JPS59171559A - Water removing amount controller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 12 Background of the Invention (Technical Field) The present invention aims to improve the amount of water removed when removing excess water from the blood, the so-called ultrafiltration amount, in hemodialysis therapy for patients with renal failure, debilitation, etc. This relates to a measuring device.

(Prior art and its problems) Hemodialysis therapy is performed using a device called a hemodialyzer. In this method, the dialysate and blood are brought into contact through a semipermeable membrane, and all water is transferred to the dialysate side due to the sound of waste products in the blood and the pressure difference due to the concentration gradient. The amount of water removed at this time (ultrafiltration amount) is equivalent to the amount of dialysate that flows out of the hemodialyzer from the start to the end of dialysis minus the amount of dialysis grams that flowed into the hemodialyzer. However, it is often difficult to accurately measure the amount of ultrafiltration at any given time during dialysis. Usually, the ultrafiltration rate is determined by measuring the patient's weight and calculating it from the weight loss. However, this time-consuming process involves eating during hemodialysis, which lasts for several hours.
Factors that cause weight fluctuations such as excretion, sweating, etc. cannot be adequately considered.

However, since this ultrafiltration rate is an extremely important medical element in the treatment of uremic patients, it is desirable to provide a method that can accurately measure it.

Therefore, a method as shown in FIG. 1 has been considered. Flowmeters 4 and 5 are provided in the middle of the inflow path 2 and outflow path 3 to the hemodialyzer 1, respectively, and the inflow and outflow amounts to the hemodialyzer 1 are measured by the flowmeters 4 and 5. The purpose is to find out the amount of water removed (ultrafiltration amount) from the difference in flow rate. That is, the difference between the results obtained by each flow meter 4 and 5 is determined by the subtractor 6, and the total amount of the difference is totaled by the integrator 7, thereby measuring the total amount of water removed and displaying it on the indicator 8. do. However, while the amount of dialysate supplied to the hemodialyzer 1 is normally 500 rn//min, the amount of water removed is approximately 5-7 minutes. 6 and integrator 7 must have an accuracy of 0.01% in order to obtain the amount of water removed with an accuracy of 1%. In other words, in order to use this method, it is necessary to use extremely expensive equipment, and flowmeters in particular are expensive and very impractical.

Based on the idea of using this flow meter, some use precision parts such as volumetric measuring chambers (
Utility Model Publication No. 53-69441, Japanese Patent Application Publication No. 55-146164
(see issue).

Even if such expensive precision parts are used, the dialysate after passing through the hemodialyzer is contaminated with waste products, so the waste products adhere to the precision parts mentioned above, resulting in long-term problems. It was difficult to obtain proper operating funds.

L. Purpose of the Invention Accordingly, the purpose of the present invention is to provide a simple and reliable water removal amount measuring device that does not use expensive precision parts, is less susceptible to the effects of adhesion of waste materials, and has a small number of component parts. I'm trying.

Another object of the present invention is to convert the present invention into an fRk unit,
It is an object of the present invention to provide a water removal amount measuring device configured so that it can be easily added to existing dialysis-related equipment that has been used in the past.

10 Specific Structure of the Invention According to the present invention, the present invention includes a hemodialyzer, an inflow circuit for supplying dialysate to the hemodialyzer, and an outflow circuit for discharging dialysate from the hemodialyzer. In a hemodialysis apparatus configured to perform dialysis by contacting a fluid with a dialyzer through the dialyzer, the flow-out circuit is configured to cut off supply and discharge of dialysate to the hemodialyzer when measuring the amount of water removed. a bypass circuit connected to the hemodialyzer, a first pressure sensor for measuring the pressure of venous blood downstream of the hemodialyzer, and a second pressure sensor for determining the pressure of the dialysate outflow circuit, connected to the outflow circuit; and a water removal amount measurement circuit configured to forcibly remove water from the dialysate in the outflow circuit, and a control configured to introduce a water removal amount measurement mode at predetermined time intervals during normal dialysis mode. The control device is configured such that in the normal dialysis mode, the dialysate flows from the inflow circuit to the outflow circuit to perform dialysis, while when the control is switched to the water removal measurement mode, the dialysate flows through the bypass circuit. The venous blood pressure measured by the first sensor and the dialysate pressure measured by the second sensor are bypassed so that there is no flow to the dialyzer in the circuit, and water is forcibly removed to the desired water removal level in the water removal amount measurement circuit. The above object can be achieved by measuring the pressure difference between the dialysis and dialysis, performing the entire dialysis according to the pressure difference in the next normal dialysis mode, and repeating this operation repeatedly. The bypass circuit is configured with a three-way valve that is automatically controlled to supply and remove dialysate to the hemodialyzer in normal dialysis mode, and to cut off the supply and removal of dialysate to the hemodialyzer in water removal measurement mode. It is preferable to do so. The water removal amount measurement circuit is
A metering pump is preferably provided as a means for forcibly removing water from the dialysate.

