JP2010234109A - Method and apparatus for deciding fistula recirculation by supply of substitution fluid during extracorporeal blood circulation treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for deciding fistula recirculation by supply of a substitution fluid during extracorporeal blood circulation treatment. <P>SOLUTION: The method decides fistula recirculation in an extracorporeal blood circulation treatment apparatus including an extracorporeal blood circulation passage and a fluid passage. In order to decide fistula recirculation, the ratio of the integration of artery pressure signals measured at an artery line at predetermined time intervals and having repeating negative and/or positive artery pressure pulses each corresponding to start or stop of a substitution pump to the integration of vein pressure signals measured at a vein line at predetermined time intervals and having repeating negative and/or positive vein pressure pulses each corresponding to start and stop of the substitution fluid pump is decided. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The invention relates to an extracorporeal blood flow path comprising a first chamber of a dialyzer or filter separated by a single membrane into a first chamber and a second chamber, and a fluid flow comprising a second chamber of the dialyzer or filter The present invention relates to a method for monitoring a replacement fluid for an extracorporeal blood processing apparatus for blood comprising a channel. Furthermore, the present invention relates to a blood extracorporeal circulation processing device using a device for detecting the supply of replacement fluid upstream or downstream of the dialyzer or filter.

  In cases of chronic renal failure, various methods are used for extracorporeal circulation treatment and / or purification of blood, usually for the purpose of removing substances contained in urine or collecting fluid. In hemodialysis, the patient's blood is purified by an external dialyzer. The dialyzer is provided with a blood chamber and a dialysate chamber separated by a semipermeable membrane. During the extracorporeal circulation of blood, the patient's blood is perfused through the blood chamber. Fresh dialysate is continuously perfused through the dialysate chamber to effectively remove substances normally contained in the urine from the blood.

During hemodialysis (HD), low molecular weight substances are mainly transported (diffused) through the membrane due to the concentration difference between the dialysate and blood, but during hemofiltration (HF), substances dissolved in plasma water, especially higher molecular weights. Material is effectively removed through the membrane of the dialyzer by high flow (convection). During blood filtration, the dialyzer functions as a filter. Hemodiafiltration (HDF) is a combination of these two methods.
In hemodiafiltration, a portion of the serum removed through the membrane is replaced with sterile replacement fluid and is carried to the extracorporeal blood flow channel either upstream of the dialyzer or downstream of the dialyzer. The supply of replacement fluid upstream of the dialyzer is called pre-dilution, and the supply downstream of the dialyzer is called post-dilution.
Hemodiafiltration devices are known in which dialysate is generated online from fresh water and concentrate and replacement fluid is generated online from dialysate.

  In this known hemodiafiltration device, the replacement fluid is conveyed from the fluid flow path of the device to the extracorporeal circulation blood flow path via a replacement fluid line. In the case of pre-dilution, the replacement fluid line leads to a connection on the arterial blood line upstream of the dialyzer or filter, whereas in the case of post-dilution, the replacement fluid line is connected to a connection on the venous blood line downstream of the dialyzer. Communicates. The replacement fluid line generally has a connector by which it can be connected to either a venous blood line or an arterial blood line. In order to interrupt the supply of liquid, a clamp or something similar to a clamp is provided on the replacement liquid line. Such a hemodiafiltration device is known, for example, from European Patent Application No. 0189561 (Patent Document 1).

  Monitoring the extracorporeal circulation of blood assumes that it is known whether the replacement fluid is carried upstream or downstream of the dialyzer or filter into the extracorporeal blood flow path. Pre-dilution and post-dilution affect for example on-line clearance measurement (OCM) based on conductivity measurements, which depends on whether the dialysate conductivity downstream of the dialyzer has been pre-diluted or post-diluted. Because.

  EP 1344458 (Patent Document 2) describes a method and apparatus for monitoring the supply of replacement fluid for an extracorporeal blood treatment apparatus for blood. In order to detect the supply of replacement fluid upstream or downstream of the dialyzer or filter, the propagation time of the pressure wave of the replacement fluid pump located in the replacement fluid line is measured. Whether the replacement liquid is supplied upstream or downstream of the dialyzer or filter is recognized based on the measurement of the propagation time. The known method assumes the use of a displacement liquid pump that generates a pressure wave.

