JP2769514B2 - Water removal control device for hemodialysis machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hemodialysis apparatus used for treating patients with renal failure, and more particularly to a water removal amount control device for controlling a water removal amount.

"Conventional technology" The ECUM method is a typical example of the water removal control that is currently performed. The ECUM method is performed as shown in FIG. That is, the blood from the patient 11 is supplied to the dialyzer 13 by the blood pump 12, and the blood from which water and waste products have been removed by the dialyzer 13 is returned to the patient 11 via the drip chamber 14. On the other hand, the dialysate is supplied to the dialyzer 13 from the liquid supply flow path 15 via the first on-off valve 16, and the dialysate from the dialyzer 13 is supplied from the drainage flow path 17 via the second on-off valve 18, The liquid is drawn by the pump 19 and drained. A branch 21 is connected between the inlet of the first on-off valve 16 and the outlet of the second on-off valve 18, and a third on-off valve 22 is inserted into the branch 21.

In the measurement mode, the first on-off valve 16 and the second on-off valve 18 are closed, the third on-off valve 22 is opened, and the water removal amount measuring pump 23 provided between the dialyzer 13 and the second on-off valve 18 is opened. Pulled,
The dialysate-side pressure Q of the dialyzer 13 at a predetermined water removal amount is measured by the pressure measuring device 24. The relationship between the difference PQ between the dialysate-side pressure Q and the blood-side pressure P (TMP: permeable membrane pressure) and the water removal amount is obtained.

In the dialysis mode, the first opening / closing valve 16 and the second opening / closing valve 18 are opened, the third opening / closing valve 22 is closed, and the dialysate is allowed to flow through the dialyzer 13 so that the TMP at this time becomes the measured TMP. I do.

There is also a system in which two reciprocating metering pumps are provided to make the inflow and outflow of dialysate to the dialyzer equal, and a third water removal pump is used to forcibly remove the amount of fluid equivalent to the amount of water removed. A typical example of this system is shown in FIG. That is, the reciprocating metering pumps 25 and 26 are provided, and these are interlocked. When the dialysate is supplied from the measuring chamber 25b of the reciprocating metering pump 25 to the dialyzer 13, the dialysate is dispensed from the dialyser 13 to the metering pump 25
Of the dialysate to be supplied to the measuring chamber 26a of the metering pump 26, and the dialysate taken into the measuring chamber 26b is drained. Conversely, when the dialysate in the metering chamber 26a of the metering pump 26 is supplied to the dialyzer 13, the dialysate from the dialyzer 13 is taken into the metering chamber 26b, and the metering pump 25 takes in the dialysate to be supplied to the metering chamber 25b. Then, the dialysate in the measuring chamber 25a is drained.

The dialysate discharged from the dialyzer 13 is also drawn by the water removal pump 27, and the amount of dialysate drawn by the water removal pump 27 is determined by the amount supplied to the dialyzer 13 by the metering pump 25 or 26 and the dialyser. The difference from the amount subtracted from 13.

By using the four measuring chambers in this way, the problem that the flow of the dialysate due to the reciprocating motion of the metering pump becomes discontinuous is solved.

[Problems to be Solved by the Invention] In the conventional system shown in FIG. 6, the amount of water removed is not measured except in the measurement mode, and the dialyzer is used when the dialysate is flowing and when it is stopped. The pressure inside the 13 is different and causes an error. With recent dialyzer, the amount of water removal per TMP is about 5 times as large as the conventional one. The error of small TMP, which was not a problem in the past, caused a large error in water removal and became a clinical problem. ing.

On the other hand, the conventional method shown in FIG. 7 has a drawback that errors between the measuring chambers need to be accumulated and that the measuring chambers need to be frequently switched, and errors occur due to the switching timing. Further, calcium carbonate is contained in the dialysate, and low-molecular-weight proteins are contained in the downstream fluid of the dialyzer. Therefore, the malfunction of the valve and the change in the volume of the pump due to these components cannot be ignored.

According to the present invention, dialysate is supplied to the dialyzer by the first rotary metering pump, and dialysate from the dialyzer is drawn by the second rotary metering pump. In the calibration mode, a closed path is formed including the first rotary metering pump and the second rotary metering pump. That is, the first rotary metering pump and the second
The flow path between the rotary metering pumps is such that no other liquid flows into and out of the dialysate. The flow rate difference between the first rotary metering pump and the second rotary metering pump is detected in a state where the closed path is formed, and the first rotary metering pump and the second rotary metering pump are detected according to the flow rate difference detection output. The flow difference with the pump is calibrated to zero. In the dialysis mode, the difference between the amount of dialysate flowing into the dialyzer and the amount of dialysate flowing out of the dialyzer, that is, the set water removal amount is drawn by the third rotary metering pump. Alternatively, the third rotary metering pump is omitted, and the second rotary metering pump is rotated more than the first rotary metering pump by the amount corresponding to the set water removal amount.

