JPH028743B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a water removal amount designation control device that performs systematic water removal from blood during dialysis by ultrafiltration.

(b) Conventional technology Managing the amount of water removed during hemodialysis is extremely important, and there is a demand for higher accuracy in the cumulative amount of water removed. Conventionally, the pressure on the blood side and the pressure on the dialysate side have been adjusted via the dialyzer. Various methods have been adopted to do this.

However, since the amount of water removed in hemodialysis is extremely small compared to the flow rate of dialysate, it is necessary to accurately know the ultrafiltration rate in order to manage water removal with high precision. , the ultrafiltration rate is determined by differences in the membrane area, membrane pressure, membrane material, etc. of the dialyzer, differences in the characteristics of each dialyzer, differences in the composition of the dialysate, differences in the blood composition of each person, and differences in the blood composition. It is difficult to control water removal with high accuracy to the specified water removal amount because it includes many variables such as changes over time, influence of dialyzer efficiency due to temperature conditions, and blood flow rate, and it is difficult to control water removal with high precision and depends on skilled empirical correction. It was hot.

(c) Problems to be solved by the invention As mentioned above, the ultrafiltration rate of a dialyzer in hemodialysis involves a large number of variables. It was extremely difficult to manage.

In particular, in recent years, the water removal efficiency of dialyzers has been improved and increased, and the amount of water removed is large even under low pressure, and measurement errors at low ultrafiltration pressure points have a large effect on the amount of water removed. It was something I had.

Furthermore, regarding the above measurement error, there is a problem with various filtration rate measuring devices provided in the dialysate side circuit for measuring the ultrafiltration rate.

In other words, the dialysis circuit of the hemodialysis circuit, especially downstream of the dialyzer, contains various metabolic substances dialyzed from the blood, so the metabolic substances may adhere to the inner wall of the meter, causing fluctuations in the measured volume, or It has been difficult to accurately measure the amount of ultrafiltration due to problems such as clogging.

The present invention was made in view of the above problems, and
It is an object of the present invention to provide a water removal amount specification control device that can control the specified water removal amount during hemodialysis with high precision without manual correction. This system integrates the amount of water removed in accordance with changes in the rate, making it possible to accurately and automatically manage the specified amount of water removed, and in particular performs highly accurate water removal management even under low ultrafiltration pressure. It is something that can be done.

(d) Means for solving the problem That is, the water removal amount specification control device of the present invention connects one chamber separated by a dialysis membrane to the blood side circuit and the other chamber to the dialysate side circuit. a dialyzer, first and second shutoff valves provided in the upstream and downstream circuits of the dialyzer in the dialysate side circuit, respectively, and a third shutoff valve that communicates the upstream and downstream sides of both shutoff valves. A bypass path with a shutoff valve, hydraulic pressure sensors that detect fluid pressure upstream and downstream of the dialyzer in the dialysate side circuit, and ultrafiltration installed downstream of the dialyzer in the dialysate side circuit. It consists of a volume measuring means, a blood pump provided in the upstream circuit of the dialyzer in the blood side circuit, and a hydraulic pressure sensor that detects the hydraulic pressure upstream of the dialyzer in the blood side circuit, In the dialysis circuit, the ultrafiltration amount measuring means is driven and controlled by a central control device that controls the opening and closing of each of the shutoff valves in response to an input signal from a sensor to alternately repeat water removal rate measurement and water removal. The filtration amount measuring means constitutes a volume measuring chamber on one side of the cylinder that communicates with the isolated blood side circuit via a flexible compartment material such as a diaphragm, and the flexible part of the volume measuring chamber and the other parts of the cylinder The pistons are inserted airtightly and retractably from the side and are airtightly connected via a non-transpiration fluid, and the relative variable of the volume measuring chamber is detected based on the variable of the amount of ejection and retraction of the piston. This is a summary.

