HANDHELD PHYSIOLOGICAL SENSOR

• US 20170188918A1
• Filed: 01/05/2016
• Published: 07/06/2017
• Est. Priority Date: 01/05/2016
• Status: Active Grant

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: OtoSense, Inc. (Analog Devices, Inc.)
• Inventors: BANET, Matthew, DHILLON, Marshal Singh, PEDE, Susan Meeks, DEPTALA, Arthur, HAYWARD, Lauren Nicole Miller, COCHRAN, Jonas Dean
• Granted Patent: US 10,092,227 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2560/0425 Ergonomically shaped housings A61B2560/0418 takes precedence
• CPC Class Codes: A61B 2560/0468 Built-in electrodes
• CPC Class Codes: A61B 5/0008 Temperature signals
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02141 Details of apparatus construction, e.g. pump units or housings therefor, cuff pressurising systems, arrangements of fluid conduits or circuits A61B5/02233, A61B5/0235 take precedence
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/0245 by using sensing means generating electric signals, i.e. ECG signals
• CPC Class Codes: A61B 5/0537 Measuring body composition by impedance, e.g. tissue hydration or fat content
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/332 Portable devices specially adapted therefor
• CPC Class Codes: A61B 5/4875 Hydration status, fluid retention of the body
• CPC Class Codes: A61B 5/6825 Hand
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor

Abstract

A handheld device measures all vital signs and some hemodynamic parameters from the human body and transmits measured information wirelessly to a web-based system, where the information can be analyzed by a clinician to help diagnose a patient. The system utilizes our discovery that bio-impedance signals used to determine vital signs and hemodynamic parameters can be measured over a conduction pathway extending from the patient'"'"'s wrist to a location on their thoracic cavity, e.g. their chest or navel. The device'"'"'s form factor can include re-usable electrode materials to reduce costs. Measurements made by the handheld device, which use the belly button as a ‘fiducial’ marker, facilitate consistent, daily measurements, thereby reducing positioning errors that reduce accuracy of standard impedance measurements. In this and other ways, the handheld device provides an effective tool for characterizing patients with chronic diseases, such as heart failure, renal disease, and hypertension.

Claims

1. A biometric sensor configured to measure a set of physiological parameters from a patient, comprising:

an arm-receiving portion comprising a first opening configured to receive a distal portion of one of the patient'"'"'s arms and first and second electrodes configured and arranged to contact the distal portion of the patient'"'"'s arm when it is received in the first opening; and

a body-contacting portion comprising an exterior-facing surface and third and fourth electrodes configured and arranged to contact a second body location that is one of the patient'"'"'s torso, legs, opposing arm, and neck when the body-contacting portion is pressed against the second body location while the distal portion of the patient'"'"'s arm is received in the first opening;

wherein the first and third electrodes are configured to inject electrical current into the patient at their respective points of contact with the patient and the second and fourth electrodes are configured to sense first and second biometric signals, respectively, which are induced by the injected electrical current;

the biometric sensor further comprising a first analog system configured to receive the first and second biometric signals and to process them to generate first and second analog physiological waveforms;

a finger-receiving portion comprising a second opening, configured and arranged to receive a finger of said one of the patient'"'"'s arms when it is received by the arm-receiving portion, and an optical system, the optical system comprising a first light source configured to irradiate the finger and a photodetector configured to receive radiation after it irradiates the finger;

a second analog system configured to receive signals from the photodetector and to process them to generate a third physiological waveform;

a first digital system configured to digitize the first and second analog physiological waveforms and to process them with computer code to determine a first physiological parameter in the set of physiological parameters; and

a second digital system configured to digitize the third physiological waveform and process it with computer code to determine a second physiological parameter in the set of physiological parameters.

2. The biometric sensor of claim 1, wherein the arm-receiving portion comprises first and second spaced-apart wall portions that form the opening, which wall portions are arranged so as to be located on opposite sides of the patient'"'"'s arm when it is inserted in the opening.

3. The biometric sensor of claim 2, wherein the first and second wall portions extend from the body-contacting portion.

4. The biometric sensor of claim 3, wherein the first and second electrodes are disposed on inner surfaces of the first and second wall portions, respectively.

5. The biometric sensor of claim 1, wherein the arm-receiving portion comprises an annular ring component that forms the opening.

6. The biometric sensor of claim 5, wherein the first and second electrodes are disposed on an inner surface of the annular ring component.

7. The biometric sensor of claim 1, wherein the arm-receiving portion comprises an inflatable cuff configured to engage the distal portion of the patient'"'"'s arm.

8. The biometric sensor of claim 7, wherein the cuff comprises a pair of inflatable bladders which oppose each other across the opening.

9. The biometric sensor of claim 8, wherein the first and second electrodes are formed from conductive, elastomeric material disposed over surfaces of the inflatable bladders that face the opening.

10. The biometric sensor of claim 7, wherein the cuff is formed from elastomeric material.

11. The biometric sensor of claim 7, wherein the cuff is formed from inelastic material.

12. The biometric sensor of claim 7, wherein the cuff is configured to be wrapped around the distal portion of the patient'"'"'s arm and secured by means of a closure member.

13. The biometric sensor of claim 1, wherein the first, second, third, and fourth electrodes each comprise a conductive material.

14. The biometric sensor of claim 13, wherein the conductive material is one of a conductive fabric, a metal component, a conductive foam, a conductive polymeric material, and a hydrogel material.

15. The biometric sensor of claim 1, wherein the first and second electrodes are each disposed on top of an inflatable bladder.

