Device and method for determining a dialysis fluid flow rate or blood flow rate for extracorporeal blood treatment
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Projected expiry 25 September 2027, counted from filing; an application has no term until it is granted.
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18 claims: 4 independent, 14 dependent
- 1Patent claims Zastrzeżenia patentowe 1. A device for determining the dialysis fluid flow rate or blood flow rate for an extracorporeal blood treatment device that has a dialyzer that is divided into a blood chamber through a semipermeable membrane through which blood flows at a given blood flow rate Qb, and a dialysis fluid chamber through which dialysis fluid flows with a given dialysis fluid flow rate Qd, wherein the device for determining the flow rate of the dialysis fluid or 1. Urządzenie do oznaczania natężenia przepływu płynu dializacyjnego lub prędkości przepływu krwi dla urządzenia do pozaustrojowej obróbki krwi, które posiada dializator, który przez półprzepuszczalną błonę jest podzielony na komorę krwi, przez którą przepływa krew z zadaną prędkością przepływu krwi Qb, i komorę płynu dializacyjnego, przez która przepływa płyn dializacyjny z zadanym natężeniem przepływu płynu dializacyjnego Qd, przy czym urządzenie do oznaczania natężenia przepływu płynu dializacyjnego lub EP 2 068 972 B1 prędkości przepływu krwi ustala natężenia przepływu płynu dializacyjnego Qd lub prędkość przepływu krwi Qb, w zależności od zadanej prędkości przepływu krwi Qb, względnie natężenia przepływu płynu dializacyjnego The blood flow velocity determines the flow rates of the dialysis fluid Qd or blood flow velocity Qb, depending on the set blood flow velocity Qbor the dialysis fluid flow rate Qdand characterized in that the device for determining the flow rate of the dialysis fluid is shaped in such a way that at the marked blood flow rate Qb this is the dialysis fluid flow rate Qd or at the indicated dialysis fluid flow rate Qd this blood flow velocity Q is determinedb at which an increase by a specific value, an increase in the value characteristic of the effectiveness of blood treatment does not fall below the lower limit of the specified value. Qdi znamienne tym, że urządzenie do oznaczania natężenia przepływu płynu dializacyjnego jest ukształtowane w taki sposób, że przy oznaczonej prędkości przepływu krwi Qb ustalane jest to natężenie przepływu płynu dializacyjnego Qd lub przy oznaczonym natężeniu przepływu płynu dializacyjnego Qd ustalana jest ta prędkość przepływu krwi Qb przy której zwiększeniu o określoną wartość, zwiększenie wielkości charakterystycznej dla skuteczności obróbki krwi nie obniża się poniżej dolnej granicy określonej wartości.
- 8Blood treatment device for extracorporeal blood treatment, with a dialyzer (1), which is divided into a blood chamber (3) through which the blood flows with 8. Urządzenie do obróbki krwi dla pozaustrojowej obróbki krwi, z dializatorem (1), który przez półprzepuszczalną błonę (2) podzielony jest na komorę krwi (3), przez którą przepływa krew z zadaną At the blood flow velocity Qb, and the dialysis fluid chamber (4) through which the dialysis fluid flows with a given dialysis fluid flow rate Qd, characterized in that the blood treatment device has a device (18) for determining the dialysis fluid flow rate or blood flow rate according to one of claims 1 to 7. EP 2 068 972 B1 prędkością przepływu krwi Qb, i komorę płynu dializacyjnego (4), przez którą przepływa płyn dializacyjny z zadanym natężeniem przepływu płynu dializacyjnego Qd, znamienne tym, że urządzenie do obróbki krwi posiada urządzenie (18) do oznaczania natężenia przepływu płynu dializacyjnego lub prędkości przepływu krwi według jednego z zastrzeżeń 1 do 7.
