AUTOMATED ADJUSTMENT OF POSTURE STATE DEFINITIONS FOR A MEDICAL DEVICE

• US 20110172927A1
• Filed: 04/28/2010
• Published: 07/14/2011
• Est. Priority Date: 01/08/2010
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Davis, Jon P., Dewing, Wende L., Panken, Eric J., Sahasrabudhe, Rajeev M., Goetz, Steven, Gokaldas, Shyam, Davenport, Lynn, Fehrmann, Elizabeth A.
• Granted Patent: US 8,758,274 B2
• Time in Patent Office: Days
• US Class Current: 702/19
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/0475 Special features of memory means, e.g. removable memory cards
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/369 Electroencephalography [EEG] devices for psychotechnics A61B5/16
• CPC Class Codes: A61B 5/389 Electromyography [EMG]
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• 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: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7475 User input or interface means, e.g. keyboard, pointing device, joystick
• CPC Class Codes: A61N 1/36071 Pain
• CPC Class Codes: A61N 1/36535 controlled by body position or posture
• CPC Class Codes: A61N 1/37247 User interfaces, e.g. input or presentation means
• CPC Class Codes: G16H 20/30 relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16H 50/20 : for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

Techniques relate to operating a medical device by classifying a detected posture state of a patient. This classification may be performed by comparing the detected posture state of the patient to posture state definitions available within the system. Each definition may be described in terms of a parameter (e.g., vector) indicative of a direction in three-dimensional space. The posture state definitions may be calibrated by automatically estimating values for these parameters, thereby eliminating the need for the patient to assume each posture state during the calibration process to capture actual parameter values. According to another aspect, the estimated parameter values may be updated as the patient assumes various postures during a daily routine. For instance, estimated vectors initially used to calibrate the posture state definitions may be changed over time to more closely represent posture states the patient actually assumes, and to further adapt to changes in a patient'"'"'s condition.

Claims

1. A system, comprising:

a storage device adapted to store definitions for respective posture states in which a patient may be classified; and

a processor adapted to receive an indication of a detected posture state of the patient, to classify the detected posture state as being one of the defined posture states, and to utilize the indication to update the definition for the posture state in which the patient is classified.

2. The system of claim 1, further comprising a posture state sensor adapted to provide the indication.

3. The system of claim 1, wherein the indication is a vector.

4. The system of claim 1, wherein the processor is adapted to determine, based on the indication, whether the detected posture state of the patient is stable, and to utilize the indication to update the definition for the posture state in which the patient is classified only if the detected posture state is stable.

5. The system of claim 4, wherein the processor is adapted to determine whether the detected posture state of the patient is stable based on whether the patient is classified in a same one of the defined posture states throughout a predetermined time period.

6. The system of claim 4, wherein the processor is adapted to determine whether the detected posture state of the patient is stable based on whether the indication has a predetermined spatial relationship to the defined posture state in which the patient is classified.

7. The system of claim 4, wherein the processor is adapted to determine whether the detected posture state of the patient is stable based on filter criteria that are adjusted over time.

8. The system of claim 7, wherein the filter criteria is adjusted based on at least one of time of day, day of week, a measured physiological parameter of the patient, or a time since the definitions were initialized.

9. The system of claim 1, further comprising a programmer to provide a trigger event, and wherein the indication is received in response to the trigger event.

10. The system of claim 9, wherein the trigger event is a request to modify a therapy provided to the patient.

11. The system of claim 9, wherein the trigger event is an indication of activity of the patient.

12. The system of claim 1, further comprising a therapy module to deliver therapy to the patient in response to the posture state in which the patient is classified.

13. The system of claim 1, wherein the processor is adapted to obtain a value to update the definition based on a weighting function that weights a value currently associated with the definition and a value associated with the received indication.

14. The system of claim 13, wherein the weighting function employs a weighting factor that is selected based on the posture state in which the patient is classified.

15. The system of claim 13, wherein the weighting function employs a weighting factor that changes over time.

16. The system of claim 13, wherein the storage device stores a revision history recording past updates to the definition for the posture state in which the patient is classified, and wherein the processor is adapted to update the definition for the posture state in which the patient is classified based on the past updates and the indication.

17. A method, comprising:

creating posture state definitions, each including a defined vector describing a corresponding posture state;

receiving from a sensor signals indicative of a detected vector describing a detected posture state of the patient; and

identifying, with a processor, one of the posture state definitions to potentially update based on the detected vector.

18. The method of claim 17, further comprising:

determining whether the detected vector meets one or more requirements associated with the identified posture state definition; and

if the detected vector meets the one or more requirements, updating a defined vector of the identified posture state definition based on the detected vector.

19. The method of claim 18, wherein determining whether the detected vector meets one or more requirements includes determining whether the detected vector is within a predetermined distance of the defined vector of the identified posture state.

20. The method of claim 18, wherein determining whether the detected vector meets one or more requirements includes determining whether the detected vector remains stable for at least a predetermined period of time.

21. The method of claim 17, further comprising:

receiving a trigger event;

in response to the trigger event, capturing one or more samples of the signals from the sensor; and

deriving the detected vector from the one or more samples.

22. The method of claim 21, wherein the trigger event is an indication received from a programmer.

23. The method of claim 18, further comprising updating the defined vector of the identified posture state definition based on a weighting function applied to the detected vector and the defined vector.

24. The method of claim 23, further comprising selecting the weighting function based on a least one of the identified posture state definition, a scheduling function, and a patient parameter.

25. A medical device, comprising:

a memory adapted to store defined vectors, each indicative of a corresponding defined posture state;

a sensor adapted to detect vectors indicative of detected posture states of a patient; and

a processor adapted to automatically update one or more of the defined vectors based on the detected vectors.

26. The device of claim 25, wherein the processor is adapted to select one or more of the detected vectors to be used to update a corresponding one of the defined vectors.

27. The device of claim 26, wherein the processor is adapted to select the one or more detected vectors based on spatial relationships between the one or more detected vectors and the corresponding one of the defined vectors.

28. The device of claim 26, wherein the processor is adapted to select the one or more detected vectors based on stability of the one or more detected vectors.

29. The device of claim 25, wherein the processor is adapted to automatically generate estimated values for use as the defined vector before the defined vectors are updated.

30. The device of claim 25, wherein the processor is adapted to initialize one or more of the defined vectors before the defined vectors are updated, the one or more defined vectors being initialized to vectors obtained from the sensor while a patient carrying the medical device assumes the corresponding defined posture state.

31. A system, comprising:

a device as in claim 25; and

a programmer to provide a trigger event to cause the processor to automatically update the defined vectors.

32. The system of claim 25, wherein the processor is adapted to automatically update one or more of the defined vectors based on the detected vectors indicating that the device has likely changed orientation with a patient.

33. A system, comprising:

means for providing an indication of a posture state of a patient;

means for classifying a posture state of a patient based on the indication and a set of defined posture vectors; and

means for updating the set of defined posture vectors based on the indication.