure at which the pulmonary fluid information is indicative of an increase in pulmonary fluid.

2. The system of claim 1, wherein the processor is configured to generate a pulmonary fluid baseline using the pulmonary fluid information, and wherein the critical pressure (P_c) includes the pressure at which the pulmonary fluid information deviates from the pulmonary fluid baseline, wherein the deviation is indicative of an increase in pulmonary fluid.

3. The system of claim 2, wherein the fluid sensor includes an impedance sensor and the information indicative of the pulmonary fluid includes an impedance, wherein the pulmonary fluid baseline includes an impedance baseline, and wherein the critical pressure (P_c) includes the pressure at which the impedance falls below the impedance baseline.

4. The system of claim 1, including an event detector coupled to the processor, the event detector configured to detect a pulmonary fluid overload event, wherein the processor is configured to compute the critical pressure (P_c) using the pressure information and the pulmonary fluid information sensed leading up to or during the detected event.

5. The system of claim 1, wherein the processor is configured to generate a pressure baseline using the pressure information, and wherein the processor is configured to compute a critical time (T_c) using the pressure information and the pulmonary fluid information, wherein the critical time (T_c) includes a duration beginning when the pressure information deviates from the pressure baseline and ending when the pressure reaches the critical pressure (P_c).

6. The system of claim 5, including an event detector coupled to the processor, the event detector configured to detect a pulmonary fluid overload event, wherein the processor is configured to compute the critical time (T_c) using the pressure information and the pulmonary fluid information sensed leading up to or during the detected event.

7. The system of claim 1, wherein the processor is configured to compute an estimated critical time (T_ec), wherein the estimated critical time (T_ec) is an estimated time until the pressure reaches the critical pressure (P_c), and wherein the processor is configured to compute the estimated critical time (T_ec) using the pressure information and the difference between the pressure information and the critical pressure (P_c).

8. The system of claim 1, wherein the processor is configured to compute an estimated decompensation time (T_ed), wherein the estimated decompensation time (T_ed) is an estimated time until the pulmonary fluid information is indicative of the pulmonary fluid associated with a previous pulmonary fluid overload event, and wherein the processor is configured to compute the estimated decompensation time (T_ed) using the pulmonary fluid information and the difference between the pulmonary fluid information and the pulmonary fluid associated with the previous pulmonary fluid overload event.

9. The system of claim 1, wherein the processor is configured to compute a filtration index (K_fi) as a function of a slope of the pressure information and a slope of the pulmonary fluid information.

10. The system of claim 9, including an event detector coupled to the processor, the event detector configure to detect a pulmonary fluid overload event, wherein the processor is configured to compute the filtration index (K_fi) using the pulmonary artery pressure information and the pulmonary fluid information sensed leading up to or during the detected event.

11. The system of claim 10, wherein the event includes at least one of a user-confirmed pulmonary fluid overload event or an automatically detected pulmonary fluid overload event, wherein the user-confirmed event includes at least one of a hospitalization or a change in medication, and wherein the automatically detected event includes at least one of information exceeding a threshold or a baseline, the information including at least one of a value or a slope.

12. The system of claim 1, wherein the pressure sensor includes an implantable chronic pulmonary artery pressure sensor configured to chronically sense information indicative of a pulmonary artery pressure of a pulmonary artery, and wherein the implantable chronic pulmonary artery pressure sensor is configured to be fixed to a location within the pulmonary artery.

13. The system of claim 1, wherein the processor is configured to provide a critical pressure (P_c) alert to a user when the pressure information is indicative that the pressure is approaching the critical pressure (P_c) or that the critical pressure (P_c) has been reached.

14. The system of claim 1, including:

a display, communicatively coupled to the processor, the display configured to receive at least one of the pressure information, the pulmonary fluid information, or the critical pressure (P_c) from the processor and provide information to a user.

15. A method comprising:

receiving information indicative of a bodily pressure;

receiving information indicative of pulmonary fluid; and

computing a critical pressure (P_c) using the pressure information and the pulmonary fluid information, wherein the critical pressure (P_c) is the pressure at which the pulmonary fluid information is indicative of an increase in pulmonary fluid.

16. The method of claim 15, including:

generating a pulmonary fluid baseline;

wherein the computing the critical pressure (P_c) includes computing a pressure at which the pulmonary fluid information deviates from the pulmonary fluid baseline, wherein the deviation is indicative of an increase in pulmonary fluid.

17. The method of claim 15, including:

detecting a pulmonary fluid overload event;

wherein the computing the critical pressure (P_c) includes using the pressure information and the pulmonary fluid information sensed leading up to or during the detected event.

18. The method of claim 15, including:

generating a pressure baseline; and

computing a critical time (T_c) using the pressure information and the pulmonary fluid information, wherein the computing the critical time (T_c) includes computing a duration beginning when the pressure information deviates from the pressure baseline and ending when the pressure reaches the critical pressure (P_c).

19. The method of claim 18, including:

detecting a pulmonary fluid overload event;

wherein the computing the critical time (T_c) includes using the pressure information and the pulmonary fluid information sensed leading up to or during the detected event.

20. The method of claim 15, including computing an estimated critical time (T_ec), wherein the estimated critical time (T_ec) is an estimated time until the pressure reaches the critical pressure (P_c), and wherein the computing the estimated critical time (T_ec) includes using the pressure information and the difference between the pressure information and the critical pressure (P_c).

21. The method of claim 15, including computing an estimated decompensation time (T_ed), wherein the estimated decompensation time (T_ed) is an estimated time until the pulmonary fluid information is indicative of the pulmonary fluid associated with a previous pulmonary fluid overload event, and wherein the computing the estimated decompensation time (T_ed) includes using the pulmonary fluid information and the difference between the pulmonary fluid information and the pulmonary fluid associated with the previous pulmonary fluid overload event.

22. The method of claim 15, including computing a filtration index (K_fi) as a function of a slope of the pressure information and a slope of the pulmonary fluid information.

23. The method of claim 22, including:

detecting a pulmonary fluid overload event;

wherein the computing the filtration index (K_fi) includes using the pressure information and the pulmonary fluid information sensed leading up to or during the detected event.

24. The method of claim 23, wherein the detecting the pulmonary fluid overload event includes detecting at least one of a user-confirmed pulmonary fluid overload event or an automatically detected pulmonary fluid overload event, wherein the user-confirmed event includes at least one of a hospitalization or a change in medication, and wherein the automatically detected event includes at least one of information exceeding a threshold or a baseline, the information including at least one of a value or a slope.

25. The method of claim 15, including at least one of:

providing a critical pressure (P_c) alert to a user when the pressure information is indicative that the pressure is approaching the critical pressure (P_c) or that the critical pressure (P_c) has been reached;

or

providing at least one of the pressure information, the pulmonary fluid information, or the critical pressure (P_c) to a user.