JP2003062066A - Hemodialysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hemodialysis device which itself detects the change in the amount of blood circulation water, especially the decrease of blood pressure accurately, precisely and swiftly without any influences of pulse flow by a blood pump or changes of a blood pump speed and without another special device. SOLUTION: In the hemodialysis device which has a blood pump composed of hemodialysis elements dialyzing blood between a blood channel and a dialytic solution channel and a tube pump set in the upper side of the hemodialysis elements in the blood channel, and is equipped with a detecting differential pressure means for detecting the differential pressure between the pressures at the upper side and the lower side of the hemodialysis elements in the blood channel and in which the differential pressure signal is output only when a roller in the blood pump reaches the previously fixed point on its rotational direction, it is characterized that the differential pressure signal is revised and carried out an operation by the correlative formula between the blood pump speed Qb memorized by the memorial element within the hemodialysis device and the differential pressure value ΔP when the rotation speed of the blood pump changes during hemodialysis and the revised differential pressure is output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hemodialysis apparatus, and more particularly to a hemodialysis apparatus capable of accurately measuring changes in circulating blood volume during hemodialysis, particularly changes in blood pressure.

[0002]

2. Description of the Related Art Hemodialysis devices have been widely put into practical use, and a typical one is, for example, Japanese Patent Publication No. 56-82.
Those described in Japanese Patent Publication No. 6-25382 and Japanese Patent Publication No. 61-25382 are known. In a hemodialysis device, a hemodialysis filter (dialyzer) with a dialysis membrane is used as a hemodialysis element for performing hemodialysis. From the blood sent from the arterial side of the patient, the hemodialysis filter is used in the hemodialysis filter. Urine components and the like are removed through the dialysis membrane between the blood channel side and the dialysate channel side, and excess water is removed,
Blood after dialysis is returned to the vein side of the patient. A blood pump, which is a tube pump provided upstream of the hemodialysis filter in the blood flow path, is usually used for sending and circulating blood to and from the patient's body.

By the way, when hemodialysis is continuously performed, the blood pressure of the patient may drop sharply. When the blood pressure drops, it must be detected promptly and appropriate measures taken, and after the blood pressure drop, it is usually necessary to keep a close eye on the patient.

The following are known as causes of this decrease in blood pressure. When hemodialysis is performed, water in the blood is removed, and when this is continued for a long time, blood cell component / blood volume (that is, the ratio of solid content in blood, which is usually called Hct [hematocrit]). The value of increases, but this H
ct may suddenly jump. It is known that this sharp rise in Hct corresponds to a sharp drop in blood pressure.

For example, as shown in FIG. 4, Hct gradually increases with the duration of hemodialysis, but Hct may rise more rapidly at some point (increase: FIG. 4).
(A) 101). Corresponding to the sudden increase 101 of Hct, as shown in FIG. 4 (B), the blood pressure sharply decreases (decrease: 102 in FIG. 4 (B)).

When such a rapid rise in Hct or a sudden drop in blood pressure occurs, it is necessary to promptly take appropriate measures such as stopping water removal in hemodialysis, and thereafter it becomes necessary to constantly monitor the patient. . Therefore, either a sharp rise in Hct or a sharp drop in blood pressure must be accurately and quickly detected.

Although a device for measuring the change in Hct is known, this device needs to measure the blood while sampling it, which requires a measuring device and an element different from the hemodialysis device. Since the measurement is performed while sampling, a time delay occurs in the detection of the sudden increase in Hct,
Difficult to detect quickly.

On the other hand, the blood pressure can be measured with a commercially available blood pressure monitor, but it usually takes time to measure the blood pressure value, so that it is also difficult to detect a rapid decrease in blood pressure. . In addition, because one arm is clamped and restrained by a measurement band (cuff) for blood pressure measurement, and the other arm is restrained for hemodialysis, both arms are restrained, and the patient is restrained. It is very unpopular with the patient because it causes discomfort.

As a method for continuously detecting the decrease in blood pressure that occurs during hemodialysis without using an Hct measuring device or a general sphygmomanometer, Japanese Patent Laid-Open No. 2000- 334036 is known.

