MEDICAL PHOTOMETER AND MEDICAL PHOTOMETER CONTROL METHOD

• US 20180116568A1
• Filed: 10/25/2017
• Published: 05/03/2018
• Est. Priority Date: 10/27/2016
• Status: Active Grant

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: UEDA, Yoshinori, UKAWA, Teiji, ITO, Kazumasa, FUJISAKI, Hideki
• Granted Patent: US 10,722,154 B2
• Time in Patent Office: Days
• CPC Class Codes: A61B 2562/0238 Optical sensor arrangements for performing transmission measurements on body tissue
• CPC Class Codes: A61B 5/1072 measuring distances on the body, e.g. measuring length, height or thickness A61B5/1076 takes precedence
• CPC Class Codes: A61B 5/1075 for measuring dimensions by non-invasive methods, e.g. for determining thickness of tissue layer A61B8/0858 takes precedence
• CPC Class Codes: A61B 5/1079 using optical or photographic means
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/7214 using signal cancellation, e.g. based on input of two identical physiological sensors spaced apart, or based on two signals derived from the same sensor, for different optical wavelengths
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01N 21/27 using photo-electric detection G01N21/31 takes precedence; circuits for computing concentration logarithmic circuits G06G7/24; photometric circuits in general G01J
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/59 Transmissivity G01N21/25 takes precedence

Abstract

A medical photometer includes a processor and a memory that stores an instruction readable by a computer. When the instruction is executed by the processor, the medical photometer acquires a first light attenuation of a first light beam that is transmitted through or reflected from a tissue of a living body, and that has a first wavelength, based on a first intensity signal corresponding to an intensity of the first light beam, acquires a second light attenuation of a second light beam that is transmitted through or reflected from the tissue, and that has a second wavelength, based on a second intensity signal corresponding to an intensity of the second light beam, calculates a tissue thickness based on a ratio of the first light attenuation and the second light attenuation, and detects an artifact of the living body based on a temporal variation of the tissue thickness.

Claims

1. A medical photometer comprising:

a first light emitter that emits a first light beam having a first wavelength;

a second light emitter that emits a second light beam having a second wavelength;

a detector that outputs a first intensity signal corresponding to an intensity of the first light beam that is transmitted through or reflected from a tissue of a living body, and a second intensity signal corresponding to an intensity of the second light beam that is transmitted through or reflected from the tissue;

a processor; and

a memory that stores an instruction readable by a computer,

wherein, when the instruction is executed by the processor, the medical photometer

acquires a first light attenuation of the first light beam based on the first intensity signal,

acquires a second light attenuation of the second light beam based on the second intensity signal,

calculates a tissue thickness based on a ratio of the first light attenuation and the second light attenuation, and

detects an artifact of the living body based on a temporal variation of the tissue thickness,

both the first light beam and the second light beam are infrared light beams or red light beams,

a ratio of a first extinction of a first light absorber at the first wavelength and a second extinction of the first light absorber at the second wavelength is different from 1,

a third extinction of a second light absorber at the first wavelength is higher than the first extinction,

a fourth extinction of the second light absorber at the second wavelength is higher than the second extinction, and

a ratio of the third extinction and the fourth extinction is approximable by 1.

2. The medical photometer according to claim 1 further comprising a notifying section that performs notification when the detected artifact exceeds a threshold value.

3. The medical photometer according to claim 1 further comprising a third light emitter that emits a third light beam having a third wavelength,

wherein a ratio of an extinction coefficient of blood at the first wavelength, and an extinction coefficient of the blood at the third wavelength is varied in accordance with a concentration of the second light absorber contained in the blood,

a ratio of an extinction coefficient of blood at the second wavelength, and an extinction coefficient of the blood at the third wavelength is varied in accordance with a concentration of the second light absorber contained in the blood,

the detector outputs a third intensity signal corresponding to an intensity of the third light beam which is transmitted through or reflected from the tissue, and,

when the instruction is executed by the processor, the medical photometer

acquires a light attenuation variation of the first light beam due to pulsation of blood in the tissue, based on the first intensity signal and/or a light attenuation variation of the second light beam due to the pulsation, based on the second intensity signal,

acquires a light attenuation variation of the third light beam due to the pulsation, based on the third intensity signal, and

calculates the concentration of the second light absorber in the blood based on the light attenuation variation of the third light beam and at least one of the light attenuation variation of the first light beam and the light attenuation variation of the second light beam.

4. A medical photometer comprising:

a processor; and

a memory that stores an instruction readable by a computer,

wherein, when the instruction is executed by the processor, the medical photometer

acquires a first light attenuation of a first light beam that has a first wavelength and that is transmitted through or reflected from a tissue of a living body, based on a first intensity signal corresponding to an intensity of the first light beam,

acquires a second light attenuation of a second light beam that has a second wavelength and that is transmitted through or reflected from the tissue of the living body, based on a second intensity signal corresponding to an intensity of the second light beam,

calculates a tissue thickness based on a ratio of the first light attenuation and the second light attenuation, and

detects an artifact of the living body based on a temporal variation of the tissue thickness,

a ratio of a first extinction of a first light absorber at the first wavelength and a second extinction of the first light absorber at the second wavelength is different from 1,

a third extinction of a second light absorber at the first wavelength is higher than the first extinction,

a fourth extinction of the second light absorber at the second wavelength is higher than the second extinction, and

a ratio of the third extinction and the fourth extinction is approximable by 1.

5. A method of controlling a medical photometer comprising:

causing the medical photometer to acquire a first light attenuation of a first light beam that has a first wavelength and is transmitted through or reflected from a tissue of a living body, based on a first intensity signal corresponding to an intensity of the first light beam;

causing the medical photometer to acquire a second light attenuation of a second light beam that has a second wavelength and is transmitted through or reflected from the tissue, based on a second intensity signal corresponding to an intensity of the second light beam;

causing the medical photometer to calculate a tissue thickness based on a ratio of the first light attenuation and the second light attenuation; and

causing the medical photometer to detect an artifact of the living body based on a temporal variation of the tissue thickness,

wherein a ratio of a first extinction of a first light absorber at the first wavelength and a second extinction of the first light absorber at the second wavelength is different from 1,

a third extinction of a second light absorber at the first wavelength is higher than the first extinction,

a fourth extinction of the second light absorber at the second wavelength is higher than the second extinction, and

a ratio of the third extinction and the fourth extinction is approximable by 1.