Acoustic sensing for respiration detection

Patent metadata

Field	Value
Publication number	US-11931578-B2
Application number	US-202117228593-A
Country	US
Kind code	B2
Filing date	Apr 12, 2021
Priority date	Apr 10, 2020
Publication date	Mar 19, 2024
Grant date	Mar 19, 2024

Abstract

The disclosure provides systems and methods for treating obstructive sleep apnea using an acoustic sensor configured to detect acoustic sounds generated by the heart and lungs. Sensory data from the acoustic sensor is used by an implanted stimulation system to determine when to deliver electrical stimulation to a nerve which innervates an upper airway muscle, such as the hypoglossal nerve, to treat sleep apnea.

First claim

What is claimed is:

1. A system for treating a subject, comprising:
at least one acoustic sensor configured to detect a plurality of acoustic signals generated by the subject;
at least one inertial sensor configured to detect an inertial signal corresponding to a movement and/or an orientation of the subject; and
a stimulator comprising:
a stimulation system configured to deliver stimulation to a nerve which innervates an upper airway muscle; and
a controller coupled to the stimulation system, to the at least one acoustic sensor, and to the at least one inertial sensor;
wherein the controller is configured to
determine a respiratory cycle of the subject based on one or more of the detected plurality of acoustic signals, wherein said determination comprises identifying an inspiratory portion of the respiratory cycle using one or more signal processing operations that introduce a linear phase delay of between 400 to 600 ms;
determine whether the subject is asleep based on one or more of the detected plurality of acoustic signals and the inertial signal, and to
cause the stimulation system to stimulate the nerve based on the determined respiratory cycle while the subject is asleep.

2. The system of claim 1 , wherein the stimulation system is configured to treat obstructive sleep apnea.

3. The system of claim 1 , wherein the acoustic sensor is a microphone capable of detecting acoustic signals generated by a heart and/or lungs of the subject.

4. The system of claim 1 , wherein the acoustic sensor is implanted in the subject and
a) positioned within a chest wall or neck of the subject, within an outer housing that contains the stimulation system or a portion thereof;
b) positioned at or in proximity to a distal end of a lead connecting the stimulation system to the nerve which innervates an upper airway muscle; and/or
c) positioned within or in proximity to a housing containing the stimulator.

5. The system of claim 1 , wherein the stimulation system is configured to deliver stimulation to the nerve which innervates an upper airway muscle using an array of electrodes, and the acoustic sensor is positioned within or in proximity to the array of electrodes.

6. The system of claim 1 , wherein the stimulation system is configured to deliver stimulation to the nerve which innervates the upper airway muscle using a lead connected to one or more electrodes, and the acoustic sensor is positioned within or in proximity to the lead.

7. The system of claim 1 , wherein the system further comprises an internal sensor configured to generate a second signal corresponding to movement of a thoracic or abdominal cavity of the subject during respiration; and the controller is further coupled to the internal sensor and configured to measure the respiratory cycle of the subject based on the second signal.

8. The system of claim 1 , further comprising at least one low pass filter, high pass filter or bandpass filter.

9. The system of claim 8 , wherein the at least one low pass filter, high pass filter or bandpass filter is implemented in hardware or software.

10. The system of claim 1 , further comprising at least one low pass filter configured to have a frequency cut-off of 0.5 Hz or lower.

11. The system of claim 1 , further comprising at least one low pass filter configured to have a frequency cut-off of 2 kHz or lower.

12. The system of claim 1 , further comprising at least one high pass filter configured to have a frequency cut-off of 100 Hz.

13. The system of claim 1 , further comprising at least one bandpass filter configured to have a low frequency cut-off of 2 Hz or below, and a high frequency cut-off of 50 Hz or above.

14. The system of claim 1 , further comprising:
a) at least one analog low pass filter or high pass filter; and/or
b) at least one digital low pass filter or high pass filter;
wherein the controller is configured to cause the stimulation system to stimulate the nerve during an inspiratory portion of respiration; during an expiratory portion of respiration; or during the inspiratory portion and the expiratory portion of respiration.

15. The system of claim 1 , wherein the one or more signal processing operations comprise a Hilbert transform.

16. A method of treating obstructive sleep apnea in a subject comprising:
acquiring inertial data from an inertial sensor implanted in the subject, wherein the inertial data comprises one or more signals corresponding to a movement or an orientation of the subject;
acquiring sensory data from an acoustic sensor implanted in the subject, wherein the sensory data comprises acoustic signals generated by a heart and/or lungs of the subject;
generating a filtered signal by filtering the sensory data using at least one low pass filter and at least one high pass filter, or at least one bandpass filter;
extracting a signal envelope from the filtered signal;
extracting a respiratory waveform corresponding to a respiratory cycle of the subject, by applying a second low pass filter to the extracted signal envelope, wherein the second low pass filter comprises a filter that introduces a linear phase delay of between 400 to 600 ms;
determining whether the subject is asleep based on the inertial data and the extracted respiratory waveform; and
stimulating a nerve innervating an upper airway muscle of the subject, wherein stimulation is applied while the subject is asleep and after detecting at least one stable respiratory cycle following an apneic event, wherein apneic events are determined based on the extracted respiratory waveform.

17. The method of claim 16 , wherein the signal envelope is extracted from the filtered signal using a Hilbert transform.

18. The method of claim 16 , wherein the sensory data is filtered using a low pass filter and a high pass filter.

19. The method of claim 16 , wherein the sensory data is filtered using at least one bandpass filter.

20. The method of claim 16 , wherein the low pass filter is configured to reduce acoustic signals generated by snoring sounds produced by the subject, and the high pass filter is configured to reduce acoustic signals generated by the subject's heart.

21. The method of claim 16 , wherein the low pass filter used to extract the respiratory waveform has a frequency cut-off of 0.1 to 1 Hz.

22. The method of claim 16 , wherein the low pass filter used to extract the respiratory waveform has a frequency cut-off of 2 Hz or below.

23. The method of claim 16 , wherein the bandpass filter is configured to have a low frequency cut-off of 2.0 Hz or below, and a high frequency cut-off of 50 Hz or above.

24. The method of claim 16 , further comprising:
acquiring a second set of sensory data from an implanted sensor corresponding to movement of the thoracic or abdominal cavity of the subject during respiration; and
wherein apneic events are determined based on the extracted respiratory waveform and the second set of sensory data.

25. The system of claim 1 , wherein the one or more signal processing operations comprise filtering using a low pass Bessel filter.

26. The method of claim 16 , wherein the second low pass filter comprises a Bessel filter.

Assignees

• The Alfred E Mann Foundation For Scient Research

Inventors

• Shelton Brian M
• Elyahoodayan Sahar
• Suri Harshit R

Classifications

• A61N1/3611 Primary

  Respiration control (stimulating respiratory organs A61N1/3601) · CPC title

• A61B7/003

  Detecting lung or respiration noise · CPC title

• A61N1/05

  for implantation or insertion into the body, e.g. heart electrode (A61N1/06 takes precedence) · CPC title

• A61N1/37217

  characterised by the communication link, e.g. acoustic or tactile · CPC title

• A61N1/3787

  from an external energy source · CPC title