JPH0112501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for adjusting the amount of ultrafiltration in a hemodialysis machine in which blood flows through one side of a dialysis membrane and dialysate flows through the other side.

In hemodialysis, water in the blood or water in the dialysate passes through a dialysis membrane through so-called ultrafiltration. Generally, patients undergoing hemodialysis have an increased amount of water in their blood that is greater than that of a normal person, and hemodialysis filters out waste products from the blood.
The water is ultrafiltered to maintain the normal water content of the blood. That is, by making the pressure on the blood side higher than the pressure on the dialysate side, water is ultrafiltered from the blood into the dialysate. The ultrafiltration rate is determined by the pressure difference on both sides of the dialysis membrane (generally called trans membrane pressure).
Abbreviated as TMP. ), the ultrafiltration rate is adjusted by adjusting the TMP. Methods for applying TMP include a method of pressurizing the blood side and a method of applying negative pressure to the dialysate side, and the former method is generally adopted. The reason is that the flow rate of dialysate is 500% in terms of dialysis efficiency, etc.
ml/min, but when the latter method is adopted, when the dialysate pressure is changed to adjust the ultrafiltration amount, the flow rate changes accordingly, and it is difficult to adjust the pressure and flow rate to the desired value. This is because it is difficult to set the value to . Therefore, a method of pressurizing the blood side is generally adopted, but pressurizing the blood causes damage to blood cell components, which is not preferable.

The present invention has been made to solve the problems of the prior art.
An object of the present invention is to provide an ultrafiltration amount adjusting device that can adjust the amount of ultrafiltration.

The device of the present invention includes a pressure control mechanism that controls dialysate pressure in a dialyzer to a negative pressure, and a constant pressure differential valve provided in an inflow circuit that supplies dialysate to the dialyzer. The constant differential pressure valve referred to herein is a valve that has a flow rate regulating valve and functions to always maintain a constant pressure difference between its inlet and outlet.

FIG. 1 is a system diagram showing an embodiment of the ultrafiltration rate adjusting device of the present invention. The dialyzer 1 has a built-in dialysis membrane, and allows blood to flow through one side of the dialysis membrane and dialysate to flow through the other side, thereby performing material exchange between the blood and the dialysate. Dialysate is supplied to the dialyzer through an inflow circuit 2 and discharged through an outflow circuit 3. Also,
Blood is extracted from the human body, supplied to the dialyzer through circuit 4, and discharged through circuit 5 to be returned to the human body. The dialysate outflow circuit 3 is provided with a pressure control mechanism that controls the dialysate pressure within the dialyzer to negative pressure. The pressure control mechanism includes a negative pressure pump 7, a pressure detector 8, and a control device 9. When the negative pressure pump 7 is operated, its suction force creates a negative pressure in the circuit 3 and the dialyzer. This negative pressure is detected by a pressure detector 8, converted into an electrical signal, sent to a control device 9, and compared with a preset value. If the detected pressure is lower than the set negative pressure degree, the amount of current applied to the pump motor is increased, and if it is higher, the amount of current is decreased to make it equal to the set value.

The dialysate inflow circuit 2 is provided with a constant differential pressure valve 10 . As mentioned above, the constant differential pressure valve is a valve that functions to always keep constant the difference ΔP=P ₁ −P ₂ between the pressure P ₁ at the inlet and the pressure P ₂ at the outlet of the flow rate regulating valve. That is, even if P ₁ or P ₂ changes, ΔP is always kept constant, so the flow rate set by the valve is kept constant. FIG. 2 is a sectional view showing an example of a constant differential pressure valve, in which the constant differential pressure mechanism section 11
Only one part is shown in detail in a sectional view, and other parts are shown in a simplified manner. The constant differential pressure valve is mainly composed of a constant differential pressure mechanism section 11 and a flow rate adjustment section 12. The constant differential pressure mechanism section 11 is divided into an upper chamber 18 and a lower chamber 19 by a diaphragm 13, and a spring 15 is attached to the upper chamber so as to push the diaphragm 13 from one side. Further, a valve 14 is provided at the entrance of the lower chamber 19, and the degree of opening changes in conjunction with the diaphragm. 18 is in communication with the flow rate adjustment section outlet via a circuit 20.
As the flow rate adjustment section 12, a device such as a needle valve that can continuously change the flow rate is used. The dialysate enters from the constant differential pressure mechanism inlet 16 at a pressure of P ₀ ,
It enters the lower chamber 19 through the valve 14. The pressure in the lower chamber is
P ₁ (P ₁ <P ₀ ), and the diaphragm 13 is pushed from below with a pressure of P ₁ . The liquid is then supplied to the flow rate adjustment section 12 through the outlet 17, and P ₂
It exits from the flow rate adjustment section at a pressure of (P ₂ < P ₁ ) and is supplied to the dialyzer. Since the upper chamber 18 of the constant differential pressure mechanism is in communication with the outlet of the flow rate adjustment section, the pressure is equal to P ₂ , and the diaphragm is pushed from the upper side by the pressure P ₂ and the force of the spring 15, and from the lower side. Balanced with power.

