APPARATUS, SYSTEM, AND METHOD FOR MONITORING PHYSIOLOGICAL SIGNS

• US 20090203972A1
• Filed: 06/01/2007
• Published: 08/13/2009
• Est. Priority Date: 06/01/2006
• Status: Active Grant

• Current Assignee: ResMed Sensor Technologies Limited (ResMed Incorporated)
• Original Assignee: BiancaMed Limited (ResMed Incorporated)
• Inventors: De Chazal, Philip, Fox, Niall, Hanley, Conor, Heneghan, Conor
• Granted Patent: US 8,562,526 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/0826 Detecting or evaluating apnoea events A61B5/4818 takes precedence
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/4818 Sleep apnoea
• 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
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems

Abstract

An apparatus, system, and method monitors the motion, breathing, heart rate and sleep state of subjects, e.g., humans, in a convenient, non-invasive/non-contact, and low-cost fashion. More particularly, the motion, breathing, and heart rate signals are obtained through processing applied to a raw signal obtained in a non-contact fashion, typically using a radio-frequency sensor. Periods of sleep disturbed respiration, or central apnea can be detected through analysis of the respiratory signal. The mean heart rate, and derived information, such as the presence of cardiac arrhythmias can be determined from the cardiac signal. Motion estimates can be used to recognize disturbed sleep and periodic limb movements. The sleep state may be determined by applying a classifier model to the resulting streams of respiratory, cardiac and motion data. A means for display of the sleep state, respiratory, cardiac, and movement status may also be provided.

Claims

1. An apparatus useful in detecting, analyzing, and displaying one or more of respiration, cardiac activity, and bodily function or movement of a living subject, the apparatus comprising:

a processor configured to analyze a signal reflected from the subject without physical contact with or mechanical coupling to the subject and to derive measurements of said one or more of respiration, cardiac activity, and bodily function or movement therefrom; and

a display configured to provide the analyzed and derived measurements to a local or remote user of the apparatus.

2. The apparatus of claim 1, further comprising a sensor coupled to the processor and arranged to receive the signal reflected from the subject.

3. The apparatus of claim 2, wherein the sensor and processor are both arranged to operate without any direct or indirect physical contact with the subject.

4. The apparatus of claim 1, wherein the reflected signal is generated by a transmitter collocated with the apparatus.

5. The apparatus of claim 4, wherein the transmitter is configured to generate an radio-frequency (RF) energy signal compatible for use with the living subject.

6. The apparatus of claim 1, further comprising a multiplier circuit arranged to multiply the reflected signal with a transmitted signal and to output a baseband signal representing said one or more respiration, cardiac, and bodily function or movement therefrom.

7. The apparatus of claim 6, wherein the processor is configured to recognize periods of bodily motion of the subject by identifying peaks in an energy envelope of the baseband signal.

8. The apparatus of claim 6, wherein the processor is configured to recognize periods of bodily motion of the subject by counting a number of threshold-crossings of the baseband signal per unit time.

9. The apparatus of claim 6, further comprising a sensor and wherein the processor is configured to receive the baseband signal and to output a processed signal in response thereto, wherein the processor is further configured to use the processed signal to distinguish breathing activity of the subject.

10. The apparatus of claim 6 further comprising a sensor and wherein the processor is configured to receive an output of the sensor and to output a processed signal in response thereto, wherein the processor is further configured to use the processed signal to distinguish a cardiac activity of the subject.

11. The apparatus of claim 6, wherein the processor is configured to determine an activity count for a measurement epoch by calculating an energy of the baseband signal relative to other epochs.

12. The apparatus of claim 6, wherein the processor is configured to run a classifier model and to determine a Cheyne-Stokes respiration pattern by processing features obtained from a respiratory signal derived from the baseband signal.

13. The apparatus of claim 6, wherein the processor is configured to determine an Apnoea-Hypopnoea Index (AHI) by processing a respiratory signal derived from the baseband signal.

14. The apparatus of claim 13, wherein the AHI is determined solely by a derived respiratory effort parameter.

15. The apparatus of claim 1, wherein the processor is configured to determine a the sleeping status of the subject by analysis of a motion signal derived from the baseband signal.

16. The apparatus of claim 1, wherein the processor is configured to run a classifier model and to determine a sleep state by combining one or more of motion signals, breathing signals, and cardiac signals provided by the classifier model.