By providing the calibration mode in this manner, the flow rates of the first rotary metering pump and the second rotary metering pump can be made exactly equal, and the dialysate can be supplied continuously, and It is not necessary to open and close frequently.

"Embodiment" FIG. 1 shows an embodiment of the present invention, and portions corresponding to FIG. 6 are denoted by the same reference numerals. In the present invention, a first rotary metering pump 31 is provided in the liquid supply channel 15 and a second rotary metering pump 32 is provided in the drain channel 17. A bypass coupler 33 is provided as a means for forming a closed path including the first rotary metering pump 31 and the second rotary metering pump 32, and connects the liquid supply channel 15 and the drain channel 17 removed from the dialyzer 13. The connection can be made through the bypass coupler 33. In the state connected to the bypass coupler 33, the first
The flow path between the rotary metering pump 31 and the second rotary metering pump 32 is a closed channel from which liquid does not flow out of anything other than the pump.

As means for detecting the flow rate difference between the first rotary metering pump 31 and the second rotary metering pump 32, the closed passage, in this example, the drainage flow path 17 on the upstream side of the second rotary metering pump 32 is provided. A pressure measuring device 34 for measuring the hydraulic pressure is provided. A third rotary metering pump 35 is branched and connected to the drainage channel 17 on the upstream side of the second rotary metering pump 32.

This device has two modes. The first is a calibration mode, and the second is a dialysis mode. In the calibration mode, the liquid supply channel 15 and the drain channel 17 are disconnected from the dialyzer 13 and connected to the bypass coupler 33. That is, the closed path is formed. In this state, the first rotary metering pump 31 and the second rotary metering pump 32 are operated at a speed of, for example, 500 ml / min. At this time, the output of the pressure measuring device 34 is monitored. If this pressure shows a tendency to increase, the flow rate of the first rotary metering pump 31 becomes the second flow rate.
This indicates that the flow rate is higher than the flow rate of the rotary metering pump 32. If the pressure decreases, the flow rate of the first rotary metering pump 31 is lower than the flow rate of the second rotary metering pump 32. Accordingly, the pressure measuring device 34 detects the flow rate difference between the first rotary metering pump 31 and the second rotary metering pump 32. The number of rotations of the first rotary metering pump 31 or the second rotary metering pump 32 is controlled so that this flow rate difference, that is, the change in the measurement pressure of the pressure measuring device 34 is eliminated. Thus, the rotation speeds of the first rotary metering pump 31 and the second rotary metering pump 32 in the dialysis mode are determined.

Next, in the dialysis mode, the liquid supply flow path 15 and the drainage flow path
17 is removed from the bypass coupler 33 and connected to the dialyzer 13 to start feeding the liquid to the dialyzer 13. At this time, the first rotary metering pump 31 and the second rotary metering pump 32 maintain the rotation speed determined in the calibration mode. The third rotary metering pump 35 operates at a rotation speed corresponding to the amount set by the water removal rate setting device. In this way, the first rotary metering pump 31 and the second rotary metering pump 32 allow the same flow rate of liquid to flow into and out of the dialyzer 13, and the third rotary metering pump 35 drains an amount corresponding to the amount of water removed. Be taken. Rotary metering pumps have quantitative characteristics that change over time.
By compensating for this drawback, it is possible to realize more accurate water removal control than a reciprocating pump.

Means for calibrating a closed path in the calibration mode include:
It is also possible to stop the flow of blood in the blood flow path and prevent water or the like from the blood from flowing into the dialysate. For example, as shown in FIG. 2, in the calibration mode, the blood tube is closed with forceps 36 and 37 at a position as close to the dialyzer 13 as possible,
And the blood pump 12 is stopped. Clamping of the blood tube by the forceps 36, 37 can be performed electrically using a solenoid or the like.

2, the third rotary metering pump 35 is omitted, and in the dialysis mode, the second rotary metering pump 32 is omitted.
Is controlled by adding the set water removal amount to the rotation speed obtained in the calibration mode.

