JPH0331053B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention detects changes in the blood concentration of an indicator dye for organ function diagnosis injected into a patient's blood using an optical sensor placed on the skin. It is related to measurement technology for measuring

[Prior Art] Conventionally, liver function (detoxification function of the liver) has been measured by measuring changes in the concentration of an indicator dye injected into the blood.

Currently, the most commonly used method for measuring liver function is a method using a blue dye, indocyan green (hereinafter referred to as ICG), as an indicator.
In this method, when ICG is injected into the blood, it is absorbed by the liver and its blood concentration decreases, so the rate of decrease (concentration disappearance rate) is measured to determine the quality of liver function. It is. This method includes a simple method (15-minute stagnation rate measurement method) and a precise method (maximum disappearance rate measurement method). In the simple method, blood cells are collected after a certain period of time (usually 15 minutes) after ICG injection, blood cells are removed by centrifugation, and the supernatant (i.e., plasma) is collected with ICG.
The concentration is measured spectrophotometrically. In the precision method, ICG
(e.g. 2, 4,
6 times (6, 9, 12, and 15 minutes)) and measure the ICG concentration. This measurement is then performed at various ICG doses for special analysis. In either case, not only is the blood sampling time-consuming and painful for the patient, but it also takes a certain amount of time to collect blood, making it difficult to measure the rate of disappearance during the most important initial period of injection (within 1 minute after injection). Also, in the blood
When the rate of decrease in ICG concentration changes rapidly, there is also the drawback that accurate measurement cannot be made using the blood sampling method described above. In order to solve these two difficulties,
There is also a method of placing an optical sensor in the artery, or making continuous measurements by causing continuous bleeding from the artery to the optical sensor part. However, all of these methods are extremely invasive to the patient, making it impossible to perform practical measurements.

In order to solve these problems, the inventor has already made the following invention. In other words, Japanese Patent Publication No. 1973-
No. 12586 (Funji Hagiwara, Lab. Yoneda), JP-A-59-189828
No. (Funji Hagiwara) and patent application No. 1989-4789 (Funji Hagiwara). In these inventions, light is irradiated from above the skin, and the scattered reflected light of the light that enters tissues such as blood vessels is received, and changes in the concentration or spectrum of indicator pigments in blood are measured. These also disclose the following sensors suitable for two-wavelength absorbance difference measurement method. Light with a wavelength that is highly absorbed by the indicator dye (hereinafter referred to as high absorption light)
Then, two light sources alternately emit light with a wavelength that is sufficiently small in absorption (hereinafter referred to as low absorption light) compared to that, and the scattered reflected light is received, and the difference in intensity of each scattered reflected light is used. A sensor is shown that measures the concentration of an indicator dye. The center wavelength of the highly absorbing light is the wavelength of the absorption peak of the indicator dye (e.g.
805nm) in ICG.
The center wavelength of the low absorption light is chosen to correspond to the wavelength at which the absorption of the indicator dye is close to zero (eg 860 nm for ICG). Two light emitting diodes or the like are used as light sources that emit high absorption light and low absorption light.

[Problems to be Solved by the Invention] The above-mentioned previous invention by the inventor not only made it possible to measure the concentration change at the initial stage of indicator dye injection, but also had the great effect of eliminating the invasiveness to the patient. However, the inventor revealed that the following problems exist. For example, in the case of ICG, which is commonly used in liver function tests, the absorption peak wavelength is 805 nm, and the wavelength close to this, where absorption is close to 0, is 860 nm. In other words, the difference between both wavelengths is only 55 nm. However,
Since the light emitting diode used as the light source has a spectral width of about 100 nm, there was a problem in that the spectra of the light from the two light sources (high absorption light and low absorption light) overlapped, significantly reducing measurement accuracy.

[Means for Solving the Problems] In the present invention, light at a high absorption wavelength of an indicator dye (hereinafter referred to as high absorption laser light) is emitted from an irradiation port toward the skin by two semiconductor laser light sources, and a light emitted by a semiconductor laser light source is Light with a low absorption wavelength of the indicator dye (hereinafter referred to as low absorption laser light) was irradiated, and the scattered reflected light was received.

