JP2004351135A - Electrode and apparatus for cardiac output measurement - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode for measuring cardiac output capable of easily mounting and reducing discomfort of a subject and the like. <P>SOLUTION: The electrode for measuring the cardiac output has a pair of electrodes 2 and 11 for conducting electric current and a pair of electrodes 7 and 14 for detecting voltage. The lengths of the electrodes 2 and 11 are in a range of 100-250 mm. It is preferable that the lengths of the electrodes 7 and 14 are in a range of 20-40 mm. It is also preferable that one of the electrodes 2 and 11 for conducting electric current and one of the electrodes 7 and 14 for detecting voltage are fixed to one of pressure-sensitive adhesive sheets 1 and 10. Furthermore, it is preferable that a measure 20 for measuring a distance between the electrodes is equipped for measuring the distance between two electrodes 7 and 14 for detecting voltage. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cardiac output measurement electrode.
The present invention also relates to a cardiac output measuring device provided with the cardiac output measuring electrode.
[0002]
[Prior art]
An electrical cardiac output meter that uses the change in bioelectrical impedance (or admittance) associated with the ejection of blood from the heart is widely used as the simplest method among noninvasive measurement methods for measuring cardiac output. I have. Many of them are measured based on the chest cylinder model of Nyboer et al. And the estimation formula of the cardiac output or stroke volume by Kubicek et al.
[0003]
In these measurements, as shown in FIG. 9, four band-shaped electrodes are attached around the chest 36 and the neck 35 around the circumference thereof, and a high-frequency minute current is applied between a pair of outer current-carrying electrodes 31 and 32. The cardiac output is calculated based on the estimation formula of Kubicek et al. By applying the voltage and measuring the voltage with the pair of inner voltage detection electrodes 33 and 34.
[0004]
A biological electrode conventionally used in these electrical impedance (or admittance) methods is a band composed of a silver-coated organic fiber or a fiber containing silver-coated organic fibers in the longitudinal direction of a band-shaped cloth member. (See, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-5-137699
[Problems to be solved by the invention]
However, with such a band-shaped electrode, it is not easy to attach the electrode to a subject (or a patient) in a supine position lying on a bed, and furthermore, there is a sense of restraint by making the electrode go around the measuring part of the living body. Discomfort to the subject (or patient) regarding the electrode mounting has become a major problem. Therefore, development of an electrode for measuring cardiac output which can be easily attached to a living body and has less discomfort due to electrode attachment is desired.
[0007]
The present invention has been made in view of such a problem, and is provided with an electrode for measuring cardiac output which can be easily worn and which can reduce discomfort of a subject or the like, and a heart provided with the electrode for measuring cardiac output. It is an object of the present invention to provide a stroke volume measuring device.
[0008]
[Means for Solving the Problems]
The cardiac output measurement electrode of the present invention is a cardiac output measurement electrode having a pair of current supply electrodes and a pair of voltage detection electrodes, wherein the length of the current supply electrode is in the range of 100 to 250 mm. There is something.
[0009]
Here, the above-mentioned voltage detection electrode preferably has a length in the range of 20 to 40 mm. Further, it is preferable that one current supply electrode and one voltage detection electrode are fixed to one sheet. Further, the sheet is preferably an adhesive sheet. Further, it is preferable that the sheet has a separation cut between the current-carrying electrode and the voltage-detecting electrode. Further, it is preferable that the dead electrode is fixed to the sheet. Further, it is preferable to have a movable connection terminal instead of one voltage detection electrode. Further, it is preferable to provide an inter-electrode distance measure for measuring the distance between the two voltage detection electrodes.
[0010]
The cardiac output measuring device of the present invention is a cardiac output measuring device including a cardiac output measuring electrode having a pair of current conducting electrodes and a pair of voltage detecting electrodes. Is in the range of 100 to 250 mm.
[0011]
Here, the above-mentioned voltage detection electrode preferably has a length in the range of 20 to 40 mm. Further, it is preferable that one current supply electrode and one voltage detection electrode are fixed to one sheet. Further, the sheet is preferably an adhesive sheet. Further, it is preferable that the sheet has a separation cut between the current-carrying electrode and the voltage-detecting electrode. Further, it is preferable that the dead electrode is fixed to the sheet. Further, it is preferable to have a movable connection terminal instead of one voltage detection electrode. Further, it is preferable to provide an inter-electrode distance measure for measuring the distance between the two voltage detection electrodes.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
First, an embodiment of the first invention relating to a cardiac output measurement electrode and a cardiac output measurement device will be described.
