Posture sensor

• US 20070142868A1
• Filed: 12/21/2005
• Published: 06/21/2007
• Est. Priority Date: 12/21/2005
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Johnson, David, Kadhiresan, Veerichetty, Moon, Loell, Franke, Karen, Tait, Brandi
• Granted Patent: US 7,848,811 B2
• Time in Patent Office: Days
• US Class Current: 607/19
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• 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 1/36535 controlled by body position or posture
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration

Abstract

A system and method determines the posture of a body. The system is first calibrated by attaching it to, or implanted it into, a body, placing the body in particular postures, and generating spectral signatures for each of those postures. Thereafter, the system generates spectral signatures for particular instants in time, correlates these instant signatures with the stored signatures, from which the posture of the body at that instant in time is determined.

Claims

1. A system comprising:

a medical device, the medical device comprising;

an accelerometer;

a controller circuit comprising a time-domain-to-frequency-domain transform module coupled to the accelerometer; and

a memory circuit, coupled to the transform module, the memory comprising one or more first spectral signatures respectively corresponding to one or more postures of a body.

2. The system of claim 1, wherein the postures comprise a standing posture, a sitting posture, a lying posture and an ambulatory posture.

3. The system of claim 1, wherein the transform module is operable to perform a Fast Fourier Transform to transform a time domain output of the accelerometer into a frequency domain output of the accelerometer.

4. The system of claim 1, wherein the memory comprises at least one second spectral signature including information about a later posture of the body, and wherein the controller is operable to compare the second spectral signature with one or more of the first spectral signatures to determine the instant posture of the body.

5. The system of claim 4, wherein the controller is operable to compare the second spectral signature with one or more of the first spectral signatures by computing at least one correlation between the second spectral signature and one or more of the first spectral signatures.

6. The system of claim 5, wherein the medical device includes an implantable cardiac function management device.

7. The system of claim 6, wherein the accelerometer may also at least partially controls a rate of pacing by the implantable cardiac function management device.

8. The system of claim 4, wherein the memory records physiologic data.

9. The system of claim 8, wherein the controller adjusts the physiologic data using the determined posture of the body.

10. The system of claim 4, wherein the first and second spectral signatures also include information about one or more of body motion, cardiac motion, or respiratory motion.

11. The system of claim 4, in which the memory records one or more statistics relating to how long the body is in a particular posture over a particular period of time.

12. The system of claim 4, comprising a communication circuit operable to communicate information about the determined posture from an implantable medical device to an adjunct device.

13. The system of claim 4, in which the controller circuit is implantable.

14. A method comprising:

detecting a time domain acceleration associated with a body;

transforming the time domain acceleration into a frequency domain acceleration; and

comparing the frequency domain acceleration with a spectral signature corresponding to a posture to obtain posture information about the body.

15. The method of claim 14, comprising comparing the frequency domain acceleration with at least one of a plurality of spectral signatures, representing corresponding particular postures, to obtain posture information about the body.

16. The method of claim 15, wherein comparing the frequency domain acceleration with at least one of a plurality of spectral signatures includes comparing one or more of a standing posture spectral signature, a sitting posture spectral signature, a lying posture spectral signature, and an ambulatory posture spectral signature.

17. The method of claim 15, comprising recording one or more statistics relating to how long the body is in a particular posture over a particular period of time.

18. The method of claim 14, in which the detecting the time domain acceleration comprises using an implantable accelerometer.

19. The method of claim 18, comprising at least partially controlling a rate of pacing using information from the same implantable accelerometer.

20. The method of claim 14, comprising:

positioning the body in a known particular posture;

detecting a time domain acceleration associated with the body in the particular posture;

transforming the time domain acceleration in the particular posture into a frequency domain acceleration in the particular posture to obtain the specified spectral signature corresponding to the particular posture; and

storing the spectral signature corresponding to the particular posture, such that the stored spectral signature is available for comparison with a subsequent frequency domain acceleration to obtain posture information about the body when it is undergoing the subsequent frequency domain acceleration.

21. The method of claim 14, wherein the comparing comprises computing a correlation between the frequency domain acceleration and the spectral signature.

22. The method of claim 14, wherein the spectral signature also includes information about one or more of body motion, cardiac motion, or respiratory motion.

23. The method of claim 14, comprising:

recording physiologic data; and

adjusting the physiologic data using the posture information about the body.

24. The method of claim 14, comprising communicating the posture information about the body between an implanted medical device and an adjunct device.

25. An implantable cardiac function management device comprising:

an accelerometer, providing a time domain acceleration signal of a living body;

a controller circuit, coupled to the accelerometer, comprising a time-domain-to-frequency-domain transform module coupled to said acceleromete; and

a memory circuit, coupled to the transform module, the memory comprising;

one or more first spectral signatures respectively corresponding to one or more postures of the body, wherein the postures comprise a standing posture, a sitting posture, a lying posture and an ambulatory posture; and

at least one second spectral signature including information about an instant posture of the body, and wherein the controller is operable to correlate the second spectral signature with one or more of the first spectral signatures to determine the instant posture of the body.

26. The device of claim 25, wherein the accelerometer also at least partially controls a rate of pacing by the implantable cardiac function management device.

27. The device of claim 25, wherein the controller adjusts the physiologic data using the determined posture of the body.

28. A system comprising:

a medical device, the medical device comprising;

a motion sensing device;

a controller circuit comprising a time-domain-to-frequency-domain transform module coupled to the accelerometer; and

a memory circuit, coupled to the transform module, the memory comprising one or more first spectral signatures respectively corresponding to one or more postures of a body.

29. The system of claim 28, wherein said motion sensing device comprises an accelerometer.