[Operation] The spectral width of semiconductor laser light is much narrower than that of LED, filtered white light, or filtered gas laser light, and is much smaller than 1 nm. Therefore, the high absorption laser light is almost only at the wavelength of the absorption peak of the indicator dye,
Low-absorption laser light also only has wavelengths that are sufficiently low for indicator dye absorption, and the total energy content is small because the spectral width is narrow. That is, the spectra of the high-absorption laser light and the low-absorption laser light do not overlap, and it is possible to obtain scattered reflected light that sufficiently contains concentration information of the indicator dye.

[Example] Fig. 1 shows an example using a sensor according to the present invention.
An overview of continuous transcutaneous measurement of blood pigment concentration using a photodetector is shown. Although the details of the internal structure of the sensor 2 are not shown, as will be described later, (1) semiconductor lasers 4a and 4b are included in the housing of the sensor 2, and (2) laser light from the outside is transmitted through a light guide. (3) containing the photodetector 6 within the housing of the sensor 2; (4) receiving light with a light guide and guiding it to the external photodetector 6; and (5) a combination of the above. This is because there are various embodiments such as those.

The operation of this device will be explained based on the conceptual diagram shown in FIG. Based on the output of the pulse oscillation circuit 8, the laser drive circuit 10 causes the first and second semiconductor lasers 4a and 4b to emit light alternately. The first and second semiconductor lasers 4a and 4b respectively emit high absorption laser beam 12a and low absorption laser beam 12b of indicator dye. These alternately emitted laser beams 12a and 12b are emitted from the irradiation port 14 of the sensor 2.
The light is irradiated from the source toward the skin 16. Capillaries 16d and blood vessels 16e are distributed in the dermis 16b and subcutaneous tissue 16c below the epidermis 16a. Since the high absorption laser beam 12a is absorbed by the indicator dye within the blood vessels 16d and 16e, the amount of scattered reflected light 20 received by the light receiving port 18 is smaller than the low absorption laser beam 12b. The scattered reflected light 20 is converted into an electric signal by the photodetector 6, and then inputted to the signal separation circuit 22. In the signal separation circuit 22, the output of the pulse oscillation circuit 8 is used to emit light from the lasers 4a and 4b. This electric signal is synchronized with , and is separated into one related to the high absorption laser beam 12a and one related to the low absorption laser beam 12b, and is applied to the absorbance calculation circuit 24. Based on this output, the absorbance calculation circuit 24 calculates
It calculates the difference in absorbance between high absorption laser light and low absorption laser light. In addition, the absorbance difference
Aλa−Aλb (where Aλa and Aλb are absorbances at wavelengths amm and bnm) is calculated by the following formula according to Beer's law.

Aλb−Aλa=logIb−logIa=log(Ib/Ia) (1) Here, Ia and Ib are the amounts of scattered reflected light corresponding to the high absorption laser beam and the low absorption laser beam, respectively. Ia and Ib are adjusted to have the same value immediately before injecting the indicator dye into the blood. The calculated temporal change in absorbance difference is displayed on the display means 26.

According to this embodiment, there is no need to provide separate photodetectors for high absorption laser light and low absorption laser light, and only one photodetector is required. That is, the structure is simple and inexpensive.

FIG. 2 shows a conceptual diagram of a similar device measuring with two photodetectors. The first and second semiconductor lasers 4a and 4b continuously emit high absorption laser beam 1.
2a and emits a low absorption laser beam 12b. The scattered reflected light 20 is separated into light that has passed through the first filter 28a and light that has passed through the second filter 28b. The first filter 28a (such as an interference filter) allows only highly absorbed light to pass through, and the second
The filter 28b allows only low absorption light to pass through. The light passing through both filters 28a and 28b is transmitted to first and second photodetectors 6a and 6b, respectively.
The signal is converted into an electrical signal and input to the absorbance calculation circuit 24. Thereafter, the temporal change in absorbance difference is displayed on the display means 26 in the same manner as in the apparatus shown in FIG.