The hemodialysis apparatus described in Japanese Patent Laid-Open No. 334036/2000 is a hemodialysis element for performing hemodialysis between a blood channel and a dialysate channel that circulate blood between the body of a patient. In a hemodialysis device having a blood pump including a tube pump provided on the upstream side of the hemodialysis element in the blood flow path, a position on the upstream side of the hemodialysis element in the blood flow path and a downstream side of the hemodialysis element Is provided with a differential pressure detecting means for detecting a differential pressure between the position of the blood pump roller and the differential pressure signal detected by the differential pressure detecting means. Output only when you come to.

However, in actual hemodialysis, the rotational speed of the blood pump may be changed during hemodialysis, and the hemodialysis of the blood flow path detected by the hemodialysis device described in Japanese Patent Laid-Open No. 2000-334036. The differential pressure between the upstream position of the element and the downstream position of the hemodialysis element will fluctuate as the speed of the blood pump changes (eg 103 in FIGS. 5A, 5B, 104
Therefore, it may be difficult to accurately detect a decrease in blood pressure.

[0012]

Therefore, the present inventors have found that
Without using Hct measuring device or general blood pressure monitor,
A method of detecting a decrease in blood pressure that occurred during hemodialysis using a hemodialysis machine alone, and a method that was not affected by fluctuations in the differential pressure value even when the blood pump speed fluctuated during hemodialysis were examined.

That is, first, in the hemodialysis apparatus, the blood flow path for circulating blood between the patient's body is
Since the upstream side of the hemodialysis filter is connected to the arterial side of the patient and the downstream side is connected to the venous side of the patient, it was noted that the differential pressure across the hemodialysis filter corresponds to the blood pressure of the patient. In other words, since the blood flow path length before and after the hemodialysis filter is constant unless the conditions are changed, the hemodialysis filter performs the same function as a so-called viscometer with respect to the pressure loss in the blood flow path, and the difference before and after that. Focusing on the fact that the pressure corresponds to the blood pressure of the patient at that time, it was found that if this differential pressure can be measured accurately and accurately, a sharp drop in blood pressure, which is a problem, can also be measured accurately and quickly.

However, by simply providing the differential pressure detecting means before and after the hemodialysis filter in the blood flow path to detect the differential pressure, a tube pump for blood supply provided in the blood flow path is formed. Since a large pulsating flow is generated by the blood pump, the pressure detected by the differential pressure detecting means fluctuates greatly, and the differential pressure to be detected, that is, the differential pressure value corresponding to the blood pressure also fluctuates greatly. Because of this fluctuation, it is actually difficult to accurately read a sharp drop in blood pressure.

A method of dealing with the above-mentioned fluctuations by software, for example, a method of smoothing the fluctuating detection characteristic value by performing a moving average processing is also conceivable. However, the time in software processing for obtaining the moving average is considered. There is a delay, which makes rapid detection difficult.

Further, in actual hemodialysis, the blood pump speed may fluctuate during hemodialysis, and the differential pressure detection means is simply provided before and after the hemodialysis filter in the blood flow path to detect the differential pressure. Only by doing so, the differential pressure fluctuates following the fluctuation of the blood pump speed, and it becomes difficult to accurately read the sharp drop in blood pressure.

Therefore, an object of the present invention is to reduce changes in circulating blood volume, particularly lowering of blood pressure, which occur during continuous hemodialysis with a hemodialysis machine alone without using an Hct measuring device or a general blood pressure monitor. An object of the present invention is to provide a hemodialysis device that can be accurately, accurately, and quickly detected without being affected by fluctuations in pulsating flow and blood pump speed due to the blood pump.

[0018]

In order to solve the above-mentioned problems, a hemodialysis apparatus of the present invention is a hemodialysis apparatus between a blood flow path and a dialysate flow path for circulating blood between the body of a patient. A hemodialysis element for performing, and a blood pump comprising a tube pump provided on the upstream side of the hemodialysis element of the blood flow path, and a position on the upstream side of the hemodialysis element of the blood flow path,
A pressure difference detecting means for detecting a pressure difference between the hemodialysis element and a position on the downstream side is provided, and a signal of the pressure difference detected by the pressure difference detecting means is provided in advance by a roller of the blood pump in the circumferential direction thereof. In a hemodialysis device which is designed to output only when a predetermined fixed position is reached, the differential pressure signal is provided inside the hemodialysis device when the rotational speed of the blood pump changes during hemodialysis. The present invention is characterized in that a correction calculation process is performed by a correlation equation between the blood pump speed Qb and the differential pressure value ΔP stored in the storage element, and the corrected differential pressure value is output.

