JP2003135433A - Instrument for measuring water content-related value in organism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an instrument for relatively easily measuring a water content- related value in an organism, specifically a pulmonary water content, without putting excessive burdens of catheter insertion or the like on a patient. SOLUTION: In the instrument for measuring a water content-related value in the organism, a light absorbing dye is injected into a blood vessel, and the dye concentration is continuously measured on the basis of continuous measurement of the pulsation of transmission light of viable tissues, thereby determining the water content-related value inside a prescribed part of the organism. The instrument is provided with a light absorption dye concentration measuring means for continuously measuring the concentration of a plurality of the light absorption dyes of different viable tissue transmission characteristics, an appearing time difference measuring means for measuring the appearing time difference of concentration changes of a plurality of the light absorption dyes of different blood vessel transmission characteristics with the light absorption dye concentration measuring means, and a water content-related value measuring means for measuring the water content-related value inside the organism prescribed part on the basis of the appearing time difference measured by the appearing time difference measuring means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for measuring a water content-related value in a predetermined region of a living body, particularly a lung water content.

[0002]

2. Description of the Related Art In the medical field, an indicator dilution method in which an indicator such as a dye is administered into a blood vessel and the concentration of the administered indicator circulating in the blood vessel is measured to measure the water content, blood volume, etc. of the living body. Has been performed for a long time, and has also been used to measure cardiac output, circulating blood volume, interstitial fluid volume, body water content, and the like. Indocyanine green (I
CG) and cold sugar solution or Na + as a water-labeling substance are simultaneously administered into a blood vessel, and by utilizing the difference in their pulmonary vascular permeability characteristics, the lung water which is the amount of water existing in the lung outside the pulmonary blood vessel I was measuring the amount. Then, lung water content was evaluated as an index for diagnosis of pulmonary edema.

However, when measuring the water content of the lung, in order to administer cold sugar solution or Na + into the blood vessel, a catheter must be inserted from the external jugular vein until its tip is located in the pulmonary artery. However, it has been a great physical and psychological burden on patients undergoing such an invasive examination.

[0004]

SUMMARY OF THE INVENTION As described above, the problem to be solved by the present invention is to reduce the burden on the patient when measuring the amount of water in a predetermined region of the living body such as the amount of water in the lungs, and to simplify the operation. An object of the present invention is to provide an in-vivo water content related value measuring device capable of measuring.

[0005]

In order to achieve the above object, the invention according to claim 1 is based on continuous measurement of pulsation of transmitted light of a living tissue by injecting a light absorbing dye into a blood vessel in a living body. An in-vivo water content-related value measuring device that continuously measures the blood dye concentration and measures the water content-related value in a predetermined region of the living body. Dye concentration measurement means, the blood absorption dye concentration measurement means, the appearance time difference measurement means for measuring the appearance time difference of the concentration change of the plurality of light absorption dyes of different blood vessel transmission characteristics, and the appearance time difference measurement means Water content related value measuring means for measuring a water content related value in a predetermined region of the living body based on the appearance time difference. As a result, a plurality of light-absorbing dyes having different biological tissue penetration characteristics are used, so that it is possible to reduce the excessive burden on the patient such as inserting a catheter, and to relatively easily measure the water content-related value in a predetermined region of the living body. You can

In the in-vivo water content-related value measuring device according to a second aspect of the present invention, the blood light-absorbing dye concentration measuring means has a plurality of light-absorbing dyes having different permeable properties in the living tissue as a plurality of light-absorbing dyes having different permeable properties in pulmonary blood vessels. Continuously measured, the appearance time difference measuring means measures the appearance time difference of the concentration change of the light-absorbing dye having different pulmonary vascular permeability characteristics, the water content-related value measuring means, the lung water content-related value based on the appearance time difference. It is characterized by measuring. Accordingly, by using the light-absorbing dyes having different pulmonary blood vessel transmission characteristics, it is possible to reduce an excessive burden on the patient such as inserting a catheter, and it is possible to relatively easily measure the lung water content.

The in-vivo water content-related value measuring device according to a third aspect is characterized in that indocyanine green, Evans blue or Coomassie blue, and indigo carmine are used as the light-absorbing dyes having different pulmonary vascular permeability characteristics. .

In the in-vivo water content-related value measuring device according to a fourth aspect, the appearance time difference measuring means determines the average circulation time point of the different light absorbing dyes obtained from the measurement result of the blood light absorbing dye concentration measuring means. It is characterized by measuring a time difference. Thus, the appropriate appearance time difference can be measured by using the average circulation time point of the light absorbing dye.