  DE 101 15 991 (Patent Document 3) describes a device for detecting stenosis in a hose system. The published document proposes that a change in the frequency spectrum of the oscillating pressure signal propagating in the hose system can determine that a stenosis (narrow site) exists in the hose system. The working principle of the known device is based on the fact that the change in the dynamics of the hose system is due to the compliance of the hose system, ie the elastic modulus under pressure.

European Patent Application No. 0189561 European Patent Application No. 1344458 specification German Patent No. 10115991

  The subject of the present invention is that, as described in paragraphs 0030 to 0036 of the original application, a festel is provided, provided that it presents a method that can recognize whether it is pre-dilution or post-dilution with a high level of reliability. Is to describe a method and a blood extracorporeal circulation treatment apparatus capable of determining recirculation and recirculation rate.

This object is achieved by a characteristic method and apparatus according to the first to fourth aspects of the present invention.
The present invention provides an embodiment but is based on measuring pressure in a fluid flow path downstream of a dialyzer or filter.
In the first embodiment, the replacement liquid pump carrying the replacement liquid is stopped and / or started.
The inventors have found that the change in pressure following the stop and / or start of the displacement pump follows a characteristic course. The supply of replacement fluid upstream or downstream of the dialyzer or filter is recognized based on the pressure change following the stop or start of the replacement fluid pump. Sudden pressure rises and / or pressure drops are characteristic parameters of pressure changes.

Basically, this recognition can only be made after a pressure change that occurs after the displacement pump has been stopped or started. However, greater reliability can be achieved if it is recognized whether pre-dilution or post-dilution is based on pressure changes both at stop and start of the replacement fluid pump and vice versa.
In a preferred embodiment where it is possible to recognize whether predilution or postdilution with a particularly high level of confidence, the replacement fluid pump that was started is stopped, restarted after a predetermined time interval, and the dialyzer or filter The pressure is measured downstream. Whether the replacement liquid is supplied upstream or downstream of the dialyzer or filter is based on a change from a preceding pressure increase to a subsequent pressure drop or a change from a preceding pressure drop to a subsequent pressure increase. Be recognized.

When the sequence from pressure increase to pressure decrease is detected, it is determined that the replacement liquid is supplied downstream of the dialyzer or filter. When the sequence from pressure decrease to pressure increase is detected, the replacement liquid is supplied. Is determined to be performed upstream of the dialyzer or filter.
One advantage is that pressure pulses propagating in the extracorporeal blood flow channel are not evaluated. As a result, it is not necessary to prepare a replacement liquid pump that generates an oscillating pressure pulse so that post-dilution replacement and pre-dilution replacement can be distinguished.
To suppress the interference signal, the oscillating pressure signal is preferably filtered using a low pass filter.
The characteristic pulse sequence following the stop and start of the replacement fluid pump is characteristic of an oscillating pressure signal in the extracorporeal blood flow path downstream of the dialyzer or filter and a pressure increase or decrease due to pre-dilution or post-dilution May occur based on a comparison with the upper and lower limits.

An apparatus for detecting the supply of replacement fluid upstream or downstream of a dialyzer or filter of a blood extracorporeal circulation processing apparatus according to the present invention includes a control device for stopping and / or starting a replacement fluid pump, and downstream of the dialyzer or filter. And a measuring device for measuring the pressure in the extracorporeal circulation blood channel and an evaluation device. The evaluation device is designed so that the supply of replacement fluid upstream or downstream of the dialyzer or filter is recognized based on changes in venous pressure after the replacement fluid pump is stopped and / or started.
The measuring device for measuring venous pressure preferably comprises a venous pressure sensor and a low-pass filter connected to the signal output end of the pressure sensor.
The evaluation device preferably comprises a comparator which compares the output signal of the pressure sensor for detecting pressure rise and / or pressure drop with a predetermined upper limit value and / or lower limit value.

The method according to the invention and the device according to the invention are advantageously used to determine the dialysis dose when supplying replacement fluid using so-called online clearance monitoring (OCM) as a function of blood flow. In addition, the present method and apparatus are useful in determining all important parameters for dialysis when a distinction is required between post-dilution and pre-dilution replacement fluid administration. The method and apparatus are also used for blood flow determination, shunt or fistula recirculation determination, relative blood volume and / or hematocrit monitoring, dialyzer or filter fill volume determination and venous needle type identification. You can also
Most of the components required for the sensing device are already present in generally known blood processing devices. For example, a venous pressure sensor can be used to measure the pressure in the extracorporeal blood flow channel downstream of the dialyzer or filter. A microprocessor controller can also be used. As a result, the expense associated with the device is relatively low.