In the above-mentioned hemodialysis apparatus, the correlation equation between the blood pump speed Qb and the differential pressure value ΔP is determined by the blood pump control means to set the blood pump speed to 2 or more at any time before or during hemodialysis. The differential pressure value at each controlled blood pump speed is operated at a speed and is sent to the hemodialysis machine, and the correlation means is arithmetically processed by the arithmetic means provided inside the hemodialysis machine to be provided inside the hemodialysis machine. It can be stored in the storage element.

Further, the correlation formula between the blood pump speed Qb and the differential pressure value ΔP is calculated by a pseudo test or the like corresponding to actual hemodialysis, and is stored in a storage element provided inside the hemodialysis machine. You can also

The differential pressure detecting means can be constituted by a differential pressure gauge or means having pressure sensors provided on the upstream and downstream sides of the hemodialysis element.

As the constant position for detecting the differential pressure, the position where the influence of the pulsation by the blood pump composed of the tube pump is reduced, that is, one of the plurality of rollers provided in the blood pump is the tube It is preferable to be at an intermediate position from the position where the pressing starts to the position where the pressing ends. Above all, the position where the influence of the pulsating flow due to the blood pump composed of the tube pump is minimized, for example, a certain position is from the position where one roller provided in the blood pump starts pressing the tube to the position where the pressing ends. It is preferably at the midpoint position or immediately before it. The tube pump forming the blood pump may be a pump having a pair of rollers, a pump having three rollers, or a pump having three or more rollers.

Only at the fixed position, the differential pressure detecting means outputs a differential pressure signal corresponding to the blood pressure of the patient. As the means for detecting the fixed position, a means having an optical element or a magnetic element provided on the rotary member for driving the roller orbit of the blood pump and the fixed member facing the rotary member can be used. For example, a structure may be employed in which a magnet is provided on one of the roller revolving drive rotary member of the blood pump and the fixed-side member facing it, and the Hall element is provided on the other.

Although the characteristic of the differential pressure signal corresponding to the blood pressure can be directly read, for example, if a means for calculating and outputting the differential value of the characteristic of the differential pressure signal is incorporated, the blood pressure in question will be a problem. It becomes possible to output the change in the differential pressure corresponding to the sudden drop more accurately and quickly.

The differential pressure signal detected by the differential pressure detecting means is
When the blood pump speed is constant, the accurate blood pressure state can be continuously monitored, but when the rotational speed of the blood pump changes during hemodialysis, the detected differential pressure value changes abruptly. Then, the detected differential pressure value is corrected and calculated by a correlation expression of the blood pump speed Qb and the differential pressure value ΔP stored in the storage element provided inside the hemodialysis apparatus, and the corrected differential pressure value is output. Thus, even when the blood pump speed changes, the fluctuation of the differential pressure value can be made extremely small, and the blood pressure state can be continuously monitored.

In the hemodialysis device according to the present invention as described above, the arteries detected by the differential pressure detection means provided over the upstream and downstream sides of the hemodialysis element during continuous hemodialysis. The differential pressure between the side pressure and the venous side is detected substantially continuously as a value corresponding to the blood pressure of the patient. Then, since the detection of the differential pressure is performed each time at a fixed position where the influence of the pulsation by the blood pump is small, the fluctuation of the differential pressure detected is suppressed to an extremely small value, and the accurate and accurate reading is possible, or It is possible to obtain it as a characteristic that can be differentiated. Further, even when the blood pump speed is changed during hemodialysis, the correction calculation process can suppress the fluctuation of the differential pressure to be extremely small. as a result,
When a sudden drop in the blood pressure of a patient occurs, the drop will be detected accurately and quickly in the initial stage.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a hemodialysis apparatus according to one embodiment of the present invention, and FIGS. 2 and 3 show the blood pump section thereof.

In FIG. 1, reference numeral 1 denotes a blood flow path for circulating blood from the arterial side 2 of the patient to return it to the vein side 3 after hemodialysis. The blood in the blood flow path 1 is quantitatively transferred by a blood pump 4 which is a tube pump, and between the blood flow path 1 and the dialysate flow path 6 in a hemodialysis filter 5 (dialyzer) as a hemodialysis element. Is hemodialyzed through the dialysis membrane 7. The dialysis membrane 7 is actually composed of a large number of hollow fiber membranes, for example, but it is schematically shown in FIG.