[0013]
FIG. 1 is a plan view showing the configuration of the cardiac output measurement electrode according to the first embodiment. As shown in FIG. 1, the cardiac output measurement electrode has a pair of current-carrying electrodes 2 and 11 and a pair of voltage detection electrodes 7 and 14. An electrode for measuring cardiac output is formed by vertically combining the current-carrying electrode 2 and the voltage-detecting electrode 7 and the current-carrying electrode 11 and the voltage-detecting electrode 14.
[0014]
The current supply electrode 2 and the voltage detection electrode 7 are fixed to the sheet 1. This sheet 1 is made of an adhesive sheet.
[0015]
The shape of the current carrying electrode 2 is a rectangular plate. The current carrying electrode 2 preferably has a length in the range of 100 to 250 mm. When the length is 100 mm or more, there is an advantage that the current distribution tends to be uniform. When the length is 250 mm or less, there is an advantage that it can be worn only on the front surface of the body.
[0016]
It is preferable that the current-carrying electrode 2 has a width in the range of 10 to 30 mm.
[0017]
The shape of the current-carrying electrode 2 is not limited to a rectangular plate. The shape of the current-carrying electrode 2 may be a composite electrode or the like in which two or three biological electrodes used for electrocardiogram measurement are equipotentially connected by connecting a conductive wire. In that case, the length to both ends of the arranged electrocardiogram measurement electrode is in the same range as the length used for the rectangular plate-shaped electrode.
[0018]
FIG. 2 is a cross-sectional view illustrating the configuration of the current-carrying electrode 2. As shown in FIG. 2, the cross-sectional structure of the present electrode is such that a living body electrode composed of a gel-like conductive adhesive substance 4 and an Ag / AgCl sheet 3 is connected to a conducting wire 6 via a connection terminal 5, High-frequency current is flowing through the living body.
[0019]
The gel conductive adhesive substance 4 is an electrolytic substance and is made of a gel of a high polymer containing sodium chloride, potassium chloride or the like.
[0020]
The Ag / AgCl sheet 3 is formed of a substrate formed of paper, a polymer film, or the like, and silver-silver chloride formed over the entire surface of one side of the substrate to a predetermined thickness, for example, 10 to 20 microns. The sheet is not limited to this Ag / AgCl sheet. In addition, silver, gold, and the like can be adopted.
[0021]
The current-carrying electrode 2 is fixed to the adhesive sheet 1. The pressure-sensitive adhesive sheet 1 is formed of a mesh-shaped pressure-sensitive adhesive sheet having air permeability.
[0022]
The configurations of the current-carrying electrode 11, the voltage detection electrodes 7, 14 and the dead electrode 17 described later are the same as the configuration of the current-carrying electrode 2 described above.
[0023]
As shown in FIG. 1, the shape of the voltage detection electrode 7 is a rectangular plate shape. The voltage detection electrode 7 preferably has a length in the range of 20 to 40 mm. When the length is 20 mm or more, there is an advantage that the potential can be sufficiently measured. When the length is 40 mm or less, there is an advantage that there is no problem in resolution.
[0024]
The voltage detection electrode 7 preferably has a width in the range of 10 to 30 mm.
[0025]
The shape of the voltage detection electrode 7 is not limited to a rectangular plate. As the shape of the voltage detection electrode 7, a biomedical electrode or the like used for electrocardiogram measurement can be adopted.
[0026]
The distance between the current-carrying electrode 2 and the voltage-detecting electrode 7 is preferably in the range of 30 mm to 50 mm. When the distance is 30 mm or more, there is an advantage that current concentration, which is an error factor, does not easily occur. When the distance is 50 mm or less, there is an advantage that the distance does not greatly affect the neck.
[0027]
In the present electrode, since it is fixed by the adhesive sheet 1, the current-carrying electrode 2 and the voltage-detecting electrode 7 can always be mounted at a predetermined distance. Therefore, it is possible to prevent the non-uniformity of the distribution of the conduction current due to improper electrode arrangement, which may cause a large error in cardiac output measurement by the impedance (or admittance) method of the living body.
Note that the same effect can be obtained for the current-carrying electrode 11 and the voltage detection electrode 14 described later.
[0028]
The current-carrying electrode 11, the voltage-detecting electrode 14, and the dead electrode 17 are fixed to the adhesive sheet 10.
[0029]
The shape, length range, width range, and other possible shapes of the current-carrying electrode 11 are the same as the above-described shape, length range, width range, and other possible shapes of the current-carrying electrode 2. It is the same as the shape.
