METHOD AND APPARATUS FOR MONITORING BREATHING CYCLE BY FREQUENCY ANALYSIS OF AN ACOUSTIC DATA STREAM

• US 20110288431A1
• Filed: 11/16/2009
• Published: 11/24/2011
• Est. Priority Date: 11/17/2008
• Status: Active Grant

• Current Assignee: University Health Network
• Original Assignee: Toronto Rehabilitation Institute
• Inventors: Fernie, Geoffrey Roy, Bradley, T. Douglas, Alshaer, Hisham
• Granted Patent: US 9,232,910 B2
• Time in Patent Office: Days
• US Class Current: 600/534
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 5/0803 Recording apparatus specially adapted therefor
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 7/003 Detecting lung or respiration noise
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R

Abstract

Disclosed herein is a method and apparatus for monitoring, identifying and determining the breathing cycle of an individual from processed acoustic signal waveform data. The breathing sounds of an individual are recorded using a microphone and digitized such that the breathing sounds may be plotted. The data is segmented and transformed to form a plurality of segments representative of a frequency spectrum. The frequency spectrum data is transformed so as to produce magnitude bins and the sum of lower magnitude bins and the sum of higher magnitude bins are determined in a sampling of segments. A Bands Ratio is determined from the sum of lower magnitude bins and the sum of higher magnitude bins in the sampling of segments. A first bands ratio is then determined within a given segment and compared to the mean bands ratio. If the first bands ratio of the given segment is greater than the mean bands ratio by at least a predetermined multiplier, the given segment is labeled as inspiration. If the first bands ratio of the given segment is less than the mean bands ratio by at least a predetermined multiplier, the given segment is labeled as expiration.

Claims

1. A method for processing acoustic signal data for use in monitoring the breathing cycle of an individual comprising:

collecting and generating a data set representative of an acoustic data stream plot of wave amplitude versus time, the data set originating from breathing sounds of an individual;

segmenting the acoustic data stream plot into segments, each spanning a predetermined time period;

transforming the acoustic data so as to produce a frequency spectrum in each segment;

transforming the frequency spectrum in each segment so as to produce a plurality of magnitude bins;

identifying a sample including a plurality of segments and determining therein a sum of lower frequency magnitude bins within a predetermined lower frequency range and a sum of higher frequency magnitude bins within a predetermined higher frequency range;

dividing the sum of higher frequency magnitude bins in the sampling by the sum of lower frequency magnitude bins so as to produce a mean bands ratio;

determining a sum of lower frequency magnitude bins and a sum of higher frequency magnitude bins within a given segment;

dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude bins within said given segment so as to produce a first bands ratio; and

determining if said first bands ratio is greater or less than said mean bands ratio by at least a predetermined multiplier so as to provide an indication of said breathing cycle.

2. The method as defined in claim 1, wherein the predetermined multiplier is at least 1.

3. The method as defined in claim 1, the predetermined multiplier being greater than 1.5.

4. The method as defined in claim 1, the predetermined multiplier being greater than 2.

5. The method as defined in any one of the preceding claims, said first bands ratio being labeled as inspiration if the first bands ratio is greater than the mean bands ratio by at least the predetermined multiplier.

6. The method as defined in any one of the preceding claims, said first bands ratio being labeled as expiration if the first bands ratio is less than the mean bands ratio by at least the predetermined multiplier.

7. The method as defined in any one of the preceding claims, the breathing sounds being collected for a period of time of from about 10 seconds to about 8 hours.

8. The method as any one of claims 1 to 6, the breathing sounds being collected for a period of time of from about 10 seconds to about 20 minutes.

9. The method as defined in any one of claims 1 to 6, the breathing sounds being collected for a period of time of from about 10 seconds to about 25 seconds.

10. The method as defined in any one of claims 1 to 6, the breathing sounds being collected for a period of time of greater than 20 minutes.

11. The method as defined in any one of claims 1 to 6, wherein the breathing sounds are collected for a period of time about 25 seconds.