The dialysate is, for example, as shown in FIG.
The dialysate supplied from the prepared dialysate supply device 8 is discharged from one chamber 9a of the measuring chamber 9 through the pressing of the membrane 10 and the hemodialysis filter 5 through the filter 11.
Is supplied to. The hemodialysed dialysate is a circulation pump 1
The water is returned to the other chamber 9b of the measuring chamber 9 by 2 and a part of the water is removed via the water removing pump 13.

A pressure sensor for detecting the pressure in the blood flow path 1 is provided at a position upstream of the hemodialysis filter 5 in the blood flow path 1, which is a position between the blood pump 4 and the hemodialysis filter 5 in this embodiment. 14 is provided, and a pressure sensor 15 is provided at a position on the downstream side of the hemodialysis filter 5. The pressure sensor 14 detects the pressure corresponding to the arterial side of the patient, the pressure sensor 15 detects the pressure corresponding to the venous side, and the differential pressure corresponds to the blood pressure of the patient at that time.
That is, the hemodialysis filter 5 has the same function as a so-called viscometer with respect to the pressure loss in the blood flow path 1, and causes a pressure loss corresponding to the blood state at that time, and the pressure loss is the blood pressure of the patient. It corresponds to.

In this embodiment, both pressure sensors 14 and 15 are
The pressure detection signal is sent to the control device 16, and the differential pressure is automatically calculated and output. Further, in the control device 16, the characteristic of the obtained differential pressure signal is differentiated, and the degree of change of the differential pressure is continuously calculated and output. Furthermore, when the calculated differential value exceeds a predetermined constant value, that is, when the degree of change in differential pressure (the degree of change in blood pressure) exceeds a certain degree, the detection state is warned. You may make it emit as a signal.

The above-mentioned differential pressure signal is transmitted to one of the pair of rollers 17 and 17 provided on the blood pump 4.
Is output only when it reaches a predetermined position in the orbiting direction. At this fixed position, for example, as shown in FIG.
An intermediate position from a position 19 at which pressing of the inner tube 18 is started to a position 20 at which pressing is completed, in particular, a pressing start position 1
It is preferable to set the midpoint position 21 from 9 to the pressing end position 20 or the position immediately before it. This position is a position where the influence of the pulsation generated by the blood pump 4 is the smallest.

The setting of the fixed position or the signal indicating that the position has been reached can be obtained by means having, for example, an optical or magnetic element. In this embodiment, means having a magnetic element, such as the magnet 22
And a Hall element 23. In the present embodiment, as shown in FIGS. 2 and 3, the magnet 22 is attached to the orbiting drive rotation member 24 of the pair of rollers 17, and the hall element 23 is attached to the fixed side member 25. Since a signal is obtained when the magnet 22 and the Hall element 23 are at positions just opposite to each other, one of the rollers 17 is set at the midpoint position 21 or the position immediately before it by appropriately setting the mounting positions of the magnet 22 and the Hall element 23. The constant position signal can be emitted when the user comes to the.

In the above-mentioned hemodialysis apparatus, the differential pressure signal of both pressure sensors 14 and 15 corresponding to the blood pressure of the patient is
It is output only when the roller 17 of the blood pump 4 reaches a certain position, and the certain position is set to the position where the influence of the pulsation by the blood pump 4 is the smallest, so that a stable differential pressure signal with extremely small fluctuation is generated. However, the blood pressure can be obtained substantially continuously and accurately, so that the change in blood pressure can be measured accurately and accurately and quickly without delay.

Therefore, even when a sudden drop in blood pressure occurs, it can be accurately and extremely quickly detected at the very early stage of the drop. If the differential pressure signal characteristic is differentiated, the problematic decrease in blood pressure can be more accurately and accurately automatically measured.

