Apparatus for measuring concentration of hemoglobin and method for the same

• US 5,722,398 A
• Filed: 11/14/1995
• Issued: 03/03/1998
• Est. Priority Date: 11/15/1994
• Status: Expired due to Term

• Current Assignee: Toa Medical Electronics Co., Ltd.
• Original Assignee: Toa Medical Electronics Co., Ltd.
• Inventors: Maekawa, Yasunori, Ishihara, Ken, Asano, Kaoru
• Primary Examiner(s): Bahr, Jennifer
• Assistant Examiner(s): WINAKUR, ERIC FRANK
• Application Number:
  US08/557,573
• Time in Patent Office: 840 Days
• Field of Search: 128/633, 128/637, 128/664, 128/665, 356/39
• US Class Current: 600/322
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters

Abstract

An apparatus for measuring a concentration of hemoglobin includes a light application device for applying light to a detection region containing a blood vessel present in a living body; an image capturing device for capturing an image of the detection region to which the light is applied; and an analyzer for analyzing the concentration of hemoglobin in blood flowing through the blood vessel by processing the captured image. The analyzer includes a light intensity detector for detecting a light intensity of a body tissue and a light intensity of blood using the captured image. It further includes a calculator for calculating the concentration of hemoglobin from a ratio of the light intensity of the body tissue relative to the light intensity of blood thus detected.

Claims

1. An apparatus for measuring a concentration of hemoglobin comprising:

light application means for applying light of a single wavelength or wavelength band to a detection region containing a blood vessel present in a living body;

image capturing means for capturing an image of the detection region to which the light is applied; and

analysis means for analyzing the concentration of hemoglobin in blood flowing through the blood vessel by processing the captured image,

the analysis means including light intensity detection means for detecting a light intensity of a body tissue and a light intensity of a region of blood flow from the captured image and calculating means for calculating the concentration of hemoglobin from a ratio of the detected light intensity of the body tissue relative to the detected light intensity of the region of blood flow.

2. The apparatus for measuring the concentration of hemoglobin of claim 1, wherein the analysis means further comprises blood vessel diameter detecting means for detecting a diameter of the blood vessel in the captured image and correction means for correcting the calculated concentration of hemoglobin based on the detected diameter of the blood vessel.

3. The apparatus for measuring the concentration of hemoglobin of claim 1, wherein the calculating means includes means for calculating a concentration C of hemoglobin from the following equation:

space="preserve" listing-type="equation">C=K·

log (I.sub.T /I.sub.B)

wherein C represents a concentration of hemoglobin, I_T represents a detected light intensity of a body tissue, I_B represents a detected light intensity of the region of blood flow and K is a constant.

4. The apparatus for measuring the concentration of hemoglobin of claim 1, wherein the light intensity detecting means includes means for examining a frequency distribution of intensity of pixels in the captured image and means for detecting an intensity A as the light intensity of the region of blood flow and an intensity B as the light intensity of the body tissue, wherein the frequency distribution indicates peak values at the intensities A and B (A<

B).

5. A method comprising the steps of:

applying light of a single wavelength or wavelength band to a detection region containing a blood vessel present in a living body;

capturing an image of the detection region to which the light is applied; and

processing the captured image to measure a concentration of hemoglobin, wherein the step of processing the captured image includes the sub-steps of,

detecting a light intensity of a body tissue and a light intensity of a region of blood flow from the captured image, and

calculating the concentration of hemoglobin from a ratio of the detected light intensity of the body tissue relative to the detected light intensity of the region of blood flow.

6. The method for measuring the concentration of hemoglobin of claim 5, wherein the sub-step of calculating the concentration of hemoglobin further includes,

detecting a diameter of the blood vessel in the captured image, and

correcting the calculated concentration of hemoglobin based on the detected diameter of the blood vessel.

7. The method for measuring the concentration of hemoglobin of claim 5, wherein the sub-step of calculating the concentration of hemoglobin includes calculating the following equation:

space="preserve" listing-type="equation">C=K·

log (I.sub.T /I.sub.B)

wherein C represents a concentration of hemoglobin, I_T represents a detected light intensity of a body tissue, I_B represents a detected light intensity of the region of blood flow and K is a constant.

8. The method for measuring the concentration of hemoglobin of claim 5, wherein the sub-step of detecting the light intensities of the body tissue and the region of blood flow includes detecting an intensity A as the light intensity of the region of blood flow and an intensity B as the light intensity of the body tissue wherein a frequency distribution on intensity of pixels in the captured image indicates peak values at the intensities A and B (A<

B).