(E) Effect That is, in the above configuration, the actual filtration rate at the low ultrafiltration pressure of the dialyzer is measured, and a virtual ultrafiltration characteristic straight line passing through the base point is calculated using the actual filtration rate as the base point, The ultrafiltration pressure to be applied to the dialyzer corresponding to the desired filtration rate is determined based on the filtration characteristic straight line, initial dialysis is started, and the upstream and downstream dialysate circuits of the dialyzer are closed during dialysis to create a closed circuit. create,
While maintaining the average dialysate pressure in the dialysate circuit at the average dialysate pressure immediately before measurement by controlling and driving an ultrafiltration rate measuring pump provided downstream of the dialyzer, The amount of ultrafiltration is measured by the pump, the corrected ultrafiltration characteristic straight line passing through the base point is calculated again from the ultrafiltration amount, and the ultrafiltration characteristic line corresponding to the desired filtration rate is calculated from the corrected ultrafiltration characteristic straight line. By integrating the ultrafiltration rate and elapsed time calculated from the ultrafiltration pressure over time obtained by determining the filtration pressure and the measured ultrafiltration amount, the amount of water removed in the measurement section is obtained, and the amount of water removed in the measurement section is obtained. After the time period for each section has elapsed, the ultrafiltration characteristic straight line is corrected again using the same means as described above to obtain the amount of water removed in successive measurement sections. During the measurement, the actual filtration rate of the dialyzer at low ultrafiltration pressure is measured at appropriate times to correct the base point, and the ultrafiltration rate is determined to determine the ultrafiltration pressure in subsequent dialysis. By using this as the base point of the filtration characteristic straight line, measurement errors can be reduced.

In addition, when the measured ultrafiltration pressure is close to the reference point pressure in calculating the correction of the ultrafiltration characteristic straight line,
By setting the actual filtration amount at a filtration pressure that exceeds the ultrafiltration pressure by, for example, about ±30 mmHg as the correction point of the straight line, the error in the slope of the ultrafiltration characteristic straight line due to the proximity of the measurement point is reduced.

In the configuration of the device of the present invention, there is generally a substantially linear relationship between ultrafiltration pressure and filtration rate in a dialyzer, but even when the ultrafiltration pressure is zero, a small amount of filtration rate is still output from the dialyzer. Based on the virtual ultrafiltration characteristic straight line calculated from the measured value of filtration amount at low ultrafiltration pressure, the average dialysis consisting of the inlet pressure and outlet pressure of the dialyzer is Since the method calculates the fluid pressure, the average dialysate pressure of each dialyzer can be obtained regardless of the dialysate pressure distribution within the dialyzer.

Furthermore, in the present invention, the average dialysate pressure value of the dialyzer (in the normal dialysis state) immediately before starting measurement is stored, and after switching to the bypass flow path, the ultrafiltration amount measurement is performed so as to maintain this pressure value. By operating the pump, measuring the filtration amount over a predetermined period of time, and calculating the corrected ultrafiltration pressure, the ultrafiltration pressure at the time of measurement is approximated to the ultrafiltration pressure during continued dialysis. It is possible to obtain an ultrafiltration rate under exactly the same conditions as dialyzer membrane pressure conditions during normal dialysis, and it is possible to measure the ultrafiltration rate and change the ultrafiltration pressure and dialysis time. Through integration, it is possible to calculate the total amount of water removed with high accuracy.

(F) Embodiment FIGS. 1 to 3 show a positive pressure hemodialysis circuit which is an embodiment of the present invention.

Reference numeral 1 designates a dialyzer in which a blood side circuit and a dialysate side circuit 3 are separated via a dialysis membrane 1a, and the blood side circuit 2 includes a blood pump 5 on the upstream side of an artery side flow path 4 and an air bubble on the downstream side. A separation trap 6 is provided, and an arterial blood pressure sensor _P3 is provided for the bubble separation trap 6, and a filtration pressure regulating throttle valve 8 is provided in the venous flow path 7.

In addition, the dialysate side circuit 3 includes an inlet 9 and an outlet 1.
A stop valve V ₁ , V ₂ is provided at each end of the stop valve V 1 , V 2 , and one stop valve is provided on the outside of the stop valve V ₁ , V ₂ .
communicated via a bypass flow path 11 having V ₃ ;
The shutoff valve V ₃ of the bypass passage 11 is replaced with another shutoff valve V ₁ ,
In addition, hydraulic pressure sensors P _{1 and} P ₂ are provided on the output path 10 side and the input path 9 side of the dialyzer ₁ , respectively. A cylinder 12 for measuring the amount of ultrafiltration is installed downstream.

As shown in FIG. 2, the ultrafiltration measurement cylinder 12 has a cylinder main body 13 separated into an upper chamber 13a and a lower chamber 13b via a flexible diaphragm 14, and the dialysate outlet 10 is connected to the upper chamber 13a. Two ports 15a, 15 that communicate the upstream and downstream sides of
b is opened to constitute a capacity detection chamber, and a piston 16 is inserted airtightly and slidably into the lower chamber 13b from the lower end, and the lower chamber 13b is filled with a non-transpiration liquid 17.

