JPH0636826Y2 - Hemodialysis machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a hemodialysis device having a function of controlling an ultrafiltration amount in a device using a dialysis technique such as an artificial kidney.

"Prior Art" A conventional hemodialysis apparatus will be described with reference to FIG.

Blood is given to the blood tube 1 from the patient's artery, sucked by the blood pump 2 and passed through the chamber 3 to the dialyzer 4.
Is supplied to. This blood comes into contact with the dialysate through the membrane in the dialyzer 4, and water and waste products in the blood move to the dialysate side. The blood removed by the dialyzer 4 is returned from the blood tube 7 to the patient's vein via the chamber 5.

On the other hand, the dialysate supplied from the dialysate supply unit 8 is supplied to the dialyzer 4 through the inlet line through the constant flow valve 9, the temperature controller 10, and the inlet valve 11 in this order. The dialysate which has taken in water and waste products from the blood in the dialyzer 4 is discharged to the drain 15 through the outlet line 13 and the outlet valve 14. A flow path including the bypass valve 16 is bypassed between the inlet line on the upstream side of the inlet valve 11 and the outlet line on the downstream side of the outlet valve 14. The bypass valve 16 is normally closed.

A pressure sensor 23 is provided in the chamber 5 to detect the pressure on the blood circuit side. In addition, the exit line near the dialyzer 4
A UF pump 17 is connected to 13.

The TMP control unit 24 takes in the data of the pressure sensors 23 and 25 and is TMP which is the differential pressure PQ between the blood circuit side pressure P and the dialysate side pressure Q.
(TRANS MEMBRANES PRESSURE) is calculated and compared with a control value of TMP corresponding to a preset ultrafiltration amount, and the negative pressure pump 50 of the outlet line 13 is controlled so as to eliminate the deviation. That is, first, in the TMP control value measurement mode, the inlet valve 11 and the outlet valve 14 are closed, the bypass valve 16 is opened, and the dialysate circuit centering on the dialyzer 4 is independent. During this period, the UF pump 17 is operated and the dialysate is sucked at a flow rate equal to the ultrafiltration flow rate set by the setting switch 21. Then, the pressure of the communicated dialysate circuit gradually begins to drop. When the pressures equilibrate, the pressure in the dialysate circuit will be constant.

During suction by the UF pump 17, the pressure value P detected by the pressure sensor 23 and the pressure Q of the dialysate detected by the pressure sensor 25.
Is taken into the TMP control unit 24, and the differential pressure PQ between P and Q, that is, TMP is sequentially calculated. The TMP after a predetermined time, for example, 5 minutes, is stored in the memory of the TMP control unit 24 as the control set value TMPO.

Next, in the dialysis mode, the inlet valve 11 and the outlet valve 14 are opened, the bypass valve 16 is closed, the UF pump 17 is stopped, and the dialyzer 4
The dialysate is distributed to. At the same time, the detection value of each pressure sensor is taken in by the TMP control unit 24, and TMP is calculated as before. This calculated TMP is compared with the previously stored control value TMPO of TMP, and the negative pressure pump 50 is controlled so as to eliminate the deviation. In this mode, the negative pressure pump 50 is controlled so as to maintain the measured TMPO of the TMP control value, that is, the differential pressure that gives the set ultrafiltration flow rate, and the ultrafiltration is performed for a predetermined time (in combination with the measurement mode, For example, 30 minutes). Thereafter, the TMP control value measurement mode and the dialysis mode are alternately and periodically performed.

"Problems to be Solved by the Invention" a) The dialyser 4 has different dialysate-side pressure loss (pressure loss that occurs when the dialysate is poured) depending on the manufacturer and type.
Specifically, it has a width of about 10-25 mmHg when flowing at 500 ml / min.