In the above hemodialysis device,
Since the pressure sensors 14 and 15 are provided at the upstream side position and the downstream side position of the hemodialysis filter 5 to read the differential pressure between the arterial side pressure and the venous side pressure, that is, a physical phenomenon, the blood pump speed fluctuates. In this case, the differential pressure value fluctuates regardless of the blood pressure state of the patient. Specifically, as shown in FIG. 5B, when the blood pump speed changes during hemodialysis (point 1
03, 104) and as shown in FIG. 5 (A), the differential pressure value also changes following the change in blood pump speed. However, since the correction calculation processing for the blood pump speed of the present invention is performed, as shown in FIG. 6 (A) with respect to changes in the blood pump speed as indicated by points 105 and 106 in FIG. 6 (B),
When the correction calculation process is not performed, the differential pressure value is 10
The levels of 7 and 109 can be corrected to the levels of 108 and 110 by performing correction calculation processing, and even when the blood pump speed changes during hemodialysis, the patient's level can be continuously and accurately corrected. The blood pressure condition can be monitored.

As the above-mentioned correction method, a correlation expression (for example, Δ) between the blood pump speed Qb and the differential pressure value ΔP stored in a storage means such as an internal memory provided inside the control device 16 is used.
P = αQb + β (FIG. 7A), ΔP = αe ^ βQb
(FIG. 7 (B)), the differential pressure value calculated from the pressure detection signal sent from the pressure sensors 14 and 15 to the control device 16 is compared with the differential pressure value corresponding to the change amount of the blood pump speed. A method of adding or subtracting values is adopted. Further, the corrected differential pressure value obtained by the automatic correction calculation of the differential pressure is output.

The correlation equation between the blood pump speed Qb and the differential pressure value ΔP used when the blood pump speed fluctuates is as follows:
Alternatively, at any point during hemodialysis, the blood pump control means operates the blood pump speed at two or more speeds, sends the differential pressure value at each controlled blood pump speed to the hemodialysis machine, and the inside of the hemodialysis machine. It is preferable to perform arithmetic processing of the correlation equation by the arithmetic means provided and store it in a storage element provided inside the hemodialysis machine. According to this method, the difference in blood condition (especially Hct) of the patient,
Reliable blood pump speed Qb regardless of the type of hemodialysis filter 5 and other hemodialysis conditions
It is possible to obtain the correlation equation between the differential pressure value ΔP and the differential pressure value ΔP.

Regarding the correlation formula between the blood pump speed Qb and the differential pressure value ΔP used when the blood pump speed fluctuates, a pseudo test corresponding to actual hemodialysis is performed in advance to calculate the correlation formula. It is also possible to employ a method of storing in advance a storage element provided inside the hemodialysis machine.

Since the change in blood pressure (change in differential pressure) corresponds to the change in Hct as before, a rapid rise in Hct can be detected accurately and quickly at the same time.

As described above, the change characteristic of the blood pressure can be detected in the state where the change of the differential pressure is extremely small with respect to the pulsation of the blood pump and the change of the blood pump speed. Therefore, when the blood pressure suddenly drops. Also, it becomes possible to take appropriate measures promptly.

Further, since the change in blood pressure is detected by the hemodialysis apparatus itself, an Hct measuring device as a separate device and a general sphygmomanometer are not required, and the overall structure of the device is simple.

In the above-mentioned embodiment, an example in which the differential pressure detecting means is constituted by the one having the two pressure sensors 14 and 15 is shown. However, a so-called differential pressure gauge is used, and both pressure detecting ends thereof are located above the hemodialysis element. It is also possible to connect downstream and directly detect the differential pressure. Also in that case, similarly to the above-described embodiment, it is preferable to appropriately perform signal processing using the control device 16 and the like.

Further, in the above embodiment, the blood pump 4
Although it is composed of a tube pump having a pair of rollers 17, it may be composed of a tube pump having three rollers or more rollers.

[0045]

As described above, according to the hemodialysis apparatus of the present invention, it is possible to accurately and accurately detect changes in the circulating blood volume of a patient during hemodialysis by the hemodialysis apparatus itself, in particular, changes in blood pressure. The measurement can be performed well and extremely quickly, and even when a problematic blood pressure drop occurs, it can be quickly dealt with at an early stage.

Furthermore, even when the blood pump speed is changed during hemodialysis due to the treatment, it is possible to continuously and accurately measure the change in the blood pressure of the patient.

Further, the present invention does not require a separate device like the Hct measuring device, and can be implemented easily and inexpensively with a simple structure.

Furthermore, since the blood pressure can be measured by the hemodialysis apparatus itself, it is not necessary to add a blood pressure measuring band (cuff) to the patient separately, and the patient is not uncomfortable.

