BODY-WORN PULSE OXIMETER

• US 20100324387A1
• Filed: 09/14/2009
• Published: 12/23/2010
• Est. Priority Date: 06/17/2009
• Status: Active Grant

• Current Assignee: Sotera Wireless Incorporated
• Original Assignee: Sotera Wireless Incorporated
• Inventors: MOON, Jim, BANET, Matt, DHILLON, Marshal, McCOMBIE, Devin
• Granted Patent: US 10,085,657 B2
• Time in Patent Office: Days
• US Class Current: 600/324
• CPC Class Codes: A61B 5/021 Measuring pressure in heart or blood vessels A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/022 by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
• CPC Class Codes: A61B 5/02225 using the oscillometric method
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1118 Determining activity level
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/349 Detecting specific parameters of the electrocardiograph cycle
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61B 5/6824 Arm or wrist
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips
• 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 body-worn system that continuously measures pulse oximetry and blood pressure, along with motion, posture, and activity level, from an ambulatory patient. The system features an oximetry probe that comfortably clips to the base of the patient'"'"'s thumb, thereby freeing up their fingers for conventional activities in a hospital, such as reading and eating. The probe secures to the thumb and measures time-dependent signals corresponding to LEDs operating near 660 and 905 nm. Analog versions of these signals pass through a low-profile cable to a wrist-worn transceiver that encloses a processing unit. Also within the wrist-worn transceiver is an accelerometer, a wireless system that sends information through a network to a remote receiver, e.g. a computer located in a central nursing station.

Claims

1. A system for monitoring both blood pressure and oxygen saturation values from a patient, comprising:

a first sensor comprising;

a first radiation source configured to emit optical radiation at a first wavelength;

a second radiation source configured to emit optical radiation at a second wavelength;

a photodetector configured to detect radiation emitted by the first radiation source after it passes through a portion of the patient to generate a first time-dependent signal, and radiation emitted by the second radiation source after it passes through a portion of the patient to generate a second time-dependent signal; and

a housing comprising the first and second radiation sources and the photodetector, the housing configured to attach to one of the patient'"'"'s fingers;

a second sensor comprising;

at least two electrodes, each configured to attach to the patient and measure electrical signals and an electrical circuit configured to receive and process the electrical signals to determine a time-dependent electrical signal; and

a processing unit configured to be worn on the patient'"'"'s arm and connected to the first sensor to receive the first and second time-dependent signals, and to the second sensor to receive the time-dependent electrical signal, the processing unit comprising a processor configured to process;

i) the first and second time-dependent signals to determine AC signals, or signals derived therefrom, to determine the oxygen saturation value; and

ii) at least one of the AC signals and the electrical signal, or signals derived therefrom, to determine the blood pressure value.

3. The system of claim 1, wherein the processing unit further comprises a motion sensor.

4. The system of claim 3, wherein the motion sensor is an accelerometer.

5. The system of claim 1, wherein the processing unit further comprises an input port for receiving a cable.

6. The system of claim 5, wherein the cable further comprises an accelerometer.

7. The system of claim 5, wherein the cable further comprises an ECG circuit.

8. The system of claim 7, wherein the ECG circuit is comprised by the second sensor.

9. The system of claim 8, wherein the second sensor further comprises an analog-to-digital converter.

10. The system of claim 9, wherein the input port is configured to receive a digital signal.

11. The system of claim 10, wherein the input port is a serial port.

12. The system of claim 11, wherein the input port is a serial port operating a CAN communication protocol.

13. The system of claim 1, wherein the housing is configured to attach to the patient'"'"'s thumb.

14. The system of claim 13, wherein the housing comprises a curved, ring-shaped portion.

15. The system of claim 14, wherein the curved, ring-shaped portion is configured to partially surround a portion of the base of the patient'"'"'s thumb.

16. The system of claim 15, wherein the curved, ring-shaped portion connects to a flexible strap.

17. The system of claim 13, wherein the first and second radiation sources are proximal to one another and separated from the photodetector by an angle between 35-55 degrees.

18. The system of claim 13, wherein the processor is further configured to process the AC signals together with a set of pre-determined coefficients selected to relate a property determined from the AC signals to the oxygen saturation value.

19. The system of claim 18, wherein the set of pre-determined coefficients are determined beforehand to correspond to an oxygen saturation value corresponding to the patient'"'"'s thumb.

20. The system of claim 1, wherein the processor is configured to determine the blood pressure value from a time difference between a feature of the time-dependent electrical signal and a feature of the AC signal.

21. The system of claim 20, wherein the processor is further configured to determine the blood pressure value before determining the oxygen saturation value.

22. The system of claim 1, wherein a single processor is configured to determine both the blood pressure value and the oxygen saturation value.

23. The system of claim 1, wherein the processor comprises a compiled component of computer code configured to determine both the blood pressure value and oxygen saturation value.

2. A system for determining both oxygen saturation and blood pressure values for a patient, comprising:

a first sensor, configured to worn around the base of the patient'"'"'s thumb, comprising at least one optical sensor for measuring an optical signal; and

a processing unit, configured to be worn on the patient'"'"'s arm and operably connected to the first sensor, the processing unit comprising a motion sensor for detecting a motion signal and an input port for receiving an electrical signal and configured to determine both oxygen saturation and blood pressure values by collectively processing the optical, electrical, and motion signals.