METHOD, SYSTEM AND DEVICE FOR SLEEP STAGE DETERMINATION USING FRONTAL ELECTRODES

• US 20080154111A1
• Filed: 12/22/2006
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Natus Medical Incorporated
• Original Assignee: Natus Medical Incorporated
• Inventors: Weinroth, Aaron Phillip, Wu, Jianping, Kurtz, Ronald Leon
• Granted Patent: US 8,244,340 B2
• Time in Patent Office: Days
• US Class Current: 600/383
• CPC Class Codes: A61B 5/291 for electroencephalography [EEG]
• CPC Class Codes: A61B 5/296 for electromyography [EMG]
• CPC Class Codes: A61B 5/398 Electrooculography [EOG], e.g. detecting nystagmus; Electroretinography [ERG]
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: A61B 5/6814 Head

Abstract

The described embodiments relate generally to methods, systems and devices for sleep stage determination using frontal electrodes. Certain embodiments relate to a system for sleep stage determination comprising a sensing unit and a processing unit. The sensing unit is positioned over a forehead area of a patient and has first, second and third electrodes for positioning at locations on or adjacent the forehead area for detecting electrical potentials of a human head. The processing unit is coupled to the sensing unit for receiving biological signals corresponding to the detected electrical potentials and processing the biological signals to determine a sleep stage of the patient. The processing of the biological signals is based on a plurality of rules.

Claims

1. A system for sleep stage determination, comprising:

a sensing unit for positioning over a forehead area of a head of a patient, the sensing unit having first, second and third electrodes for positioning at locations on or adjacent the forehead area for detecting electrical potentials of a human head;

a processing unit in communication with the sensing unit for receiving biological signals corresponding to the detected electrical potentials and processing the biological signals to determine a sleep stage of the patient, the processing being based on a plurality of rules.

2. The system of claim 1, wherein the sensing unit comprises a flexible member having the first, second and third electrodes located thereon.

3. The system of claim 2, wherein the first electrode is located on the flexible member for positioning adjacent a nasion area of the head.

4. The system of claim 2, wherein the second and third electrodes are located on the flexible member for positioning over opposed lateral forehead portions.

5. The system of claim 1, wherein one of the first, second and third electrodes acts as a reference electrode.

6. The system of claim 2, wherein conductors are formed on the flexible member for electrically coupling the first, second and third electrodes to an output connector coupled to the processing unit.

7. The system of claim 2, further comprising a fourth electrode located on the flexible member intermediate the second and third electrodes for positioning over a central forehead portion.

8. The system of claim 4, wherein the second and third electrodes are located on the flexible member for positioning higher on the forehead than Fp1 and Fp2 electrode positions.

9. The system of claim 7, wherein the fourth electrode is located on the flexible member for positioning above the first electrode.

10. The system of claim 9, wherein the first and fourth electrodes are located on the flexible member for positioning along a vertical center line of the head.

11. The system of claim 9, wherein the fourth electrode is located on the flexible member for positioning lower on the forehead than a Fz electrode position.

12. The system of claim 7, wherein the fourth electrode acts as a reference electrode.

13. The system of claim 4, wherein the second and third electrodes are located on the flexible member for positioning laterally beyond respective Fp1 and Fp2 electrode positions.

14. The system of claim 7, wherein the second, third and fourth electrodes are positioned along a line.

15. The system of claim 4, wherein the first, second and third electrodes are positioned in a triangular configuration.

16. The system of claim 15, wherein the triangular configuration is an isosceles triangular configuration.

17. The system of claim 7, wherein the first, second, third and fourth electrodes are positioned in one of a T-shaped, cross-shaped and Y-shaped configuration.

18. The system of claim 6, wherein the conductors comprise a printed flexible material.

19. The system of claim 4, wherein the second and third electrodes have a separation of 70 to 110 mm.

20. The system of claim 19, wherein the separation is 80 to 100 mm.

21. The system of claim 20, wherein the separation is about 90 mm.

22. The system of claim 7, wherein the first and fourth electrodes have a separation of 35 to 55 mm.

23. The system of claim 22, wherein the separation is 40 to 50 mm.

24. The system of claim 23, wherein the separation is about 44 mm.

25. The system of claim 1, further comprising a data store associated with the processing unit for storing computer program instructions which, when executed by the processing unit, cause the processing unit to determine the sleep stage.

