BODY-WORN MONITOR FOR MEASURING RESPIRATORY RATE

• US 20110257555A1
• Filed: 04/19/2010
• Published: 10/20/2011
• Est. Priority Date: 04/19/2010
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: McCOMBIE, Devin, BANET, Matt, DHILLON, Marshal
• Granted Patent: US 8,979,765 B2
• Time in Patent Office: Days
• US Class Current: 600/538
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0809 by impedance pneumography
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/7257 using Fourier transforms

Abstract

The invention provides a system for measuring respiratory rate (RR) from a patient. The system includes an impedance pneumography (IP) sensor, connected to at least two electrodes, and a processing system that receives and processes signals from the electrodes to measure an IP signal. A motion sensor (e.g. an accelerometer) measures at least one motion signal (e.g. an ACC waveform) describing movement of a portion of the patient'"'"'s body to which it is attached. The processing system receives the IP and motion signals, and processes them to determine, respectfully, frequency-domain IP and motion spectra. Both spectra are then collectively processed to remove motion components from the IP spectrum and determine RR. For example, during the processing, an algorithm determines motion frequency components from the frequency-domain motion spectrum, and then using a digital filter removes these, or parameters calculated therefrom, from the IP spectrum.

Claims

1. A system for measuring respiratory rate from a patient, comprising:

an impedance pneumography system comprising;

i) a connecting portion configured to connect to a plurality of electrodes configured to be worn on the patient;

ii) a differential amplifier configured to receive electrical signals from each of the plurality of electrodes and process them to generate an analog impedance pneumography signal; and

iii) an analog-to-digital converter configured to convert the analog impedance pneumography signal into a digital impedance pneumography signal;

a motion-sensing system comprising;

i) a motion detector configured to generate an analog motion signal; and

ii) an analog-to-digital converter configured to convert the analog motion signal into a digital motion signal; and

a processing system, configured to be worn on the patient'"'"'s body at a different location than the impedance pneumography system and the motion-sensing system, the processing system configured to receive a cable that transmits both the digital impedance pneumography signal and the digital motion signal, and comprising a processor in electrical communication with the cable and configured to receive the digital impedance pneumography and digital motion signals and collectively process them to determine the patient'"'"'s respiratory rate.

6. The system of claim 1, further comprising a sensor module that comprises both the impedance pneumography system and the motion sensing system.

7. The system of claim 6, wherein the sensor module further comprises a skin temperature sensor.

8. The system of claim 6, wherein the sensor module further comprises a sensor for measuring an electrocardiogram.

9. The system of claim 6, wherein the sensor module further comprises a microprocessor.

10. The system of claim 9, wherein the microprocessor is configured to process the digital impedance pneumography signal and digital motion signal before they are transmitted through the cable to the processing system.

11. The system of claim 10, wherein the microprocessor is configured to digitally filter the digital impedance pneumography signal and digital motion signal before they are transmitted through the cable to the processing system.

12. The system of claim 1, wherein the cable is configured to attach to the patient'"'"'s arm.

13. The system of claim 12, wherein the cable further comprises an embedded accelerometer.

14. The system of claim 1, wherein the motion-sensing system comprises an accelerometer.

15. The system of claim 14, wherein the accelerometer is configured to generate at least three analog motion signals, each corresponding to a different axis on the patient, and the analog-to-digital converter is configured to convert each of the three analog motion signals into a unique digital motion signal.

16. The system of claim 15, wherein the processing system is further configured to receive a digital motion signal corresponding to each axis on the patient, and collectively process the digital motion signals to determine a posture corresponding to the patient.

17. The system of claim 16, wherein the processing system is further configured to generate an alarm based on both a posture and respiratory rate corresponding to the patient.

18. The system of claim 6, wherein the sensor module comprises a connector configured to connect directly to a first electrode.

19. The system of claim 18, wherein the sensor module is further configured to connect through a cable harness to a second and third electrode.

20. The system of claim 1, wherein the processing system further comprises a display configured to render a value of respiratory rate.

21. The system of claim 1, wherein the processing system further comprises a wireless transmitter configured to wirelessly transmit a value of respiratory rate.

2. A system for measuring respiratory rate from a patient, comprising:

an impedance pneumography system comprising;

i) a connecting portion configured to connect to a plurality of electrodes configured to be worn on the patient;

ii) a differential amplifier configured to receive electrical signals from each of the plurality of electrodes and process them to generate an analog impedance pneumography signal; and

iii) an analog-to-digital converter configured to convert the analog impedance pneumography signal into a digital impedance pneumography signal;

a motion-sensing system comprising;

i) a motion detector configured to generate an analog motion signal; and

ii) an analog-to-digital converter configured to convert the analog motion signal into a digital motion signal;

a processing system, configured to be worn on the patient'"'"'s body at a different location than the impedance pneumography system and the motion-sensing system, the processing system configured to receive a cable that transmits both the digital impedance pneumography signal and the digital motion signal, and comprising a processor in electrical communication with the cable and configured to receive the digital impedance pneumography and digital motion signals and transmit them to a remote computer; and

the remote computer, configured to receive the digital impedance pneumography and digital motion signals, or mathematical derivatives thereof, collectively process these signals with an algorithm to determine the patient'"'"'s respiratory rate, and then transmit a value describing the respiratory rate back to the processing system for display on the patient'"'"'s body.

3. A system for measuring respiratory rate from a patient, comprising:

an impedance pneumography system comprising;

i) a connecting portion configured to connect to a plurality of electrodes configured to be worn on the patient;

ii) a differential amplifier configured to receive electrical signals from each of the plurality of electrodes and process them to generate an analog impedance pneumography signal; and

iii) an analog-to-digital converter configured to convert the analog impedance pneumography signal into a digital impedance pneumography signal;

a motion-sensing system comprising;

i) a motion detector configured to generate an analog motion signal; and

ii) an analog-to-digital converter configured to convert the analog motion signal into a digital motion signal;

a processing system, configured to be worn on the patient'"'"'s body at a different location than the impedance pneumography system and the motion-sensing system, the processing system configured to receive a cable that transmits both the digital impedance pneumography signal and the digital motion signal, and comprising a processor in electrical communication with the cable and configured to receive the digital impedance pneumography and digital motion signals and transmit them to a remote computer; and

the remote computer, configured to receive the digital impedance pneumography and digital motion signals, or mathematical derivatives thereof, collectively process these signals with an algorithm to determine the patient'"'"'s respiratory rate.

4. A system for measuring respiratory rate from a patient, comprising:

a sensor module, configured to be worn on the patient'"'"'s torso, comprising an impedance pneumography sensor configured to measure a digital impedance pneumography signal, a motion sensor configured to measure a digital motion signal, and a serial transceiver configured to transmit the digital signals through a cable configured to attach to the patient'"'"'s arm; and

a processing system, configured to be worn on the patient'"'"'s wrist, comprising a connector that receives the cable, and a processor that receives digital impedance pneumography and motion signals from the cable and processes them with an algorithm that includes at least three unique calculations for determining respiratory rate, with the calculation being selected depending on the patient'"'"'s degree of motion.

5. A system for measuring respiratory rate from a patient, comprising:

a sensor module, configured to be worn on the patient'"'"'s torso, comprising an impedance pneumography sensor configured to measure a digital impedance pneumography signal, a motion sensor configured to measure a digital motion signal, and a serial transceiver configured to transmit the digital signals through a cable; and

a processing system, configured to be worn on the patient'"'"'s wrist, comprising a connector that receives the cable, and a processor that receives digital impedance pneumography and motion signals from the cable and collectively processes them with an algorithm for determining respiratory rate.