Phonospirometry for non-invasive monitoring of respiration
First Claim
1. A method for obtaining a volume of respiration signal from a sound signal representing respiration, the method comprising:
- detecting respiration start/stop;
comparing an intensity of said sound signal to a threshold to determine whether said sound signal intensity is sufficiently strong with respect to background noise so as to provide a reliable measure of tracheal flow;
transforming said sound signal to a flow signal;
interpolating values for said flow signal when said sound signal intensity is below said threshold; and
integrating said flow signal and said interpolated values of said flow signal over at least one of an inspiration cycle and an expiration cycle to obtain a volume of breath signal for said at least one cycle.
5 Assignments
0 Petitions
Accused Products
Abstract
To compensate for the poor signal-to-noise ratio when transforming a patient tracheal sound signal into a respiration flow signal, the transformed signal is used when the sound signal is above a threshold, and interpolated values are used when the sound signal is below the threshold. A volume of breath signal is reliably obtained. Respiration start/stop is detected either by analyzing the sound signal or by physical measurement of the patient. A wearable device incorporating the sound signal processing method can provide an immediate indication or alarm when the volume of breath signal indicates a condition requiring medical attention.
-
Citations
20 Claims
-
1. A method for obtaining a volume of respiration signal from a sound signal representing respiration, the method comprising:
-
detecting respiration start/stop;
comparing an intensity of said sound signal to a threshold to determine whether said sound signal intensity is sufficiently strong with respect to background noise so as to provide a reliable measure of tracheal flow;
transforming said sound signal to a flow signal;
interpolating values for said flow signal when said sound signal intensity is below said threshold; and
integrating said flow signal and said interpolated values of said flow signal over at least one of an inspiration cycle and an expiration cycle to obtain a volume of breath signal for said at least one cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
firstly interpolating said flow signal during inspiration from a point of detecting said respiration start/stop at which said flow is determined to be zero until said sound signal intensity reaches said threshold and has a value determined by said transforming; and
secondly interpolating said flow signal at an end of said inspiration cycle as said sound signal intensity drops below said threshold at an end of inspiration and a zero flow value point determined using a function continuous between said flow signal value at a point where said sound signal intensity drops below said threshold and said flow signal value at a point where said sound signal intensity rises above said threshold at a beginning of expiration.
-
-
3. The method as claimed in claim 1, wherein said volume of breath signal is obtained only for said inspiration cycle, said volume of breath signal for said expiration cycle over a large number of cycles being equal to said volume of breath signal for said inspiration cycle.
-
4. The method as claimed in claim 3, wherein said steps of comparing and transforming involve analysis which is the same for both inspiration and expiration.
-
5. The method as claimed in claim 2, wherein said firstly and said secondly interpolating comprises linear interpolating.
-
6. The method as claimed in claim 1, further comprising a step of averaging said volume signal over time to obtain a tidal volume signal.
-
7. The method as claimed in claim 3, further comprising a step of averaging said volume signal over time to obtain a tidal volume signal.
-
8. The method as claimed in claim 1, wherein said step of detecting respiration start/stop comprises analyzing said sound signal.
-
9. The method as claimed in claim 1, wherein said step of detecting respiration star/stop comprises physically measuring at least one of chest and abdomen position or motion.
-
10. The method as claimed in claim 1, further comprising a step of monitoring a time of said respiration start/stop to obtain a respiratory frequency signal.
-
11. The method as claimed in claim 1, further comprising a step of averaging said flow signal during inspiration and generating a mean inspiratory flow signal.
-
12. The method as claimed in claim 1, further comprising a step of calibrating a sound signal to flow signal transform function by measuring treacheal flow directly while recording said sound signal over a period of time and setting parameters of said transform function to provide flow values corresponding to said measured tracheal flow.
-
13. The method as claimed in claim 3, further comprising a step of calibrating a sound signal to flow signal transform function by measuring tracheal flow directly while recording said sound signal over a period of time and setting parameters of said transform function to provide flow values corresponding to said measured tracheal flow.
-
14. An apparatus for non-invasive monitoring of respiration comprising:
-
at least one microphone for obtaining a sound signal from a person, said sound signal representing respiration;
means for detecting inspiration start and stop;
means for transforming said sound signal to a flow signal, said transforming means receiving data from transfer function register means and threshold value register means;
means for generating interpolated values for said flow, signal when said sound signal is below said threshold value; and
integrator means for integrating said flow signal to produce a volume of respiration signal. - View Dependent Claims (15)
-
-
16. A method for obtaining at least one of a diagnosis and a prognosis of a respiratory disease comprising the steps of:
-
placing at least one microphone on a patient to obtain a sound signal from respiration of said patient;
processing said sound signal to obtain a volume of respiration signal;
monitoring said volume of respiration signal over time;
analyzing said volume signal over time to obtain at least one parameter indicative of said diagnosis and/or prognosis. - View Dependent Claims (17, 18, 19, 20)
detecting respiration start/stop;
comparing an intensity of said sound signal to a threshold to determine whether said sound signal intensity is sufficiently strong with respect to background noise so as to provide a reliable measure of tracheal flow;
transforming said sound signal to a flow signal;
interpolating values for said flow signal when said sound signal intensity is below said threshold; and
integrating said flow signal and said interpolated values of said flow signal over at least one of an inspiration cycle and an expiration cycle to obtain a volume of breath signal for said at lest one cycle.
-
-
18. The method as claimed in claim 17, wherein said at least one cycle is inspiration, and said interpolating comprises:
-
firstly interpolating said flow signal during inspiration from a point of detecting said respiration start/stop at which said flow is determined to be zero until said sound signal intensity reaches said threshold and has a value determined by said transforming; and
secondly interpolating said flow signal at an end of said inspiration cycle as said sound signal intensity drops below said threshold at an end of inspiration and a zero flow value point defined using a function continuous between said flow signal value at a point where said sound signal intensity drops below said threshold and said flow signal value at a point where said sound signal intensity rises above said threshold at a beginning of expiration.
-
-
19. The method as claimed in claim 18, wherein said volume of breath signal is obtained only for said inspiration cycle, said volume of breath signal for said expiration cycle over a large number of cycles being to said volume of breath signal for said inspiration cycle.
-
20. The method as claimed in claim 17, further comprising steps of:
-
attaching a wearable eye device to said patient, said device having signal processing means for carrying out said step of processing; and
analyzing said volume of breath signal and generating an alarm when said volume of respiration signal has characteristics representing a condition in need of medical attention.
-
Specification