In the TMP measurement mode, the measurement is performed in the state where the dialysate is not flowing, and in the dialysis mode, the dialysate is flowed and controlled by the TMP measured in the TMP measurement mode. Therefore, the pressure loss causes an error. Particularly recently, a dialyzer with an ultrafiltration capacity (a dialyzer that removes 1 ml of water when 1 mmHg of TMP is added for 1 hour is called ultrafiltration capacity 1, which is 3-7 for a normal dialyzer) exceeds 10. The TMP for obtaining the required ultrafiltration flow rate UFR is lower than that of conventional dialyzers when dialysis is performed using this, and the pressure loss in the dialyzer causes a control error (removal amount of water removal). The difference between the displayed value and the amount of water actually removed from the blood circuit side) is now greatly affected.

b) Ultrafiltration flow rate UF by setting switch 21 in measurement mode
Although R is set, the control error tends to increase as the set amount increases. This was because the control error increased with the value of TMP generated as a result of being sucked by the ultrafiltration flow rate UFR set in the TMP measurement mode as a parameter. This is because even with the same set amount, the control error was different due to the difference in the dialyzer (due to the setting switch).

An object of the present invention is to provide a hemodialysis device in which the control error is minimized.

"Means for solving the problem" In this invention, a new pressure sensor is provided in the inlet line to the dialyzer, and the detection value of the outlet side pressure sensor and the detection of the inlet side pressure sensor which are related to the dialysate side pressure are detected. Set value ratio TM
It is calculated based on the P control value, and the TMP during dialysis is obtained from the ratio and the detection values of the pressure sensors on the outlet side and the inlet side.

For example, dialysate pressure on the inlet side is Q1, dialysate pressure on the outlet side is Q.
2, and the set TMP control value is TMPO, the ratio of Q1 and Q2 involved in the dialysate side pressure is calculated by the following equation.

K = (− 0.003) × TMPO + 0.5 From this ratio and Q1 and Q2, the pressure on the dialysate side during dialysis is calculated by the following equation.

 Q ′ = K × Q1 + (1-K) × Q2 The calculated value Q ′ is used to calculate the TMP during dialysis.

As described above, according to the present invention, Q1, Q2, which are related to the dialysate-side pressure Q ′ during dialysis, based on the set TMPO control value.
The ratio (ratio) of is changed, and correct control is possible without being affected by pressure loss.

[Embodiment] An embodiment of the present invention will be described with reference to FIG. The same parts as those in FIG. 6 are designated by the same reference numerals, and duplicate description will be omitted.

In this example, a pressure sensor 26 having the same characteristics as the pressure sensor 25 is attached to the inlet line 12 between the inlet valve 11 and the dialyzer 4. Thus, by detecting not only the pressure on the downstream side of the dialyzer 4 (pressure sensor 25) but also the pressure on the upstream side (pressure sensor 26), the control error due to the difference in the dialyzer is made as small as possible. , TMP is intended to reduce the control error due to the difference.

The control of this device will be described with reference to the flowchart of FIG.

a) TMP control value measurement mode The inlet valve 11 and the outlet valve 14 are closed, the bypass valve 16 is opened, and the UF pump 17 is sucked at a speed corresponding to the set value of the ultrafiltration amount (step SO). During suction by the UF pump 17, the value P detected by the pressure sensor 23 on the blood circuit side, the value Q1 detected by the pressure sensor 26 on the dialysate side, and the value Q2 detected by the pressure sensor 25 are Sequentially taken into the TMP control unit 24, Is calculated (step 1).

on the other hand, Whether or not the value of is stable is determined, and if it is considered to be stable, the process proceeds to the next step (step S2).

The TMP control value at this time is stored in the memory in the TMP control unit 24 as TMPO (mmHg) (step S3).

Perform the following constant calculation.

K = (− 0.003) × TMPO + 0.5 (limited to K ≧ 0) When TMPO exceeds 166 mmHg, the value of K becomes negative, but in this case, K = 0 is controlled (step S4).

b) Dialysis mode The valves 11, 14, 16 are switched (step S5), and the dialysate is circulated in the dialyzer 4, and at the same time, the data of the pressure sensors P, Q1, Q2 are taken into the TMP controller 24. (Step S6),
The following operations are performed.

