Detection of patient's position and activity status using 3D accelerometer-based position sensor

• US 20030040776A1
• Filed: 08/24/2001
• Published: 02/27/2003
• Est. Priority Date: 08/24/2001
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Kroll, Mark W., Bornzin, Gene A., Sorensen, Chris
• Granted Patent: US 6,658,292 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/36521 the parameter being derived from measurement of an electrical impedance
• CPC Class Codes: A61N 1/36542 controlled by body motion, e.g. acceleration
• CPC Class Codes: A61N 1/36585 controlled by two or more physical parameters

Abstract

An implantable cardiac stimulation device is equipped with an accelerometer-based sensor to sense a patient'"'"'s movement and produce a vertical acceleration component indicative of a patient'"'"'s acceleration in a vertical direction. A vertical velocity component is computed from the vertical acceleration component. The device further includes a minute ventilation sensor to sense minute ventilation of the patient. Coupled to the various sensors is a processor that is programmed to determine a patient'"'"'s position and activity status, such as whether the patient is ascending/descending stairs or is sitting up from a lying position, based on the vertical velocity and minute ventilation data. The patient'"'"'s status dictates whether to administer cardiac pacing therapy to the patient and the kind of therapy to be applied.

Claims

1. A method for operating an implantable stimulation device, comprising:

obtaining a vertical acceleration parameter indicative of a patient'"'"'s acceleration in a vertical direction; and

determining a patient'"'"'s status based at least in part on the vertical acceleration parameter.

2. The method of claim 1, wherein the obtaining comprises:

receiving sensor data from an accelerometer-based position sensor; and

deriving the vertical acceleration parameter from the sensor data.

3. The method of claim 1, wherein the determining comprises evaluating, based on the vertical acceleration parameter, whether the patient moves from a supine position to an upright position.

4. The method of claim 1, further comprising administering pacing therapy according to the patient'"'"'s position and activity status.

5. The method of claim 1, further comprising:

sensing one or more other cardiac-related parameters, the cardiac-related parameters being assigned weightings to represent proportional influence that the cardiac-related parameters have on determining pacing rates; and

adjusting the weightings based on the vertical acceleration parameter.

6. The method of claim 1, further comprising determining a vertical velocity parameter indicative of a patient'"'"'s velocity in the vertical direction as a function of the vertical acceleration parameter.

7. The method of claim 6, further comprising determining, based on the vertical velocity parameter, whether the patient is walking upstairs or downstairs.

8. One or more computer-readable media having computer-readable instructions thereon which, when executed by a programmable stimulation device, cause the stimulation device to execute the method of claim 1.

9. A method for operating an implantable stimulation device, comprising:

determining a vertical acceleration parameter indicative of a patient'"'"'s acceleration in a vertical direction;

determining a vertical velocity parameter as a function of the vertical acceleration parameter;

determining a minute ventilation parameter; and

ascertaining whether a patient is moving vertically upwards or vertically downwards based on one or more of the vertical acceleration parameter, the vertical velocity parameter, and the minute ventilation parameter.

10. The method of claim 9, wherein the determining a vertical acceleration parameter comprises:

receiving sensor data from an accelerometer-based position sensor; and

deriving the vertical acceleration parameter from the sensor data.

11. The method of claim 9, wherein the ascertaining comprises deciding the patient is moving vertically upwards in an event that the vertical acceleration parameter is changing, the vertical velocity is positive and the minute ventilation parameter increases above a threshold level.

12. The method of claim 9, wherein the ascertaining comprises deciding the patient is moving vertically downwards in an event that the vertical acceleration parameter is changing, the vertical velocity is negative and the minute ventilation parameter fails to increase above a threshold level.

13. The method of claim 9, wherein the ascertaining comprises deciding the patient is moving from a supine position to an upright position in an event that the vertical acceleration parameter becomes active after a prolonged period of inactivity.

14. One or more computer-readable media having computer-readable instructions thereon which, when executed by a programmable stimulation device, cause the stimulation device to execute the method of claim 9.