[Brief description of drawings]

FIG. 1 is a schematic device system diagram of a hemodialysis apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a blood pump unit of the apparatus of FIG.

FIG. 3 is a schematic side view of the blood pump unit in FIG.

FIG. 4 is a characteristic diagram showing a case where a rapid increase in Hct and a rapid decrease in blood pressure occur during hemodialysis.

FIG. 5 is a characteristic diagram showing changes in the differential pressure of the hemodialysis element when the blood pump speed is changed during hemodialysis.

FIG. 6 is a characteristic diagram in which correction calculation processing is performed on the differential pressure of the hemodialysis element when the blood pump speed is changed during hemodialysis.

FIG. 7 is a characteristic diagram showing a correlation between a differential pressure of a hemodialysis element and a blood pump speed.

[Explanation of symbols]

1 blood flow path 2 arterial side 3 venous side 4 blood pump 5 hemodialysis filter (dialyzer) as a hemodialysis element 6 dialysate flow path 7 dialysis membrane 8 prepared dialysate supply device 9 measuring chamber 10 membrane 11 filter 12 circulation pump 13 Dewatering Pumps 14 and 15 Pressure Sensor 16 Control Device 17 Pair of Rollers 18 Tube 19 Pressing Start Position 20 Pressing End Position 21 Midpoint Position 22 Magnet 23 Hall Element 24 Rotating Drive Rotating Member 25 Fixed Side Member 101 Hct Rapid Ascending Region 102 Blood pressure rapid decrease area 103, 104, 105, 106 Blood pump speed change points 107, 109 Hemodialysis element differential pressure level (without correction calculation processing) 108, 110 Hemodialysis element differential pressure level (with correction calculation processing)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masami Oda             Maeda 1386 Maeda, Urasoe City, Okinawa Prefecture             21-402 F term (reference) 4C077 AA05 BB01 DD07 EE01 HH03                       HH13 HH15 JJ03 JJ13 JJ16                 4D006 GA13 KE06P KE06Q PB09                       PC41

Claims (7)

[Claims] 1. A hemodialysis element for performing hemodialysis between a blood channel and a dialysate channel for circulating blood between the body of a patient and a hemodialysis element provided upstream of the hemodialysis element in the blood channel. And a blood pump comprising a tube pump, and a differential pressure detecting means for detecting a differential pressure between a position on the upstream side of the hemodialysis element in the blood flow path and a position on the downstream side of the hemodialysis element. In the hemodialysis device, the signal of the differential pressure detected by the differential pressure detecting means is provided only when the roller of the blood pump comes to a predetermined constant position in the circumferential direction thereof. When the rotational speed of the blood pump changes during hemodialysis, the differential pressure signal is corrected and calculated by a correlation expression between the blood pump speed Qb and the differential pressure value ΔP stored in a storage element provided inside the hemodialysis machine. And corrected differential pressure value Hemodialysis apparatus being characterized in that so as to output. 2. The correlation formula between the blood pump speed Qb and the differential pressure value ΔP is calculated by operating the blood pump speed at 2 or more speeds by the blood pump control means at any time before or during hemodialysis. The differential pressure value at each controlled blood pump speed is sent to the hemodialysis device, the correlation means is arithmetically processed by the arithmetic means provided inside the hemodialysis device, and is stored in the storage element provided inside the hemodialysis device. The hemodialysis apparatus according to claim 1, wherein: 3. A correlation formula between the blood pump speed Qb and the differential pressure value ΔP is calculated by a pseudo test corresponding to actual hemodialysis and stored in a storage element provided inside the hemodialysis device. The hemodialysis apparatus according to claim 1, wherein 4. The differential pressure detecting means is a differential pressure gauge, or
The hemodialysis device according to any one of claims 1 to 3, further comprising pressure sensors provided on the upstream and downstream sides of the hemodialysis element. 5. A fixed position is an intermediate position from a position where one of the plurality of rollers provided in the blood pump starts pressing the tube to a position where the pressing ends.
The hemodialysis device according to any one of claims 1 to 4. 6. The means for detecting a fixed position comprises a means having an optical or magnetic element, which is provided on a roller revolving drive rotary member of a blood pump and a stationary member facing the rotary member. The hemodialysis device according to any one of 1 to 5. 7. The hemodialysis apparatus according to claim 1, further comprising means for calculating and outputting a differential value of the characteristic of the differential pressure signal.