BODY-WORN MONITOR FOR MEASURING RESPIRATION RATE

• US 20110066062A1
• Filed: 09/14/2009
• Published: 03/17/2011
• Est. Priority Date: 09/14/2009
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: BANET, Matt, DHILLON, Marshal, McCOMBIE, Devin
• Granted Patent: US 10,595,746 B2
• Time in Patent Office: Days
• US Class Current: 600/534
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• 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 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0535 Impedance plethysmography for measuring blood flow A61B5/0295
• 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 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6823 Trunk, e.g., chest, back, abdomen, hip
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/721 using a separate sensor to detect motion or using motion information derived from signals other than the physiological signal to be measured
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B

Abstract

The invention provides a multi-sensor system that uses an algorithm based on adaptive filtering to monitor a patient'"'"'s respiratory rate. The system features a first sensor selected from the following group: i) an impedance pneumography sensor featuring at least two electrodes and a processing circuit configured to measure an impedance pneumography signal; ii) an ECG sensor featuring at least two electrodes and an ECG processing circuit configured to measure an ECG signal; and iii) a PPG sensor featuring a light source, photodetector, and PPG processing circuit configured to measure a PPG signal. Each of these sensors measures a time-dependent signal which is sensitive to respiratory rate and, during operation, is processed to determine an initial respiratory rate value. An adaptive digital filter is determined from the initial respiratory rate. The system features a second sensor (e.g. a digital 3-axis accelerometer) that attaches to the patient'"'"'s torso and measures an ACC signal indicating movement of the chest or abdomen that is also sensitive to respiratory rate. This second signal is processed with the adaptive filter to determine a final value for respiratory rate.

Claims

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

a cable 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;

an accelerometer system comprising;

i) an accelerometer configured to generate an analog motion signal; and

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

a processing system comprising a processor in electrical communication with the cable and configured to receive the digital data stream and collectively process the digital impedance pneumography and motion signals to determine the patient'"'"'s respiratory rate.

3. The system of claim 1, wherein the impedance pneumography system is comprised by a terminal end of the cable.

4. The system of claim 3, wherein the cable comprises a housing at its terminal end that comprises the impedance pneumography system.

5. The system of claim 4, wherein the housing further comprises the accelerometer system.

6. The system of claim 4, wherein the housing further comprises a temperature sensor.

7. The system of claim 6, wherein the temperature sensor is a thermocouple.

8. The system of claim 1, wherein the cable comprises at least one conductor configured to transmit both a first digital data stream representing the digital impedance pneumography signal or information calculated therefrom, and a second digital data stream representing the digital motion signal or information calculated therefrom.

9. The system of claim 8, wherein the first digital data stream comprises a first header portion and a first data portion, the first header portion indicating that the first data portion comprises impedance pneumography information or information calculated therefrom.

10. The system of claim 8, wherein the first digital data stream comprises a first header portion and a first data portion, the first header portion indicating that the first data portion comprises motion information or information calculated therefrom.

11. The system of claim 1, wherein the transceiver component is a serial transceiver.

12. The system of claim 11, wherein the serial transceiver is a CAN transceiver configured to transmit a digital data stream according to the CAN protocol.

13. The system of claim 1, wherein the impedance pneumography system further comprises an ECG system for measuring heart rate from the patient.

14. The system of claim 1, wherein the processing system further comprises a display configured to render impedance pneumography information.

15. The system of claim 14, wherein the display is further configured to render at least one of respiratory rate and a time-dependent waveform indicating respiratory rate.

16. The system of claim 1, wherein the impedance pneumography system is comprised by a single integrated circuit.

17. The system of claim 13, wherein the ECG and impedance pneumography systems are comprised by a single integrated circuit.

18. The system of claim 13, wherein the ECG system connects to one of three, five, and twelve electrodes.

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

a processing system configured to be worn on a patient'"'"'s body comprising a processor configured to receive a digital data stream from a cable comprising a motion sensor and an impedance pneumography sensor, and collectively process motion signals and respiratory signals in the digital data stream to determine respiratory rate; and

,

a cable comprising the motion sensor and the impedance pneumography sensor, each sensor comprising an analog-to-digital converter configured to generate a digital signal, and a transceiver component configured to transmit the digital data stream through the cable and to an external system.