Further, the piston 16 is a quantitative actuator mechanism formed by displacing a drive direction conversion transmission mechanism 19 such as a screw mechanism via a pulse motor 18 controlled by a rotation speed control mechanism 20a of a central controller 20, for example. Therefore, the insertion/extraction drive with respect to the cylinder body 13 can be adjusted.

Reference numeral 21 denotes a venous pressure interlocking element provided at the end of the outlet 10, and as shown in FIG. 3, the upper and lower housings 22,
The lumen formed by 23 is divided by a flexible diaphragm 24 to form a pressurizing chamber 25 and a circulation chamber 26, and a filtration pressure adjustment chamber is provided in the pressurizing chamber 25 downstream of the dialyzer 1 in the blood side circuit 2. A pressurizing port 27 is opened which communicates with the downstream side of the throttle valve 8 via the bubble separation trap 6'.

Further, reference numeral 28 is a discharge port which is opened in the circulation chamber 26 by forming a valve seat 29 at the inner end facing the flexible diaphragm 24, and an input port 30 is opened on the side of the circulation chamber 26. The input port 30 and the discharge port 28 are communicated between the bypass passage 11 and the hydraulic pressure sensor _P1 .

In the above configuration, the dialysate side circuit 3 closes the shutoff valve V ₃ of the bypass flow path 11 and closes the other closed valves V ₁ ,
Perform normal dialysis with V ₂ open, and conversely with the shut-off valve
The amount of ultrafiltration is detected with V ₁ and V ₂ closed and V ₃ closed.

That is, when measuring the limited filtration amount, the shutoff valve V ₁ ,
When V ₂ is closed and V ₃ is opened, the dialysate flows through the bypass channel 11, and the dialysate side 3 of the dialyzer 1 constitutes a thread with both ends closed.

However, the filtrate from the blood side circuit 2 enters the blocked thread through the dialysis membrane 1a of the dialyzer 1 and increases in volume, and in the method of the present invention, the increased fluid is transferred to the ultrafiltration rate measurement cylinder. 12, a non-transpiration liquid 17 and a piston 16 are provided in the cylinder 13 via a flexible diaphragm 14 for a predetermined period of time.
The pulse motor 18 is controlled via the central controller 20 so that the movement of the pulse motor 18 is detected as the rotational speed of the pulse motor 18, and the fluid pressure sensors P ₁ and P ₂ at the time of measurement match the values during normal dialysis immediately before the measurement. to drive and control.

Depending on this measurement direction, the dialyzer 1 in the normal dialysis state
The amount of ultrafiltration can be measured per unit time without changing the average dialysate pressure value, and the ultrafiltration rate at the time of measurement can be obtained from this amount of ultrafiltration.

In addition, the venous pressure interlocking element 21 can maintain the back pressure of the dialyzer 1 at the same pressure in conjunction with the venous pressure, and can reduce the water removal pressure to zero, regardless of the venous pressure of the hemodialysis patient. Since it is possible to achieve an ultrafiltration pressure, it controls the dialysis system when a low filtration rate is desired.

Next, a method for specifying and controlling the amount of water removed using the hemodialysis circuit configured as described above will be described in detail.

(a) First, in order to investigate the characteristics of the dialyzer 1 to be used, as shown in Fig. 4, the actual filtration rate (ml) at a low ultrafiltration pressure P _L (for example, 30 mmHg) is measured, and the Calculate the filtration rate UF _L and set the coordinates P _L , UF _L
Based on.

(b) Virtual extreme characteristic straight line from the base point P _L and UF _L above
In addition to estimating Y' (obtained from the display characteristics and actual volume values of various commercially available dialyzers),
Calculate the average dialysate pressure from the outlet pressure P ₁ and the inlet pressure P ₂ by taking into account the parameters of the dialyzer characteristics.

(c) Next, determine the ultrafiltration pressure P _R corresponding to the desired ultrafiltration rate UF _R from the virtual ultrafiltration line Y′, and (d) calculate the filtration rate again using the ultrafiltration pressure P _R. measure,
Calculate the ultrafiltration rate UF _P.

(e) Next, determine the filtration pressure P corresponding to the desired ultrafiltration rate by using the straight line passing through the two points P _L , UF _L , P _R , and UF _R as the actual ultrafiltration characteristic line Y, and determine the filtration pressure P corresponding to the desired ultrafiltration rate. Actual dialysis begins at low pressure.

After a certain period of time has passed, the ultrafiltration rate is measured again, and depending on the fluctuation of the measured filtration rate, the actual ultrafiltration special straight line Y is changed to Y'', and the ultrafiltration pressure P is corrected to P'', and then again. Move on to actual dialysis.

