POSTURE STATE DETECTION USING SELECTABLE SYSTEM CONTROL PARAMETERS

• US 20100010384A1
• Filed: 04/30/2009
• Published: 01/14/2010
• Est. Priority Date: 07/11/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Panken, Eric J., Skelton, Dennis M.
• Granted Patent: US 8,688,225 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: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/686 Permanently implanted devices, e.g. pacemakers, other stimulators, biochips A61B5/6861 takes precedence
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• CPC Class Codes: A61N 1/36062 Spinal stimulation
• CPC Class Codes: A61N 1/36139 with automatic adjustment
• 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
• CPC Class Codes: A61N 1/37247 User interfaces, e.g. input or presentation means
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Techniques for detecting and classifying a posture state of a patient are disclosed, wherein a posture state includes at least one of a posture and/or an activity state related to motion. In one embodiment, one or more signals indicative of at least one of posture and activity state of the patient may be sensed by a sensor. Control logic may be provided to process the one or more sensed signals in a selectable manner. This selectable manner may be based on current posture state data describing a posture state in which the patient has previously been classified. Alternatively or additionally, this current posture state data may describe a posture state transition previously undergone by the patient. The one or more signals that are so processed may then be used to classify a posture state of the patient.

Claims

1. A medical device system, comprising:

a storage device to store current posture state data describing a posture state in which a patient has previously been classified;

a sensor to sense one or more signals indicative of at least one of a posture and an activity state of the patient; and

control logic to process the one or more signals in a selectable manner that is based on the current posture state data, and to classify a patient as being in a posture state indicated by the processed one or more signals.

2. The system of claim 1, wherein the sensor is a three-axis accelerometer.

3. The system of claim 1, wherein the sensed one or more signals are sampled at a sampling rate selected based on the current posture state data.

4. The system of claim 1, wherein the sensed one or more signals are filtered to retain selected frequencies that are selected based on the current posture state data.

5. The system of claim 1, wherein the control logic includes an M-of-N filter to identify a posture state indicated by M of N sampled posture states, and wherein at least one of M and N is selected based on the current posture state data.

6. The system of claim 1, wherein the control logic includes an episode detector to determine whether a processed one of the one or more signals crosses a signal level identified by a transition threshold and does not re-cross the transition threshold for at least a time period identified by a transition duration, wherein at least one of transition threshold and transition duration are selected based on the current posture state data.

7. The system of claim 1, further including response logic to initiate a response based on the posture state indicated by the processed one or more signals.

8. The system of claim 7, wherein the response is further based on the current posture state data.

9. The system of claim 7, wherein the control logic includes dwell time logic to impose a dwell time before the response logic initiates the response.

10. The system of claim 9, wherein the dwell time is selected based on the current posture state data.

11. The system of claim 7, wherein the response involves a therapy delivered to the patient.

12. The system of claim 1, wherein the control logic updates the current posture state data to indicate the posture state indicated by the processed one or more signals.

13. The system of claim 1, wherein the control logic processes the one or more signals to derive a vector indicative of at least one of posture and activity state.

14. The system of claim 1, wherein the control logic processes the one or more signals to derive an activity level indicative of activity state.

15. A method, comprising:

receiving a signal from a sensor that indicates a posture state of a patient;

obtaining current posture state data identifying a posture state in which the patient was most recently classified;

processing the received signals in a manner that is based on the current posture state data to determine at least one of an activity state and a posture of the patient; and

initiating a medical device a response based on the classification of the processed signals.

16. The method of claim 15, further including updating the current posture state data to describe the classification of the processed signals.

17. The method of claim 15, wherein initiating the response includes delivering therapy to the patient based on the classification of the processed signals.

18. The method of claim 15, further including sampling the signal from the sensor at a rate based on the current posture state data.

19. The method of claim 15, wherein the current posture state data identifies a transition associate with the posture state in which the patient was most recently classified, and wherein processing of the received signals is performed in a manner that is based on the transition.

20. A method, comprising:

receiving a signal from a sensor that indicates a posture state of a patient;

obtaining from a storage device current posture state data identifying a posture state in which the patient was most recently classified;

processing the received signal based on the current posture state data to determine an activity state of the patient; and

updating the current posture state data based on the determined activity state of the patient.

21. The method of claim 20, further including:

processing the received signal based on the current posture state data to determine a posture of the patient; and

updating the current posture state data based on the determined posture of the patient.

22. The method of claim 21, wherein at least one of determining the activity state of the patient and determining the posture of the patient is performed based on a sampling rate selected from the current posture state data.

23. The method of claim 21, wherein at least one of determining the activity state of the patient and determining the posture of the patient comprises filtering frequencies selected based on the current posture state data.

24. The method of claim 20, further comprising delivering therapy to the patient based on the determined activity state of the patient.

25. The method of claim 24, further comprising delivering therapy to the patient via an implanted therapy delivery device.

26. The method of claim 21, wherein at least one of determining the activity state of the patient and determining the posture of the patient comprises obtaining a sum of N successive samples of the received signal, wherein N is selected based on the current posture state data.

27. A digital storage medium for storing instructions executed to cause a processor to perform a method, comprising:

receiving signals indicating a posture of a patient;

retrieving current posture state data indicating a posture state in which the patient was classified;

processing the received signals in a manner controlled by the current posture state data; and

determining from the processed signals a classification of the posture of the patient.

28. The storage medium of claim 27, wherein the method further comprises:

receiving signals indicating an activity state of the patient;

processing the received signals indicating the activity state in a manner controlled by the current posture state data; and

determining a classification of the activity state of the patient.

29. The storage medium of claim 27, wherein the method further comprises controlling delivery of therapy to the patient based on the classification of the posture.

30. The storage medium of claim 27, wherein the signals indicating a posture of the patient are also indicative of activity.