The pressure values determined by the first and second pressure sensors can be configured to use an average value of a plurality of measured values.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The water removal amount control device according to the present invention will be described in detail below with reference to preferred embodiments shown in the accompanying drawings.

Generally, in hemodialysis, a blood pump 11 is used in a hemodialyzer 10.
While pressurizing the blood g to flow into the blood circuit 12, the dialysate passes through the inflow circuit 13 and outflow circuit 14 to the hemodialyzer 1.
The blood is refluxed to 0 and the dialysate is brought into contact with the dialysate in a hemodialyzer.

At this time, although the amount of water removed from the blood is a very important factor, it was not possible to titrate it using conventional methods such as measuring the flow rate of dialysate, as described above.

In the present invention, based on the idea that the pressure difference (filtration pressure) between the venous blood pressure to be dialyzed and the dialysate pressure after dialysis is correlated with the amount of water removed, this pressure difference is determined in relation to the desired amount of water removed, and the calculated pressure is Dialysis is performed according to the difference, and automatic control is performed to appropriately correct the set pressure difference over time and perform appropriate water removal.

Therefore, as shown in FIG. 2, a pressure sensor 15 for measuring venous blood pressure is installed in the blood circuit 12 downstream of the hemodialyzer 10, and a pressure sensor 16 for measuring the pressure of dialysate after dialysis is installed in the blood circuit 12 downstream of the hemodialyzer 10. It is installed in the circuit 14. When the control is switched from normal dialysis mode to water removal measurement mode,
A bypass circuit 17 is provided which interrupts the supply of dialysate to the hemodialyzer 10-- as well as the removal of dialysate therefrom. The bypass circuit has one three-way valve for each inflow and outflow circuit.
It is preferable to install 8, l'l, and H and connect these with a conduit 20. Further, a water removal amount measuring circuit 21 is connected to and provided in the outflow circuit 14. The water removal amount measurement circuit only needs to be configured so that water can be forcibly removed from the dialysate in the outflow circuit, and in the example shown in FIG.
3, and remove water at the end of the pipe 22;
has.

In addition, the bypass circuit 17 and the water removal amount measurement circuit 21 are
A three-way valve 18.19, if it can be configured to perform switching control as described above, if necessary.
Other valves may be used instead, such as multiple two-way valves or pinch pulp.

The pressure sensors 15, 16 and the three-way valve 18 described above are
, 19, the metering pump 23 is connected to the external discharge control device 25 and controlled through the water removal amount measurement mode and the dialysis mode. The control device 25 has a microcomputer 26,
The signal from the pressure sensor is further processed by an amplifier 27, an AD converter 28, etc., and then inputted to a microcomputer 26. Switching control between the water removal amount measurement mode and the dialysis mode, including pressure measurement with the pressure sensor 15, 16, operation of the three-way valve 18, 19, operation of the metering pump 23, etc.
All of this is done by the control device 25 as will be described later. In the control device 25, the correction cycle setting 2 of the water removal amount measurement mode is set.
9. Water removal rate setting 30, water removal amount display 31, pressure display 32, etc. can be set and displayed as required.

(1) Specific operation of the invention Next, the control operation of the water removal amount control device according to the invention will be briefly explained.

