Surgery – Diagnostic testing – Measuring or detecting nonradioactive constituent of body...
Patent
1998-06-11
2000-05-09
Winakur, Eric F.
Surgery
Diagnostic testing
Measuring or detecting nonradioactive constituent of body...
600473, 600476, A61B 500
Patent
active
060615834
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a noninvasive blood analyzer. The analyzer of the present invention is capable of transcutaneously monitoring an amount of a blood constituent such as hemoglobin concentration or hematcrit in real time with an improved repeatability without sampling blood from a living body.
2. Background Art
The hematology test of blood in a peripheral blood vessel is one of the most important and frequently performed tests in the clinical examination. Particularly, test items essential for the diagnosis on the case of anemia are hemoglobin concentration and hematocrit. The hematology test currently performed requires blood sampling from patients. However, the frequent blood sampling imposes a burden on patients and creates a risk of infection due to accidental sticking with an injection needle.
In view of the foregoing, there have been proposed apparatuses for transcutaneous (noninvasive) measurement on the aforesaid test items. For example, Japanese Examined Patent Publication No. HEI- 3-71135 discloses a hemoglobin concentration measurement apparatus for measuring blood hemoglobin on the basis of a change in the light intensity due to pulsation of light of a plurality of wavelengths projected onto a living body. Similarly, U.S. Pat. No. 5,372,136 discloses a system and method for determining hematocrit in blood by utilizing pulsation and the like.
However, a problem associated with the accuracy accompanies these arts for determining an absolute value, because the volume of the blood to be a test subject is not determined. Further, it is predicted that the measurements may vary depending on the body part to which the sensor is attached, resulting in a poor repeatability.
U.S. Pat. No. 4,998,533 discloses an apparatus for performing measurement on the aforesaid test categories on the basis of an image of a blood stream in blood capillary, which however, requires a large-scale construction. Although it has been reported that a transmitted light image of blood vessels in a part of a living body such as a finger can be obtained, no attempt has been made to perform a quantitative analysis on the aforesaid test items by analyzing the transmitted light image.
DISCLOSURE OF THE INVENTION
In view of the foregoing, the present invention provides an apparatus and method which are adapted to obtain a transmitted light image of a blood vessel in tissues of a living body such as a finger and analyze the transmitted light image with a simplified construction for performing measurement on the aforesaid test items with an improved repeatability.
More specifically, when light is allowed to pass through body tissues including a blood vessel and a transmitted light image is picked up, a blood vessel portion of the image is dark because of light absorption by blood constituent contained in blood, and the other image portion is bright because the other part of the body tissues transmits the light. In accordance with the present invention, the concentration of a blood constituent (e.g., hemoglobin) is quantified by a comparison of image densities and, when required, the determined concentration is corrected on the basis of the depth at which the blood vessel is present.
In accordance with the present invention, there is provided a noninvasive blood analyzer which comprises: a light source for illuminating a part of tissues of a living body including a blood vessel; an image pickup section for picking up an image of the illuminated blood vessel and tissues; and an analyzing section for analyzing the picked image; the analyzing section analyzing image density of the blood vessel in the picked image to compute an amount of a blood constituent and output a compution result.
In the present invention, the living body is meant by mammals including human, and the part of the tissues of the living body is meant by a part of tissues as they are in the living body, e.g., a finger or earlobe, but not meant by tissues separated from the living body.
In the analyzer of the present inventio
REFERENCES:
patent: 4998533 (1991-03-01), Winkelman
patent: 5372136 (1994-12-01), Steuer et al.
patent: 5722398 (1998-03-01), Ishihara et al.
Asano Kaoru
Ishihara Ken
Kouchi Yasuhiro
Kusuzawa Hideo
Sysmex Corporation and Ken Ishihara
Winakur Eric F.
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