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

• US 6,658,292 B2
• Filed: 08/24/2001
• Issued: 12/02/2003
• Est. Priority Date: 08/24/2001
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Kroll, Mark W., Bornzin, Gene A., Sorensen, Chris
• Primary Examiner(s): Bockelman, Mark
• Application Number:
  US09/939,051
• Publication Number:
  US 20030040776A1
• Time in Patent Office: 830 Days
• Field of Search: 607/5, 607/17-24, 607/77, 607/62, 600/301, 600/341, 600/373, 600/374, 600/595
• US Class Current: 607/19
• 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 from an implanted sensor, the vertical acceleration parameter indicative of a patient'"'"'s acceleration in a vertical direction;

determining a vertical velocity parameter indicative of a patient'"'"'s velocity in the vertical direction as a function of the vertical acceleration parameter; and

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

2. The method of claim 1, wherein the implanted sensor is an acceleration-based position sensor and wherein the obtaining comprises:

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

deriving the vertical acceleration parameter from the sensor data.

3. The method of claim 1, wherein the determining the patient'"'"'s status 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 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, wherein the vertical acceleration parameter is integrated over time to produce the vertical velocity parameter.

7. 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.

8. The method of claim 1, further comprising indicating, based on the vertical velocity parameter, whether the patient is walking upstairs or downstairs.

9. The method of claim 8, wherein the vertical acceleration parameter is integrated over time to produce a vertical velocity parameter.

10. The method of claim 9, further comprising:

wherein the vertical acceleration parameter is integrated over time to produce a vertical velocity parameter; and

storing the vertical velocity parameter over time to establish a plurality of vertical velocity parameter data points which may be represented by a curve;

wherein the curve is positive when the patient is walking upstairs; and

wherein the curve is negative when the patient is walking downstairs.

11. The method of claim 10, wherein the curve is positive and increases as the patient begins walking upstairs and the curve smoothes to a substantially constant vertical velocity parameter when the patient reaches a normal stride, and wherein the curve is negative and the amplitude increases as the patient begins walking downstairs and the curve smoothes to a substantially constant vertical velocity parameter when the patient reaches a normal stride.

12. 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.

13. The method of claim 12, 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.

14. The method of claim 12, wherein the ascertaining comprises deciding the patient is moving vertically upwards in an event that the vertical acceleration parameter is changing, the vertical velocity parameter is positive and the minute ventilation parameter increases above a threshold level.

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

16. The method of claim 12, 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.

17. 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 12.

18. The method of claim 12, wherein the vertical acceleration parameter is integrated over time to produce the vertical velocity parameter.

19. A method for operating an implantable device, comprising:

generating a vertical acceleration component from an implanted sensor, the vertical acceleration parameter indicative of a patient'"'"'s acceleration in a vertical direction;

applying the vertical acceleration component to determine the activity level of the patient;

integrating the vertical acceleration component over time to establish a vertical velocity component; and

applying the vertical velocity component to indicate whether the patient is walking in a vertically upward direction or a vertically downward direction.

20. The method of claim 19, further comprising administering pacing therapy according to the patient'"'"'s activity level and whether the patient is walking in a vertically upward direction or a vertically downward direction.

21. The method of claim 19, further comprising:

establishing a minute ventilation of the patient; and

applying the minute ventilation in combination with the vertical acceleration component and the vertical velocity component to administer pacing therapy.