16. The biometric sensor of claim 15, wherein the sensor further comprises a microprocessor-controlled pneumatic inflation system configured and arranged to control inflation and deflation of the inflatable bladders.

17. The biometric sensor of claim 16, wherein the pneumatic system comprises a pump and a valve.

18. The biometric sensor of claim 16, wherein the first and second electrodes are formed from elastomeric fabric which stretches and contracts with the inflatable bladders as the bladders are inflated and deflated.

19. The biometric sensor of claim 1, further comprising a circuit board disposed within the sensor.

20. The biometric sensor of claim 19, wherein the analog and digital systems are disposed on the circuit board and the digital system includes a microprocessor that is programmed with said computer code to process the analog physiological waveform to determine the physiological parameter.

21. The biometric sensor of claim 20 wherein the first and second electrodes are in electrical, signal-conducting contact with the analog system.

22. The biometric sensor of claim 1, wherein the first analog system comprises a differential amplifier configured to amplify a difference between the first and second biometric signals to generate the first and second analog physiological waveforms.

23. The biometric sensor of claim 22, wherein the first and second analog physiological waveforms are impedance waveforms, and wherein the first analog waveform comprises AC information and the second physiological waveform comprises DC information.

24. The biometric sensor of claim 23, wherein the first analog waveform comprises heartbeat-induced pulsations.

25. The biometric sensor of claim 23, wherein the physiological parameter is stroke volume.

26. The system of claim 1, wherein the computer code is configured to process the first analog physiological waveform to calculate a derivative and determine a dΔ

Z(t)/dt waveform.

27. The system of claim 26, wherein the computer code is configured to determine a maximum value of the dΔ

Z(t)/dt waveform.

28. The system of claim 26, wherein the computer code is configured to determine an area of a pulse in the dΔ

Z(t)/dt waveform.

29. The system of claim 26, wherein the computer code is configured to estimate an ejection time from the dΔ

Z(t)/dt waveform.

30. The system of claim 29, wherein the computer code is configured to determine i) a maximum value of the dΔ

Z(t)/dt waveform ((dΔ

Z(t)/dt)_max, and ii) a left ventricular ejection time (LVET) from the dΔ

Z(t)/dt waveform.

31. The system of claim 26, wherein the computer code is configured to process the second analog physiological waveform to estimate a baseline impedance (Z₀).

32. The system of claim 31, wherein the computer code is configured to determine stroke volume (SV) from the equation:

33. The system of claim 31, wherein the computer code is configured to determine stroke volume (SV) from the equation:

34. The biometric sensor of claim 1, wherein the third physiological waveform is a photoplethysmogram waveform.

35. The biometric sensor of claim 34, wherein the photoplethysmogram waveform comprises a set of heartbeat-induced pulses, and the computer code is configured to calculate a time difference between the pulses to determine the patient'"'"'s heart rate.

36. The biometric sensor of claim 1, wherein the optical system further comprises a second light source configured to irradiate the finger and the photodetector is configured to receive radiation from both the first and second light sources after they irradiate the finger.

37. The biometric sensor of claim 36, wherein the second analog system is configured 1) to receive signals from the photodetector that are generated with radiation from the first light source and to process them to generate the third physiological waveform;

and

     2) to receive signals from the photodetector that are generated with radiation from the second light source and to process them to generate a fourth physiological waveform.

38. The biometric sensor of claim 37, wherein the first light source is configured to emit optical radiation between 880 and 920 nm.

39. The biometric sensor of claim 38, wherein the first light source is configured to emit optical radiation around 905 nm.

40. The biometric of claim 37, wherein the second light source is configured to emit optical radiation between 640 and 680 nm.

41. The biometric sensor of claim 40, wherein the second light source is configured to emit optical radiation around 660 nm.

42. The biometric sensor of claim 37 wherein the first and second light sources and the photodetector are connected to a common surface of the optical system.

43. The biometric sensor of claim 42, wherein the photodetector is configured to receive infrared radiation from the first and second light sources after it reflects off of the patient'"'"'s finger.

44. The biometric sensor of claim 1, wherein the first and second light sources are connected to a top surface of the optical system so as to irradiate an upper surface of the patient'"'"'s finger when it is positioned within the second opening.

45. The biometric sensor of claim 44, wherein the photodetector is connected to a bottom surface of the optical system so as to irradiate a lower surface of the patient'"'"'s finger when it is positioned within the second opening.

46. The biometric sensor of claim 45, wherein the photodetector is configured to receive infrared radiation from the first and second light sources after it is transmitted through the patient'"'"'s finger.

47. The biometric sensor of claim 37, wherein the second digital system comprises computer code configured to analyze the third analog physiological waveform to determine an AC infrared component thereof (infrared(AC)) and a DC infrared component thereof (infrared(DC)).

48. The biometric sensor of claim 37, wherein the second digital system comprises computer code configured to analyze the fourth physiological waveform to determine a red AC component thereof (red(AC)) and a red DC component thereof (red(DC)).

49. The biometric sensor of claim 48, wherein the second digital system comprises computer code configured to collectively analyze the infrared(AC), infrared(DC), red(AC), and red(DC) components to determine a pulse oximetry value.

50. The biometric sensor of claim 49, wherein the second digital system comprises computer code configured to collectively analyze the infrared(AC), infrared(DC), red(AC), and red(DC) components according to the following equation to determine a ratio of ratios (RoR):

51. The biometric sensor of claim 50, wherein the second digital system comprises computer code configured to process the RoR according to the following equation to determine said pulse oximetry value:

pulse oximetry value=(a+b×

RoR+c×

RoR)×

100

wherein a, b, and c are pre-determined constants.