DEVICE FOR DETERMINING RESPIRATORY RATE AND OTHER VITAL SIGNS

• US 20090018409A1
• Filed: 07/11/2008
• Published: 01/15/2009
• Est. Priority Date: 07/11/2007
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Triage Wireless, Inc.
• Inventors: Zhou, Zhou, Kopotic, Robert J., Dhillon, Marshal Singh, Terry, Andrew S., Banet, Matthew J., Visser, Henk II
• Granted Patent: US 8,506,480 B2
• Time in Patent Office: Days
• US Class Current: 600/301
• CPC Class Codes: A61B 2560/0412 Low-profile patch shaped housings
• CPC Class Codes: A61B 2560/0462 Apparatus with built-in sensors
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/02055 Simultaneously evaluating both cardiovascular condition and temperature
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/0823 Detecting or evaluating cough events
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/25 Bioelectric electrodes therefor
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• CPC Class Codes: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: G16H 40/67 for remote operation

Abstract

A body-worn sensor that measures respiratory rate and other vital signs using an acoustic sensor (e.g., a small-scale sensor). The body-worn sensor features a chest-worn patch sensor that combines both the acoustic sensor and an ECG electrode into a single adhesive patch. To measure blood pressure, the device additionally performs a ‘composite’ PTT-based measurement that features both pressure-dependent and pressure-free measurements. The acoustic sensor measures respiration rate by recording sounds related to the patient'"'"'s inspiration and expiration. The acoustic sensor is typically placed near the patient'"'"'s trachea, but can also be placed on the middle right and left side of the chest, and the middle right and left side of the back.

Claims

1. A system configured to be worn on the body of a patient and comprising:

a sensor assembly comprising;

at least two electrodes, each configured to contact the patient'"'"'s skin to detect separate electrical signals representing activity of the patient'"'"'s heart; and

an acoustic sensor configured to detect an acoustic signal from the patient'"'"'s breathing; and

a controller unit configured to be worn on the patient'"'"'s body, and further configured to connect to the sensor assembly through a connector, the controller unit comprising;

an analog-signal processing circuit comprising a first amplifier configured to receive the electrical signals from the electrodes and generate an analog electrical waveform therefrom, and a second amplifier configured to receive the acoustic signal from the acoustic sensor and generate an analog acoustic waveform therefrom;

analog-to-digital converter circuitry configured to receive the analog electrical waveform and generate a digital electrical waveform therefrom, and to receive the analog acoustic waveform and generate a digital acoustic waveform therefrom; and

a processing circuit programmed to use the digital electrical waveform to determine a value for a vital sign for the patient, and to use the digital acoustic waveform to determine a respiratory rate for the patient.

2. The system of claim 1, wherein the sensor assembly further comprises a substrate that supports the acoustic sensor and at least one of the at least two electrodes.

3. The system of claim 1, further comprising an optical sensor including a light source and a photodetector, and configured to be proximal to the patient'"'"'s skin to generate an optical signal representing a flow of blood within the patient.

4. The system of claim 3, wherein said vital sign is blood pressure, wherein the analog-signal processing circuit also comprises a third amplifier configured to receive the optical signal from the photodiode and generate an analog optical waveform therefrom, wherein the analog-to-digital converter circuitry is further configured to receive the analog optical waveform and generate a digital optical waveform therefrom, and wherein the processing circuit is further programmed to use both the digital optical waveform and the digital electrical waveform to determine the value of said vital sign.

5. The system of claim 1, wherein the processing circuit is programmed to determine the respiratory rate from the digital acoustic waveform by filtering the digital acoustic waveform.

6. The system of claim 5, wherein the filtering involves applying a bandpass filter.

7. The system of claim 5, wherein the filtering involves successively applying each of a plurality of bandpass filters.

8. The system of claim 7, wherein the plurality of bandpass filters comprises a first bandpass filter and a second bandpass filter, wherein the first bandpass filter passes a first band of frequencies and the second bandpass filter passes a second band of frequencies that is different from the first band of frequencies.

9. The system of claim 8, wherein all of the frequencies of the first band of frequencies are above the second band of frequencies.

10. The system of claim 8, wherein the frequencies of first band of frequencies are greater than 100 Hz.

11. The system of claim 8, wherein the frequencies of the second band of frequencies are less than 1 Hz.

12. The system of claim 1, further comprising a wireless transmitter and wherein the processing circuit is further programmed to send said value for said vital sign and the respiratory rate to a remote device via the wireless transmitter.

13. The system of claim 1, further comprising a flexible armband connected to the controller unit and serving to attached the controller unit to the patient'"'"'s arm during use.

