Method of analyzing sleep disorders

• US 5,961,447 A
• Filed: 01/21/1997
• Issued: 10/05/1999
• Est. Priority Date: 04/21/1994
• Status: Expired due to Fees

• Current Assignee: SNAP Diagnostics, LLC
• Original Assignee: SNAP Laboratories, LLC
• Inventors: Raviv, Gil, Weingarten, Charles Z.
• Primary Examiner(s): Lacyk, John P.
• Application Number:
  US08/792,931
• Time in Patent Office: 987 Days
• Field of Search: 600/300, 600/528, 600/529, 600/586, 600/587, 600/483, 600/484, 128/848
• US Class Current: 600/300
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• 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 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise

Abstract

The invention provides a method of detecting, analyzing sleep disorders. The method includes the step of monitoring sound produced by a sleeping subject through a sensor proximate the sleeping subject and continuously recording the monitored sound. The method further includes identifying snoring within the recorded sound and analyzing the identified snoring to localize upper airway structural sources of snoring.

Claims

1. A method of detecting and analyzing sleep disorders comprising the steps of:

monitoring sound produced by a sleeping subject;

digitizing the monitored sound at a sampling rate sufficiently high and for periods of sufficient duration to capture apnea and snoring information;

recording at least a portion of the digitized monitored sound;

identifying at least one of snoring and apnea within the recorded sound; and

analyzing the identified snoring and/or apnea to locate upper airway structural sources generating the snoring and/or the apnea.

2. The method as in claim 1 further comprising the step of displaying portions of the recorded sound and listening to selected portions selected based upon the displayed portions.

3. The method as in claim 1 further including the step of searching the recorded sound for temporal gaps exceeding an apnea threshold and upon detecting such a temporal gap outputting an indication of apnea.

4. The method as in claim 1 further including the step of analyzing the recorded sound using frequency domain methods.

5. The method as in claim 1 wherein the digitizing is performed for multiple periods each of which is substantially less than the entire duration that the sleeping subject is asleep.

6. The method of claim 2 further comprising the step of allocating a separate recording channel for each of at least two microphones for continuously recording the monitored sound.

7. The method as in claim 1 further comprising the step of recording physiological data of the sleeping subject including at least one parameter from the group including blood oxygen desaturation level, body position, respiration effort, and video image of the sleeping subject.

8. The method as in claim 1 further comprising the step of using two separate microphones, one proximate the nose and one proximate the mouth and ruling out the nose or mouth of the sleeping subject as the source of the snoring or breathing when the sound from the respective microphone is negligible.

9. The method as in claim 2 wherein the step of recording further comprises the step of reducing the digital monitored sound and storing the result as a reduced file and wherein the step of displaying comprises displaying the reduced file.

10. The method as in claim 1 wherein the step of monitoring the sound of the sleeping subject further comprises the step of detecting an audio signal from the sleeping subject through use of at least one cordless microphone.

11. The method as in claim 1 wherein the step of analyzing the monitored sound for respiratory system structural sources of snoring further comprises the step of generating a raw data file and a reduced file.

12. The method as in claim 1 further comprising the step of automatically identifying a data interval of the recorded sound as breathing by comparison with an amplitude breathing threshold and temporal breathing threshold.

13. The method as in claim 12 further comprising the step of automatically identifying a data interval of the recorded sound as snoring by evaluating a frequency content of the spectrum in the data interval and comparison with a sound threshold.

14. The method as in claim 1 further comprising the step of analyzing for structural sources of snoring while the monitored sound is recorded through use of a processor attached to the recorder.

15. The method of claim 4 further comprising the step of using a plurality of temporal sizes of data for frequency analyzing the snoring.

16. The method of claim 11 further comprising the step of tabulating and outputting a number indicating total velum, non-velum and mixed snore during a time interval.

17. The method of claim 1 further comprising the step of comparing the monitored sound with a first recording threshold level and deactivating the recorder when the monitored sound exceeds the first threshold level for at least a first time period and otherwise reactivating recording when the monitored sound does not exceed the threshold for a second time period.

18. The method of claim 1 further comprising the step of reducing the digitized monitored sound and storing the result as a reduced data file.