In the in-vivo water content-related value measuring apparatus according to a fifth aspect, the blood absorption dye concentration measuring means includes a dye selecting means for selectively inputting an absorption dye to be injected into a subject, and the dye selecting means. It is characterized by comprising switching means for switching so as to drive the light emitting means which emits a wavelength suitable for the selected light absorbing dye based on the input information. As a result, the light emitting means can be driven and measured according to the light absorbing dye arbitrarily selected by the operator.

In the in-vivo water content-related value measuring device according to a fifth aspect, the blood absorption dye concentration measuring means includes a dye selecting means for selectively inputting an absorption dye to be injected into the subject, and the dye selecting means. It is characterized by comprising an arithmetic expression setting means for setting an arithmetic expression suitable for the selected absorption dye based on the input information. As a result, the measurement can be performed by an appropriate calculation according to the absorption dye arbitrarily selected by the operator.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the in-vivo water content related value measuring device according to the present invention will be described below. Figure 1
FIG. 1 is a block diagram showing the overall configuration of an in-vivo water content related value measuring device according to the present invention. The light emission drive unit 1 includes LEDs 1 to 4 that generate four different wavelengths of light to the biological tissue 2, LED drivers 1 to 3 that drive these LEDs, and a changeover switch 1
a, and a dye selection means 1b for selectively inputting what a dye (light absorbing substance) is as an indicator to be administered for inspection. The wavelengths of light emitted from the LEDs 1 to 4 are λ1 to 4 respectively. The light receiving unit 3 is composed of a photodiode arranged so as to face the LEDs 1 to 4 so as to receive the light from the LEDs 1 to 4 transmitted by the living tissue 2, and the signal is an amplifier 4 and an A / D converter 5 Is input to the I / O port of the digital computer 6 via the, processed by the CPU 8, and the measurement result and the like are displayed on the display unit 12.

The living tissue 2 is a peripheral tissue such as a finger or an earlobe. The dye selection unit 1b may be provided on the probe that holds a finger, an ear, or the like and emits / receives light, or may be provided on the apparatus main body. When a dye to be administered for inspection from the light-absorbing substance selection means 1b is set, at least three LEDs 1 to 4 which emit light of an appropriate wavelength for detecting the dye are selected, The changeover switch 1a operates. The criteria for the selection will be described later.

FIG. 2 shows an example of a usage state of the apparatus of this embodiment. The probe 20 of the present apparatus is attached to the earlobe 26 of the subject. This probe 20 has a clip 20A, and the clip 20A is provided on one of the opposing sandwiching portions of the clip 20A.
2 are provided, and the photodiode shown in FIG. 2 is provided on the other side. As shown in FIG. 1, the light emitted from the LEDs 1 to 4 is set so as to pass through the earlobe 26 and reach the photodiode. The probe 20 is connected to the apparatus main body 22 via a lead wire 21 as shown in FIG. The display unit 12 and the key input unit 11 described above appear on the outside of the device body 22.

Next, the operation of this apparatus will be described. A dye to be administered for inspection from the dye selecting means 1b is preset, and at least three LEDs 1 to 4 which emit light of an appropriate wavelength for detecting the dye are selected. The CPU 8 outputs a control signal to each of the LED drivers 1 to 4 via the I / O port 7. Then, the LEDs selected by the changeover switch are alternately blinked every predetermined time. The light receiving portion 3 is L transmitted by the earlobe 26.
It receives the light from the ED and outputs a signal. The output signal regarding the transmitted light of each wavelength is input to the I / O port of the digital computer 6 via the amplifier 4 and the A / D converter 5, and processed by the CPU 8. This detection method is a pulse photometry method.

Here, the administered dye and living tissue 2
A suitable wavelength to be transmitted to the laser will be described. Indigo carmine (IDG) is used as a dye that penetrates pulmonary blood vessels. Then, any one of indocyanine green (ICG), Evans blue, and Coomassie blue is used as the dye that does not penetrate the pulmonary blood vessels. Considering the sufficient absorption due to the absorption characteristics of these dyes, the appropriate LED wavelengths for use of the respective dyes are as follows.

[0016]

[Table 1]

In the pulse photometry method, in order to calculate the extinction ratio Φ described later, it is also necessary to use a wavelength that is not affected by any dye, for example, 940 nm.

