DETECTING POSTURE SENSOR SIGNAL SHIFT OR DRIFT IN MEDICAL DEVICES

• US 20110270134A1
• Filed: 04/30/2010
• Published: 11/03/2011
• Est. Priority Date: 04/30/2010
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Skelton, Dennis M.
• Granted Patent: US 9,566,441 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• 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

Abstract

In general, the disclosure relates to medical devices and systems for detecting the posture state of patient. For example, a medical system may detect a posture state of a patient and deliver therapy based at least in part on the detected patient posture state. In some examples, the system may comprise a posture sensor that generates posture sensor data when a patient is in a posture state, and a processor that receives the first posture sensor data, compares the first posture state data to reference posture sensor data, and detects the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison. In some examples, the processor may be configured to determine one or more offset correction values to apply to posture sensor data generated by the posture sensor when the at least one of sensor signal drift or sensor signal shift is determined to be present.

Claims

1. A method comprising:

receiving posture sensor data from a posture sensor;

comparing the posture sensor data from the posture sensor to reference posture sensor data; and

detecting the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison,

wherein the posture sensor data is indicative of a posture state of a patient.

2. The method of claim 1, wherein comparing the posture sensor data from the posture sensor to reference posture sensor data comprises determining one or more differences between the posture sensor data and the reference posture sensor data, and wherein detecting the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison comprises detecting the presence of the at least one of sensor signal drift or sensor signal shift based on the one or more differences between the posture sensor data and the reference posture sensor data.

3. The method of claim 1, further comprising:

determining an offset correction value based at least in part on the reference posture sensor data; and

applying the offset correction value to a posture detection algorithm configured to detect patient posture state based at least in part on posture sensor data sensed via the posture sensor.

4. The method of claim 1, wherein the posture sensor data comprises first posture sensor data received from the posture sensor when a patient is in a first posture state, and the reference posture sensor data comprises first reference posture sensor data associated with the first posture state of the patient.

5. The method of claim 4, wherein the reference posture sensor data comprises baseline posture sensor data defined based on posture sensor data generated by the posture sensor when the patient previously occupied the first posture state.

6. The method of claim 4, further comprising:

receiving second posture sensor data from the posture sensor when the patient is in a second posture state;

comparing the second posture sensor data from the posture sensor to second reference posture sensor data associated with the second posture state; and

wherein the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor is detected based at least in part on the comparisons of the first posture sensor data and the second posture sensor data to the respective reference posture sensor data.

7. The method of claim 6, wherein the second reference posture sensor data associated with the second posture state is substantially the same as the first reference posture sensor data associated with the first posture state.

8. The method of claim 1, wherein the posture sensor comprises a multiple-axis accelerometer sensor, wherein the posture sensor data includes at least one of signal output values for respective axes or a magnitude vector determined based on signal output values from respective axes generated by the posture sensor.

9. The method of claim 1, further comprising generating an alert indicative of the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison.

10. The method of claim 1, further comprising:

delivering therapy to the patient, wherein the therapy is delivered according to the posture state of the patient determined via the posture sensor; and

suspending delivery of the therapy when the at least one of sensor signal drift or sensor signal shift for the posture sensor is detected.

11. The method of claim 10, further comprising:

determining an offset correction value based on the reference posture sensor data;

applying the offset correction value to a posture detection algorithm configured to detect patient posture state based on sensed posture sensor data; and

resuming the suspended therapy after the offset correction value is applied to the posture detection algorithm.

12. The method of claim 1, further comprising receiving a command to initiate delivery of therapy, wherein the therapy is delivered according to the posture state of the patient determined via the posture sensor, wherein the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison is detected based on the receipt of the command to initiate delivery of the therapy.

13. The method of claim 1,

wherein the posture sensor comprises an accelerometer sensor including a first sensor output along a first axis, a second sensor output along a second axis, and a third sensor output along a third axis,

wherein the posture sensor data comprises first posture sensor data from the posture sensor when the patient occupies a first posture state, second posture sensor data from the posture sensor when the patient occupies a second posture state, and third posture sensor data from the posture sensor when the patient occupies a third posture state, and

wherein each of the first, second, and third posture sensor data includes respective posture vector magnitude values determined based on the first, second, and third sensor outputs when the patient occupies the respective posture states.

14. The method of claim 13, further comprising:

determining, upon detecting the presence of at least one of sensor signal drift or sensor signal shift, a first offset correction value for first posture sensor data of the first posture sensor data;

applying the first offset correction value to the second and third posture sensor data;

comparing the first, second, and third posture sensor data with the first offset correction applied to reference posture sensor data; and

determining whether to apply the first offset correction value to posture sensor data used to detect patient posture state based on the comparison of the first, second, and third posture sensor data with the first offset correction applied to reference posture sensor data.