12. The method as defined in any one of the preceding claims, each of the segments representing a time period of from about 50 ms to about 1 second.

13. The method as defined in any one of claims 1 to 11, each of the segments representing a time period of from about 100 ms to about 500 ms.

14. The method as defined in any one of claims 1 to 11, each of the segments representing a time period of about 200 ms.

15. The method as defined in any one of the preceding claims, the lower frequency range being from about 0 Hz to about 500 Hz.

16. The method as defined in any one of claims 1 to 14 the lower frequency range being from about 10 Hz to about 400 Hz.

17. The method as defined in any one of the preceding claims, the higher frequency range being from about 500 Hz to about 25,000 Hz.

18. The method as defined in any one of claims 1 to 16, the higher frequency range being from about 400 Hz to about 1,000 Hz.

19. The method as defined in any one of the preceding claims, the sampling of the plurality of segments being selected from the recording randomly.

20. The method as defined in any one of claims 1 to 18, the sampling of the plurality of segments including substantially all of the segments in the recording.

21. The method as defined in claim 1, the mean bands ratio being determined from at least two segments preceding the first bands ratio segment.

22. The method as defined in any of the preceding claims, further comprising, before the generating step, collecting the breathing sounds with at least one microphone.

23. The method as defined in claim 22, the audio collecting of breathing sounds of an individual comprising airflow sounds resultant from the individual'"'"'s breathing applying air pressure to a diaphragm of the microphone.

24. The method as defined in claim 22, the collecting of breathing sounds of an individual comprising breathing sounds resultant from the breathing of the individual being recorded by the microphone.

25. The method as defined in claim 22, the collecting of breathing sounds of an individual comprising airflow sounds resultant from the individual'"'"'s breathing applying air pressure to a diaphragm of the microphone and actual breathing sounds resultant from the individual being recorded by the microphone.

26. The method as defined in claim 22, wherein the collection of breathing sounds is digitized in real-time.

27. The method as defined in claim 22, wherein the processing of the collected waveform data is performed in real-time.

28. The method as defined in claim 22, wherein the breathing sounds are collected by at least a first microphone and a second microphone;

the first microphone operable to collect breathing sounds and airflow sounds resultant from the individual'"'"'s breathing applying air pressure to a diaphragm of the first microphone; and

the second microphone operable to collect breathing sounds of the individual.

29. The method as defined in claim 28, further comprising, before the generating step, filtering acoustic data of an output representative of second microphone from the acoustic signal data representative of an output of the first microphone so as to provide an acoustic data stream of an audio recording of substantially airflow sounds of the individual.

30. The method as defined in claim 22, the at least one microphone being provided in a structure including one or more openings of sufficient size to minimize airflow resistance and be substantially devoid of dead space.

31. An apparatus for transforming acoustic signal data breathing sounds into a graphical representation indicative of breathing cycle phases including inspiration phases and expiration phases comprising:

at least one microphone for collecting acoustic signal data resultant from the breathing of an individual during a given time period;

an acoustic signal data digitizing module for digitizing the acoustic signal data to produce an acoustic data stream plot representative of wave amplitude versus time;

at least one processor operable for receiving the acoustic data stream plot, the processor configured for;

segmenting the acoustic data stream plot into a plurality of segments of a predetermined length of time;

transforming the acoustic data stream in each of the plurality of segments so as to produce a plurality of frequency specta wherein each frequency spectrum is representative of one of the plurality of segments;

transforming each frequency spectrum so as to produce a plurality of magnitude bins in each segment;

determining a sum of lower frequency magnitude bins within a predetermined lower frequency range and a sum of higher frequency magnitude bins within a predetermined higher frequency range within a sampling of the plurality segments;

dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude bins in the sampling so as to produce a mean bands ratio;

determining a sum of lower frequency magnitude bins and a sum of higher frequency magnitude bins within a given segment;

dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude bins within said given segment so as to produce a first bands ratio;

comparing said mean bands ratio to said first bands ratio and determining if said first bands ratio is greater or less than said mean bands ratio by at least a predetermined multiplier so as to determine if said given segment is an inspiration phase or an expiration phase of the breathing cycle; and

an information relay module in communication with the at least one processor for providing the transformed data to an operator as first indicia representing inspiration and expiration.