The second embodiment of the present invention is premised on the use of a replacement liquid pump that generates a pressure wave.
The supply of replacement fluid upstream or downstream of the dialyzer or filter propagates into the extracorporeal blood flow path and is a characteristic (or characteristic) reference signal (or characteristic) based on a comparison of the oscillating pressure signal due to the replacement fluid pump ( Or a reference signal). The method and apparatus according to the present invention provides for whether the frequency spectrum of the oscillating pressure signal propagates through the dialyzer in the case of predilution or without the dialyzer in the case of postdilution. It is based on the fact that it depends on how. Similarly, the pressure pulse amplitude varies as a function of pre-dilution or post-dilution.
In the case of a known blood extracorporeal circulation processing apparatus, for example, a blood pump disposed in an extracorporeal circulation blood channel upstream of a dialyzer or a filter is added to the vibration pressure signal of the replacement fluid pump propagating in the extracorporeal circulation blood channel. Overlapping oscillating pressure signals due to or due to devices placed in a fluid flow path including, for example, a concentrate pump, ultrafiltration pump or equilibrium chamber. For this reason, the oscillating pressure signal resulting from the replacement fluid pump is obtained from the pressure measured in the extracorporeal circulation blood channel. In order to avoid measurement errors, the dialyzer or filter can also be separated from the fluid flow path.

  A preferred embodiment that can detect the supply of replacement fluid with a particularly high level of confidence provides the signal of a blood pump located in the extracorporeal circulation blood channel upstream of the dialyzer or filter as a characteristic reference signal. However, this pump also generates an oscillating pressure signal. This embodiment is based on the premise that during pre-dilution, the vibration of the oscillating pressure signal of the blood pump and the replacement fluid pump propagating through the dialyzer and hose system is hardly different. On the other hand, in post-dilution, the oscillating pressure signal of the replacement fluid pump and the blood pump are substantially different because the oscillating pressure signal of the replacement fluid pump does not propagate through the dialyzer. This provides features that are not only relatively different between pre-dilution and post-dilution, but also absolutely different.

In order to obtain the pressure signals of the blood pump and replacement fluid pump, preferably a Fourier analysis of the pressure signal measured downstream of the dialyzer or filter is performed. Preferably, the amplitudes of at least two harmonic components are determined from the pressure signals of the replacement fluid pump and the blood pump. At least one first evaluation factor is determined from a ratio (quotient) of at least one higher order harmonic component and at least one lower order harmonic component of the replacement fluid pump, and at least one second evaluation factor is blood It is determined from the ratio (quotient) of at least one higher order harmonic component and at least one lower order harmonic component of the pump.
In practice, in order to form the two evaluation coefficients by Fourier transform, the coefficients of the second and higher harmonic components of the pressure signal of the blood pump and / or the replacement fluid pump are set to the values of the pressure signals of the blood pump and / or the replacement fluid pump. It has proven to be sufficient to standardize on the coefficients of the first harmonic components.
If the difference between the first evaluation coefficient and the second evaluation coefficient is greater than a predetermined limit value, it is determined that post-dilution is performed, and the difference between the first evaluation coefficient and the second evaluation coefficient is greater than the predetermined limit value. If it is smaller, it is determined that predilution has been performed.

An apparatus for detecting the supply of a replacement fluid to a blood extracorporeal circulation processing apparatus according to the present invention includes a measuring apparatus and an evaluation apparatus for measuring a pressure in an extracorporeal circulating blood channel downstream of a dialyzer or a filter. The evaluation device comprises means for obtaining an oscillating pressure signal resulting from the replacement liquid pump, means for comparing the oscillating pressure signal with a characteristic reference signal, and a pressure signal and characteristic reference signal of the replacement liquid pump. And means for detecting pre-dilution or post-dilution based on the comparison.
Predilution and postdilution can be distinguished only by evaluating the pressure signal of the replacement liquid pump at the start of the dialysis treatment, but are preferably distinguished using the blood pump pressure signal in combination.
In general, no other equipment or devices are required other than a measuring device for measuring the pressure in the extracorporeal blood flow channel downstream of a dialyzer or filter that is part of a known blood processing device.