15. A cardiac stimulation device comprising:

an accelerometer-based sensor to sense a patient'"'"'s movement;

a processor operably coupled to the accelerometer-based sensor, the processor being configured to determine whether to administer cardiac pacing therapy to the patient based on a vertical acceleration component indicative of acceleration in a vertical direction during the patient'"'"'s movement; and

a pacing generator configured to administer the cardiac pacing therapy as directed by the processor.

16. The cardiac stimulation device of claim 15, wherein the accelerometer-based sensor comprises a three-dimensional accelerometer.

17. The cardiac stimulation device of claim 15, wherein the processor integrates the vertical acceleration component over time to produce a vertical velocity component.

18. The cardiac stimulation device of claim 17, wherein the processor determines whether the patient is moving upstairs or downstairs based on the vertical velocity component.

19. The cardiac stimulation device of claim 18, further comprising a minute ventilation sensor to sense minute ventilation, the process being operably coupled to the minute ventilation sensor and configured to confirm whether a patient is moving upstairs or downstairs based on the minute ventilation sensed by the minute ventilation sensor.

20. The cardiac stimulation device of claim 17, wherein the processor determines whether the patient is moving from a supine position to an upright position based on the vertical velocity component.

21. The cardiac stimulation device of claim 20, wherein, upon determination that the patient is moving from the supine position to the upright position, the processor directs the pacing generator to generate a pacing rate effective to counteract effects of orthostatic hypotension.

22. A cardiac stimulation device comprising:

an accelerometer-based sensor to sense a patient'"'"'s movement and produce a vertical acceleration component indicative of a patient'"'"'s acceleration in a vertical direction;

a minute ventilation sensor to sense minute ventilation;

a processor operably coupled to the accelerometer-based sensor and the minute ventilation sensor, the processor being configured to determine a patient'"'"'s activity based on the vertical acceleration component and the minute ventilation; and

a pacing generator configured to administer cardiac pacing therapy as directed by the processor.

23. The cardiac stimulation device of claim 22, wherein the accelerometer-based sensor comprises a three-dimensional accelerometer.

24. The cardiac stimulation device of claim 22, wherein the processor integrates the vertical acceleration component over time to produce a vertical velocity component and determines whether the patient is moving upstairs or downstairs based on the vertical velocity component and the minute ventilation.

25. The cardiac stimulation device of claim 22, wherein the processor integrates the vertical acceleration component over time to produce a vertical velocity component and determines whether the patient is moving from a supine position to an upright position based on the vertical velocity component.

26. An implantable cardiac rhythm management device, comprising:

acceleration means for obtaining a vertical acceleration parameter indicative of acceleration of a patient'"'"'s movement in a vertical direction;

processing means for integrating the vertical acceleration parameter over time to a vertical velocity parameter;

determination means for determining a patient'"'"'s status based on the vertical velocity parameter; and

therapy administration means, response to the determination means, for administering cardiac pacing therapy to the patient based on changes in the patient'"'"'s status.

27. The implantable cardiac rhythm management device of claim 26, wherein the acceleration means comprises a three-dimensional accelerometer.

28. The implantable cardiac rhythm management device of claim 26, wherein the patient'"'"'s status comprises at least one of a position status and an activity status.

29. The implantable cardiac rhythm management device of claim 26, further comprising minute ventilation means for obtaining a minute ventilation parameter indicative of a patent'"'"'s minute ventilation, the determination means being configured to determine whether the patient is moving upstairs or downstairs based on the vertical velocity parameter and the minute ventilation parameter.

30. A programmable cardiac stimulation device having a memory and a processor, the cardiac stimulation device being programmed to perform tasks comprising:

obtaining a vertical velocity component of a patient'"'"'s movement in the vertical direction; and

administering pacing therapy to a patient based on the vertical velocity component.

31. The programmable cardiac stimulation device of claim 30, wherein the cardiac stimulation device is programmed to perform additional tasks comprising:

obtaining a minute ventilation component indicative of a patient'"'"'s minute ventilation; and

detecting whether a patient is moving vertically upwards or vertically downwards from the vertical velocity component and the minute ventilation component.

32. The programmable cardiac stimulation device of claim 30, wherein the cardiac stimulation device is programmed to perform additional tasks comprising administering orthostatic compensation in an event that the vertical velocity component is suggestive of the patient moving from a supine position to an upright position.