Now, in order to adjust the ultrafiltration rate, if we change the pressure inside the dialyzer to P _{2 -} α, then the upper chamber 1
The pressure at point 8 also becomes P ₂ −α, and the force pushing the diaphragm also decreases by α, so the diaphragm is pushed upward. As a result, the valve 14 also moves upward, so the degree of opening decreases and P ₁ decreases to P ₁ −α. In other words, the pressure of the dialysate at the inlet of the flow rate adjustment section is P ₁ - α, and the pressure at the outlet is P ₂ - α, so the differential pressure △P = (P ₁ - α) - (P ₂ - α )=P ₁ −
P ₂ and remains constant. As a result, the flow rate set at the optimum level by the flow rate adjustment section is always maintained constant even if the pressure fluctuates.

As mentioned above, by installing a constant differential pressure valve, the flow rate can always be kept constant even if the pressure is changed, so TMP during dialysis can be adjusted freely to create an ultrafiltration program suitable for each patient. It can be changed. It should be noted that the above-described embodiments are merely illustrative, and a constant differential pressure valve or pressure control mechanism composed of other mechanisms may also be employed.

Further, this ultrafiltration rate adjusting device includes an ultrafiltration rate measuring mechanism 21. The ultrafiltration rate measurement mechanism 21 includes a flowmeter 2 provided in the dialysate inflow circuit 2.
2. Flowmeter 23 provided in the dialysate outflow circuit 3;
and a calculation unit 24 that calculates the ultrafiltration amount by comparing the integrated values of these flowmeters.
The calculation unit 24 is connected to the pressure control device 9 using an electric circuit.
The ultrafiltration program is connected to the ultrafiltration system, and is configured to compare the measured ultrafiltration amount with a preset ultrafiltration amount and adjust the TMP, so that the set ultrafiltration program is faithfully executed. There is. When the ultrafiltration amount measuring mechanism is provided in this way, the pressure will be adjusted frequently, but since a constant differential pressure valve is provided, a stable flow rate can always be maintained. On the other hand, if a simple flow rate adjustment valve is installed instead of a constant differential pressure valve, changing the pressure will change the flow rate, and if you try to restore the flow rate to the original value, the pressure will change, creating a vicious cycle. , it is difficult to perform proper dialysis.

In addition, the ultrafiltration rate measuring mechanism and the pressure control mechanism are
It is not necessarily necessary to be electrically connected, and the pressure may be controlled manually while viewing the displayed ultrafiltration amount.

As described above, the ultrafiltration rate adjusting device of the present invention is equipped with a constant differential pressure valve, so that the TMP can be freely changed without changing the flow rate, so the ultrafiltration rate can be adjusted easily and reliably. It can be adjusted to Furthermore, since TMP is controlled by applying negative pressure to the dialysate, hemodialysis can be performed extremely safely without fear of damaging the blood.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an embodiment of the ultrafiltration rate adjusting device of the present invention, and FIG. 2 is a sectional view of an example of a constant differential pressure valve. DESCRIPTION OF SYMBOLS 1... Dialyzer, 2... Dialysate inflow circuit, 3... Dialysate outflow circuit, 10... Constant differential pressure valve, 11... Constant differential pressure mechanism part, 12... Flow rate adjustment part, 21... Ultrafiltration rate measurement mechanism.

Claims (1)

[Claims] 1 In a hemodialysis device in which blood flows through one side of a dialysis membrane, dialysate flows through the other side, and substance exchange is performed between the blood and dialysate by maintaining the pressure on the dialysate side at negative pressure. , an inflow circuit that supplies dialysate to the dialyzer is equipped with a constant differential pressure valve to keep the flow rate constant, and an outflow circuit that discharges dialysate from the dialyzer is equipped with a pressure detector and a negative pressure pump; Flowmeters are installed in each of the flowmeters, and a calculation unit and ultrafiltration rate setting means are provided for calculating the ultrafiltration rate by comparing the detected values of these flowmeters, and the ultrafiltration rate setting means is configured to set the ultrafiltration rate and a preset limit. The pressure detected by the pressure detector is controlled by comparing the amount of ultrafiltration with the amount of ultrafiltration and changing the amount of current applied to the negative pressure pump in order to achieve a preset amount of ultrafiltration. Features: Ultrafiltration rate adjustment device.