As means for detecting the flow rate difference between the first rotary metering pump 31 and the second rotary metering pump 32, as shown in FIG. 3, a closed path in the calibration mode, for example, the downstream side of the first rotary metering pump 31 Variable capacity measurement chamber in communication with the liquid supply path 15
38 may be provided, and the change amount of the variable portion of the measurement chamber 38 may be read by means 39 for reading. As the measurement chamber 38 having a variable capacity, a piston having a small coefficient of friction, a bellows cylinder, or the like can be used. As the means 39 for reading the change amount, a linear motion type variable resistor can be used. When the calibration mode is over, the dialysis mode blocks the piping to the variable volume measurement chamber 38.

Further, as a means for detecting the flow rate difference in the calibration mode, as shown in FIG. 4, an opening dispenser 41 such as a mespipet or the like is communicated with a closed passage, for example, a liquid supply passage 15 downstream of the first rotary metering pump 31. May be provided to read the fluctuation of the liquid level in the open container 41.

In the calibration mode, the pump rotation speed of the first rotary metering pump 31 or the second rotary metering pump 32 is controlled so that the flow rate difference becomes zero, but this control may be performed via a mechanical transmission. For example, as shown in FIG. 5, a first rotary metering pump 31 is directly controlled by a motor 42 and a second rotary metering pump 32 is controlled by a motor 42 via a mechanical transmission 43. In the calibration mode, the pressure
The mechanical transmission 43 is controlled according to the fluctuation of the measured pressure to make the flow difference between the first rotary metering pump 31 and the second rotary metering pump 32 zero. As the mechanical transmission 43, an automatic transmission that can change the position of the belt can be used.

In the above description, a Moino pump is used as a rotary metering pump, and a pulse motor can be used as a drive source of the pump. In addition, the third rotary metering pump 35
The dialysate may be provided to the dialyzer 13 by reducing the amount of the dialysate by an amount corresponding to the amount of water removed by providing the dialyser 13 at the inflow side of the dial 13. A metering mechanism using a cup may be provided on the discharge side of the third rotary metering pump 35 to measure the amount of water removed, and correct the rotation speed of the third rotary metering pump 35.

[Effect of the Invention] The water removal capacity of a dialyzer has been increased, and the control accuracy of the conventional water removal amount control method is poor, and it cannot be practically used for such a dialyzer. The present invention can solve this problem and can realize a water removal amount control device that can sufficiently cope with a high water removal capacity membrane.

Compared to using a reciprocating metering pump with a measuring chamber, there is no need to open and close the valve frequently, and by inserting the calibration mode properly, the correct control is always performed without accumulating errors. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment of the present invention, FIG. 3 is a block diagram showing another example of the flow difference detecting means, and FIG. Is a block diagram showing still another example, FIG. 5 is a block diagram showing another example of the means for controlling the flow rate difference to zero, FIG. 6 and FIG.
The figures are block diagrams each showing a conventional water removal amount control device.

Claims (6)

(57) [Claims] 1. A blood dialyser for supplying a dialysate to a dialyzer through a liquid supply channel, removing waste from the blood supplied to the dialyzer, and discharging the waste together with the dialysate to a drainage channel. A first rotary metering pump inserted into the liquid supply channel, a second rotary metering pump inserted into the drainage channel, the first rotary metering pump and the second rotary metering pump. Means for forming a closed path including the flow path; flow rate difference detecting means for detecting a flow rate difference between the first rotary metering pump and the second rotary metering pump in a state where the closed path is formed; Means for reducing the flow rate difference between the first rotary metering pump and the second rotary metering pump to zero based on the detection output of (1). 2. The blood according to claim 1, wherein said means for forming said closed path is means for removing said liquid supply flow path and said drainage flow path from said dialyzer and connecting them to a bypass coupler. Water removal control device for dialysis machine. 3. The apparatus according to claim 1, wherein the means constituting the closed passage is means for stopping the flow of blood flowing into and out of the dialyzer. 4. The apparatus according to claim 1, wherein said flow rate difference detecting means is a pressure measuring device for measuring a liquid pressure in said closed passage between said first rotary metering pump and said second rotary metering pump. A device for controlling the amount of water removed from a hemodialysis apparatus according to claim 1. 5. A flow rate difference detecting means is driven by a variable capacity measuring chamber connected to the closed path between the first rotary metering pump and the second rotary metering pump, and a variable section of the measuring chamber. 2. The apparatus according to claim 1, further comprising means for reading the amount of change to be made. 6. An open container connected to the closed circuit between the first rotary metering pump and the second rotary metering pump, and a means for reading a liquid level of the open container. 2. The apparatus for controlling the amount of water removed in a hemodialysis apparatus according to claim 1, wherein