Probe and apparatus for determining concentration of light-absorbing materials in living tissue

• US 6,671,526 B1
• Filed: 10/20/2000
• Issued: 12/30/2003
• Est. Priority Date: 07/17/1998
• Status: Expired due to Term

• Current Assignee: Nihon Kohden Corporation
• Original Assignee: Nihon Kohden Corporation
• Inventors: Xie, Cheng-tai, Fuse, Masayoshi, Aoyagi, Takuo, Takeda, Sunao, Kanemoto, Michio
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): McCrosky, David J.
• Application Number:
  US09/692,044
• Time in Patent Office: 1,166 Days
• Field of Search: 600/310, 600/311, 600/336, 600/323, 600/322, 600/316, 600/324, 600/473, 600/476
• US Class Current: 600/310
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor

Abstract

A probe 1 includes a light irradiating device 2 and a light receiving device 3, which are oppositely disposed sandwiching living tissue 10. The light irradiating device 2 includes a light source 5 and a scattering plate 6 located in front of the light source 5. The light receiving device 3 includes a photo diode 8 and a light scattering portion. With such an arrangement, of the attenuation of the living tissue 10, non-absorbing attenuation is free from the wavelength. A ratio of absorbing attenuation and a thickness of a blood layer is not affected by a thickness of living tissue. Further, the absorbing attenuation is not dependent on a depth of the blood layer.

Claims

1. A probe comprising:

a light irradiating device for irradiating living tissue with light, said light irradiating device including a light source for emitting a plurality of lights of different wavelengths;

a first light scattering plate located in front of said light source; and

a light receiving device for receiving light from said living tissue , said light receiving device including a photo-electric transducing portion for producing a signal based on an intensity of light received on a light sensitive surface, and a second light scattering plate located in front of said photo-electric transducing portion;

wherein said light receiving device includes a light mixing portion provided between said second light scattering plate and said light sensitive surface.

2. A probe according to claim 1, wherein said light mixing portion includes a closed space defined by an inner light reflective wall of a housing, said second light scattering plate and the light sensitive surface.

3. A probe according to claim 1, wherein said light mixing portion is positioned between said photo-electric transducing portion and said second light scattering portion.

4. A probe according to claim 1, wherein said photo-electric transducing portion and said second light scattering portion are disposed opposite each other.

5. A probe according to claim 1, wherein said light receiving device includes a housing for accommodating said photo-electric transducing portion, and a surface of said housing contacting said second scattering plate is light reflective.

6. A probe according to claim 1, wherein said first light scattering plate and said second light scattering plate transmit light diffusively.

7. An apparatus for determining concentration of light-absorbing materials in living tissue, comprising:

a probe comprising;

a light irradiating device for irradiating living tissue with light, said light irradiating device including a light source for emitting a plurality of lights of different wavelengths;

a first light scattering portion located in front of said light source; and

a light receiving device for receiving light from said living tissue, said light receiving device including a photo-electric transducing portion for producing a signal based on an intensity of light received on a light sensitive surface, and a second light scattering portion, said light receiving device further including a light mixing portion provided between said second light scattering portion and said light sensitive surface, and concentration-ratio processing means for computing at least one ratio of concentrations of a plurality of light-absorbing materials in said living tissue based on an output signal of said photo-electric transducing portion of said probe.

8. An apparatus for determining concentration of light-absorbing materials in living tissue according to claim 7, wherein said concentration-ratio processing means obtains a variation of an optical attenuation of said living tissue based on a pulsating component of an output signal of said photo-electric transducing portion, and computes a ratio of concentrations of a plurality of light-absorbing materials based on the obtained attenuation variation.

9. An apparatus for determining concentration of light-absorbing materials in living tissue according to claim 8, wherein said concentration-ratio processing means includes:

attenuation variation component detecting means for obtaining attenuation variation components Δ

A1, Δ

A2, . . . , Δ

An of the respective wavelengths from variations of lights transmitted through or reflected by said living tissue when said living tissue is irradiated by said light irradiating device;

variation component ratio detecting means for obtaining a ratio φ

ij of each of an “

m”

number of combinations of two attenuation variation components (Δ

Ai, Δ

Aj) selected from an “

n”

number of attenuation variation components Δ

A1, Δ

A2, . . . , Δ

An obtained by said attenuation variation component detecting means, and

computing means for computing at least one of an oxygen saturation and a ratio of concentrations of light-absorbing materials in blood based upon an “

m”

number of simultaneous equations about said respective wavelengths and an “

m”

number of ratios φ

ij obtained by said variation component ratio detecting means, on the assumption that said attenuation variation component is the sum of the attenuation variation components of absorbing attenuation and non-absorbing attenuation.

10. An apparatus for determining concentration of light-absorbing materials in living tissue according to claims 7, wherein said first light scattering portion includes a first light scattering plate, and second light scattering portion includes a second light scattering plate.

11. An apparatus for determining concentration of light-absorbing materials in living tissue according to claim 7, wherein said light mixing portion includes a closed space defined by an inner light reflective wall of a housing, said second light scattering portion and the light sensitive surface.

12. An apparatus for determining concentration of light-absorbing materials in living tissue according to claim 7, wherein said light receiving device includes a housing for accommodating said photo-electric transducing portion, and a surface of said housing contacting said second scattering portion is light reflective.