- 11Method for determining the dialysis fluid flow rate or blood flow rate for an extracorporeal blood treatment device that has a dialyzer that is divided into a blood chamber through a semipermeable membrane through which blood flows at a given blood flow rate Qb, and a dialysis fluid chamber through which dialysis fluid flows with a given dialysis fluid flow rate Qd, wherein the dialysis fluid flow rate Qd or blood flow velocity Qb is determined depending on the set blood flow velocity Qb, or the dialysis fluid flow rate Qdi characterized in that depending on the blood flow rate Qb this is the dialysis fluid flow rate Qd or depending on the flow rate of the dialysis fluid Qd this blood flow velocity Q is determinedbat which an increase by a specific value, an increase in the characteristic size for blood treatment efficiency does not fall below the lower limit of the specified value. 11. Sposób oznaczania natężenia przepływu płynu dializacyjnego lub prędkości przepływu krwi dla urządzenia do pozaustrojowej obróbki krwi, które posiada dializator, który przez półprzepuszczalną błonę jest podzielony na komorę krwi, przez którą przepływa krew z zadaną prędkością przepływu krwi Qb, i komorę płynu dializacyjnego, przez która przepływa płyn dializacyjny z zadanym natężeniem przepływu płynu dializacyjnego Qd, przy czym natężenie przepływu płynu dializacyjnego Qd lub prędkości przepływu krwi Qb ustala się w zależności od zadanej prędkości przepływu krwi Qb, względnie natężenia przepływu płynu dializacyjnego Qdi znamienny tym, że w zależności od prędkości przepływu krwi Qb ustala się to natężenie przepływu płynu dializacyjnego Qd lub w zależności od natężenia przepływu płynu dializacyjnego Qd ustala się tę prędkość przepływu krwi Qb, przy której zwiększeniu o określoną wartość, zwiększenie wielkości charakterystycznej dla efektywności obróbki krwi nie chodzi poniżej dolnej granicy określonej wartości.
- 1818A 18B 18A 18B 9 9 EP 2 068 972 Β1 EP 2 068 972 Β1 Fig. 2 ιοοο Fig. 3 Fig. 2 ιοοο Fig. 3 EP 2 068 972 B1 EP 2 068 972 B1 QD [ml / min] qd optimal [ml / min] QD [ml/min] qd optymalne [ml/min] Fig. 4 Fig. 4 Fig.5 Figure 5 EP 2 068 972 Β1 EP 2 068 972 Β1 Fig. 6 Fig. 6 - ΚΒ Α [ml / min] Κ [ml / min - ΚΒ Α [ml/min] Κ [ml/min Fig. 7 Fig. 7 EP 2 068 972 Β1 EP 2 068 972 Β1 Fig. 8 Fig. 8 Fig. 9 Fig. 9 EP 2 068 972 Β1 EP 2 068 972 Β1 Poniższa Usta publikacji cytowanych przez zgłaszającego ma na celu wyłącznie pomoc dla czytającego i nie stanowi części dokumentu patentu europejskiego. Pomimo, że dołożono największej staranności przy jej tworzeniu, nie można wykluczyć błędów lub przeoczeń i EUP nie ponosi żadnej odpowiedzialności w tym względzie. The following Mouth of publications cited by the applicant is intended solely to assist the reader and does not form part of the European patent document. Although the greatest care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard. Dokumenty patentowe cytowane w opisie • US5100554A [0004] [0004] · DE 69531137T2 [0005] • WO 9532010 A [0005] • US 5092836 A [0009] Patent documents cited in the description • US5100554A [0004] [0004] DE 69531137T2 [0005] • WO 9532010 A [0005] • US 5092836 A [0009] Documents not relating to patent literature cited in the description · JE SIEGDELLB. TERSTEEGENArtificiai Organs, 1986, vol. 10, 3219-225 [0008] Dokumenty nie odnoszące się do literatury patentowej cytowane w opisie · J.E. SIEGDELLB. TERSTEEGENArtificiai Organs, 1986, vol. 10, 3219-225 [0008] PUBLICATIONS CITED IN THE DESCRIPTION PUBLIKACJE CYTOWANE W OPISIE
Independent claims4
76 paragraphs in 1 section, as filed
[0001] The invention relates to a device and method for determining the dialysis fluid flow rate or blood flow rate for an extracorporeal blood treatment device that has a dialyzer that is divided into a blood chamber through a semipermeable membrane through which blood flows at a given blood flow rate. In addition, the invention relates to a blood treatment device with a device for determining a dialysis fluid flow rate or blood flow rate and a method for operating an extracorporeal blood treatment device.
