SLEEP STAGE DETECTION

• US 20090192556A1
• Filed: 09/25/2008
• Published: 07/30/2009
• Est. Priority Date: 01/25/2008
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Wu, Jianping, Molnar, Gregory F., Denison, Timothy J., Miyazawa, Gabriela C.
• Granted Patent: US 9,072,870 B2
• Time in Patent Office: Days
• US Class Current: 607/3
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/01 Measuring temperature of body parts ; Diagnostic temperature sensing, e.g. for malignant or inflamed tissue clinical contact thermometers G01K13/20
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• 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 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/316 Modalities, i.e. specific diagnostic methods
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/374 Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
• CPC Class Codes: A61B 5/4082 Diagnosing or monitoring movement diseases, e.g. Parkinson, Huntington or Tourette
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• CPC Class Codes: A61M 2021/0072 with application of electrical currents
• CPC Class Codes: A61M 21/02 for inducing sleep or relaxation, e.g. by direct nerve stimulation, hypnosis, analgesia for massage A61H; electrotherapy A61N, e.g. applying alternating or intermittent electric currents for producing anaesthesia A61N1/36021
• CPC Class Codes: A61M 2205/3523 using telemetric means
• CPC Class Codes: A61M 2205/3553 remote, e.g. between patient's home and doctor's office
• CPC Class Codes: A61M 2205/3584 using modem, internet or bluetooth
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission
• CPC Class Codes: A61M 2205/50 : with microprocessors or computers
• CPC Class Codes: A61M 2205/52 : with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2230/005 : Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/04 : Heartbeat characteristics, e.g. ECG, blood pressure modulation
• CPC Class Codes: A61M 2230/08 : Other bio-electrical signals
• CPC Class Codes: A61M 2230/10 : Electroencephalographic signals
• CPC Class Codes: A61M 2230/205 : partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/30 : Blood pressure A61M2230/04 takes precedence
• CPC Class Codes: A61M 2230/42 : Rate
• CPC Class Codes: A61M 2230/50 : Temperature
• CPC Class Codes: A61M 2230/60 : Muscle strain, i.e. measured on the user
• CPC Class Codes: A61M 2230/63 : Motion, e.g. physical activity
• CPC Class Codes: A61M 2230/65 : Impedance, e.g. conductivity, capacity
• CPC Class Codes: A61M 5/1723 : using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: A61N 1/36078 : Inducing or controlling sleep or relaxation non-implantable stimulator A61M21/00
• CPC Class Codes: A61N 1/36139 : with automatic adjustment
• CPC Class Codes: G16H 20/17 : delivered via infusion or injection
• CPC Class Codes: G16H 20/30 : relating to physical therapies or activities, e.g. physiotherapy, acupressure or exercising
• CPC Class Codes: G16H 20/70 : relating to mental therapies, e.g. psychological therapy or autogenous training
• CPC Class Codes: G16H 40/63 : for local operation

Abstract

Therapy delivery to a patient may be controlled based on a determined sleep stage of the patient. In examples, the sleep stage may be determined based on a frequency characteristic of a biosignal indicative of brain activity of the patient. A frequency characteristic may include, for example, a power level within one or more frequency bands of the biosignal, a ratio of the power level in two or more frequency bands, or a pattern in the power level of one or more frequency bands over time. A therapy program may be selected or modified based on the sleep stage determination. Therapy may be delivered during the sleep stage according to the selected or modified therapy program. In some examples, therapy delivery may be controlled after making separate determinations of a sleep stage based on the biosignal and another physiological parameter, and confirming that the sleep stage determinations are consistent.

Claims

1. A method comprising:

receiving a biosignal that is indicative of activity within a brain of a patient;

determining a frequency characteristic of the biosignal;

comparing the frequency characteristic of the biosignal to at least one of a threshold value or template; and

determining a sleep stage of the patient based on the comparison between the frequency characteristic of the biosignal and the at least one of the threshold value or template, wherein the sleep stage occurs during a sleep state of the patient, the sleep state comprising a plurality of sleep stages.

2. The method of claim 1, wherein the biosignal comprises a local field potential within the brain of the patient.

3. The method of claim 2, wherein the local field potential comprises at least one of an electroencephalogram (EEG) or an electrocorticogram (ECoG).

4. The method of claim 1, wherein the frequency characteristic comprises a power level of the biosignal within one or more frequency bands.

5. The method of claim 4, wherein the one or more frequency bands comprises at least one of a frequency band in a range of about 10 Hertz to about 30 Hertz or in a range of about 5 Hertz to about 10 Hertz.

6. The method of claim 1, wherein the frequency characteristic comprises a ratio of power levels in two or more frequency bands of the biosignal.

7. The method of claim 6, wherein the frequency characteristic comprises the ratio of power levels in at least one of a beta frequency band and an alpha frequency band of the biosignal, a sigma frequency band and a high beta frequency band of the biosignal or a theta frequency band and an alpha beta frequency band of the biosignal.

