JPH0576870B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an apparatus for systematically removing water stored in the body in hemodialysis, which measures the amount of dialysate supplied to a dialyzer and measures the amount of dialysate that passes through the dialyzer. The present invention relates to a water removal amount control method and a water removal amount control device in hemodialysis, in which water is systematically removed from blood by specifying an increase amount after the water is removed.

[Conventional technology]

Accurate control of the amount of water removed during hemodialysis is extremely important, and various methods have been used in the past to control the pressure on the blood side and the pressure on the dialysate side via a dialyzer using ultrafiltration.

[Problem to be solved by the invention]

However, in hemodialysis, the amount of water removed is extremely small compared to the flow rate of the dialysate, so in order to manage water removal with high precision, it is necessary, for example, to know the ultrafiltration rate intermittently and measure the amount of water removed. There are ways to control it, but
In general, the ultrafiltration rate is affected by many variables such as differences in the physical characteristics of the type of dialyzer, differences in the composition of the blood to be dialyzed, and changes over time, so the specified amount of water removed must be managed with high precision. It was difficult to do so. In addition, in clinical dialysis, proteins and fats are contained in the fluid discharged from the dialyzer, and they adhere to the fluid passages and metering structures, causing measurement errors.
The method of controlling the amount of water removed using a piston pump or the like having a movable part has the problem of increasing movable resistance and accelerating wear, resulting in errors over time.

The present invention has been made in view of the above problems, and proposes a new water removal amount control method that can manage and correct the water removal amount with high precision in hemodialysis, and also implements this method to perform highly accurate water removal management. The object of the present invention is to provide a water removal amount control device that can perform the following steps.

[Means to solve the problem]

The method and device for controlling the amount of water removed in hemodialysis according to the present invention accomplishes the tasks based on the basic concept shown below.

Basic concept of structure As shown in Fig. 1, the water removal rate control device for hemodialysis of the present invention includes (1) independent dialysate measuring chambers MCi and MCo provided on the supply/drain side of the dialysate circuit. .

(2) A suction pump PU is installed downstream of the drain side metering chamber MCo.

(3) The dialysate measuring chamber is divided by a diaphragm and has two left and right compartments, and the left and right compartments are alternately switched between the suction side and the discharge side by switching valves SVi and SVi installed at the communication port of the chamber. To switch to the side.

(4) Pressure detectors PSi and PSo are provided on the dialysate supply side circuit and the drainage side, respectively, and based on the input information, the suction pump PU and the switching valve SVi,
A central controller CPU is provided to control and drive the SVo.

In the hemodialysis circuit, (5) there are two diaphragms in the dialysate measuring chamber on at least either the supply side or the drain side of the dialyzer DL, and the capacity of the central chamber between the diaphragms can be increased or decreased. Becomes a structure.

(6) Stop the flow of dialysate to the dialyzer DL, and
It is equipped with solenoid valves Vi, Vo, and VB that can conduct the bypass circuit installed in parallel with the DL.

This is the gist of the matter.

Basic concept of control method In addition, the water removal control method using the water removal amount control device in hemodialysis is as follows: (1) Switching of the inlets and outlets of independent dialysate measuring chambers MCi and MCo provided on the supply and drain sides of the dialyzer DL. Valve SVo, SVi pressure sensor PSo,
Central control unit CPU based on pressure information from PSi
Switch between them.

(2) The central controller CPU calculates the differential value of the signal obtained from the pressure detectors PSo and PSi, and when the value falls within a certain range, the switching valve is activated.
Operate SVo and SVi.

(3) The central control unit CPU detects the cycle of each switching valve SVo and SVi on the liquid supply/drainage side, and calculates the difference between the cycles on the liquid supply/drainage side.

(4) Calculate the amount of water removed from the difference in the cycles, and control the suction pump PU so that it is equal to the requested amount.