1 is a highly simplified schematic diagram of a first embodiment of a blood extracorporeal circulation treatment device according to the present invention comprising devices for detecting pre-dilution and post-dilution. It is the graph which showed the change of the venous pressure with time in the extracorporeal circulation blood flow path in the downstream of the dialyzer or filter in the case of post-dilution. It is the graph which showed the change of the venous pressure with time in the case of predilution. FIG. 6 is a graph showing mean venous pressure as a function of time measured during in vitro HDF dialysis therapy in the case of post-dilution. It is the graph which showed the average venous pressure in the case of predilution. 1 is a simplified schematic diagram of an embodiment of a blood extracorporeal circulation treatment apparatus according to the present invention. It is the table | surface which showed the frequency spectrum of the pressure wave in the extracorporeal circulation blood flow path resulting from a substitution fluid pump and a blood pump, and described the standardization factor of the pressure signal of the blood pump and substitution fluid pump in the case of post-dilution. It is the table | surface which showed the frequency spectrum of the pressure wave in the extracorporeal circulation blood flow path resulting from a substitution fluid pump and a blood pump, and described the standardization factor of the pressure signal of the blood pump and substitution fluid pump in the case of predilution.

Hereinafter, embodiments of the method according to the present invention and the blood processing apparatus according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram of the essential components of a hemodiafiltration device including equipment for detecting the supply of replacement fluid in an extracorporeal blood flow channel upstream or downstream of a dialyzer or filter. It will be understood that a filter is included when the dialyzer is described below.

The hemodiafiltration device includes a dialyzer 1 separated by a semipermeable membrane 2 into a first chamber 3 through which blood flows and a second chamber 4 through which dialysate flows. The first chamber 3 operates in the extracorporeal circulation blood channel 5A, and the second chamber 4 operates in the fluid channel 5B of the hemodiafiltration device.
The extracorporeal circulation blood flow path 5A includes an arterial blood line 6 communicating with the inlet 3a of the blood chamber 3 and a venous blood line 7 communicating with the outlet 3b of the blood chamber 3 of the dialyzer 1. An arterial drip chamber 8 is arranged in the arterial blood line 6 and a venous drip chamber 9 is arranged in the venous blood line 7 in order to remove bubbles. The patient's blood is carried through the blood chamber of the dialyzer by an arterial blood pump 10, in particular a roller pump, which is arranged on the arterial blood line 6.

The fluid flow path 5 </ b> B includes a dialysate supply line 11 that communicates with the inlet 4 a of the dialysate chamber 4 and a dialysate discharge line 12 that communicates from the outlet 4 b of the dialysate chamber 4 of the dialyzer 1. Fresh dialysate flows from a dialysate supply source (not shown) through the dialysate supply line 11 into the dialysate chamber, and spent dialysate passes from the dialysate chamber through the dialysate discharge line 12 to a drain not shown. Drained to the line. In general, an equilibration device provided in a hemodiafiltration device for equilibrating fresh dialysate and spent dialysate is not shown for clarity of illustration. Similarly, additional equipment for cleaning and cleaning the system is not shown.
The dialysate supply line 11 includes a first portion 11 a that leads to an inlet 13 a of a first chamber of a sterile filter 16 that is separated by a membrane 14 into a first chamber 13 and a second chamber 15, and a first chamber of the filter 16. 13 includes a second portion 11b leading from the outlet 13b of 13 to the inlet 4a of the dialysate chamber 4.

  During the dialysis treatment, the dialysate can be supplied, for example, as a replacement liquid from the fluid flow path 5B through the replacement liquid line 17 to the extracorporeal circulation blood flow path 5A. The fluid line 17 includes two line portions 17a, 17b, 17c, and 17d at both ends. Line portion 17a is connected to first outlet 15a of sterile filter 16, while connectors 18a, 18b are connected to line portions 17c and 17d. By means of two connectors 18 a, 18 b, the replacement fluid line 17 can be connected to a connection line 19 leading to the arterial drip chamber 8 and / or a connection line 20 leading to the venous drip chamber 9. The connection lines 19 and 20 are provided with connectors 19a and 20a corresponding to this purpose. The hose clamps 17e, 17f are adapted to the hose line portions 17c, 17d and can optionally establish fluid communication to the arterial or venous drip chambers 8,9. It is also possible to connect the replacement liquid line 17 to both connection lines 19, 20 and to keep both these hose clamps 17e, 17f open.