According to this embodiment, it is possible to continuously measure the scattered reflected light caused by the low absorption laser beam and the high absorption laser beam, and the influence of noise is small, making it possible to perform highly accurate measurement.

FIGS. 3A and 3B show examples of the sensor used to measure the concentration shown in FIG. 1.

FIGS. 3A and 3B show examples of the sensor used to measure the concentration shown in FIG. 1.

3A and 3B show that the first and second semiconductor lasers 4a and 4b and the semiconductor photodetector 6 are housed in the housing of the sensor 2. In FIGS. As the semiconductor photodetector 6, a photoconductive cell, a photodiode, a phototransistor, an avalanche photodiode, etc. can be used. Figure 3A
is a vertical sectional view, and FIG. 3B is a bottom view. Irradiation port 1
4 consists of an irradiation window 14a and an irradiation window 14b, each of which is fitted with transparent bodies 80a and 80b (glass, acrylic resin, etc.) to protect the semiconductor lasers 4a and 4b. A transparent body 82 is also fitted in the light receiving port 18 to protect the semiconductor photodetector 6. The contact surface 3 that comes into contact with the skin is formed into a planar shape or a shape close to this which is convenient for contact. A micro heater 36 as a heating means and a thermistor 38 as a temperature measuring means are provided inside the partition wall 34 made of a thermally conductive and light-opaque material (metal, etc.). Heater 36 is heated by thermistor 3
8, and the partition wall 34 is 43°C to 45°C.
(usually about 44°C). This heats the skin 16, expands the blood vessels 16d and 16e therein, and increases the amount of blood within the skin (hyperemia phenomenon due to heating). As a result, the absorbance of ICG in the blood increases, significantly increasing the sensitivity and accuracy of measurement. According to this embodiment, the sensor 2 is freed from restraint by a fiber bundle (a bundle of many fibers) that is difficult to bend, and the sensor 2 has a high degree of freedom. That is, since the sensor 2 can be brought into light and uniform contact with the skin, highly accurate measurements can be performed without the influence of external light or the problem of blood flow obstruction due to blood vessel compression.

The embodiment of the sensor used in the concentration measuring device shown in FIG. 1 has been shown above.
This is shown in Figure A and Figure 4B.

In FIGS. 4A and 4B, first and second semiconductor photodetectors 6a and 6b are built into the sensor 2. FIG. 4A shows a longitudinal sectional view, and FIG. 4B shows a bottom view. First and second filters 28a and 28b
(interference filter, etc.) to the first and second light receiving windows 1
It is fitted in 8a and 18b.

[Effect of the invention] This invention uses a semiconductor laser with an extremely narrow spectral width as a light source, so even when the wavelengths of high absorption light and low absorption light are close to each other, the spectra of the two do not overlap and accuracy is improved. It is possible to perform high-level measurements.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a single photodetector type blood pigment concentration continuous measuring device using the sensor of the present invention, and FIG. 2 is a diagram showing a similar measuring device using two photodetectors. 3A and 3B are diagrams showing an embodiment of a sensor suitable for the measuring device shown in FIG.
Figures A and 4B are diagrams showing an embodiment of a sensor suitable for the measuring device shown in Figure 2. 2...Sensor, 4a...First semiconductor laser,
4b...Second semiconductor laser, 6...Photodetector, 6
a...First photodetector, 6b...Second photodetector, 1
4... Irradiation port, 18... Light receiving port. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A contact surface that comes into contact with the skin, an irradiation port provided on the contact surface, and indocyan green, which is an indicator dye for liver function tests in blood, directed from the irradiation port toward the skin. two semiconductor lasers for irradiating high absorption laser light with a wavelength of substantially 805 nm with high absorption and low absorption laser light with a wavelength of substantially 860 nm with low absorption; a phototransistor having a light receiving aperture provided on a contact surface for receiving scattered reflected laser light; a partition separating the irradiation aperture and the light receiving aperture; a heater for heating the contact surface to 43°C to 45°C; A liver function test characterized by comprising: a small-sized container that stores each element; a flexible cord that stores a power supply line that supplies power to the semiconductor laser and an electric wire that transmits the output signal of the phototransistor. skin semiconductor laser sensor.