(5) Measuring chambers MCi, MCo on the supply side and drain side
It is difficult to make the volumes exactly equal due to limitations in accuracy due to the materials and the fact that waste products from blood adhere to the inside of the chamber during dialysis.
Therefore, periodically (about 2 to 3 times per dialysis) the bypass solenoid valve VB is opened, and the solenoid valves Vi,
With Vo closed and dialysate flow to the dialyzer DL stopped, each of the above switching valves SVi,
By detecting the switching cycle of SVo and calculating a correction value, errors due to differences in weighing chamber capacity are corrected.

To correct the error due to the difference in the capacity of the measuring chambers, two diaphragms are installed in the dialysate measuring chamber on at least one of the supply side and the drain side of the dialyzer DL, and the volume of the central chamber between the diaphragms is adjusted. By making it possible to increase or decrease the
This can be done directly without calculating the correction value.

(6) That is, with the bypass solenoid valve VB periodically opened and the solenoid valves Vi and Vo closed to stop the flow of dialysate to the dialyzer DL, the capacity provided in the drain side measurement chamber MCo is Open regulating valve SVm.
The switching operation of the switching valves SVi and SVo on both the liquid supply and drain sides is temporarily stopped, and the measurement chamber on the liquid supply side is
All the dialysate in the chamber on the side that supplies fluid to the dialyzer DL of MCi is sent to the drain side metering chamber MCo through the bypass solenoid valve VB, and after a while, the volume adjustment valve SVm is closed.

Thereafter, the switching operation is restarted and the bypass state is released.

By the above operation, the difference in capacity between the liquid supply side measurement chamber MCi and the liquid discharge side measurement chamber MCo is corrected by the liquid that has flowed between the diaphragms of the liquid side measurement chamber MCo.

[Effect]

The above control method will be explained in detail.

Drain side dialysate measuring chamber MCo volume
Vo, the volume of the dialysate metering chamber MCi on the fluid supply side.
Vi, the dialysate flow rate is A, under bypass condition, the cycle of the fluid supply side switching valve SVi is Ti, and the cycle of the drain side switching valve SVo is To: Ti=Vi/A...(1) To=Vo/ A Therefore, Vo=(To/Ti)*Vi Therefore, if the correction coefficient is β, β=To/Tl…(2).

Under normal dialysis conditions, the fluid supply side switching valve
Assuming that the period of SVi is Ti, the period of the drain side switching valve SVo is To, and the difference between the periods is T, the relationship with water removal rate α is as follows: T=Ti−To=(Vi/A)−{β* Vi/(A+α)} =Vi*{A*(1-β)+α}/{A*(A
+α)} …(3) From equation (1), A=Vi/Ti, so from equation (3), remove A and find the removal rate α
When transformed into the formula, α=[Vi*{(1-β)-T/Ti}]/(T-
Ti), and by measuring T and Ti, the water removal rate α can be determined. Therefore, the total amount of water removed is determined as the product of the water removal rate α and the dialysis time.

In addition, the capacity of the central chamber between the diaphragms can be increased or decreased, allowing direct access to the drainage side measurement chamber.
If the capacities of MCo and the drain side measurement chamber MCo are matched, Vi=Vo and β=1, so equation (3) becomes α=Vi*(-T/Ti)/(T-Ti ) …(4) becomes.

Therefore, being able to adjust the capacity of the waste liquid side measuring chamber and the liquid supply side measuring chamber to be equal as described above means that it is possible to constantly correct errors in capacity changes due to temperature expansion of the measuring timer and mechanical wear. This means that the accuracy function can be guaranteed.

In addition, since the metering mechanism is composed of a diaphragm, it is possible to completely eliminate measurement errors during operation, improve water removal accuracy, and prevent wear of the metering circuit and generation of air bubbles. Coupled with this configuration, highly accurate water removal management control in hemodialysis can be achieved.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The water removal amount control method and water removal amount control device in hemodialysis of the present invention will be described below with reference to the drawings.

