FILTERING OF A PHYSIOLOGIC SIGNAL IN A MEDICAL DEVICE

• US 20100076514A1
• Filed: 10/31/2008
• Published: 03/25/2010
• Est. Priority Date: 09/19/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Greenhut, Saul E., Kleckner, Karen J., Erickson, Mark K., Cho, Yong K., Bennett, Tommy D., Sperling, Charles P., Corey, Robert A., Shrivastav, Maneesh
• Granted Patent: US 8,047,999 B2
• Time in Patent Office: Days
• US Class Current: 607/18
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• 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 5/0215 by means inserted into the body catheters A61M25/00
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/6846 specially adapted to be brought in contact with an internal body part, i.e. invasive
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585
• CPC Class Codes: A61N 1/3702 Physiological parameters A61N1/365 takes precedence; evoked response A61N1/371
• CPC Class Codes: A61N 1/37258 Alerting the patient

Abstract

A system and method for filtering a pressure signal in a medical device in which a sensor terminal senses the pressure signal, an electrode terminal receives cardiac electrical signals, a signal filtering system filters the sensed pressure signal in response to a determined heart rate to generate a heart-rate dependent frequency response, and a microprocessor derives a respiration signal in response to the heart rate dependent frequency response, and determines metrics of hemodynamic function in response to the derived respiration signal.

Claims

1. A system for filtering a pressure signal in a medical device, comprising:

a sensor terminal sensing the pressure signal;

an electrode terminal receiving cardiac electrical signals;

a signal filtering system filtering the sensed pressure signal in response to a determined heart rate to generate a heart-rate dependent frequency response; and

a microprocessor deriving a respiration signal in response to the heart rate dependent frequency response, and determining metrics of hemodynamic function in response to the derived respiration signal.

2. The system of claim 1, wherein the microprocessor determines the heart rate in response to the sensed cardiac electrical signal.

3. The system of claim 1, wherein the microprocessor determines a cardiac component of the pressure signal, and determines the heart rate in response to the determined cardiac component.

4. The system of claim 1, wherein sensing the pressure signal comprises sensing an intracardiac chamber pressure signal.

5. The system of claim 1, wherein the signal filtering system comprises:

a first filter having a first frequency response corresponding to a heart rate greater than a heart rate threshold; and

a second filter having a second frequency response different from the first frequency response, the second frequency response corresponding to a heart rate being less than the heart rate threshold.

6. The system of claim 5, wherein the microprocessor selects the first filter and the second filter one at a time in a sequential manner in response to the determined heart rate, and derives the respiration signal as a continuous signal comprising sequential outputs of the first filter and the second filter.

7. The system of claim 5, wherein the microprocessor selects the first filter and the second filter simultaneously for parallel filtering of the pressure signal, and derives the respiration signal in response to a first respiration signal component corresponding to an output of the first filter and a second respiration signal component corresponding to an output of the second filter.

8. The system of claim 5, wherein the first filter and the second filter each comprise multiple filtering stages.

9. The system of claim 8, wherein the first filter is a subset of the multiple stages of the second filter.

10. The system of claim 8, wherein the signal filtering system decimates the pressure signal following at least one of the multiple stages.

11. A method for filtering a pressure signal in a medical device system, comprising:

sensing the pressure signal via a sensor terminal;

determining a heart rate;

filtering the sensed pressure signal in response to the determined heart rate to generate a heart-rate dependent frequency response;

deriving a respiration signal in response to the heart rate dependent frequency response; and

determining metrics of hemodynamic function in response to the derived respiration signal.

12. The method of claim 11, further comprising sensing a cardiac electrical signal via an electrode terminal, wherein the heart rate is determined in response to the sensed cardiac electrical signal.

13. The method of claim 11, further comprising determining a cardiac component of the pressure signal, wherein the heart rate is determined in response to the determined cardiac component.

14. The method of claim 11, wherein sensing the pressure signal comprises sensing an intracardiac chamber pressure signal.

15. The method of claim 11, wherein filtering the sensed pressure signal comprises filtering the pressure signal using a first filter having a first frequency response corresponding to a heart rate greater than a heart rate threshold and a second filter having a second frequency response different from the first frequency response, the second frequency response corresponding to a heart rate being less than the heart rate threshold.

16. The method of claim 15, wherein the first filter and the second filter are selected one at a time in a sequential manner in response to the determined heart rate and the respiration signal is obtained as a continuous signal comprising sequential outputs of the first filter and the second filter.

17. The method of claim 15, wherein filtering the pressure signal comprises selecting the first filter and the second filter simultaneously for parallel filtering of the pressure signal, and wherein the respiration signal comprises a first respiration signal component corresponding to an output of the first filter and a second respiration signal component corresponding to an output of the second filter.

18. The method of claim 15, wherein the first and second filters each comprise multiple filtering stages.

19. The method of claim 18, wherein the first filter is a subset of the multiple stages of the second filter.

20. The method of claim 18, further comprising decimating the pressure signal following at least one of the multiple stages.

21. A system for filtering a pressure signal in a medical device, comprising:

means for sensing the pressure signal via a sensor terminal;

means for determining a heart rate;

means for filtering the sensed pressure signal in response to the determined heart rate to generate a heart-rate dependent frequency response;

means for deriving a respiration signal in response to the heart rate dependent frequency response; and

means for determining metrics of hemodynamic function in response to the derived respiration signal.

22. The system of claim 21, wherein means for filtering the sensed pressure signal comprises means for filtering the pressure signal using a first filter having a first frequency response corresponding to a heart rate greater than a heart rate threshold and a second filter having a second frequency response different from the first frequency response, the second frequency response corresponding to a heart rate being less than the heart rate threshold.

23. The system of claim 22, further comprising means for selecting the first filter and the second filter one at a time in a sequential manner in response to the determined heart rate, and the means for deriving the respiration signal derives the respiration signal as a continuous signal comprising sequential outputs of the first filter and the second filter.

24. The system of claim 22, further comprising means for selecting the first filter and the second filter simultaneously for parallel filtering of the pressure signal, and wherein the respiration signal comprises a first respiration signal component corresponding to an output of the first filter and a second respiration signal component corresponding to an output of the second filter.

25. The system of claim 22, wherein the first and second filters each comprise multiple filtering stages.

26. The method of claim 25, wherein the first filter is a subset of the multiple stages of the second filter.