BIOLOGICAL SIGNAL MEASURING SYSTEM AND BIOLOGICAL SIGNAL MEASURING APPARATUS

• US 20140213884A1
• Filed: 01/22/2014
• Published: 07/31/2014
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: Hirabara, Hideaki, Kobayashi, Naoki
• Granted Patent: US 9,521,969 B2
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 2505/01 Emergency care
• CPC Class Codes: A61B 5/0053 by applying pressure, e.g. compression, indentation, palpation, grasping, gauging
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/6826 Finger

Abstract

A biological signal measuring system includes: a light emitter emitting a first light beam and a second light beam; a light receiver outputting first and second signals in accordance with light intensities of the first and second light beams that have been passed through or reflected from a living tissue of a subject; a first calculating section acquiring a light attenuation of the first and second light beams based on the first and second signals; a second calculating section acquiring a blood-derived light attenuation based on the light attenuation of the first and second light beams; a third calculating section identifying a blood fill time for filling the living tissue, based on a temporal change of the blood-derived light attenuation associated with pressurization of the living tissue; and an outputting section outputting the identified blood fill time.

Claims

1. A biological signal measuring system comprising:

a light emitter which is configured to emit a first light beam having a first wavelength, and a second light beam having a second wavelength;

a light receiver which is configured to output first and second signals respectively in accordance with received light intensities of the first and second light beams that have been passed through or reflected from a living tissue of a subject;

a first calculating section which is configured to acquire a light attenuation of the first light beam based on the first signal, and a light attenuation of the second light beam based on the second signal;

a second calculating section which is configured to acquire a blood-derived light attenuation based on the light attenuation of the first light beam, and the light attenuation of the second light beam;

a third calculating section which is configured to identify a blood fill time for filling the living tissue, based on a temporal change of the blood-derived light attenuation associated with pressurization of the living tissue; and

an outputting section which is configured to output the identified blood fill time.

2. The biological signal measuring system according to claim 1, wherein

the second calculating section acquires the blood-derived light attenuation based on a difference of the light attenuation of the first light beam and the light attenuation of the second light beam.

3. The biological signal measuring system according to claim 1, wherein

the second calculating section applies a rotation matrix to the light attenuation of the first light beam and the light attenuation of the second light beam, thereby acquiring the blood-derived light attenuation.

4. The biological signal measuring system according to claim 1, further comprising a fourth calculating section which is configured to acquire a signal in which a component of a frequency that is lower than a predetermined frequency is removed from a signal indicative of the blood-derived light attenuation, wherein

the third calculating section identifies the blood fill time based on a temporal change of the signal which is acquired by the fourth calculating section after the pressurization of the living tissue is released.

5. The biological signal measuring system according to claim 4, further comprising a fifth calculating section which is configured to acquire a logarithm of a value of the signal acquired by the fourth calculating section, wherein

the third calculating section identifies the blood fill time based on a gradient of a regression line which is obtained from a temporal change of the logarithm after the pressurization of the living tissue is released.

6. The biological signal measuring system according to claim 1, wherein

when an amount of the change of the blood-derived light attenuation is larger than a predetermined value, a measurement of the blood fill time by the third calculating section is automatically started.

7. The biological signal measuring system according to claim 1, further comprising:

a cuff which is adapted to be attached to the subject in a manner that the cuff can pressurize the living tissue; and

a cuff pressure controlling section which is configured to control an air pressure inside the cuff.

8. A biological signal measuring apparatus comprising:

a signal receiving section which is configured to receive a first signal corresponding to an intensity of a first light beam that has been passed through or reflected from a living tissue of a subject, and that has a first wavelength, and a second signal corresponding to an intensity of a second light beam that has been passed through or reflected from the living tissue, and that has a second wavelength;

a first calculating section which is configured to acquire a light attenuation of the first light beam based on the first signal, and a light attenuation of the second light beam based on the second signal;

a second calculating section which is configured to acquire a blood-derived light attenuation based on the light attenuation of the first light beam, and the light attenuation of the second light beam; and

a third calculating section which is configured to identify a blood fill time for filling the living tissue, based on a temporal change of the blood-derived light attenuation associated with pressurization of the living tissue.

9. A method of controlling a biological signal measuring apparatus comprising a signal receiving section which is configured to receive a first signal corresponding to an intensity of a first light beam that has been passed through or reflected from a living tissue of a subject, and that has a first wavelength, and a second signal corresponding to an intensity of a second light beam that has been passed through or reflected from the living tissue, and that has a second wavelength, the method comprising:

acquiring a light attenuation of the first light beam based on the first signal, and a light attenuation of the second light beam based on the second signal;

acquiring a blood-derived light attenuation based on the light attenuation of the first light beam, and the light attenuation of the second light beam;

identifying a blood fill time for filling the living tissue, based on a temporal change of the blood-derived light attenuation associated with pressurization of the living tissue; and

outputting the identified blood fill time.

10. A program causing a computer to execute the method according to claim 9.

11. A non-transitory computer-readable recording medium storing a program causing a computer to execute the method according to claim 9.