FIG. 1 shows the dialysate circuit of the water removal rate control device according to the present invention, in which the A side of the dialyzer DL is the dialysate side, and the B side is the blood side. With the sign Vi
Vo is an inflow side solenoid valve and a discharge side solenoid valve provided in the dialysate supply side and discharge side flow path of the dialyzer DL, respectively, and constitutes a bypass flow path 1 having a bypass solenoid valve VB, and an inflow side solenoid valve The valve Vi is connected to a deaerator DG provided on the fresh dialysate supply side IN via a switching valve SVi, thereby forming a dialysate supply side circuit 2. In addition, the discharge side solenoid valve Vo is connected to the waste dialysate discharge side via the switching valve SVo.
It is connected to the suction pump PU installed upstream of DRAIN to form the waste liquid circuit 3, and the switching valves SVi and SVo are connected to the pressure sensors PSi and PSo installed in the dialysate supply side circuit 2 and the waste liquid circuit 3, respectively. The suction pump PU is controlled by the input information of the suction pump PU, and is driven by a central control unit CPU that detects the switching time and controls the suction pump PU. The symbol MCi is a metering chamber on the liquid supply side that is branch-connected to the switching valve SVi, and is partitioned by a diaphragm 4, and consists of two compartments on the left and right whose suction and discharge sides are reversed by the switching valve SVi (Fig. 2). The diaphragm 4 has a structure in which the diaphragm 4 is a slippery film such as a thin silicone rubber film that adheres to the inner wall of the chamber without adhesion, and extends along the left and right sides of the inner wall facing each other. Furthermore, MCo is a drain side metering chamber branched and connected to the switching valve SVo, and two diaphragms 5, 5' whose suction side and discharge side are reversed by the switching valve SVo.
It has a central chamber 6 between two left and right compartments divided by diaphragms 5 and 5', and the diaphragms 5 and 5' are connected to the inner wall of the chamber similarly to the liquid supply side metering chamber MCi. It is composed of a slippery film such as a thin silicone rubber film that adheres without sticking, and has a structure that extends along the left and right sides of the opposing inner walls. The drain side metering chamber MCo is
The central chamber 6 is connected to the liquid reservoir 7 via the volume adjustment valve SVm.
It becomes a structure that communicates with Moreover, the deaerator DG
A part of the dialysate supply side circuit 2 supplied from the dialysate is configured with an air bubble detector AD and a float FL.

The water removal amount control device with the above configuration is the deaerator DG.
The fresh dialysate degassed by the pump is introduced into one side chamber of the supply side metering chamber MCi through the switching valve SVi passage, and the diaphragm 4 that partitions the chamber is expanded and moved to fill the chamber to its full capacity. (See Figure 2).

Since the diaphragm 4 is shaped to extend along the left and right sides of the opposing inner walls, when the inflowing dialysate stops flowing at the moment when one chamber of the fluid supply side metering chamber MCi reaches fullness, it flows into the inflow side pipe. Pressure rises rapidly. This pressure increase phenomenon is detected by a pressure detector.
It can be detected by PSi, and the electrical signal can be used to operate the switching valve SVi. . When the switching valve SVi is operated, the dialysate flows into the chamber on the opposite side of the metering chamber MCi on the liquid supply side, and the pressure in the dialysate supply side circuit 2 detected by the pressure detector PSi also returns to the original level. The process from detecting the fullness of one side chamber to changing the inflow path is an instantaneous operation, and the switching valve SVi changes the liquid path of both compartments at the same time, and the one side chamber that was being filled before switching is The switching of the passages allows fresh dialysate to be sent to the circuit of the dialyzer DF. Dialysis machine
The waste liquid that has passed through the DF is transferred to the metering chamber on the liquid supply side.
It is guided by the drain side measuring chamber MCo, which has the same capacity as the MCi, and operates by alternately inflowing and discharging waste liquid from the left and right chambers, and actively sucks the liquid using the suction pump PU.

The central chamber 6 of the drain side metering chamber MCo is filled with a non-volatile liquid (silicone oil, paraffin oil, etc.) free of bubbles and dissolved gases, and the liquid reservoir 7 is filled by opening and closing the volume adjustment valve SVm. The central chambers 6 are communicated and closed, and the volume of the central chamber 6 is increased or decreased to adjust the volume of the drain side metering chamber MCo. Also, the drain side metering chamber
Pressure detector installed in PU between MCo and suction pump
PSo detects the pressure signals of inflow and filling of the left and right chambers of the chamber, and operates the switching valve SVo to measure the volume.