  In order to tighten and close the replacement liquid line 17, a closing device 21, for example a hose clamp, is provided downstream of the sterile filter 16, which clamp is preferably actuated electromagnetically. The replacement liquid is carried by an occlusion pump, in particular a roller pump 22, into which the replacement liquid line 17 is inserted. Such roller pumps are part of the state of the art. Such roller pumps are equipped with several rollers 22a, 22b, by which the cross section of the hose line carrying the fluid can be reduced. In this way, a pressure wave is formed that can propagate in both directions through the substitution liquid line. It should be understood that the first embodiment of the blood extracorporeal circulation processing apparatus according to the present invention does not require an occlusion pump that generates a pressure wave as a replacement liquid pump. Alternatively, a replacement liquid pump that does not generate pressure waves can be used to carry the replacement liquid. This is one advantage of this embodiment.

In order to disconnect the dialyzer 1 from the fluid flow path 5B, electromagnetically actuated closing devices 25 and 26 are prepared in the dialysate supply line 11 upstream of the dialyzer 1 and the dialysate discharge line 12 downstream of the dialyzer 1, respectively.
Blood pump 10, replacement fluid pump 22 and closure devices 21, 25 and 26 are individually connected via control lines 10 ', 22', 21 ', 25' and 26 ', thereby taking into account certain processing parameters. It is connected to a central controller 27 in which the components are controlled.

  To operate the hemodiafiltration device as a hemodialysis device, the closure device 21 is closed so that dialysate flows through the dialysate chamber 4 of the dialyzer. In order for the hemodiafiltration device to operate as a hemodiafiltration device, sterile dialysate is optionally dispensed from the sterile filter 16 into the arterial drip chamber 8 (pre-dilution) or venous drip chamber 9 (post-dilution). The closure device 21 is opened to flow. However, if the dialysate supply to the dialysate chamber 4 of the dialyzer is interrupted, the hemodiafiltration device can be operated as a simple blood filtration device. In order to interrupt the supply of dialysate, the closure device 25 is closed upstream of the dialyzer.

  The device for detecting pre-dilution and post-dilution is provided with a control device that forms part of the central control device 27 of the blood treatment device. Further, the detection device is provided with a measuring device 28 and an evaluation device 29 for measuring the pressure of the extracorporeal circulation blood channel downstream of the dialyzer 3. A pressure sensor 28 attached to the drip chamber 9 is provided as a measuring device, which generates an electrical pressure signal as a function of venous pressure. The pressure signal of the pressure sensor 28 is sequentially transmitted to the evaluation device 29 via the data transfer line 30 and transferred to the control device 27 via the data transfer line 31. The evaluation device 29 includes a low-pass filter 29a for filtering the pressure signal of the pressure sensor 28, and a comparator 29b by which the pressure signal is compared with a predetermined upper limit value and lower limit value.

  In the following, the detection of the supply of replacement fluid upstream or downstream of the dialyzer will be described in detail. The control device 27 of the detection device stops the replacement fluid pump 22 that is already operating, preferably at the start of the blood treatment, in order to start the measurement. After the elapse of a predetermined time interval, the control device 27 starts the replacement liquid pump 22 again. The pressure sensor 28 measures the venous pressure while the replacement fluid pump is stopped. The venous pressure signal of the pressure sensor 28 filtered by the low-pass filter 29a is a pressure increase after the replacement liquid pump is stopped and a pressure decrease after the replacement liquid pump is started or a pressure decrease after the replacement liquid pump is stopped and the replacement liquid pump. Is compared with the upper limit value and the lower limit value in the comparator 29b of the evaluation device 29.