Q ′ = K × Q1 + (1-K) × Q2 ... Step S7 TMP ′ = PQ ′ ………… Step S8 The TMPO fetched earlier is compared with the value of TMP ′ of the operation result (Step S9), If TMPO> TMP '(step S
10) Raise the voltage so that the negative pressure pump 50 is rotated a lot,
Conversely, if TMPO <TMP '(step S11), negative pressure pump 50
The control is added to lower the voltage to reduce the rotation of. When TMPO = TMP '(step S12) Negative pressure pump 50
The voltage retains its previous state so that the rotation of is not changed. As a result, TMPO is controlled to become TMP '.

After that, the measurement mode and the dialysis mode are alternately and periodically performed.

Next, the reason for using the expression of K in step S ₄ will be described.

Average value using values Q1 and Q2 detected by pressure sensors 26 and 25, respectively When T is controlled as the measured TMP, the error tends to increase in the direction of excessive water removal as the TMP value increases, as shown in FIG.

In order to reduce this error, pressure sensors 26 and 25
The control ratio (distribution ratio) of the detected values Q1 and Q2 is TMP
I thought it would be better to change it with O as a parameter.
Figure 4 shows the relationship between TMP and distribution ratio based on Figure 3. If TMPO approaches zero, Q1: Q2 ＝ 0.5:
When it becomes 0.5 and TMPO becomes 166, Q1: Q2≈0: 1. The equation for this relationship is K = (− 0.003) × TMPO + 0.5.

However, although TMPO ≤ 166 in Fig. 4, the value is below Q2, it cannot be considered that the proper control value is out of the values of the two pressure sensors 26 and 25. It is considered to be a thing. Also TM
When PO exceeds 166, control is performed by the value of Q2 (K = 0).

The control result using such K is as shown in Fig. 5, and the error fluctuates up and down around 0 g / min, and the tendency of Fig. 3 that the error increases as TMP increases disappears. .

"Effects of the device" Up to now, the control error has been large depending on the type of dialyzer, but with this device we were able to reduce the error variation due to the difference in the dialyzer. In other words, by measuring the pressure loss on the dialysate side, which is unique to the dialyzer, and controlling the TMP under the same conditions in any dialyzer with a negative pressure pump, the disadvantages of this system are eliminated. I was able to cover it and improve the accuracy. Further, by using the two sensors on the dialysate side and controlling by the above calculation, the control error could be reduced to a lower TMP value than a higher TMP value.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing an operation example of FIG. 1, and FIG. 3 is a TMP of a conventional device.
Of the distribution ratio K
Fig. 5 is a graph showing an example of the relationship between TMP and control error of this device, and Fig. 6 is a block diagram showing a conventional hemodialysis device.

Claims (1)

[Scope of utility model registration request] 1. A dialyzer, a blood flow path and a dialysate flow path connected to the dialyzer, pressure detection means for detecting the pressure in each flow path, and an outlet side and an inlet side of the dialyzer. The dialysate flow path is simultaneously opened and closed, and when the dialysate is opened, hemodialysis is performed, and when closed, a flow path blocking means that forms a closed flow path including the dialyzer and the dialysate side pressure detection means, and the closed flow. TMP (transmembrane pressure) as the difference between the detection value of both the blood side pressure detection means and the dialysate side pressure detection means connected to the pump that draws in a preset flow rate liquid separator when the closed flow path is formed. While calculating and storing the TMP at the time of pump suction as the TMP control value, the TMP when the dialysis fluid flow path is opened by the flow path blocking means becomes the TMP control value. Blood equipped with a TMP control unit for controlling the pressure of the flow path In the analyzer, as the dialysate-side pressure detecting means, pressure sensors are provided on the outlet side and the inlet side of the dialyzer, respectively, and the detected values of the outlet-side pressure sensor and the inlet-side pressure sensor that are involved in the dialysate-side pressure. Is calculated based on the TMP control value, and the dialysate side pressure during dialysis is calculated from the ratio and the detection values of the outlet side and inlet side pressure sensors, and the calculated value is used. A hemodialysis device characterized by calculating TMP during dialysis.