JPS5825454B2 - In-vivo impedance distribution measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-vivo impedance distribution measuring device useful for diagnosing lung function and the like.

In recent years, demand for pulmonary function testing devices has increased due to the increase in respiratory diseases associated with air pollution and the aging of the population.

In particular, demand is shifting from traditional methods that assess lung function globally to methods that allow local testing.

One of them is to examine local ventilation distribution.

Conventionally known methods for testing ventilation distribution include having the patient inhale a radioisotope and observing the ventilation distribution using a scintillator, or connecting spirometers to the left and right bronchi to observe the left and right ventilation distribution. .

However, all of these methods have problems such as negligible pain or burden on the patient, and furthermore, it is difficult to dynamically grasp the ventilation distribution.

This invention was made to solve the above-mentioned problems, and uses a two-dimensionally arranged electrode group to understand the ventilation distribution of the lungs and other biological information as an impedance distribution and display it two-dimensionally. This provides an in-vivo impedance distribution measuring device that can non-invasively and dynamically grasp biological functions.

Hereinafter, this invention will be explained in detail with reference to Examples.

FIG. 1 is a block diagram showing an embodiment of the present invention.

1 is a two-dimensionally arranged electrode group, which is arranged on a base material 2 made of, for example, a flexible plate or sheet,
Its surface is attached to the body surface of a living body, for example, the chest, by some kind of pressure contact means.

Lead wires 3 are individually connected to the electrode group 1, and these lead wires 3 are connected to a current-carrying electrode selection circuit 4 and a detection electrode selection circuit 5.

The energized electrode selection circuit 4 selects any two electrodes of the electrode group 1 under the control of the control device 6 and supplies a high frequency current from the high frequency power source 7 between the selected electrodes.

The detection electrode selection circuit 5 selects, from the electrode group 1, any two electrodes near the electrode selected and energized by the energized electrode selection circuit 4, and supplies the voltage between the electrodes to the amplifier 8.

Note that each of these selection circuits 4 and 5 is constituted by a group of electronic switches such as transistors, the number of which is the same as the number of electrodes of the electrode group 1, for example.

Further, the high frequency power source 7 is preferably a constant current source so that a voltage corresponding to the chest impedance between the two electrodes selected by the detection electrode selection circuit 5 appears accurately between the two electrodes.

The voltage between the two electrodes selected by the detection electrode selection circuit 5 is amplified by an amplifier 8 and supplied as a brightness modulation signal to a Z-axis input terminal of a display device 9 such as a CRT.

Further, display position designation signals in both the X and Y axis directions are applied from the control device 6 to the X and Y axis input terminals of the display device 9.

Next, a case will be described in which the operation of the apparatus of this embodiment is used for testing lung function.

When the operation starts, the control device 6 selects a certain combination of four electrodes from the electrode group 1, for example, a combination of E, to E4, according to a predetermined program.
A selection signal corresponding to E is supplied to the energized electrode selection circuit 4,
Selection signals corresponding to E2 to E3 are supplied to the detection electrode selection circuit 5, and at the same time, a drive signal is supplied to the power supply 7.

As a result, electrode E1. A rectangular pulsed or sinusoidal high frequency current is supplied to electrode E4, and along with this, electrode E2. The voltage generated between E3 is supplied to the amplifier 8 through the detection electrode selection circuit 5 and applied to the Z-axis input terminal of the display device 9.

On the other hand, the control device 6 at this time supplies information on the maximum impedance detection sensitivity position in the living body determined by the positional relationship of the electrodes E1 to E4 to the X and Y axis input terminals of the display device 9.

In other words, when detecting impedance in a living body using four electrodes, the impedance at all positions near the four electrodes in the living body is detected uniformly. Impedance is most sensitively detected.

If the specific position is the maximum impedance detection sensitivity position and, for example, the four electrodes E, -E4 selected as described above are on a straight line, E2. The midpoint of E3 (indicated by the one-dot chain line) is the maximum impedance detection sensitivity position, and information on the coordinates (xty) of this position is supplied to the X and Y axis input terminals of the display device 9 as a display position designation signal. .

Since the screen of the display device 9 corresponds to the array surface of the electrode group 1, the position of the coordinates (Xty) on the screen ultimately depends on the magnitude of the output voltage of the amplifier 8, that is, the position of the electrode E2. E3
The brightness is modulated according to the size of the thoracic impedance between the two.

Thereafter, operations similar to those described above are performed for all different combinations of four electrodes in electrode group 1.

That is, the same operation is performed while sequentially shifting the combination of four electrodes by one electrode in the X direction in FIG. 1, and when completed, the same operation is performed by shifting the combination of four electrodes by one electrode in the Y direction.

When the energization and detection of the entire electrode group 1 and the display based thereon, that is, one scan, are completed in this way, the same operation is repeated again from the beginning to perform the scan again.

As a result, an image as shown in FIG. 3 representing the impedance distribution state of the chest, in other words, the ventilation distribution state of the lungs, is displayed on the screen of the display device 9 in one scan.

Then, by repeating similar scans, moment-to-moment changes in the ventilation distribution state are dynamically displayed.

Note that the maximum impedance detection sensitivity position in the depth direction determined by the combination (positional relationship) of the four electrodes E1 to E4 is when El and E2 and E3 and E4 are close to each other.From the midpoint of E2 and E3 to E2. Distance to E3, that is E2,8
This is 1/2 of the interval between 3.

That is, in order to set the position p at depth d on the dashed-dotted line as the maximum position p of three-dimensional impedance detection sensitivity considering the depth direction as shown in FIG.
2. After bringing E3 and E4 close to each other, E2. E3
may be set at a distance d from the midpoint (dotted chain line).

Therefore, by changing the combination of the four electrodes, it is possible to measure the thoracic impedance distribution at any depth, and thereby the ventilation distribution at any cross section.

In the above explanation, a case has been described in which the ventilation distribution in the lungs is measured by measuring the impedance distribution, but it is also possible to measure the distribution of pulmonary circulation blood flow if used under respiratory arrest.

Furthermore, the present invention can be used as a testing device for not only lung function but also biological functions that can generally be detected as changes in impedance.

Furthermore, in the embodiment described above, the power source 7 was driven intermittently every time the control device 6 selected a combination of electrodes in the electrode group 1, but it is of course possible to drive the power source 7 continuously with one oscillation.

As explained above, this invention measures the impedance distribution in the living body using a non-invasive method that does not cause pain to the patient and places a relatively small burden on the patient by attaching a group of electrodes to the body surface. It has the advantage of being able to test biological functions and to dynamically grasp the functions continuously over time.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a biological impedance distribution measuring device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of its operation, and FIG. 3 is a diagram showing an example of display according to the present invention. 1... Electrode group, 4... Current-carrying electrode selection circuit, 5... Detection electrode selection circuit, 9...
Display device.

Claims (1)

[Claims] A group of electrodes arranged in 12 dimensions and attached to the body surface of a living body,
An energizing means that sequentially selects any two electrodes of this electrode group and energizes between the electrodes; and energizing means that selects two electrodes near the electrodes energized by the energizing means from the electrode group and calculates the voltage between the electrodes. The maximum impedance detection sensitivity position in the living body is determined by the positional relationship between the detection means to be detected, the electrode energized by the energization means, and the electrode whose voltage is detected by the detection means, using the voltage detected by the detection means as impedance information. An in-vivo impedance distribution measuring device comprising means for two-dimensionally displaying the information in correspondence with the in-vivo impedance distribution.