FIG. 2A shows the basic change in venous pressure over time for post-dilution, and FIG. 2B shows the basic change in venous pressure over time for pre-dilution. In the case of post-dilution, it is clear that the pressure initially increases and then decreases. In the case of predilution, the pressure initially decreases and then increases. The evaluation device recognizes whether post-dilution or pre-dilution is performed based on these two characteristic changes. The results can be displayed visually and / or audibly on a display device not shown.
3A and 3B show the venous pressure as a function of time during which the predetermined time during which the displacement pump is stopped is relatively long. When the time interval is short, the maximum and / or minimum values are very close. In order to start the measurement, the substitution liquid pump that has already been started is stopped for a predetermined time interval. In principle, however, it is also possible to start the replacement liquid pump that was initially stopped for a predetermined time interval.

  The characteristic changes in the pressure signal shown in FIGS. 2A and 2B are due to changes in blood viscosity during pre-dilution or post-dilution. In the case of post-dilution, the blood viscosity decreases due to the supply of replacement fluid in the venous blood line 7 downstream of the drip chamber 9. When the replacement fluid pump 22 is stopped, blood viscosity increases in this portion of the venous blood line. An increased pressure drop occurs on the venous needle. As a result, venous pressure increases. When the replacement fluid pump is restarted, the blood viscosity in the venous blood line 7 downstream of the drip chamber 9 decreases and the venous pressure decreases. As a result, a pressure pulse with a positive sign occurs after the displacement pump is stopped, and a pressure pulse with a negative sign occurs after the pump is started (FIG. 2A). The pulse width depends on the ratio of the blood volume between the dialysate chamber 3 and the drip chamber 9 of the dialyzer 1 as well as the blood flow. On the other hand, in the case of pre-dilution, the order of the signs of the pressure pulses after stopping and starting the replacement liquid pump is reversed. When the pump stops, a pressure drop occurs, and a pressure rise occurs after the pump is started (FIG. 2B).

  Figures 3A and 3B show in vitro HDF dialysis treatment with blood flow adjusted to 250 mL / min, displacement rate for pre- and post-dilution to 70 mL / min, and ultrafiltration rate adjusted to 0 mL / hr The mean venous pressure [mmHg] as a function of time is shown. In practice, it has been found that the amplitudes of pressure rise or pressure drop are different from each other. However, in both the pre-dilution and post-dilution cases, a pressure increase or pressure decrease can be clearly recognized. The predetermined upper and lower limits must be set so that they are below or above the maximum or minimum value. However, on the other hand, the upper and lower limits must be above or below the pressure fluctuations that overlap the pressure signal.

  A determination can be made regarding fistula circulation based on positive and / or negative pressure pulses. A repetition of the pressure pulse sequence that can be detected in the venous blood line 7 using the venous pressure sensor 28 and that can be detected in the arterial blood line 6 using the arterial pressure sensor indicates recirculation. The integration of the pressure signal of the arterial pressure sensor at a predetermined time interval where repeated negative and / or positive pressure pulses occur and the venous pressure sensor 28 at a predetermined time interval when negative and / or positive pressure pulses occur. The ratio of the pressure signal to the integral is used as a measure of recirculation. The recirculation rate Rez [%] is calculated by the following equation:

  If the blood supply rate (Qb) is known with respect to the filling amount (VPD) of the hose portion between the inlet 3a of the dialysate chamber 3 of the dialyzer 1 and the connectors from the substitution fluid lines 17 and 20 to the drip chamber 9, a pressure pulse The result can be obtained from the time difference (Δt) between the start and end of the rise or pressure pulse drop. The filling amount (VPD) is calculated by the following equation:

Further, in the case of HDF pre-dilution, the blood supply rate (Qb) at a predetermined time interval between the stop of the replacement liquid pump 22 and the pressure drop and / or the time interval between the start of the replacement liquid pump and the start of the pressure increase. ), The filling amount (VPD) of the hose portion between the inlet 3a of the dialysate chamber 3 and the venous needle can be calculated. In the case of post-HDF dilution, a similar relationship exists: the pressure difference between the stoppage of the replacement liquid pump and the start of the pressure pulse rise and / or the time difference between the start of the replacement liquid pump and the start of the pressure pulse drop. Is monitored.
When the filling amount and time difference of the hose portion are known, the true blood flow rate can be determined by the reverse method.

If the relationship between hematocrit, blood pressure drop and / or blood pressure rise, blood supply rate and needle shape is known, the pressure rise and / or drop amplitude provides information on the needle type. If the type of needle is known, a corresponding result can be obtained for hematocrit.
Thereby, the change in hematocrit can be monitored by the change in the amplitude of the pressure pulse during the dialysis treatment.