[0002] In methods of blood purification therapy, such as hemodialysis, hemofiltration and hemodiafiltration, the patient's blood is directed through the extracorporeal bloodstream in which the dialyzer is located, or a filter that is divided into a blood chamber and a dialysis fluid chamber or filtrate chamber through a semi-permeable membrane. . With hemofiltration, both hemodialysis and hemofiltration are performed. The invention relates to all blood purification therapy methods in which blood flows through the blood chamber and the dialysis fluid through the dialyzer fluid chamber.
[0003] Various physical and / or chemical quantities are known with which the dialyzer efficiency and / or the effectiveness of dialysis treatment can be administered. A well-known quantity for dialyzer efficiency is K clearance. K clearance is a partial flow of total flow through a dialyzer that is completely freed from the substance. For the effectiveness of dialysis treatment, the so-called KT / V dialysis index, which is defined for urea as the quotient of the K clearance product for urea and the effective time T of dialysis treatment and the patient's V-volume, is crucial.
[0004] US 5,100,554 describes a method for determining clearance in which the electrolyte transfer in a dialyzer is measured at each time at two different input concentrations of the dialysate. From US 5,100,554 it is known that the effectiveness of dialysis treatment is dependent on the blood flow velocity and the flow rate of the dialysis fluid.
[0005] DE 695 31 137 T2 (WO 95/32010) describes a method and apparatus for optimizing the effectiveness of dialysis treatment, wherein during treatment the size characteristic of the dialysis treatment effectiveness is measured and the dialysis treatment parameter is determined based on the measured value to achieve optimal effectiveness of dialysis treatment. The publication shows in detail that the processor increases selected parameters, for example, the blood flow rate, in steps, in specific increments, whereby the urea sensor constantly measures the characteristic quantity in which the sample of the dialysate effluent is taken. By comparing the currently measured concentration with the previous concentration, it is determined whether the current concentration is lower or higher than the previous concentration. When the current concentration is lower than the set concentration, then the conclusion is that the previous concentration represents the optimal value. Therefore, a maximum concentration should be set.
[0006] Known dialysis devices with a constant dialysis fluid flow rate that were not user-adjustable have been operated in the past. In contrast, newer devices allow you to manually set different flow rates of dialysis fluid, for example 300, 500 and 800 ml / min. W i * · '/ *
To obtain a high clearance, substantially higher dialysis fluid flow rates at higher blood flow rates are required.
[0007] When setting a specific dialysis fluid flow rate, it should be taken into account that while a higher dialysis fluid flow rate can be obtained with a high clearance, however, the costs of providing fresh and removing the used dialysis fluid increase. Therefore, in practice, a relatively high clearance is sought with a relatively low consumption of dialysis fluid. [0008] It is known that with the widespread use of dialyzers with a ratio of blood flow rate to a dialysis fluid flow rate of 1: 2, there is only a slight decrease in clearance compared to an unchanging dialysis fluid flow rate of 500 ml / min (JE Siegdell, B. Tersteegen, Artificial Organs, 10 (3) pages 219 to 225, 1986). [0009] Therefore, US 5,092,836 proposes to control the dialysis fluid flow rate depending on the blood flow velocity according to given criteria. In particular, it is proposed to set the flow rate of the dialysis fluid, which is created by multiplying the blood flow velocity by a solid factor. In addition to the linear relationship between the blood flow rate and the dialysis fluid flow rate, a numerical data field has been proposed, which for each blood flow rate of a given dialyzer gives the dialysis fluid flow rate at which a certain percentage of the maximum that would have to be obtained assuming an infinitely high fluid flow rate dialysis. In practice, this figure can be, for example, 95%.
[0010] The object underlying the invention is to propose a device and method for determining the optimal dialysis fluid flow rate or blood flow rate for extracorporeal blood treatment, taking into account the requirement for high efficiency of dialysis treatment on the one hand, and low dialysis fluid consumption on the other hand. A further object of the invention is to provide a blood treatment device with which dialysis treatment can be carried out with relatively high efficiency at a relatively low dialysis fluid flow rate. It is also an object of the invention to propose a method for operating a blood treatment device to be able to carry out dialysis treatment with relatively high efficiency at moderate consumption of dialysis fluid.