17. The apparatus of claim 1, wherein the processor is configured to recognize a central apnea condition by determining that breathing and motion activity of the subject are below a predetermined threshold for a period of time.

18. The apparatus of claim 1, wherein the processor is configured to recognize a respiratory distress condition of the subject by comparing a derived respiratory frequency with an existing set of respiratory measurements.

19. The apparatus of claim 1, further comprising a visual indication device by which a sleep status of the subject determined by the processor is signaled to a user.

20. The apparatus of claim 1, further comprising a visual indication device by which breathing parameter of the subject determined by the processor is signaled to a user.

21. The apparatus of claim 1, further comprising a visual indication device by which a bodily movement of the subject determined by the processor is signaled to a user.

22. The apparatus of claim 1, further comprising a visual indication device by which a heart rate of the subject determined by the processor is signaled to a user.

23. The apparatus of claim 1, wherein the signal reflected from the subject comprises a radio-frequency (RF) signal.

36. The apparatus of claim 1, wherein the processor is configured to determine a phase difference associated with said signal reflected from the subject and to derive one or more of said measurements therefrom.

24. A system for measuring, analyzing, and displaying one or more of a respiration parameter, cardiac activity, and bodily movement or function of a living subject, the system comprising:

a transmitter arrangement configured to propagate a radio frequency (RF) signal toward the subject;

a receiver arranged to receive an RF signal reflected from the subject and to determine a phase difference between the propagated RF signal and the reflected RF signal;

a processor arranged to analyze the phase difference to produce measurements of one or more of a respiration parameter, cardiac activity, and a bodily movement or function, and

a monitor to provide selected information to a local or remote user of the system by either an audible or visual indication, or both.

25. The system of claim 24, further comprising at least one auxiliary sensor coupled to the processor.

26. The system of claim 25, wherein said at least one auxiliary sensor comprises one or more of an acoustic sensor, temperature sensor, humidity sensor, and a light sensor.

27. A method for measuring, analyzing, and displaying one or more physiological parameters of a living subject, the method comprising:

sensing a signal reflected from the living subject;

processing and analyzing the reflected signal by determining a phase difference associated with the signal reflected from the living subject;

deriving said one or more physiological parameters pertaining to said living subject, said one or more physiological parameters comprising one or more of a respiration parameter, cardiac activity, and bodily movement or function of a subject; and

making selected derived information available to a user.

28. The method of claim 27, wherein said step of making comprises displaying the selected derived information on a monitor.

29. The method of claim 27, further comprising sounding an audible alarm in response to a determination that one or more of said one or more physiological parameters is outside a normal limit.

30. The method of claim 27, wherein said physiological parameters comprise an Apnoea-Hypopnoea Index (AHI) obtained by analyzing a respiratory signal derived from the reflected radio signal.

31. The method of claim 27, wherein said processing and analyzing the reflected signal comprises obtaining a baseband signal by multiplying a transmitted signal by the reflected signal.

32. The method of claim 31, further comprising analyzing the baseband signal with a classifier and determining an activity count in response to a classification result.

33. The method of claim 32, further comprising using the determined activity count to determine said one or more physiological parameters.

34. The method of claim 27, wherein said step of sensing comprises sensing a radio-frequency (RF) signal.

35. A computer-readable medium containing computer instructions thereon which, when executed on a computer, carry out the functions of measuring, analyzing, and displaying one or more physiological parameters of a living subject by:

processing and analyzing a signal reflected from the living subject by determining a phase difference associated with the reflected signal;

deriving said one or more physiological parameters pertaining to said living subject, said one or more physiological parameters comprising one or more of a respiration parameter, cardiac activity, and bodily movement or function of a subject; and

making selected derived information available to a user.

37. An apparatus useful in detecting, analyzing, and displaying one or more of respiration, cardiac activity, and bodily function or movement of a living subject, the apparatus comprising:

a processor configured to analyze a signal reflected from the subject and to derive measurements of said one or more of respiration, cardiac activity, and bodily function or movement therefrom, wherein said processor determines a phase difference associated with said signal reflected from the subject to derive one or more of said measurements; and

a display configured to provide the analyzed and derived measurements to a local or remote user of the apparatus.