Optical analyzer for measuring a construction ratio between components in the living tissue

• US 4,446,871 A
• Filed: 12/15/1980
• Issued: 05/08/1984
• Est. Priority Date: 01/25/1980
• Status: Expired due to Fees

• Current Assignee: Minolta Camera Kabushiki Kaisha
• Original Assignee: Minolta Kabushiki Kaisha
• Inventors: Imura, Kenji
• Primary Examiner(s): Howell, Kyle L.
• Assistant Examiner(s): HANLEY, JOHN C
• Application Number:
  US06/216,526
• Time in Patent Office: 1,240 Days
• Field of Search: 128/633, 128/634, 128/665, 128/666, 128/664, 356/39-42
• US Class Current: 600/323
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427

Abstract

An optical analyzer such as oximeter is provided including a source of light having a plurality of different wavelengths. At least two or more of the different wavelengths have a fixed relationship of light absorption after coaction with hemoglobin oxide. The light is directed at the subject tissue and received after coaction by an optical probe. A first signal representative of the degree of light absorption at a predetermined standard wavelength is determined and then an attempt is made to match a second wavelength having a fixed relationship of light absorption to the predetermined standard wavelength, e.g., equal absorption, to generate a second signal representative of the second wavelength, whereby the amount of hemoglobin oxide can be determined in the bloodstream.

Claims

1. An oximeter for obtaining information indicative of the level of hemoglobin oxide in living tissue, comprising:

a source of light having a plurality of different wavelengths susceptible of coaction with both hemoglobin and hemoglobin oxide;

means for directing the light at the subject tissue;

means for measuring the degree of light absorption at a predetermined standard wavelength;

means for finding a second wavelength in which the degree of absorption is equal to that at the predetermined standard wavelength; and

means for determining the level of oxygen saturation in the blood from the second wavelength.

2. The invention of claim 1 wherein said means for determining includes means for storing a plurality of hemoglobin oxide values corresponding to a plurality of respective wavelengths at which the absorption is equal to that of the standard wavelength;

means for addressing the stored hemoglobin oxide values in response to the second wavelength, and means for providing an indication of the hemoglobin oxide value of the tissue corresponding to the matched second wavelength.

3. The invention of claim 1 further including filter means for removing any noise components from the signal.

4. The invention of claim 1 wherein said means for finding includes a plurality of band pass filters for selective interaction with the source of light to provide a plurality of wavelengths for finding said second wavelength.

5. The invention of claim 4 further including a rotatable member for supporting the band pass filters and encoding means to generate a position signal indicative of each band pass filter when interacting with the source of light whereby the means for finding can determine a particular second wavelength.

6. An oximeter for measuring an oxygen saturation, which is defined as a ratio of the hemoglobin oxide to the sum of the hemoglobin and the hemoglobin oxide, in living tissue comprising:

means for providing a source light;

means for directing the source light at the living tissue;

means for receiving the source light after coaction with the living tissue;

means for determining the intensity of the light received by the receiving means at a predetermined standard wavelength;

means for searching for another wavelength at which the intensity of light received by the receiving means is equal to that of the standard wavelength of light determined by the determining means; and

means for providing a record of values for the level of hemoglobin oxide as a function of a plurality of wavelengths at which the light absorption of said wavelengths is equal to the absorption at a predetermined standard wavelength;

and means for finding the level of hemoglobin oxide from the another wavelength in accordance with the preparatorily known recorded valves of hemoglobin oxide.

7. The invention of claim 6 further comprising a second means for determining an intensity of the ligth received by the receiving means at a predetermined second standard wavelength, a second means for searching for a second wavelength at which the intensity of light received by the receiving means is equal to that of the second standard wavelength of light determined by the second determining means, means for examining whether or not the second wavelength is within a predetermined range of wavelengths, and means responsive to the examining means for selecting the second wavelength when it is within the predetermined wavelength range and for selecting said another wavelength when the second wavelength is outside the predetermined wavelength range, and means for using said selected wavelength in said means for determining.

8. An optical analyzer for measuring a construction ratio of the hemoglobin oxide to the sum of the hemoglobin and the hemoglobin oxide to determine oxygen saturation in tissue comprising:

means for providing a source light;

means for directing the source light at the tissue;

means for receiving the source light after contact with the tissue;

means for determining the intensity of the light received by said receiving means at a predetermined standard wavelength;

means for searching for another wavelength at which the intensity of light received by said receiving means is equal to that of said standard wavelength of light determined by said determining means;

means for indicating an oxygen saturation level from said another wavelength including means for storing a plurality of previously known values of oxygen saturation corresponding to respective different wavelengths, and means for taking one oxygen saturation value from said storing means in response to said another wavelength whereby the wavelength found by said searching means is converted into a corresponding level of oxygen saturation for indicating the oxygen saturation in the living tissue.

9. The invention of claim 8, wherein said light source means includes a light exit for directing the source light to the living tissue and said receiving means includes a light entrance for receiving the source light reflected by the living tissue.

10. The invention of claim 8, wherein said light exit and light entrance are positioned so as not to contact the surface of the living tissue.

11. The invention of claim 10, wherein said searching means includes means for sequentially scanning different wavelengths to measure each intensity thereof.

12. A method of optically determining the level of hemoglobin oxide in living tissue by directing predetermined wavelengths of light at the tissue and photoelectrically measuring the light absorption, comprising the steps of:

preparatorily knowing and recording values for a the level of hemoglobin oxide as a function of a plurality of wavelengths at which the light absorption of said wavelengths is equal to the absorption at a predetermined standard wavelength;

measuring the amount of light absorption of the predetermined standard wavelength;

exposing the living tissue to a plurality of differnt wavelengths of light;

determining which of the different wavelength is absorbed to a degree equal to that of the standard wavelength, and

finding the level of hemoglobin oxide from the determined wavelength in accordance with the preparatorily known recorded values of hemoglobin oxide.