[0030]
Assuming that the center axis of the cardiac output measurement electrode is the center in the width direction of the interelectrode distance measure 20, the longitudinal center of the current-carrying electrode 11 is eccentric to the right (on the drawing) from the center axis. The reason for this eccentricity is that the three electrodes of the voltage detection electrode 14, the current supply electrode 11, and the dead electrode 17 are formed on the adhesive sheet.
[0031]
The shape, length range, width range, and other possible shapes of the voltage detection electrode 14 are the same as the shape, length range, width range, and other possible shapes of the voltage detection electrode 7 described above. It is the same as the shape.
[0032]
The range of the distance between the current-carrying electrode 11 and the voltage detection electrode 14 is the same as the range of the distance between the current-carrying electrode 2 and the voltage detection electrode 7 described above.
[0033]
Also, a gel-like conductive adhesive material processed into a spot on the left side of the lower current-carrying electrode 11 so that the bioimpedance (or admittance) value at the place where the voltage detection electrode is mounted can be measured simultaneously. And a dead electrode 17 composed of an Ag / AgCl sheet. Of course, this is not a problem for the measurement of cardiac output, even if it is not used if an individual bioimpedance (or admittance) value is unnecessary.
[0034]
An inter-electrode distance measure 20 for measuring the distance L between the two voltage detection electrodes 7 and 14 is provided. The upper end (on the drawing) of the inter-electrode distance measure 20 is fixed to the adhesive sheet 1. The inter-electrode distance measure 20 is slidably supported by a through portion 21 on the adhesive sheet 10. The distance L between the electrodes for voltage detection required for calculating the cardiac output can be easily measured by the electrode distance measure 20.
[0035]
The cardiac output measuring device according to the present embodiment includes the cardiac output measuring electrode having the above-described current-carrying electrode and voltage detecting electrode.
[0036]
Next, a case where the above-described electrode for cardiac output measurement is applied to cardiac output measurement will be described.
The estimation formula of the cardiac output of Kubicek et al. Widely used in the impedance (or admittance) method is constructed based on the cylindrical model of Nyboer et al. In order to calculate the cardiac output using this formula, The chest, which is the measurement site, needs to correspond to the cylindrical model. For this purpose, it is necessary to measure the current distribution on the body surface, measure the current distribution on the entire thoracic body surface, and examine whether the current distribution corresponds to the cylindrical model.
[0037]
Since it is difficult to visualize the current, it is possible to estimate the chest current distribution by creating an equipotential distribution diagram of the chest from the property that the current flows perpendicular to the equipotential lines. Estimating the current distribution on the body surface by creating an equi-impedance distribution map of the thoracic body surface by making use of the fact that the equipotential line and the equi-impedance line are equal if the conducting current is constant. Becomes possible.
[0038]
Here, the thoracic average impedance immediately before blood flows into the aorta (that is, at the end of ventricular diastole) is defined as a Zo signal, and an equi-impedance distribution diagram created by this is used as a Zo map.
[0039]
An ideal Zo map corresponding to the cylindrical model is uniformly distributed over the entire chest as shown in FIG. However, it is known that the actual bioimpedance differs depending on the tissue, and the anisotropy of the bioimpedance greatly differs depending on the direction of the flowing current or the measurement direction, the applied frequency, etc. This is one of the causes of measurement errors.
[0040]
In the band-shaped electrode used conventionally, a chest current distribution having a correlation coefficient r = 0.96 with respect to an ideal Zo map as shown in FIG. 4 was realized by wrapping around the chest and neck. . However, in the case of a band-shaped electrode, it is necessary to wrap around the chest and neck in order to correspond to the cylindrical model on which the measurement principle is based. In the case of (1), there is a problem that it is difficult to mount the electrodes and that the measurement is uncomfortable in long-time measurement.
[0041]
Therefore, in order to simplify the electrode mounting, the shape and position of the electrode were variously changed, a Zo map on the surface of the thorax body was created, and the electrode arrangement considered to be applicable to the cylindrical model was examined. As a result, a tape-like current-carrying electrode having a length of 15 cm is arranged on the upper 30 mm of the clavicle and the lower 30 mm of the xiphoid process without circling the band-shaped electrode around the chest and neck as in the related art. As shown in FIG. 5, it was found that a correlation coefficient r = 0.92 with respect to an ideal Zo map and a chest current distribution almost equivalent to that of a conventional band-shaped electrode could be obtained.
