System and method for determining sleep stage

Patent metadata

Field	Value
Publication number	US-11801009-B2
Application number	US-202016846959-A
Country	US
Kind code	B2
Filing date	Apr 13, 2020
Priority date	Sep 19, 2012
Publication date	Oct 31, 2023
Grant date	Oct 31, 2023

Abstract

Methods and apparatus monitor health by detection of sleep stage. For example, a sleep stage monitor ( 100 ) may access sensor data signals related to bodily movement and/or respiration movements. At least a portion of the detected signals may be analyzed to calculate respiration variability. The respiration variability may include one or more of variability of respiration rate and variability of respiration amplitude. A processor may then determine a sleep stage based on one or more of respiration variability and bodily movement, such as with a combination of both. The determination of sleep stages may distinguish between deep sleep and other stages of sleep, or may differentiate between deep sleep, light sleep and REM sleep. The bodily movement and respiration movement signals may be derived from one or more sensors, such as non-invasive sensor (e.g., a non-contact radio-frequency motion sensor or a pressure sensitive mattress).

First claim

The invention claimed is:

1. A method in a controller of a flow generator of respiratory therapy apparatus that is configured to generate a respiratory therapy, the method of the controller comprising:
accessing one or more detected signals comprising movement components of a subject, the movement components including a bodily movement component and a respiration movement component, the one or more detected signals generated by one or more flow sensors;
analysing at least a portion of the detected signals to calculate respiration variability, the respiration variability comprising one or more of variability of respiration rate and variability of respiration amplitude, the analysing including setting a respiration rate stability threshold value depending on a comparison of the variability of a measured respiratory rate signal with a respiration rate threshold value;
generating an indication of sleep stage based on combining the respiration variability and the bodily movement component;
executing a therapy parameter determination process that receives, as input, the generated sleep stage indication; and
setting a treatment operation of the flow generator with an output of the therapy parameter determination process, the setting of the treatment operation being based, at least in part, on the generated sleep stage indication.

2. The method of claim 1 , wherein the bodily movement component comprises one or more general bodily movements comprising turning over, twitching and adjusting position.

3. The method of claim 1 , wherein the therapy parameter determination process receives further input comprising one or more of a measure of ventilation, a measure of inspiratory flow limitation, a measure of a presence of apnea and/or hypopnea, and a measure of a presence of snore.

4. The method of claim 1 , wherein the therapy parameter determination process determines a treatment pressure as a function of the sleep stage.

5. The method of claim 4 , wherein the therapy parameter determination process determines the treatment pressure as a function of measures of one or more of flow limitation, apnea, hypopnea, sleep stage and snore.

6. The method of claim 4 , wherein the therapy parameter determination process determines the treatment pressure based on a target ventilation from a target ventilation determination process.

7. The method of claim 1 , wherein the one or more detected signals further comprise one or more signals generated by one or more non-contact sensors that are configured to transmit sensing waves towards the subject.

8. The method of claim 7 , wherein the one or more non-contact sensors receive a reflected radio-frequency signal from the subject to generate the one or more detected signals.

9. The method of claim 7 , wherein the one or more non-contact sensors comprise an ultrasonic sensor.

10. The method of claim 7 , wherein a sensor of the one or more non-contact sensors comprises a monitor device producing a plurality of signals corresponding to a user who is proximate to the sensor, wherein two of the signals are representative of user motion and two of the signals are representative of user breathing.

11. The method of claim 10 , wherein the controller processes the signals that are representative of user breathing by spectral analysis to determine inband breathing power for each signal.

12. The method of claim 1 , wherein the controller provides feedback to the subject comprising a sequence of the indications of sleep stages over a night.

13. The method of claim 12 , wherein the feedback is in real time and controls one or more environmental factors comprising one or more of ambient temperature, ambient light level, ambient noise and ambient odour.

14. The method of claim 12 , wherein the feedback controls an electronic device comprising a radio, a television or an entertainment device.

15. The method of claim 1 , further comprising detection of a presence or absence of a person.

16. The method of claim 1 , further comprising generating an estimate of power spectral density and calculating respiration rate with the estimate of power spectral density.

17. The method of claim 1 , further comprising, in the controller, evaluating short-term and long-term correlations of respiration rate by detrended fluctuation analysis.

18. The method of claim 1 , wherein the generating of the indication of sleep stage comprises identifying an epoch of deep sleep to distinguish it from other epochs of sleep or wake.

19. The method of claim 1 , wherein the analysing comprises calculating a respiration rate range for each of a number of epochs,
comparing each calculated respiration range with the set respiration rate stability threshold value; and
classifying the epoch as a deep sleep if the calculated respiration range is smaller than the set respiration rate stability threshold value, or otherwise classifying the epoch as light sleep.

20. The method of claim 1 , further comprising adjusting the respiration rate stability threshold value based on estimating signal quality of an input movement signal from a movement sensor.

21. The method of claim 1 , wherein the method comprises classifying periods of sleep as either deep sleep or REM sleep on a basis of the variability of respiration rate during the period.

22. The method of claim 21 , wherein a period of relatively high variation of respiration rate is considered as an indication of a REM sleep period, and a period of relatively low variation of respiration rate is considered to be associated with a state of deep sleep.

23. The method of claim 1 , further comprising extracting breath statistics from a transformed signal, the transformed signal being transformed from the one or more detected signals.

24. The method of claim 23 wherein the extracted breath statistics comprise one or more of a mean of breath interval, a mean of breath amplitude, variation of breath interval and variation of breath amplitude.

25. The method of claim 1 , wherein the indication of sleep stage comprises a series of indications for a plurality of epochs, the series of indications comprising two or more of: a wake stage, a light sleep stage, a deep sleep stage and a rem sleep stage.

26. The method of claim 1 , further comprising generating signals indicative of movement to generate the indication of sleep stage with one or more of a respiratory inductance plethysmography sensor, pressure sensors embedded in a sensor film, a sensor mattress, a bioimpedance measurement system, an end-tidal CO2 respiratory monitor, and an optical sensor.

27. The method of claim 1 , wherein a breath analyzer of the controller detects peaks and zero crossings in an input signal.

28. The method of claim 27 , wherein the breath analyzer determines breath interval and amplitude for each breath.

29. Apparatus for generating a respiratory therapy for a subject comprising:
a flow generator configured to generate a respiratory therapy;
a controller configured to control operation of the flow generator; and
one or more flow sensors configured to generate one or more signals comprising movement components of a subject, the movement components including a bodily movement component and respiration component;
wherein the controller comprises a processor configured to:
access the one or more generated signals;
analyse at least a portion of the one o

Assignees

• Resmed Sensor Tech Ltd

Inventors

• Mcdarby Gareth
• O'Hare Emer
• Phillips Paul
• Heneghan Conor
• Murray Trevor

Classifications

• A61B5/4812 Primary

  Detecting sleep stages or cycles · CPC title

• A61B5/05

  Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves (measuring movement of the entire body or parts thereof A61B5/11; detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof A61B5/24) · CPC title

• A61B5/0507

  using microwaves or terahertz waves · CPC title

• A61B5/0816

  Measuring devices for examining respiratory frequency (measuring frequency of electric signals G01R23/00) · CPC title

• A61B5/113

  occurring during breathing · CPC title