26. The system of claim 1, wherein the processing unit comprises a signal conditioning unit for receiving the detected electrical potentials, conditioning the electrical potentials to generate the biological signals and providing the biological signals to a processor within the processing unit.

27. The system of claim 25, wherein the plurality of rules are stored in the data store.

28. The system of claim 1, wherein the plurality of rules are empirically derived based on correlation of physiological conditions with particular biological signals or signal patterns.

29. The system of claim 6, wherein the output connector is formed at an end of a connector limb of the flexible member.

30. The system of claim 1, wherein the electrical potentials correspond to at least one of EEG, EOG and EMG signals.

31. The system of claim 1, further comprising a pre-processing unit coupled to the sensing unit for conditioning the detected electrical potentials.

32. The system of claim 31, wherein the pre-processing unit is comprised in the processing unit.

33. The system of claim 31, wherein the pre-processing unit comprises a wireless transmitter for wirelessly transmitting the biological signals to a receiver of the processing unit.

34. The system of claim 33, wherein the wireless transmitter is a low-power, short-range transmitter.

35. The system of claim 1, wherein the first, second and third electrodes are removably attachable to the sensing unit.

36. The system of claim 2, wherein the flexible member comprises a flexible plastic substrate.

37. The system of claim 2, wherein the flexible member comprises a woven material.

38. The system of claim 1, further comprising one or more sensors coupled to the processing unit and located away from the head for detecting movement of a body of the patient.

39. The system of claim 38, wherein the one or more sensors comprise one or more accelerometers.

40. The system of claim 38, wherein the one or more sensors comprise one or more electromyographic sensors.

41. A method of sleep stage determination, comprising:

receiving electrical potentials corresponding to biological signals from an electrode assembly positioned over a head of a patient;

processing the biological signals to determine EEG signals, EOG signals and EMG signals; and

determining a sleep stage of the patient based on the EEG signals, the EOG signals and the EMG signals and a plurality of rules.

42. The method of claim 41, wherein the rules are based on empirically derived correlations of EEG, EOG and EMG signal activity with one or more stages of sleep.

43. The method of claim 41, wherein the electrode assembly comprises first, second and third electrodes positioned at locations on or adjacent the forehead area, the first electrode being positioned adjacent a nasion area of the head and the second and third electrodes being positioned over respective laterally opposed forehead areas.

44. The method of claim 43, wherein the second and third electrodes are positioned above and laterally beyond respective Fp1 and Fp2 positions.

45. The method of claim 41, further comprising, prior to the step of receiving, positioning a sensing unit comprising the frontal electrode assembly over the forehead area, the sensing unit being configured to sense electrical potentials corresponding to the biological signals.

46. The method of claim 41, wherein the sleep stage is determined on an epoch by epoch basis.

47. The method of claim 46, wherein for an epoch, the step of determining includes evaluating the EEG signals, the EOG signals and the EMG signals received during the epoch according to the plurality of rules and assigning a sleep stage categorization to the epoch.

48. The method of claim 47, wherein the step of determining includes evaluating the EEG signals, the EOG signals and the EMG signals received during a plurality of epochs according to the plurality of rules and assigning a sleep stage categorization to the epoch.

49. The method of claim 47, wherein the step of determining is based on previous undecided epochs and last determined epochs and the plurality of rules.

50. The method of claim 41, further comprising receiving further electrical potentials corresponding to body movement of the patient, wherein the determining is also based on the further electrical potentials.

51. The method of claim 50, further comprising positioning one or more body movement sensors in relation to a body of the patient away from the head to provide the further electrical potentials.

52. The method of claim 51, wherein the one or more sensors comprise one or more accelerometers.

53. The method of claim 51, wherein the one or more sensors comprise one or more electromyographic sensors.

54. Computer readable storage storing computer program instructions which, when executed by a computer processor, cause the computer processor to perform the method of:

receiving electrical potentials corresponding to biological signals from an electrode assembly positioned over a head of a patient;

processing the biological signals to determine EEG signals, EOG signals and EMG signals; and

determining a stage of sleep of the patient based on the EEG signals, the EOG signals and the EMG signals and a plurality of rules.