[0042]
Further, an equi-impedance distribution diagram based on the pulsation component ΔZ superimposed on the Zo signal in the entire chest and near the median is defined as a ΔZ map. Therefore, when the anatomical positional relationship of the lungs is superimposed on the ΔZ map as shown in FIG. 6, a good correlation was not obtained with the ideal ΔZ map such that a cylindrical model can be applied to the entire thorax. However, by focusing on the vicinity of the median and defining a local cylindrical model (medial region 39 surrounded by a thick line), a result of a correlation coefficient r = 0.93 can be obtained for an ideal ΔZ map. Was.
[0043]
Based on these results, assuming a local cylindrical model near the median, and using the center of the clavicle and the xiphoid process where the ΔZ waveform changes the most as the voltage detection electrodes, the accuracy is the same as the conventional electrode arrangement. It turned out that it became measurable.
[0044]
It is preferable that the voltage detection electrode 7 be mounted in an area near the center of the collarbone. When worn in this region, there is an advantage that impedance (or admittance) changes are noticeable due to changes in blood volume in the ascending aorta due to ventricular contraction.
[0045]
It is preferable that the voltage detection electrode 14 be mounted in an area around the xiphoid process. When mounted in this range, there is the advantage that impedance (or admittance) changes are small.
[0046]
In order to compare the measurement accuracy of this electrode, the electrode for voltage detection of this electrode is placed at the center of the clavicle and at the xiphoid process. In comparison with the measured pulse output, the correlation coefficient was r = 0.98 and the regression coefficient a = 1.19, which was almost the same as the measurement value of the band-shaped electrode conventionally used. .
[0047]
Therefore, the electrode of the present embodiment can be used in the electric impedance (or admittance) method by replacing the band-shaped electrode conventionally used, and the current-carrying electrode and the voltage-detecting electrode pair are adhered to each other. Since the electrodes are integrated by a sheet, the electrodes can be mounted very easily. By using only the front of the thorax, even a tester (or patient) in a supine position can easily wear the electrodes, and there is no need to wrap around the circumference. This has the effect of reducing the discomfort of the subject.
In addition, since an inter-electrode distance measure is attached, there is an effect that the distance between the electrodes for voltage detection, which is necessary for the expression for estimating cardiac output by Kubicek et al., Can be easily measured.
[0048]
Next, an embodiment of the second invention according to the cardiac output measurement electrode and the cardiac output measurement device will be described.
[0049]
As shown in FIG. 7, the structure is basically the same as that of the first embodiment shown in FIG. 1. However, in the electrode configuration of the first embodiment, depending on the size of the subject (or patient), There is a possibility that the distance between the electrode and the electrode for voltage detection must be 30 mm or more, or 30 mm or less.
[0050]
Therefore, separation sheets 23 and 24 are provided on the sheet between the current-carrying electrode and the voltage-detecting electrode. That is, by providing cuts 23 and 24 for separation in advance in the adhesive sheet so that the current-carrying electrode and the voltage-detecting electrode can be separated from each other, and having a structure in which the voltage-detecting electrode has a margin, The distance between the electrode for voltage detection and the electrode for voltage detection can be arbitrarily set. Accordingly, there is an effect that a subject (or a patient) that cannot perform measurement in the first embodiment can perform measurement using the electrode of the present invention instead of the band-shaped electrode.
[0051]
The cardiac output measuring device according to the present embodiment includes the cardiac output measuring electrode having the above-described current-carrying electrode and voltage detecting electrode.
[0052]
Next, a third embodiment of the invention relating to the cardiac output measurement electrode and the cardiac output measurement apparatus will be described.
[0053]
As shown in FIG. 8, the configuration is basically the same as that of the first embodiment shown in FIG. It has a movable connection terminal instead of one voltage detection electrode. That is, for example, a voltage detection connectable to an electrocardiogram electrode so that a bioimpedance (or admittance) value at an arbitrary location can be measured simultaneously with the cardiac output, not at the position of the voltage detection electrode of the first embodiment. A separate electrode clip 27 is provided.
[0054]
This makes it possible to correct the error by measuring the bioimpedance (or admittance) value at a different location from the normal voltage detection electrode when a measurement error occurs with the standard electrode arrangement. The effect is as follows.
[0055]
The cardiac output measurement device according to the present embodiment includes the above-described current supply electrode, voltage detection electrode, and cardiac output measurement electrode having a movable connection terminal.
[0056]
Note that the present invention is not limited to the above-described embodiment, but can adopt various other configurations without departing from the gist of the present invention.
[0057]
【The invention's effect】
The present invention has the following effects.