15. The method of claim 13, wherein the first posture state, second posture state, and third posture state are approximately orthogonal to each other.

16. A medical device comprising:

a posture sensor configured to generate posture sensor data; and

a processor configured to receive the posture sensor data, compare the posture sensor data to reference posture sensor data, and detect at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison,

wherein the posture sensor data is indicative of a posture state of a patient.

17. The medical device of claim 16, wherein the processor compares the posture sensor data from the posture sensor to reference posture sensor data by at least determining one or more differences between the posture sensor data and the reference posture sensor data, and wherein the processor detects the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison by at least detecting the presence of the at least one of sensor signal drift or sensor signal shift based on the one or more differences between the posture sensor data and the reference posture sensor data.

18. The medical device of claim 16, wherein the processor is configured to determine an offset correction value based at least in part on the reference posture sensor data;

and apply the offset correction value to a posture detection algorithm configured to detect patient posture state based at least in part on posture sensor data sensed via the posture sensor.

19. The medical device of claim 16, wherein the posture sensor data comprises first posture sensor data received from the posture sensor when a patient is in a first posture state, and the reference posture sensor data comprises first reference posture sensor data associated with the first posture state of the patient.

20. The medical device of claim 19, wherein the reference posture sensor data comprises baseline posture sensor data defined based on posture sensor data generated by the posture sensor when the patient previously occupied the first posture state.

21. The medical device of claim 19, wherein the processor receives second posture sensor data from the posture sensor when the patient is in a second posture state, compares the second posture sensor data from the posture sensor to second reference posture sensor data associated with the second posture state, and wherein the processor detects the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparisons of the first posture sensor data and the second posture sensor data to the respective reference posture sensor data.

22. The medical device of claim 21, wherein the second reference posture sensor data associated with the second posture state is substantially the same as the first reference posture sensor data associated with the first posture state.

23. The medical device of claim 16, wherein the posture sensor comprises a multiple-axis accelerometer sensor, wherein the posture sensor data includes at least one of signal output values for respective axes or a magnitude vector determined based on signal output values from respective axes generated by the posture sensor.

24. The medical device of claim 16, wherein the processor generates an alert indicative of the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison.

25. The medical device of claim 16, wherein the processor controls delivery of therapy to the patient via therapy module, wherein the therapy is delivered according to the posture state of the patient determined via the posture sensor;

and suspends the delivery of the therapy when the at least one of sensor signal drift or sensor signal shift for the posture sensor is detected.

26. The medical device of claim 25, wherein the processor determines an offset correction value based on the reference posture sensor data, applies the offset correction value to a posture detection algorithm configured to detect patient posture state based on sensed posture sensor data;

and resumes the suspended therapy after the offset correction value is applied to the posture detection algorithm.

27. The medical device of claim 16, wherein the processor receives a command to initiate delivery of therapy according to the posture state of the patient determined via the posture sensor, wherein the processor determines the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison is detected based on the receipt of the command to initiate delivery of the therapy.

28. The medical device of claim 16,

wherein the posture sensor comprises an accelerometer sensor including a first sensor output along a first axis, a second sensor output along a second axis, and a third sensor output along a third axis,

wherein the posture sensor data comprises first posture sensor data from the posture sensor when the patient occupies a first posture state, second posture sensor data from the posture sensor when the patient occupies a second posture state, and third posture sensor data from the posture sensor when the patient occupies a third posture state, and

wherein each of the first, second, and third posture sensor data includes respective posture vector magnitude values determined based on the first, second, and third sensor outputs when the patient occupies the respective posture states.

29. The medical device of claim 28, wherein the processor determines, upon detecting the presence of at least one of sensor signal drift or sensor signal shift, a first offset correction value for first posture sensor data of the first posture sensor data, applies the first offset correction value to the second and third posture sensor data;

compares the first, second, and third posture sensor data with the first offset correction applied to reference posture sensor data; and

determines whether to apply the first offset correction value to posture sensor data used to detect patient posture state based on the comparison of the first, second, and third posture sensor data with the first offset correction applied to reference posture sensor data.

30. The medical device of claim 28, wherein the first posture state, second posture state, and third posture state are approximately orthogonal to each other.

31. A computer-readable storage medium comprising instructions for causing one or more processors to:

receive posture sensor data from a posture sensor;

compare the posture sensor data from the posture sensor to reference posture sensor data; and

detect the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison,

wherein the posture sensor data is indicative of a posture state of a patient.

32. A system comprising:

means for receiving posture sensor data from a posture sensor;

means for comparing the posture sensor data from the posture sensor to reference posture sensor data; and

means for detecting the presence of at least one of sensor signal drift or sensor signal shift for the posture sensor based at least in part on the comparison,

wherein the posture sensor data is indicative of a posture state of a patient.