RESPIRATORY-ANALYSIS SYSTEMS

• US 20030045806A1
• Filed: 04/20/2000
• Published: 03/06/2003
• Est. Priority Date: 05/16/1997
• Status: Active Grant

• Current Assignee: Resmed Limited (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: BRYDON, JOHN WILLIAM ERNEST
• Granted Patent: US 6,547,743 B2
• Time in Patent Office: Days
• US Class Current: 600/534
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/043 in a linear array
• 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 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1102 Ballistocardiography
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• CPC Class Codes: A61B 5/6892 Mats
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00

Abstract

A movement sensitive mattress (2) is disclosed that has a plurality of independent like movement sensors (5) for measuring movement at different locations on the mattress to generate a plurality of movement signals. The signals are processed to derive respiratory variables including rate, phase, maximum effort and heartrate. Such variables can be combined to derive one or more diagnostic variables including apnea and laboured breathing classifications.

Claims

1. A mattress for monitoring patient movement for a patient lying on the mattress, the mattress including at least a plurality of independent like movement sensors for measuring movement at different locations on the mattress to generate a plurality of independent movement signals.

2. A mattress as claimed in claim 1, wherein the number of movement sensors is in the range three to ten.

3. A mattress as claimed in either one of claim 1 or claim 2, wherein the movement sensors are formed by piezoelectric elements.

4. A mattress as claimed in claim 3, wherein said elements are fabricated from polyvinylidene fluoride (PVDF) material.

5. A mattress as claimed in either one of claims 3 or 4, wherein at least some of the elements are arranged to measure lateral strain across the mattress.

6. A mattress as claimed in any one of claims 3 to 5, further comprising a compressible filling surrounded by an outer layer, and wherein said elements are attached to an inner surface of the outer layer.

7. A mattress as claimed in any one of claims 3 to 5, wherein the elements are laminated between two thin conformable elastic sheets.

8. A mattress as claimed in any one of claims 3 to 7, further comprising separate transition connector connected to each element in such a manner as to avoid strain between the strip and the respective connector during use of the mattress.

9. A mattress as claimed in any one of claims 3 to 7, further comprising a single bus transition connector to which each element is connected.

10. A mattress as claimed in any one of claims 3 to 7, wherein said elements are integrally formed from a single composite sheet of piezoelectric material by forming a series of staggered parallel cuts in said sheet in such a way that each element is formed between two adjacent cuts.

11. A respiratory analysis system for monitoring at least one respiratory variable for a patient, the system comprising:

a mattress upon which the patient can lie, having a plurality of independent like movement sensors for measuring movement at different locations on the mattress to generate a plurality of independent movement signals; and

processing means receiving and processing said movement signals to derive said respiratory variable(s).

12. A system as claimed in claim 11, wherein the processor means is operable to bandpass filter the movement signals, and correlate the spatial distribution of the filtered signals at a given time with the spatial distribution of an earlier time to produce a respiratory rate as a said respiratory variable.

13. A system as claimed in claim 12, wherein the processor means is operable to monitor the value of the past time correlation of the spatial distribution of the filtered signals, and detects a reduction of the duration of signal matching as indicative of a change in respiratory phase, being a further said respiratory variable.

14. A system as claimed in claim 13, wherein the processor means is further operable to determine the elapsed time between the last two respiratory phase changes as indicative of respiratory rate, being a further said respiratory variable.

15. A system as claimed in claim 11, wherein the processor means is operable to bandpass filters one or more of the movement signals, takes the modulus of the filtered signal(s), low pass filters the modulus signal(s), and either (i) averages or (iii) measures the maximum output of the low pass filtered signal(s) over either the entire duration of each breath or each phase separately to give the respiratory effort as a said respiratory variable.

16. A system as claimed in claim 11, wherein the processor means is operable to bandpass filter the movement signals, and correlate the spatial distribution of the filtered signals at a given time with the spatial distribution of an earlier time to produce a heartrate as a said respiratory vehicle.