32. The apparatus as defined in claim 31, further comprising a sensor for sensing respiratory movements of an abdomen or rib region of the individual and generating a signal indicative thereof, the processor being operative to receive the signal and to identify respiratory expansion during inspiration and respiratory contraction during expiration, the information relay being operable to provide data to an operator generated as second indicia representing the respiratory movements.

33. The apparatus as defined in claim 31, the information relay module being provided as a display module for displaying the transformed data as a processed wave amplitude versus time plot;

the inspiration phases being identifiable by rising regions of said processed wave amplitude versus time plot; and

the expiration phases being identifiable by falling regions of said processed wave amplitude versus time plot.

34. The apparatus as defined in claim 31, the information relay module operable so as to provide an operator audio cues representing the inspiration and expiration phases of an individual'"'"'s breathing.

35. The apparatus as defined in claim 31, the information relay module being provided as a display module operable for displaying visual cues representing the inspiration and expiration phases of an individual'"'"'s breathing.

36. The apparatus as defined in claim 31, the information relay module operable so as to provide an operator printed visual indicia representing the inspiration and expiration phases of an individual'"'"'s breathing.

37. The apparatus as defined in claim 31, wherein the breathing sounds are collected by at least a first microphone and a second microphone;

the first microphone operable to collect acoustic signal data breathing sounds and airflow sounds resultant from the individual'"'"'s breathing applying air pressure to a diaphragm of the first microphone; and

the second microphone operable to collect acoustic signal data breathing sounds of the individual.

38. The apparatus as defined in claim 37, wherein the acoustic signal data collected by the second microphone are subtracted from the acoustic signal data collected by the first microphone so as to provide an acoustic signal data recording of substantially airflow sounds of the individual.

39. The apparatus as defined in claim 31, the at least one microphone being provided in a structure including one or more opening sufficient to reduce airflow resistance and be substantially devoid of dead space.

40. An apparatus for transforming acoustic signal data breathing sounds into a graphical representation indicative of breathing cycle phases including inspiration phases and expiration phases comprising:

at least one microphone for collecting acoustic signal data resultant from the breathing of an individual during a given time period;

an acoustic signal data digitizing module for receiving and digitizing sounds via a transducing link from the at least one microphone, the audio signal digitizing module operable to produce an acoustic data stream plot representative of wave amplitude versus time;

a module for segmenting a plurality of adjacent audio samples from the acoustic data stream plot into a plurality of segments of a predetermined length of time;

a module for transforming the acoustic data stream in each of the plurality of segment so as to produce a plurality of frequency spectra wherein each frequency spectrum is representative of one of the plurality of segments;

a module for transforming each frequency spectrum so as to produce a plurality of magnitude bins in each segment;

a module for determining a sum of lower frequency magnitude bins within a predetermined lower frequency range and a sum of higher frequency magnitude bins within a predetermined higher frequency range within a sampling of the plurality segments;

a module for dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude bins in the sampling of the plurality of segments so as to produce a mean bands ratio;

a module for determining a sum of lower frequency magnitude bins and a sum of higher frequency magnitude bins within a given segment;

a module for dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude within said given segment so as to produce a first bands ratio;

a module for comparing said mean bands ratio to said first bands ratio and determining if said first bands ratio is greater or less than said mean bands ratio by at least a predetermined multiplier so as to determine if said given segment is an inspiration phase or an expiration phase of the breathing cycle; and

an information rely module in communication with the module for comparing said mean bands ratio to said first bands ratio for providing the transformed data to an operator as indicia representing inspiration and expiration.