8. The method of claim 1, wherein the frequency characteristic comprises a trend in a power level of the biosignal within one or more frequency bands over time.

9. The method of claim 1, wherein the threshold value and the template are determined based on information specific to the patient.

10. The method of claim 1, wherein determining the sleep stage based on the frequency characteristic comprises determining whether the patient is in one of a plurality of sleep stages that are associated with the frequency characteristic.

11. The method of claim 1, further comprising controlling therapy delivery to the patient during the sleep stage based on the determined sleep stage.

12. The method of claim 11, wherein controlling therapy comprises selecting a therapy program based on the determined sleep stage.

13. The method of claim 11, wherein controlling therapy comprises modifying at least one therapy parameter value of a stored therapy program based on the determined sleep stage.

14. The method of claim 11, wherein controlling therapy comprises at least one of activating or deactivating therapy delivery to the patient based on the determined sleep stage.

15. The method of claim 11, wherein controlling therapy comprises controlling at least one of delivery of electrical stimulation to the brain of the patient or delivery of a therapeutic agent to the patient.

16. The method of claim 1, further comprising determining whether the patient is in the sleep state.

17. The method of claim 16, further comprising determining an activity level of the patient, wherein determining whether the patient is in the sleep state comprises determining whether the patient is in the sleep state based on the activity level of the patient.

18. The method of claim 16, further comprising monitoring a physiological parameter of the patient, wherein the physiological parameter comprises at least one of an activity level, posture, heart rate, electrocardiogram morphology or core temperature, wherein determining whether the patient is in the sleep state comprises determining whether the patient is in the sleep state based on the physiological parameter.

19. The method of claim 1, wherein the sleep stage comprises a first sleep stage and the frequency characteristic comprises a first frequency characteristic, the method further comprising:

determining a second frequency characteristic of the biosignal;

determining a second sleep stage of the patient based on the second frequency characteristic of the biosignal; and

controlling therapy delivered to the patient during the second sleep stage based on the determined second sleep stage.

20. The method of claim 1, wherein determining the sleep stage of the patient comprises determining a sleep stage group based on the comparison between the frequency characteristic of the biosignal and the at least one of the threshold value or template, the sleep stage group comprising at least two different sleep stages.

21. The method of claim 1, wherein the frequency characteristic comprises a first frequency characteristic within a first frequency band, the method further comprising determining a second frequency characteristic of the biosignal within a second frequency band that is different than the first frequency band, wherein comparing the frequency characteristic of the biosignal to at least one of the threshold value or the template comprises comparing a ratio of the first and second frequency characteristics to the threshold value, and determining the sleep stage of the patient comprises determining the sleep stage of the patient based on the comparison of the ratio to the threshold value.

22. The method of claim 1, further comprising:

determining a first sleep stage determination based on the frequency characteristic of the biosignal;

receiving a physiological signal indicative of a physiological parameter of the patient, wherein the physiological signal is different than the biosignal; and

determining a second sleep stage determination based on the physiological signal,

wherein determining the sleep stage of the patient further comprises determining the sleep stage based on the first and second sleep stages determinations.

23. The method of claim 22, wherein the physiological parameter comprises at least one of an activity level, posture, heart rate, respiration rate, respiratory volume, blood pressure, blood oxygen saturation, partial pressure of oxygen within blood, partial pressure of oxygen within cerebrospinal fluid, muscular activity, core temperature, arterial blood flow or galvanic skin response of the patient.

24. A method comprising:

sensing a biosignal from a brain of a patient;

determining a frequency characteristic of the biosignal;

determining whether the patient is in at least one of an awake state, a first sleep stage or a second sleep stage based on the frequency characteristic of the biosignal;

activating therapy delivery to the patient if the patient is in the awake state or the first sleep stage; and

deactivating or decreasing an intensity of therapy delivered to the patient if the patient is in the second sleep stage.

25. The method of claim 24, wherein the first sleep stage comprises at least one of a Stage 1 or rapid eye movement sleep stage.

26. The method of claim 24, wherein the second sleep stage comprises at least one of a Deep Sleep or Stage 2 sleep stage.

27. A system comprising:

a sensing module that senses a biosignal generated within a brain of a patient; and

a processor that receives the biosignal from the sensing module, determines a frequency characteristic of the biosignal, compares the frequency characteristic of the biosignal to at least one of a threshold value or template, and determines a sleep stage of the patient based on the comparison between the frequency characteristic of the biosignal and the at least one of the threshold value or the template, wherein the sleep stage occurs during a sleep state of the patient, the sleep state comprising a plurality of sleep stages.

28. The system of claim 27, further comprising a medical device that delivers therapy to the patient under a control of the processor.