14. The system of claim 1, wherein the processing circuit is further programmed to process the digital electrical waveform to determine a second respiratory rate, to analyze at least one of the digital electrical waveform and the digital acoustic waveform for unwanted noise and, based on said analysis, to select either the first-mentioned respiratory rate or the second respiratory rate.

15. The system of claim 1, wherein the sensor assembly also includes an adhesive layer to attach the sensor assembly to the patient'"'"'s body.

16. The system of claim 1, wherein the acoustic sensor comprises a microphone.

17. A system configured to be worn on the body of a patient and comprising:

a sensor assembly comprising;

at least two electrodes, each configured to contact the patient'"'"'s skin to detect separate electrical signals representing activity of the patient'"'"'s heart; and

an acoustic sensor configured to detect an acoustic signal from the patient'"'"'s breathing; and

a controller unit configured to be worn on the patient'"'"'s body, and further configured to connect to the sensor assembly through a connector, the controller unit comprising;

an analog-signal processing circuit comprising a first amplifier configured to receive the electrical signals from the electrodes and generate an analog electrical waveform therefrom, and a second amplifier configured to receive the acoustic signal from the acoustic sensor and generate an analog acoustic waveform therefrom;

analog-to-digital converter circuitry configured to receive the analog electrical waveform and generate a digital electrical waveform therefrom, and to receive the analog acoustic waveform and generate a digital acoustic waveform therefrom; and

a processing circuit programmed to use the digital electrical waveform to determine a first respiratory rate, and to use the digital acoustic waveform to determine a second respiratory rate, the processing circuit further programmed to analyze at least one of the digital electrical waveform and the digital acoustic waveform and, based on said analysis, select either the first respiratory rate or the second respiratory rate.

18. The system of claim 17, wherein the processing circuit is programmed to determine the second respiratory rate from the digital acoustic waveform by filtering the digital acoustic waveform.

19. The system of claim 18, wherein the filtering involves applying a bandpass filter.

20. The system of claim 18, wherein the filtering involves successively applying each of a plurality of bandpass filters.

21. The system of claim 20, wherein the plurality of bandpass filters comprises a first bandpass filter and a second bandpass filter, wherein the first bandpass filter passes a first band of frequencies and the second bandpass filter passes a second band of frequencies that is different from the first band of frequencies.

22. The system of claim 21, wherein all of the frequencies of the first band of frequencies are above the second band of frequencies.

23. The system of claim 21, wherein the frequencies of first band of frequencies are greater than 100 Hz.

24. The system of claim 21, wherein the frequencies of the second band of frequencies are less than 1 Hz.

25. A system configured to be worn on the body of a patient and comprising:

a sensor assembly comprising;

an optical sensor comprising a light source and a photodetector, and further configured to be proximal to the patient'"'"'s skin to generate an optical signal representing a flow of blood within the patient; and

an acoustic sensor configured to detect an acoustic signal from the patient'"'"'s breathing; and

a controller unit configured to be worn on the patient'"'"'s body, and further configured to connect to the sensor assembly through a connector, the controller unit comprising;

an analog-signal processing circuit comprising a first amplifier configured to receive the optical signal from the photodiode and generate an analog optical waveform therefrom, and a second amplifier configured to receive the acoustic signal from the acoustic sensor and generate an analog acoustic waveform therefrom;

analog-to-digital converter circuitry configured to receive the analog optical waveform and generate a digital optical waveform therefrom, and to receive the analog acoustic waveform and generate a digital acoustic waveform therefrom; and

a processing circuit programmed to use the digital optical waveform to determine a first respiratory rate, and to use the digital acoustic waveform to determine a second respiratory rate, the processing circuit further programmed to analyze at least one of the digital optical waveform and the digital acoustic waveform and, based on said analysis, select either the first respiratory rate or the second respiratory rate.

26. The system of claim 25, wherein the processing circuit is programmed to determine the second respiratory rate from the digital acoustic waveform by filtering the digital acoustic waveform.

27. The system of claim 26, wherein the filtering involves applying a bandpass filter.

28. The system of claim 26, wherein the filtering involves successively applying each of a plurality of bandpass filters.

29. The system of claim 28, wherein the plurality of bandpass filters comprises a first bandpass filter and a second bandpass filter, wherein the first bandpass filter passes a first band of frequencies and the second bandpass filter passes a second band of frequencies that is different from the first band of frequencies.

30. The system of claim 29, wherein all of the frequencies of the first band of frequencies are above the second band of frequencies.

31. The system of claim 29, wherein the frequencies of first band of frequencies are greater than 100 Hz.

32. The system of claim 29, wherein the frequencies of the second ban of frequencies are less than 1 Hz.