41. A computer implemented apparatus for transforming acoustic signal data breathing sounds into a graphical representation indicative of breathing cycle phases including inspiration phases and expiration phases comprising:

at least one microphone for collecting acoustic signal data breathing sounds resultant from the breathing of an individual during a given time period;

an acoustic signal data digitizing module for receiving and digitizing sounds via a transducing link from the at least one microphone, the audio signal digitizing module operable to produce an acoustic data stream plot representative of a wave amplitude versus time;

at least one processor operable for receiving the acoustic data stream plot, the processor configured for;

segmenting a plurality of adjacent audio samples from the acoustic data stream plot into a plurality of segments of a predetermined length of time;

transforming the acoustic data stream in each of the plurality of segments so as to produce a plurality of frequency spectra wherein each frequency spectrum is representative of one of the plurality of segments;

transforming each frequency spectrum so as to produce a plurality of magnitude bins in each segment;

determining a sum of lower frequency magnitude bins within a predetermined lower frequency range and a sum of higher frequency magnitude bins within a predetermined higher frequency range within a sampling of the plurality segments;

dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude bins in the sampling of the plurality of segments so as to produce a mean bands ratio;

determining a sum of lower frequency magnitude bins and a sum of higher frequency magnitude bins within a given segment;

dividing the sum of higher frequency magnitude bins by the sum of lower frequency magnitude bins within said given segment so as to produce a first bands ratio;

comparing said mean bands ratio to said first bands ratio and determining if said first bands ratio is greater or less than said mean bands ratio by at least a predetermined multiplier so as to determine if said given segment is an inspiration phase or an expiration phase of the breathing cycle; and

an information rely module in communication with the at least one processor for providing the transformed data to an operator as indicia representing inspiration and expiration.

42. A method for processing acoustic signal data for use in monitoring a breathing cycle of an individual comprising:

generating a data set representative of an acoustic data stream plot of wave amplitude versus time, the data set originating from breathing sounds of an individual;

transforming the acoustic data stream plot to yield at least one relatively higher frequency spectral characteristic and at least one relatively lower frequency spectral characteristic;

determining a proportional value of the relatively higher frequency spectral characteristics to the relatively lower frequency spectral characteristics; and

generating at least first output indicative of an inspirational breathing phase according to a first range of the proportional value and/or at least one second output indicative of an expirational breathing phase according to a second range of the second proportional value.

43. A device for processing acoustic signal data for use in monitoring a breathing cycle of an individual comprising:

means for generating a data set representative of an acoustic data stream plot of wave amplitude versus time, the data set originating from breathing sounds of an individual;

means for transforming the acoustic data stream plot to yield at least one relatively higher frequency spectral characteristic and at least one relatively lower frequency spectral characteristic;

means for determining a proportional value of the relatively higher frequency spectral characteristic to the relatively lower frequency spectral characteristic; and

means for generating at least first output indicative of an inspirational breathing phase according to a first range of the proportional value and/or at least one second output indicative of an expirational breathing phase according to a second range of the second proportional value.

44. A method for processing acoustic signal data for use in monitoring inspirational and expirational phases of a breathing cycle of an individual comprising:

generating a data set representative of an acoustic data stream plot of wave amplitude versus time, the data set originating from breathing sounds of an individual;

transforming the acoustic data stream plot to yield inspirational spectral data for at least one inspirational phase and expirational spectral data for at least one expirational phase; and

characterizing the shape of the inspirational and expirational frequency spectra for tracking breathing activities to identify inspirational and expirational breathing phases in subsequent breathing cycles.

45. A device for processing acoustic signal data for use in monitoring inspirational and expirational phases of a breathing cycle of an individual comprising:

means for generating a data set representative of an acoustic data stream plot of wave amplitude versus time, the data set originating from breathing sounds of an individual;

means for transforming the acoustic data stream plot to yield inspirational spectral data for at least one inspirational phase and expirational spectral data for at least one expirational phase; and

means for characterizing the shape of the inspirational and expirational frequency spectra for tracking breathing activities to identify inspirational and expirational breathing phases in subsequent breathing cycles.