FIG. 3 shows a timing chart of the control device of the present invention. Normally, it is operated in dialysis mode, and a correction time (for example, 4 minutes) called water removal measurement mode is introduced every fixed water removal correction cycle (for example, every hour), and the sequence is controlled by a correction cycle timer and a correction time timer. (See control line 1.N in Figure 3).

In normal dialysis mode, the three-way valves 18 and 19 are in the position shown by the solid line, and dialysate is circulated from the monitoring device 36 through the inflow circuit 13, the hemodialyzer 1o, and the outflow circuit 14, and blood dialysis is performed. It will be done. On the other hand, when the dialysis mode is switched to the correction mode of the water removal measurement mode and the power switch of the control device of the present invention is turned on, the three-way valve 18.19
is switched to the position shown by the dotted line, and the dialysate is returned from the inflow circuit 13 via the bypass line 20 to the outflow circuit 14 to the monitoring device @ 36, and at the same time the dialysate circuit is sealed by switching both three-way valves. , the dialysate supply and drainage are shut off.

In the water removal amount measurement (correction) mode, the metering pump 23 rotates at a speed corresponding to the set water removal rate, water is removed by the e-cam, and the actual water removal amount is displayed on the meter 24. At this time, filtration pressure is generated on both sides of the dialysis membrane of the hemodialyzer depending on the water removal rate at that time.

This filtration pressure is measured via the pressure sensor 'J-15.
2 is displayed as the pressure target value. In order to increase the accuracy of the amount of water removed, it is preferable to use a pressure sensor to average the values measured every 0.1 seconds, for example.

In this manner, when a predetermined period of time has elapsed in the correction mode, the correction mode ends and the mode shifts to the dialysis mode. At this time, three-way valve 1
8.19 is again at the position shown by the solid line, and the dialysate is supplied to the hemodialyzer 10 to perform dialysis. During the dialysis mode, both the stored pressure target value and the actual pressure value, which changes from moment to moment, are displayed on the pressure display 32 and serve as a guideline for adjusting the filtration pressure.

When the actual pressure value is equal to the pressure target value, the water removal rate is assumed to be equal to the set water removal rate, and when there is a difference between the actual pressure value and the pressure target value, the water removal rate is determined according to the difference. By correcting the amount of water removed, the amount of water removed can be calculated and integrated and displayed as the amount of water removed display 31.

As shown in Fig. 3, when the predetermined correction cycle time has elapsed, the correction mode (water removal amount measurement mode) is automatically activated.
, and the above-described operation is performed again. As an example of specific control, FIG. 4 shows a main routine, FIG. 5 shows a water removal amount measurement routine, and FIG. 6 shows a pressure sampling routine.

Further, in the control device of the present invention, the amount of water removed is calculated by the following calculation.

Set water removal rate Q (t/h) Pressure target value obtained during correction R (mmHg) 7.5
Pressure value P (xHg) averaged every second Pressure value d (sxHg) corresponding to the difference between the true filtration pressure value and P
) Water removal amount for 7.5 seconds q (ml) Next, a specific example of the water removal amount control device of the present invention will be shown.

As the metering pump 23, the pump characteristics shown in FIG.
A 30-La type pump having the Ecam characteristics shown in the figure was used. Examples of recorder records showing test results using such a pump are shown in FIGS. 9 and 10. In both figures, a indicates the target pressure value, b indicates the filtration pressure, and C indicates the amount of water removed. Furthermore, the accuracy of measuring the amount of water removed at this time is shown in FIG.

As can be seen from the water removal measurement accuracy diagram in FIG. 11, there is some error between the displayed water removal amount and the actually measured water removal amount.

It is desirable that this be as small as possible. In the device of the present invention, water removal jetf is measured indirectly using the filtration pressure value, but there is a discrepancy between the true filtration pressure and the filtration pressure measured by this device due to the following two points, which may be the cause of the error. It has become. If this At is taken into account, the accuracy can be further improved.

(1) Pressure difference caused by the difference in height between the hemodialyzer and the pressure measurement point.