Next, an example is shown in which indocyanine green (ICG) is used as the dye that does not penetrate the pulmonary blood vessels and indigo carmine (IDG) is used as the dye that penetrates the pulmonary blood vessels. The three wavelengths of light used for measurement are λ1 = 805
nm, λ2 = 620 nm, λ3 = 940 nm, and have the following characteristics, respectively. λ1: There is a large amount of light absorbed by indocyanine green,
There is almost no absorption by indigo carmine. λ2: There is a large amount of light absorption by indigo carmine, but there is almost no light absorption by indocyanine green. λ3: There is almost no light absorption due to indigo carmine and light absorption due to indocyanine green. Hereinafter, suffixes 1, 2, and 3 added to the symbols used indicate light of these wavelengths.

The extinction degrees A1, A2, and A3 of light of three wavelengths that have passed through living tissues including blood are shown by the Lambert-Beer equation as follows. A1 = log (Ie1 / It1) = (Eh1.Hb + Ec1.Cc + Ed1.Cd) .. DELTA.D (1) A2 = log (Ie2 / It2) (2) = (Eh2.Hb + Ec2.Cc + Ed2.Cd) .ΔD ) A3 = log (Ie3 / It3) (3) = (Eh3.Hb + Ec3.Cc + Ed3.Cd) .ΔD (3) Where, Ie: Irradiation light intensity (energy per unit area) It: Transmitted light intensity (unit) Energy per area) Eh: extinction coefficient of hemoglobin Ec: extinction coefficient of indocyanine green (ICG) Ed: extinction coefficient of indigo carmine (IDG) Hb: blood hemoglobin concentration Cc: indocyanine green (ICG) concentration Cd : Concentration of indigo carmine (IDG) ΔD: Blood thickness suffix changed by pulsation Suffix 1,2,3: Number of each wavelength λ

Then, the extinction ratios Φ12 and Φ32 are defined as follows. Φ12 = A1 / A2 = {(Eh1 · Hb + Ec1 · Cc + Ed1 · Cd) · ΔD} / {(Eh2 · Hb + Ec2 · Cc + Ed2 · Cd) · ΔD} (4) Φ32 = A3 / A2 = {(Eh3 · Hb + Ec3 · Cc + Ed3 * Cd) * [Delta] D} / {(Eh2 * Hb + Ec2 * Cc + Ed2 * Cd) * [Delta] D} (5) Solving this equation for Cc / Hb and Cd / Hb gives the following. Cc / Hb = {(Φ32 ・ Eh2-Eh3) ・ (Φ12 ・ Ed2-Ed1)-(Φ12 ・ Eh2-Eh1) ・ (Φ32 ・ Ed2-Ed3)} / {(Φ32 ・ Ed2-Ed3) ・ (Φ12 ・Ec2-Ec1)-(Φ12 ・ Ed2-Ed1) ・ (Φ32 ・ Ec2-Ec3)} (6) Cd / Hb = {(Φ32 ・ Eh2-Eh3) ・ (Φ12 ・ Ec2-Ec1)-(Φ12 ・ Eh2- Eh1) ・ (Φ32 ・ Ec2-Ec3)} / {(Φ32 ・ Ec2-Ec3) ・ (Φ12 ・ Ed2-Ed1)-(Φ12 ・ Ec2-Ec1) ・ (Φ32 ・ Ed2-Ed3)} (7)

In equations (6) and (7), Eh
(Hemoglobin extinction coefficient), Ec (indocyanine green (ICG) extinction coefficient), and Ed (indigo carmine (IDG) extinction coefficient) are known, and the extinction ratio Φ1
2.Since Φ32 can measure the measured value over time,
Cc / Hb and Cd / Hb can also be obtained over time. This arithmetic processing is performed by the CPU 8.

At the time of measurement, a mixed dye of indocyanine green (ICG) which does not penetrate the pulmonary blood vessels and indigo carmine (IDG) which penetrates the pulmonary blood vessels is injected into the vein of the subject. FIG. 3 shows the state of detection of both pigments in the earlobe 26 (see FIG. 2) of the subject at the periphery thereafter. The horizontal axis is the time axis, and 0 is set at the time of dye injection. The horizontal axis is the dye concentration. Here, the hemoglobin concentration Hb in the formulas (6) and (7) is obtained by another measuring device by a blood sampling method such as CO-oximetr, and is substituted into the formulas (6) and (7), as shown in FIG. Such a specific density value can be obtained. As can be seen from FIG. 3, there is a time lag in the appearance of both pigments due to the difference in the permeability of the pulmonary blood vessels, and indocyanine green (ICG), which is a pigment that does not penetrate the pulmonary blood vessels, appears earlier. I understand.