17. A system as claimed in any one of claims 12 to 15, wherein the processor means is further operable to combine one or more of said respiratory rate variable, respiratory phase variable and respiratory effort variable to give one or more of derived diagnostic variables including apnea and laboured breathing classifications.

18. A system as claimed in any one of claims 11 to 17, further comprising pre-possessing means to receive said movement signals, pre-process them by equalising each movement signal and/or deconvolve spatially the movement signals, thereby isolating each signal from all others and pass said pre-processed signals to said processing means.

19. A system as claimed in any one of claims 11 to 18, further including output and/or storage means for outputting and/or storing said respiratory variables and/or said derived diagnostic variables.

33. A system or method as claimed in any one of respective claims 11 to 32 further wherein one or more of the respiratory variables and/or derived diagnostic variables are used to control the output treatment pressure of a CPAP machine.

34. A system or method as claimed in any one of respective claims 11 to 32, further wherein one or more of the respiratory variables and/or derived diagnostic variables are used to monitor CPAP treatment effectiveness and/or patient compliance.

20. A method for monitoring patient movement for a patient lying on a mattress, the method comprising the steps of:

measuring displacement due to body movement at a plurality of independent positions length-wise of a portion of the body to derive independent signals representative of respective individual body displacement at said positions.

21. A method for monitoring at least one respiratory variable for a patient lying on a mattress, the method comprising the steps of:

measuring displacement due to body movement at a plurality of independent positions length-wise of a portion of the body to derive independent signals representative of respective individual body displacement at said positions; and

processing said movement signals to derive said respiratory variable(s).

22. A method as claimed in claim 21, comprising the further step of combining one or more of said respiratory variables to give one or more derived diagnostic variables.

23. A method as claimed in either one of claim 21 or claim 22, comprising the further step of pre-processing said movement signals by equalisation and/or spatial deconvolution before performing said processing and/or further processing.

24. A respiratory analysis system for monitoring at least one respiratory variable for a patient, comprising:

input means to receive a plurality of signals indicative of patient movement; and

processor means to process said received signals to derive said respiratory variable(s).

25. A system as claimed in claim 24, wherein processor means is operable to bandpass filter the movement signals, and correlate the spatial distribution of the filtered signals at a given time with the spatial distribution of an earlier time to produce a respiratory rate as a said respiratory variable.

26. A system as claimed in claim 25, wherein the processor means is operable to monitor the value of the past time correlation of the spatial distribution of the filtered signals, and detects a reduction of the duration of signal matching as indicative of a change in respiratory phase, being a further said respiratory variable.

27. A system as claimed in claim 26, wherein the processor means is further operable to determine the elapsed time between the last two respiratory phase changes as indicative of respiratory rate, being a further said respiratory variable.

28. A system as claimed in claim 24, wherein the processor means is operable to bandpass filters one or more of the movement signals, takes the modulus of the filtered signal(s), low pass filters the modulus signal(s), and either (i) averages or (ii) measures the maxium output of the low pass filtered signal(s) over either the entire duration of each breath or each phase separately to give the average effort as a said respiratory variable.

29. A system as claimed in claim 24, wherein the processor means is operable to bandpass filter the movement signals, and correlate the spatial distribution of the filtered signals at a given time with the spatial distribution of an earlier time to produce a respiratory rate as a said respiratory vehicle.

30. A system as claimed in any one of claims 25 to 39, wherein the processor means is further operable to combine one or more of said respiratory rate variable, respiratory phase variable, and respiratory phase effort variable to give one or more of derived diagnostic variables including apnea and laboured breathing classifications.

31. A system as claimed in any one of claims 24 to 30, further comprising pre-possessing means to receive said movement signals, pre-process them by equalising each movement signal and/or deconvolve the spatially movement signals, thereby isolating each signal from all others and pass said pre-processed signals to said processing means.

32. A system as claimed in any one of claims 24 to 31, further including output and/or storage means for outputting and/or storing said respiratory variables and/or said derived diagnostic variables.