29. The system of claim 28, wherein the medical device comprises the sensing module.

30. The system of claim 28, wherein the medical device comprises the processor.

31. The system of claim 27, further comprising a medical device programmer that comprises the processor.

32. The system of claim 27, wherein the biosignal comprises a local field potential within the brain of the patient.

33. The system of claim 27, wherein the frequency characteristic comprises a power level of the biosignal within one or more frequency bands.

34. The system of claim 33, wherein the one or more frequency bands comprises at least one of a frequency band in a range of about 10 Hertz to about 30 Hertz or in a range of about 5 Hertz to about 10 Hertz.

35. The system of claim 27, wherein the frequency characteristic comprises a ratio of power levels in two or more frequency bands of the biosignal.

36. The system of claim 27, wherein the frequency characteristic comprises a trend in a power level of the biosignal within one or more frequency bands over time.

37. The system of claim 27, wherein the processor determines whether the patient is in a sleep stage group based on the comparison between the frequency characteristic of the biosignal and the at least one of the threshold value or the template to determine the sleep stage of the patient.

38. The system of claim 27, wherein the processor controls therapy delivered to the patient during the sleep stage based on the determined sleep stage.

39. The system of claim 38, wherein the processor controls therapy delivery by at least selecting a therapy program based on the determined sleep stage.

40. The system of claim 38, wherein the processor controls therapy delivery by at least modifying at least one therapy parameter value of a stored therapy program based on the determined sleep stage.

41. The system of claim 38, further comprising a medical device, wherein the processor controls therapy delivery by at least one of activating or deactivating therapy delivery by the medical device to the patient based on the determined sleep stage.

42. The system of claim 27, wherein the processor determines whether the patient is in the sleep state.

43. The system of claim 42, further comprising a motion sensor that generates a motion signal indicative of patient motion, wherein the processor receives the motion signal, determines an activity level of the patient based on the motion signal, and determines whether the patient is in the sleep state based on the activity level of the patient.

44. The system of claim 42, wherein the sensing module comprises a first sensing module, the system further comprising a sensing module that generates a physiological signal indicative of a physiological parameter of the patient, wherein the physiological parameter comprises at least one of an activity level, posture, heart rate, electrocardiogram morphology, or core temperature, wherein the processor receives the physiological signal and determines whether the patient is in the sleep state based on the physiological signal.

45. The system of claim 27, wherein the frequency characteristic comprises a first frequency characteristic within a first frequency band, and the processor determines a second frequency characteristic of the biosignal within a second frequency band that is different than the first frequency band, and determines the sleep stage of the patient based on the first and second frequency characteristics.

46. The system of claim 27, wherein the sensing module comprises a first sensing module, the system further comprising a second sensing module that generates a physiological signal indicative of a physiological parameter of the patient, wherein the physiological signal is different than the biosignal, wherein the processor determines a first sleep stage determination based on the frequency characteristic of the biosignal, receives the physiological signal from the second sensing module, determines a second sleep stage determination based on the physiological signal, and determines the sleep stage of the patient based on the first and second sleep stages determinations.

47. The system of claim 27, wherein the processor determines the sleep stage of the patient by at least determining the patient is in at least one of an awake state, a first sleep stage or a second sleep stage based on the frequency characteristic of the biosignal, and activates therapy delivery to the patient if the patient is in the awake state or the first sleep stage and deactivates or decreases an intensity of therapy delivered to the patient if the patient is in the second sleep stage.

48. A system comprising:

means for receiving a biosignal that is indicative of activity within a brain of a patient;

means for determining a frequency characteristic of the biosignal;

means for comparing the frequency characteristic of the biosignal to at least one of a threshold value or template; and

means for determining a sleep stage of the patient based on the comparison between the frequency characteristic of the biosignal and the at least one of the threshold value or template, wherein the sleep stage occurs during a sleep state of the patient, the sleep state comprising a plurality of sleep stages.

49. The system of claim 48, further comprising means for controlling therapy delivered to the patient during the sleep stage based on the determined sleep stage

50. A computer-readable medium comprising instructions that cause a processor to:

receive a biosignal that is indicative of activity within a brain of a patient;

determine a frequency characteristic of the biosignal;

compare the frequency characteristic of the biosignal to at least one of a threshold value or template; and

determine a sleep stage of the patient based on the comparison between the frequency characteristic of the biosignal and the at least one of the threshold value or template, wherein the sleep stage occurs during a sleep state of the patient, the sleep state comprising a plurality of sleep stages.

51. A method comprising:

monitoring a biosignal during a sleep state of a patient, wherein the biosignal is indicative of activity within a brain of a patient;

evaluating one or more frequency characteristics of the biosignal;

determining a sleep stage of the patient, wherein the sleep stage occurs during the sleep state of the patient, the sleep state comprising a plurality of sleep stages; and

associating the one or more frequency characteristics of the biosignal with the sleep stage, wherein the one or more frequency characteristics comprises at least one of a threshold value or a template.