Next, the difference in appearance time of both dyes is measured.
For this purpose, here, the average circulation time MTT is used to determine the time difference. Therefore, a method of obtaining the average circulation time MTT will be described with reference to FIG. Concentration Cg of a pigment shown in FIG.
The initial circulation curve is obtained using the Cg-t curve showing the relationship between time and time. In order to obtain this curve, first, two points which are 80% and 40% lower than the first peak value of the Cg-t curve are obtained, and an exponential decay curve passing through these two points is obtained.
Cg value goes from zero to the peak value and then 80% of the peak value
An initial circulation curve is formed from the Cg · t curve until the above and the exponential curve obtained as described above. Next, find the total area enclosed by the initial circulation curve and the t-axis, and calculate Cg
The straight line when this area is divided into two by a straight line parallel to the axis and t
The point of intersection with the axis, that is, MTT, is determined, and this time point is defined as the average circulation time point Tm.

Next, a method for obtaining the lung water content will be described.
The relationship between lung water content and average circulation time can be expressed by the following equation. LW = CO * (MTT (IDG) -MTT (ICG)) (8) where LW [L]: lung water content CO [L / min]: cardiac output MTT (IDG): indigo carmine (IDG) Average circulation time of MTT (ICG): average circulation time of indocyanine green (ICG) The CPU 8 can obtain and substitute the average circulation time of indigo carmine (IDG) and indocyanine green (ICG).

The cardiac output CO is determined by the dose D [mg] of indocyanine green (ICG), the initial circulation curve shown in FIG. 4 and the initial circulation area S surrounded by the t-axis (hatched portion). It is calculated by dividing the sum of). That is, CO [L / min] = D [mg] / S [mg.min / L] In this way, CO [L / min], MTT (I
DG), MTT (ICG)
W can be calculated.

Although indocyanine green (ICG) has been described as a pigment that does not permeate pulmonary blood vessels, Evans blue or Coomassie blue may be used instead. In that case, an LED that emits light of the wavelength shown in Table 1 may be used as λ1. Also,
In the above formula, indocyanine green (ICG)
Instead of the coefficient relating to each dye, the coefficient relating to each dye may be replaced.

In order to use any dye selected by the operator, such as indocyanine green (ICG), Evans blue or Coomassie blue, as the dye that does not penetrate the pulmonary blood vessels, The dye selection means 1b can be used. As an LED,
An LED that emits a wavelength suitable for detection of each dye and dye selection means 1b are provided in advance in the probe. Then, the operator selects and inputs the type of the dye used for the measurement, which is arbitrarily selected by the operator, by the dye selecting means 1b. In response to this, the changeover switch 1a is operated so as to drive the LED that emits the wavelength suitable for the selected dye. Further, the information on the selected dye type is sent to the CPU 8 via the I / O port, and the coefficient and the like for appropriate calculation are set. In addition,
The dye selecting unit 1b may be installed on the apparatus main body side instead of the probe side, and the changeover switch may be switched so as to drive an appropriate LED from the dye selecting unit 1b installed on the device main body side. . Alternatively, a coefficient or the like for appropriate calculation on the apparatus main body side may be set, and a dedicated probe for measuring the selected dye may be used as the probe.

Further, a mixed dye, which is a mixture of a pulmonary blood vessel permeation dye and an impermeable dye, was injected into a subject, but the average circulation time may be measured by dividing both dyes and the calculation according to equation (8) may be performed. . This method requires attention such as using each injection time as a reference.

[0029]

According to the first to fourth aspects of the present invention, a plurality of light absorbing dyes having different biological tissue permeability properties, particularly light absorbing dyes having different pulmonary vascular permeability properties are used, and the light absorbing dye is injected into a blood vessel. By measuring the time difference between the appearance of each light-absorbing dye in the periphery of the, and measuring the in-vivo water content-related value, especially the lung water content, it is relatively easy to measure without placing an excessive burden on the patient such as inserting a catheter. be able to. Further, according to the inventions of claims 5 to 6, by the dye selecting means for selectively inputting any light absorbing dye selected by the operator, the light emitting means suitable for the measurement using the selected dye is appropriately emitted. Since various wavelengths and arithmetic expressions can be used, it is possible to perform appropriate measurement while allowing the operator the freedom of measurement.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the overall configuration of an in-vivo water content related value measuring device according to the present invention.