FIG. 4 is a highly simplified schematic diagram of yet another embodiment of a blood treatment apparatus according to the present invention. The blood processing apparatus of FIG. 4 is not different from the blood processing apparatus of FIG. 1 except for an apparatus for detecting pre-dilution and post-dilution. For this reason, the component corresponding to each other is displayed with the same reference symbol.
This detection device is similarly provided with a venous pressure sensor 28 for measuring the pressure in the venous blood line 7. The evaluation device 50 receives the venous pressure signal of the pressure sensor 28 via the data transfer line 30. The evaluation device 50 includes a Fourier analysis device 50a that performs Fourier analysis of the venous pressure signal.

The present method for detecting pre-dilution or post-dilution assumes that the replacement liquid pump 22 and the blood pump 10 are pumps that generate pressure waves, such as occlusion pumps, particularly roller pumps. The frequency of the pressure wave generated by the blood pump 10 is much higher than the frequency of the pressure wave of the replacement liquid pump because the speed of the blood pump is much higher than that of the replacement liquid pump. The pressure wave of the blood pump can be identified from the wave. In the case of predilution, the pressure wave of the replacement liquid pump 22 is not only between the drip chamber 8 and the inlet 3a of the dialysate chamber 3 but also the hose portion of the replacement liquid lines 17, 19, 20 before reaching the pressure sensor 28. Between the hose portion of the arterial blood line 6, the dialysate chamber and the venous blood line 7 also pass. On the other hand, in the case of post-dilution, the pressure wave does not pass through the dialysate chamber and the corresponding venous blood line portion. The action of the dialysate chamber 3 and the associated venous blood line portion can be described as a propagation function. If the dialyzer and the associated line portion are located within the propagation path of the pressure wave, the pressure waves and their frequency spectral changes, particularly higher frequency dynamics, are more strongly attenuated.
There is no need to know the propagation function accurately to detect pre-dilution or post-dilution. It is sufficient if the relationship between the pressure signal of the replacement fluid pump and the pressure signal of the blood pump is clarified.

  The pressure signal measured using the pressure sensor 28 includes both the blood pump 10 pressure signal and the replacement fluid pump 22 pressure signal. The Fourier analysis device 50a of the evaluation device 50 decomposes the pressure signals of the blood pump 10 and the replacement fluid pump 22 measured using the pressure sensor 28 into signal components resulting from the blood pump and / or the replacement fluid pump.

  FIGS. 5A and 5B show the frequency spectrum of the venous pressure signal determined by Fourier transform in the case of post-dilution or pre-dilution. The measurements shown in the figure were determined in a laboratory test with blood flow adjusted to 300 mL / min, replacement fluid flow rate to 80 mL / min, and ultrafiltration rate adjusted to 100 mL / hr. In the frequency spectrum, it is possible to recognize the coefficients of the primary storm wave component and the higher-order storm wave component caused by the blood pump 10 and the replacement fluid pump 22.

  The evaluation apparatus 50 calculates an index between a coefficient of a higher-order storm wave component such as a secondary or tertiary storm wave component and a coefficient of a primary storm wave component, that is, a standardization coefficient of spectral shunting. The standardization factor of the replacement fluid pump represents the first evaluation factor, and the standardization factor of the blood pump represents the second evaluation factor. In order to compare the evaluation coefficients of the replacement fluid pump and the blood pump, the evaluation device 50 is provided with another device 50b. If the evaluation factor of the replacement fluid pump is substantially above the evaluation factor of the blood pump, it is determined that post-dilution exists (FIG. 5A). If the evaluation factor of the replacement fluid pump is only slightly above or near the evaluation factor of the blood pump, or if both evaluation factors are the same, it is determined that predilution is present (FIG. 5B). Detection of pre-dilution or post-dilution based on the comparison of evaluation coefficients is performed by the device 50c.

  The device 50c for recognizing pre-dilution or post-dilution is equipped with a device for generating the difference between the two evaluation factors. The difference is compared to a predetermined limit value that has been determined so that it can be reliably discriminated between pre-dilution and post-dilution. Post-dilution exists when the difference between the first evaluation coefficient and the second evaluation coefficient is larger than the predetermined limit value, and pre-dilution exists when the difference between the first evaluation coefficient and the second evaluation coefficient is smaller than the predetermined limit value. To do. The results can be displayed visually and / or audibly on a display device not shown.