In a cardiac output measurement electrode having a pair of current-carrying electrodes and a pair of voltage detection electrodes, by setting the length of the current-carrying electrode to a predetermined range, In the provided cardiac output measuring device, by setting the length of the current-carrying electrode to a predetermined range, the cardiac output measuring electrode can be easily attached and the discomfort of the subject or the like can be reduced.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of a cardiac output measurement electrode according to a first embodiment.
FIG. 2 is a cross-sectional view illustrating a configuration of a current-carrying electrode.
FIG. 3 is a diagram showing an ideal Zo map corresponding to a cylindrical model.
FIG. 4 is a diagram showing a Zo map when a conventional band-shaped electrode is used.
FIG. 5 is a diagram showing a Zo map when the cardiac output measurement electrode according to the present embodiment is used.
FIG. 6 is a diagram showing a ΔZ map when the cardiac output measurement electrode according to the present embodiment is used.
FIG. 7 is a plan view showing a configuration of a cardiac output measurement electrode according to a second embodiment.
FIG. 8 is a plan view showing a configuration of a cardiac output measurement electrode according to a third embodiment.
FIG. 9 is a diagram showing a conventional cardiac output measurement electrode having a pair of current-carrying electrodes and a pair of voltage detection electrodes, and a mounted state thereof.
[Explanation of symbols]
1 ‥‥ adhesive sheet, 2 ‥‥ current carrying electrode, 3 通電 Ag / AgCl sheet, 4 ‥‥ gel conductive adhesive substance, 5 ‥‥ connection terminal, 6 ‥‥ conductor, 7 ‥‥ voltage detection electrode , 8 ‥‥ connection terminal, 9 ‥‥ conductor, 10 ‥‥ adhesive sheet, 11 ‥‥ current carrying electrode, 12 ‥‥ connection terminal, 13 ‥‥ conductor, 14 ‥‥ voltage detection electrode, 15 ‥‥ connection terminal , 16 ‥‥ conductor, 17 ‥‥ dead electrode, 18 ‥‥ connection terminal, 19 ‥‥ conductor, 20 ‥‥ interelectrode distance measure, 21 メ ジ ャ ー thread, 22 部 release sheet, 23, 24 ‥‥ separation Cut, 25, 26 ‥‥ extension wire, 27 ‥‥ voltage detection electrode clip, 31, 32 ‥‥ current supply electrode, 33, 34 ‥‥ voltage detection electrode, 35 ‥‥ neck, 36 ‥‥ chest, 37 ° Z ₀ map, 38 ° ΔZ map, 39 ° median area, 40 ° lung

Claims (16)

In a cardiac output measurement electrode having a pair of current-carrying electrodes and a pair of voltage detection electrodes,
The electrode for measuring cardiac output is characterized in that the current-carrying electrode has a length in the range of 100 to 250 mm. 2. The cardiac output measuring electrode according to claim 1, wherein the voltage detecting electrode has a length in a range of 20 to 40 mm. The cardiac output measurement electrode according to claim 1, wherein one current supply electrode and one voltage detection electrode are fixed to one sheet. 4. The cardiac output measuring electrode according to claim 3, wherein the sheet is an adhesive sheet. 4. The cardiac output measurement electrode according to claim 3, wherein the sheet has a separation cut between the current supply electrode and the voltage detection electrode. 4. The cardiac output measuring electrode according to claim 3, wherein the dead electrode is fixed to a seat. The cardiac output measuring electrode according to claim 1, further comprising a movable connection terminal instead of one voltage detecting electrode. 2. The cardiac output measuring electrode according to claim 1, further comprising an inter-electrode distance measure for measuring a distance between the two voltage detecting electrodes. In a cardiac output measurement device including a cardiac output measurement electrode having a pair of current conducting electrodes and a pair of voltage detection electrodes,
The said current supply electrode has a length in the range of 100-250 mm, The cardiac output measuring apparatus characterized by the above-mentioned. The cardiac output measuring device according to claim 9, wherein the voltage detecting electrode has a length in a range of 20 to 40 mm. 10. The cardiac output measuring device according to claim 9, wherein one current supply electrode and one voltage detection electrode are fixed to one sheet. The cardiac output measuring device according to claim 11, wherein the sheet is an adhesive sheet. 12. The cardiac output measuring device according to claim 11, wherein the sheet has a separation cut between the current-carrying electrode and the voltage-detecting electrode. The cardiac output measuring device according to claim 11, wherein the dead electrode is fixed to a seat. 10. The cardiac output measuring device according to claim 9, further comprising a movable connection terminal instead of one voltage detection electrode. The cardiac output measuring device according to claim 9, further comprising an inter-electrode distance measure for measuring a distance between the two voltage detecting electrodes.

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