FIG. 2 is an explanatory diagram showing a usage state of the measuring apparatus according to the present invention.

FIG. 3 is a characteristic curve diagram showing the relationship between dye concentration and time measured by the measuring device according to the present invention.

FIG. 4 is an explanatory diagram showing a method for obtaining an average circulation time by the measuring device according to the present invention.

[Explanation of symbols]

1 Light emission drive 1a Changeover switch 1b Dye selection means 2 living tissue 3 Light receiving part 4 amplifier 5 A / D converter 6 digital computer 7 I / O port 8 CPU 9 ROM 10 RAM 11 Key input section 12 Display

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Usuda             1-34-1 Nishiochiai, Shinjuku-ku, Tokyo Japan             Within Koden Kogyo Co., Ltd. (72) Inventor Yoshiaki Takamura             1-34-1 Nishiochiai, Shinjuku-ku, Tokyo Japan             Within Koden Kogyo Co., Ltd. (72) Inventor Park Takeda             1-34-1 Nishiochiai, Shinjuku-ku, Tokyo Japan             Within Koden Kogyo Co., Ltd. (72) Inventor Masayoshi Fuse             1-34-1 Nishiochiai, Shinjuku-ku, Tokyo Japan             Within Koden Kogyo Co., Ltd. (72) Inventor Teiji Ugawa             1-34-1 Nishiochiai, Shinjuku-ku, Tokyo Japan             Within Koden Kogyo Co., Ltd. F-term (reference) 4C038 KK00 KL05 KL07 KX04

Claims (6)

[Claims] 1. In a living body, a light absorbing dye is injected into a blood vessel, the blood dye concentration is continuously measured based on continuous measurement of pulsation of transmitted light of living tissue, and a water content-related value in a predetermined region of the living body is measured. In the in-vivo water content-related value measuring device, a blood absorption dye concentration measuring means for continuously measuring the concentration of a plurality of light absorption dyes having different biological tissue transmission characteristics, and the blood absorption characteristic by the blood absorption dye concentration measuring means. Appearance time difference measuring means for measuring the appearance time difference of the concentration change of a plurality of different absorption dyes, based on the appearance time difference measured by the appearance time difference measuring means, the water content to measure the water content related value in a predetermined region of the living body An in-vivo water content related value measuring device comprising: a water content related value measuring means. 2. The in-vivo water content-related value measuring device according to claim 1, wherein the blood light-absorbing dye concentration measuring means has a plurality of light-absorbing dyes having different biological tissue transmission characteristics, Concentration is continuously measured, the appearance time difference measuring means measures the appearance time difference of the concentration change of the light-absorbing dye having different pulmonary vascular permeability characteristics, and the water content related value measuring means is the lung water content based on the appearance time difference. An in-vivo water content related value measuring device characterized by measuring a related value. 3. The in-vivo water content-related value measuring device according to claim 2, wherein indocyanine green, Evans blue or Coomassie blue, and indigo carmine are used as the light-absorbing dyes having different pulmonary vascular permeability characteristics. A device for measuring the value of water content in a living body. 4. Any one of claims 1 to 3
In the in-vivo water content-related value measuring device according to one of the above, the appearance time difference measuring means measures the time difference between the mean circulation time points of the different light absorbing dyes obtained from the measurement result of the blood light absorbing dye concentration measuring means. Characteristic device for measuring in-vivo water content-related value. 5. Any one of claims 1 to 4
In the in-vivo water content-related value measuring device according to one of the embodiments, the blood absorption dye concentration measurement means is a dye selection means for selectively inputting an absorption dye to be injected into the subject, and based on input information by the dye selection means. An in-vivo water content-related value measuring device comprising: switching means for switching so as to drive a light emitting means that emits a wavelength suitable for each selected light absorbing dye. 6. Any one of claims 1 to 4.
In the in-vivo water content-related value measuring device according to one of the embodiments, the blood absorption dye concentration measurement means is a dye selection means for selectively inputting an absorption dye to be injected into the subject, and based on input information by the dye selection means. An in-vivo water content related value measuring device comprising an arithmetic expression setting means for setting an arithmetic expression suitable for the selected light absorbing dye.