Being able to constantly correct for capacitance changes due to temperature expansion during measurement, errors due to mechanical wear, etc. is an important element for guaranteeing precision functions.

The function of artificial dialysis is to remove waste products, which are uremic substances, from the blood, and the purpose is to diffuse them through the difference in concentration with the dialysate and remove water. Therefore, the removal of water is performed physically by the pressure difference between the blood and the dialysate across the membrane of the dialyzer. Physiologically, the amount of water in the body is an important element of life, and appropriate promotion management is required for dialysis machines. In addition, in recent years, membrane manufacturing technology for dialyzers has improved, and the water removal characteristics have significantly improved, making it important to carry out planned water removal management, its accuracy, and equipment maintenance management.

Currently, even in devices used clinically, the piston pump link mechanism causes errors due to wear etc. in the central functional part that measures and removes water.
In addition, there are safety and stability problems in controlling water removal, such as using a structure that causes air bubbles, such as a gear pump, in the liquid circuit between the measuring instruments.

However, in the present invention, by adjusting the capacity of the supply side measuring chamber MCi and the waste side measuring chamber MCo to be equal at the start of dialysis,
Being able to constantly correct for capacitance changes due to temperature expansion and errors due to mechanical wear of the measuring instrument is an important factor in guaranteeing accuracy functions, and this allows the device to maintain high accuracy for many years.
In particular, errors when specifying a low water removal amount can be suppressed.

〔Effect of the invention〕

As described above, the water removal amount control device according to the present invention uses a diaphragm in the metering mechanism, so that it is possible to eliminate measurement errors caused by the operation of this part, and it is possible to improve water removal accuracy. Therefore, the effects after implementing the present invention are extremely large.

[Brief explanation of drawings]

Fig. 1 is a dialysate circuit diagram of the water removal rate control device according to the present invention, and Fig. 2 is an explanatory diagram of the operation of the liquid supply side metering chamber, where a is a right ventricular inflow state, a left ventricular fluid feeding state, and b is a switching valve. In the operating state, c shows the left ventricular inflow state and the right ventricular fluid delivery state. FIG. 3 is an explanatory diagram of the operation showing the right ventricular inflow state and the left ventricular fluid delivery state of the drain side measuring chamber. DL...Dylyzer, Vi, Vo...Solenoid valve, SVi, SVo
…Switching valve, VB…Bypass solenoid valve, SVm
…capacity adjustment valve, DG…deaerator, PU…suction pump, PSi, PSo…pressure detector, CPU…central control unit, MCi…liquid supply side metering chamber, MCo
…Drain side metering chamber, AD…Air bubble detector,
4, 5...Diaphragm, 7...Liquid pool.

Claims (1)

[Scope of Claims] 1. A switching valve SVi provided independently on the supply/drainage side of the dialysate circuit, having two left and right compartments each partitioned by a diaphragm, and provided at each inlet and outlet. Dialysate measuring chambers MCi and MCo have a structure in which the two chambers are alternately switched to the suction side and the discharge side by SVo, a suction pump PU installed downstream of the drainage side measuring chamber MCo, and the dialysate of the dialyzer DL. The suction pump PU and both switching valves are activated based on input information from pressure detectors PSi and PSo installed on the supply side circuit and drain side, respectively.
In a hemodialysis circuit consisting of a central controller CPU that controls and drives SVi and SVo, two diaphragms are installed in the dialysate measuring chamber on at least one of the supply side and the drain side of the diaphragm DL. The dialyzer has a structure in which the capacity of the central chamber between the diaphragms can be increased or decreased, and
A bypass circuit parallel to the DL is constructed, and the dialyzer
Three solenoid valves Vi, Vo, which make it possible to stop the flow of dialysate to the DL and connect the bypass circuit.
A water removal amount control device for hemodialysis, characterized in that it corrects an error resulting from a difference in capacity between the two measuring chambers forming a VB. 2. The water removal amount control device for hemodialysis according to claim 1, further comprising a deaeration device having a bubble detector in the circuit of the pressure sensor PSi of the dialysate supply side circuit.