Respiratory-analysis systems

• US 6,547,743 B2
• Filed: 04/20/2000
• Issued: 04/15/2003
• Est. Priority Date: 05/16/1997
• Status: Expired due to Term

• Current Assignee: Resmed Limited (ResMed Incorporated)
• Original Assignee: Resmed Limited (ResMed Incorporated)
• Inventors: Brydon, John William Ernest
• Primary Examiner(s): Nasser, Robert L.
• Assistant Examiner(s): MALLARI, PATRICIA C
• Application Number:
  US09/423,951
• Publication Number:
  US 20030045806A1
• Time in Patent Office: 1,090 Days
• Field of Search: 600/534, 600/529
• 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 has a plurality of independent, like movement sensors for measuring movement at different locations on the mattress to generate a plurality of independent movement signals. The signals are processed to derive respiratory variables including rate, phase, maximum effort or heart rate. Such variables can be combined to derive one or more diagnostic variables including apnea and labored breathing classifications.

Claims

1. A mattress for monitoring patient movement for a patient lying on the mattress, the mattress including a plurality of independent, like movement sensors for measuring movement at different locations on the mattress to generate a plurality of independent movement signals each configured to be processed independently of the remaining 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 claim 1, 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 claim 3, wherein at least some of the elements are arranged to measure lateral strain across the mattress.

6. A mattress as claimed in claim 3, further comprising 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 claim 3, wherein the elements are laminated between two thin conformable elastic sheets.

8. A mattress as claimed in claim 3, further comprising a separate transition connector connected to each of said elements in such a manner as to avoid strain between the strip and each said connector during use of the mattress.

9. A mattress as claimed in claim 3, further comprising a single bus transition connector to which each of the elements is connected.

10. A mattress as claimed in claim 3, 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 of the elements 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

a processor to receive and process said movement signals to derive said at least one respiratory variable.

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

13. A system claimed in claim 12, wherein the processor is programmed to detect a change in respiratory phase by monitoring a value of the earlier time correlation of the spatial distribution of the filtered signals, and detects a change in respiratory phase when the processor detects a reduction of duration of signal matching as indicative of a change in respiratory phase, said reduction of duration being a further said at least one respiratory variable.

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

15. A system as claimed in claim 12, wherein the processor is programmed to derive a diagnostic variable from said at least one respiratory variable.

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

17. A system as claimed in claim 11, wherein the processor is programmed to bandpass filter at least one of the movement signals, take a modulus of the at least one filtered signal, low pass filters each said modulus signal, and at least one of (i) average and (ii) measure a maximum output of each said low pass filtered signal over one of an entire duration of each breath and each phase separately to give respiratory effort as said at least one respiratory variable.

18. A system claimed in claim 11, further comprising a pre-processor to receive said movement signals, pre-process the movement signals by one of equalizing each of the movement signals and deconvolving spatially the movement signals, and pass said pre-processed signals to said processor.

19. A system as claimed in claim 11, further including an output device for outputting said at least one respiratory variable.

20. A system as claimed in claim 11, further including a storage device for storing said at least one respiratory variable.

33. A system or method as claimed in claim 11, further wherein said at least one respiratory variable is used to control the output treatment pressure of a CPAP device.

34. A system or method as claimed in claim 11, wherein said at least one respiratory variable is used to monitor one of CPAP treatment effectiveness and, patient compliance.

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

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 at least one respiratory variable.

22. A method as claimed in claim 21, further comprising deriving a diagnostic variable from said at least one respiratory variable.

23. A method as claimed in claim 21, further comprising pre-processing said movement signals by one of equalization and spatial deconvolution before performing said processing.

24. A respiratory analysis system for monitoring at least one respiratory variable of a patient, comprising an input device to receive a plurality of signals indicative of patient movement;

and a processor to process said received signals to derive said at least one respiratory variable.

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

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

27. A system as claimed in claim 26, wherein the processor is further programmed to determined an elapsed time between a last two respiratory phase changes as indicative of respiratory rate, said elapsed time being a further said at least one respiratory variable.

28. A system as claimed in claim 25, wherein the processor is further programmed to derive a diagnostic variable from said at least one respiratory variable.

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

30. A system claimed in claim 24, wherein the processor is programmed to bandpass filter at least one of the movement signals, take a modulus of the at least one filtered signal, low pass filter each said modulus signal, and at least one of (i) average and (ii) measure a maximum output of each said low pass filtered signal over one of an entire duration of each breath and each phase separately to give respiratory effort as said at least one respiratory variable.

31. A system as claimed in claim 24, further comprising a pre-processor to receive said movement signals, pre-process the movement signals by one of equalizing each movement signal and deconvolving spacially the movement signals, and pass said pre-processed signals to said processor.

32. A system as claimed in claim 24, further including an output device for outputting said at least one respiratory variable.

35. A system as claimed in claim 24, further including a storage device for storing said at least one respiratory variable.

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

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

a processor to receive and process said movement signals to derive said at least one respiratory variable.

37. A mattress for monitoring patient movement for a patient lying on the mattress, the mattress including a plurality of independent movement sensors for measuring movement at different locations on the mattress to generate a plurality of independent movement signals each configured for independent processing.

38. A method for monitoring patient movement for a patient lying on a mattress, the method comprising 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.

39. A method as claimed in claim 38, wherein each of the independent signals is configured for independent processing.