19. The method of claim 1 further comprising the step of reducing the digitized monitored sound and storing the reduced data in conjunction with selected portions of the digitized monitored sound.

20. The method of claim 3 wherein the step of searching comprises electronically processing the recorded sound to automatically detect temporal gaps exceeding an apnea threshold, and automatically generating an indication of apnea detection upon detecting such a temporal gap.

21. A method of detecting and analyzing sleep disorders comprising the steps of:

monitoring sound produced by a sleeping subject; and

identifying snoring within the monitored sound;

identifying a soft palate of the sleeping subject as a source of the snoring when the frequency content of the snoring is substantially a fundamental frequency of between a predetermined upper and lower frequency threshold and harmonics of the fundamental frequency.

22. The method of claim 21 further comprising identifying non-velum sources of the sleeping subject as the source of the snoring when the frequency content of the snoring is substantially of a fundamental frequency greater than an upper threshold frequency and harmonics of the fundamental frequency.

23. The method of claim 21 further comprising identifying one of pharyngal and nose as the source of snoring when a fourier transform of the recorded sound indicates a diffuse sound source.

24. The method of claim 23 further comprising recording at least a portion of the monitored sound.

25. The method of claim 23 further comprising identifying apnea events by electronically processing the monitored sound to automatically detect temporal gaps exceeding an apnea threshold.

26. A method for use in detecting and analyzing sleep disorders comprising the steps of:

monitoring sound produced by a sleeping subject including a recording at least a portion of the monitored sound;

comparing the monitored sound with a first recording threshold level; and

deactivating recording when the monitored sound exceeds the first threshold level for at least a first time period.

27. The method of claim 26 further comprising reactivating recording when the monitored sound does not exceed the threshold for a second time period.

28. The method of claim 27 further comprising comparing the monitored sound with a second threshold and reactivating the recorder when the monitored sound exceeds the first and second thresholds for a third time period.

29. The method of claim 26 wherein the step of monitoring comprises providing a buffer to continuously buffer a short segment of monitored sound.

30. A method of detecting and analyzing sleep disorders comprising the steps of:

monitoring sound produced by a sleeping subject;

electronically processing the monitored sound to automatically identify breathing events;

electronically processing the monitored sound to automatically detect temporal gaps in the breathing events to identify apnea events;

electronically processing the monitored sound to automatically identify snoring events.

31. The method of claim 30 further comprising automatically identifying an interval of the monitored sound as breathing by comparison with an amplitude breathing threshold and a temporal breathing threshold.

32. The method of claim 30 further comprising automatically determining the duration and a relative maximum for breathing events.

33. The method of claim 30 further comprising generating a reduced data file from raw data of the monitored sound and using the reduced data file to perform at least a portion of the electronic processing.

34. The method of claim 30 wherein automatically identifying snoring events further comprises identifying local maxima within the monitored sound.

35. The method of claim 30 further comprising automatically identifying an interval of the monitored sound as snoring by evaluating frequency content of the spectrum of the interval and by comparison with a snoring threshold.

36. The method of claim 34 wherein automatically identifying snoring events further comprises performing fourier transforms based on the local maxima.

37. A method for use in detecting and analyzing sleep disorders comprising the steps of:

monitoring sound produced by a sleeping subject;

storing at least a portion of the monitored sound;

displaying at least portions of the stored monitored sound or of data derived from the monitored sound;

listening to selected portions of the displayed portions.

38. The method of claim 37 wherein at least one predetermined classification of breathing event is apnea.

39. The method of claim 37 wherein at least one predetermined classification of breathing event is snoring.

40. The method of claim 38 further comprising listening to selected portions of the displayed portions selected based upon the displayed portions to identify snoring events.

41. The method of claim 38 wherein the monitored sound in digitized and reduced to form a reduced data file, and the step of displaying comprises displaying portions of the reduced data file.

42. The method of claim 37 wherein the step of storing further comprises storing portions of the monitored sound determined using a sound threshold.

43. The method of claim 42 wherein the sound threshold is at least one of an upper volume threshold to identify periods of loud sound levels and a low volume threshold to identify periods of low sound levels.

44. The method of claim 37 wherein the step of listening comprises listening to portions selected automatically.