(2) Pressure loss that occurs when dialysate or blood flows between the hemodialyzer and the pressure measurement point.

(2) Specific Effects of the Invention The water removal amount control device according to the present invention provides many advantages over conventional devices as described below.

(1) Because it does not use a large number of precise and expensive flowmeters, flow chambers, etc. as in the past, it is not affected by deterioration in accuracy due to waste materials that adhere to them, and the number of parts is extremely small. Therefore, a comparatively accurate and inexpensive water removal amount control device can be obtained.

(2) Since it is configured to be able to correct the water removal ft at regular intervals, it is possible to effectively track and compensate for changes in the dialysis system over time.

(3) The device of the present invention can be made into a unit and used as an addition to a conventional device, and can be used in addition to a conventional monitoring device to improve the accuracy of the amount of water removed.

[Brief explanation of drawings]

Figure □ is the conventional one. Limitless amin determination device. 2 is a configuration diagram of the water removal amount control device of the present invention, FIG. 3 is a timing chart 2 of the water removal amount control device of the present invention, and FIGS. 4, 5, and 6 are diagrams of the water removal amount control device of the present invention. A flowchart of the water removal amount control device, FIGS. 7 and 8 are diagrams showing the characteristics of the metering pump used, FIGS. 9 and 10 are records of test results of the device of the present invention, and FIG. 11 is a diagram of the device of the present invention. Accuracy in measuring the amount of water removed? FIG. Explanation of symbols 10...Hemodialyzer, 11...Blood pump, 12...
・Blood circuit, 13... Inflow circuit, 14... Outflow circuit, 15° 16... Pressure sensor, 17... - Bypass circuit, 18° 19... Three-way valve, 20... - Bypass pipe line , 21...Water removal amount measuring circuit, 22...Water removal amount measurement pipe line, 23... Metering pump, 24... Measuring instrument, 25
...Control device, 26...Microcomputer, 2
7... Amplifier, 28... AD converter, 29... Correction cycle setting device, 30... Water removal perforation setting device, 31...
・Water removal amount indicator, 32...Pressure indicator, 33.34,
35...Flow of dialysate, 36...Monitoring device Figure 6 Figure 2 Figure 7 Figure 7 Pump rotation speed (rpm)

Claims (4)

[Claims] (1) A hemodialyzer, an inflow circuit for supplying dialysate to the hemodialyzer, and an outflow circuit for discharging dialysate from the hemodialyzer, and blood and dialysate are transported through the dialyzer. A hemodialysis apparatus configured to perform dialysis by contacting the hemodialyzer includes a bypass circuit connected to the outflow circuit that cuts off the supply and discharge of dialysate to the hemodialyzer when measuring the amount of water removed; a first pressure sensor that measures the pressure of venous blood downstream of the dialyzer; a second pressure sensor that measures the total pressure of the dialysate outflow circuit; a water removal amount measuring circuit configured to be able to perform water removal; and a control device configured to introduce a water removal amount measurement mode at predetermined time intervals during a normal dialysis mode, the control device comprising: In normal dialysis mode, the dialysate flows from the inflow circuit to the outflow circuit to perform dialysis, but when the control is switched to water removal measurement mode, the dialysate does not flow to the hemodialyzer through the bypass circuit. the total measurement of the pressure difference between the venous blood pressure by the first sensor and the dialysate pressure by the second sensor when water is forcibly removed to a desired amount in the water removal amount measuring circuit In the next normal dialysis mode, dialysis is performed according to the pressure difference, and this operation is repeated. (2) The bypass circuit is automatically controlled to supply and remove dialysate to the hemodialyzer in normal dialysis mode, and completely shut off the supply and removal of dialysate to the hemodialyzer in water removal measurement mode. The water removal amount control device according to claim 1, which comprises a valve. (3) The water removal amount measuring circuit includes a metering pump as means for forcibly removing water from the dialysate.
The water removal amount control device according to item 1 or 2. (4) The pressure values measured by the first and second pressure sensors are configured to use an average value of a plurality of measurement values. The water removal amount control device described.