Furthermore, it is known that the ultrafiltration rate of the dialyzer 1 changes over time, as shown in FIG. 5, even if other conditions are the same.

However, in a dialysis device that has a bypass circuit and measures the ultrafiltration rate over time, it is not possible to measure the ultrafiltration rate continuously.
In the present invention, the total amount of water removed is obtained by integrating the ultrafiltration rate at the time of measurement and the elapsed time. To calculate the total amount, for example, divide the time between measurement time T ₁ and T ₂ into two, and divide the first half into two. Ultrafiltration rate at the previous T ₁ measurement
By integrating based on UF ₁ , and then integrating the latter half based on ultrafiltration rate UF ₂ at the time of T ₂ measurement and adding them sequentially, it is possible to calculate the total amount of water removed with high precision that approximates the true value. can.

In addition, during the aforementioned dialysis, the base point P _L ,
By re-measuring UF _L , it is possible to improve the dialysis accuracy under low ultrafiltration pressure and to
When calculating P _L and UF _L , if the specified ultrafiltration pressure for water removal is close to the base point, set the measured ultrafiltration pressure to approximately 30 mm, for example.
It is preferable to shift the Hg pressure to a high or low pressure position so that the coordinates of the two points P _L , UF _L , P _R , and UF _R through which the actual ultrafiltration characteristic straight line Y passes are not close to each other.

As described above, according to the configuration of the present invention, the ultrafiltration rate is repeatedly measured over time to perform actual dialysis, so that a predetermined amount of water removal can be reliably obtained.

(G) Effects of the Invention As described above, the water removal amount specification control device of the present invention eliminates differences in membrane area, membrane thickness, membrane material, etc. depending on the type of dialyzer, and differences in characteristics of each dialyzer. , differences in concentration and composition of dialysate, differences in blood composition between individuals and changes in blood composition over time, influence of temperature conditions on dialysis efficiency, and blood flow rate. Not only can the water removal test be controlled with extremely high precision without any problems, but the water removal test can be performed in a short time, reducing the effect on dialysis time.The practical effects of implementing the present invention are extremely high. big.

[Brief explanation of drawings]

The drawings show an embodiment of the water removal amount designation control device according to the present invention, and FIG. 1 is a dialysis circuit diagram, FIG. 2 is a schematic front cross-sectional view of a cylinder for measuring ultrafiltration amount, and FIG.
The figures are front sectional views of the venous pressure interlocking element, Figures 4 and 5.
The figure is a graph illustrating a measurement calculation method using the device of the present invention. 1 - dialyzer, 2 - blood side circuit, 3 - dialysate side circuit, 5 - blood pump, 6 - bubble separation trap,
8, 22 - Throttle valve for adjusting filtration pressure, 11 - Bypass path, 12 - Cylinder for measuring ultrafiltration rate, 18 - Pulse motor, 20 - Central controller, 21 - Venous pressure interlocking element, P ₁ , P ₂ , P ₃ ~ Liquid pressure sensor, V ₁ , V ₂ ,
V ₃ ~ Shutoff valve.

Claims (1)

[Claims] 1 A dialyzer in which one chamber separated by a dialysis membrane is connected to the blood side circuit and the other chamber is connected to the dialysate side circuit, and the dialysate side circuit is connected to the upstream and downstream circuits of the dialyzer. A bypass path having first and second shutoff valves provided, a third shutoff valve that communicates the upstream and downstream sides of the two shutoff valves, and a dialysate side circuit that connects the upstream and downstream sides of the dialyzer. each liquid pressure sensor that detects liquid pressure, an ultrafiltration rate measuring means provided downstream of the dialyzer in the dialysate side circuit, and a blood pump provided in the upstream circuit of the dialyzer in the blood side circuit; , a fluid pressure sensor that detects fluid pressure on the upstream side of the dialyzer in the blood side circuit, and a central controller controls opening and closing of each of the shutoff valves based on input signals from each of the fluid pressure sensors. In a dialysis circuit that alternately repeats water velocity measurement and water removal to drive and control the ultrafiltration amount measuring means, the ultrafiltration amount measuring means is connected to one side of the cylinder through a flexible compartment material such as a diaphragm. A volume measuring chamber is configured which communicates with the isolated blood side circuit, and the flexible part of the volume measuring chamber and the piston inserted in the cylinder from the other side in an airtight manner so as to be freely retractable and retractable are connected airtightly through a non-transpiration fluid. A water removal amount specifying control device characterized in that the device is connected to each other and has a structure in which a relative variable of a capacity measuring chamber is detected based on a variable of the amount of protrusion and retraction of the piston.