  The present invention is of high industrial applicability with respect to a method or device for monitoring the supply of replacement fluid upstream or downstream of a dialyzer or filter disposed in an extracorporeal blood flow channel.

DESCRIPTION OF SYMBOLS 1 Dializer 2 Semipermeable membrane 3 Blood chamber 3a Inlet of blood chamber 3b Outlet of blood chamber 4 Dialysate chamber 4a Inlet of dialysate chamber 4b Outlet of dialysate chamber 5A Extracorporeal circulation blood channel 5B Fluid channel 6 Arterial blood line 7 Vein Blood line 8 Arterial drip chamber 9 Venous drip chamber 10 Arterial blood pump 11 Dialysate supply line 11a 1st part 11b 2nd part 12 Dialysate discharge line 13 1st chamber 13a 1st chamber inlet 13b 1st chamber outlet 14 Membrane 15 Second chamber 16 Aseptic filter 17 Replacement liquid line 17a to 17d Line portion 17e, 17f Hose clamp 18a, 18b, 19a, 20a Connector 19, 20 Connection line 21 Closing instrument 22 Replacement liquid pump 22a, 22b Roller 25, 26 Electric Magnetically actuated closure device 27 Central control device 28 Pressure sensor 29, 50 Evaluation device 29a Low-pass filter 29b Comparator 50a Fourier analysis device

Claims (4)

An extracorporeal blood flow path including a first chamber of a dialyzer or filter separated into a first chamber and a second chamber, and a fluid flow path including a second chamber of the dialyzer or filter, and a replacement fluid pump Determining the recirculation of festels for an extracorporeal blood circulation treatment apparatus in which a replacement fluid is supplied upstream or downstream of the dialyzer or filter comprising:
When the replacement fluid pump is stopped, started and / or started, stopped, the pressure in the arterial line upstream of the extracorporeal blood flow channel of the dialyzer or filter is measured, and the extracorporeal blood flow channel of the dialyzer or filter The pressure in the venous line downstream of
Arterial pressure signal at predetermined time intervals measured in the arterial line, each with repeated negative and / or positive arterial pressure pulses, according to the start or stop of the replacement fluid pump to determine the festel recirculation And the integration of the venous pressure signal over a given time interval measured in the venous line, with repeated negative and / or positive venous pressure pulses, respectively, depending on whether the displacement pump is started or stopped. A method of determining recirculation characterized by seeking.   The method of claim 1, wherein the pressure in the flow path is measured by a pressure sensor that transmits what is filtered by a low pass filter. An extracorporeal blood flow path (5A) separated by a membrane (2) into a first chamber (3) and a second chamber (4) and comprising a first chamber (3) of a dialyzer (1) or a filter, and said dialyzer Alternatively, the fluid flow path (5B) including the second chamber of the filter and the replacement fluid line (17) in which the replacement fluid pump (22) is arranged to flow into the extracorporeal circulation blood channel upstream or downstream of the dialyzer or filter. , 19, 20),
A blood extracorporeal circulation processing apparatus comprising: means for determining festel recirculation;
The means for determining the festel recirculation measures the pressure in the arterial line in the extracorporeal blood flow channel upstream of the control unit (27) for stopping and / or starting the replacement fluid pump, the dialyzer or filter. And a measurement unit (28) for measuring the pressure of a venous line in the extracorporeal circulation blood flow path downstream of the dialyzer or filter, and start or stop of a replacement fluid pump to determine festel recirculation According to the integration of the arterial pressure signal at a predetermined time interval measured in the arterial line, each with repeated negative and / or positive arterial pressure pulses, and according to the start or stop of the replacement fluid pump, respectively. Veins at predetermined time intervals measured on the venous line with negative and / or positive venous pressure pulses Apparatus characterized by consisting the evaluation unit is designed to determine the ratio of the integral of the force signal (29).   4. The device according to claim 3, wherein the measuring unit for measuring the pressure in the extracorporeal blood flow channel upstream and downstream of the dialyzer (1) or filter comprises arterial and venous pressure sensors.

Images