[0011] According to the invention, the solution to this task is achieved by the features of claims 1, 8 and 11. Preferred embodiments of the invention are the subject of the dependent claims.
[0012] In the device according to the invention and in the method according to the invention, the determination of the dialysis fluid flow rate or blood flow velocity for the extracorporeal blood treatment device, at the determined blood flow velocity Q<sub>b</sub> this is the dialysis fluid flow rate Q<sub>d</sub>, at which an increase by a certain value, an increase in the size characteristic of the effectiveness of blood treatment does not fall below the lower limit of the specified value. Alternatively, at a determined dialysis fluid flow rate, this blood flow rate Q is determined<sub>b</sub>at which an increase by a specific value, an increase in the size characteristic of the effectiveness of blood treatment does not fall below the lower limit of the specified value.
In this connection, the device according to the invention and the method according to the invention start from the fact that from the optimal value for the dialysis fluid flow rate, at the marked blood flow rate, or for the blood flow velocity, at the determined dialysis fluid flow rate,
If the rate of dialysis fluid flow rate or blood flow rate is further increased, it is still possible to achieve an increase in dialysis treatment efficiency, additional dialysis fluid, or a further increase in blood flow rate that is required for this type of treatment with greater efficiency, but is not it is in economic proportion to the resulting increase in efficiency. So, as a purposeful criterion, a working point is sought at which the consumption of additional dialysis fluid that would be necessary to increase the clearance will not exceed a certain value, i.e. it is determined how much ml / min of dialysis fluid is ready to be used to obtain one further ml / min clearance at which a further increase in the blood flow rate that would be required to increase the clearance by a certain value will not exceed the specified value.
[0014] Different treatment methods can be marked with different blood treatment efficiencies, with such a dialysis fluid flow rate Q determined for each treatment method.<sub>d</sub> or blood flow velocity Q<sub>b</sub>, at which an increase by a certain value, an increase in the value characteristic of the effectiveness of blood treatment does not fall below the lower limit of value assigned to each treatment method.
[0015] In practice, a ratio of 10: 1 has been proven for the quotient Q<sub>d</sub>/ K dialysis fluid flow rate Q<sub>d</sub> and clearance K. However, a ratio in the range of 5: 1 to 20: 1 is also generally acceptable. [0016] Optimal flow rate of dialysis fluid Q<sub>dopt</sub> or blood flow velocity Q<sub>Bop</sub>t depends not only on the blood flow rate or dialysis fluid flow rate, but also on the dialyzer that is used for dialysis treatment. Therefore, the device according to the invention and the method according to the invention provides for determining the optimal flow rate of the dialysis fluid or the blood flow rate depending on the characteristic of the dialyzer, in particular the mass transfer coefficient kOA of the dialyzer.
[0017] Optimal dialysis fluid flow rate Q<sub>dopt</sub>, as a function of blood flow velocity Q<sub>b</sub> and the size characteristic of the dialyzer, especially the mass transfer coefficient kOA, can be stored in the memory of the dialysis device as a three-dimensional family of characteristics. Due to disk space, the family of characteristics is preferably described by a suitable mathematical equation by which the optimal dialysis fluid flow rate can be calculated for the marked blood flow velocities and mass transfer coefficients. The three-dimensional family of characteristics is preferably approximated by a higher order polynomial, especially a third order polynomial with two or a series of variables, including all mixed words. The same applies to the alternative optimal blood speed as a function of dialysis fluid flow rate.
[0018] In order to calculate the optimal dialysis fluid flow rate or blood flow rate, the device according to the invention preferably has a calculation unit by which the optimum flow rate is calculated for a specific dialyzer or different dialyzers with different mass transfer coefficients depending on the blood flow rate. dialysis fluid, or vice versa.
[0019] The device according to the invention and the method according to the invention for determining the dialysis fluid flow rate or blood flow rate can be used to present to the physician during dialysis treatment a proposal for setting the optimal dialysis fluid flow rate or
EP 2 068 972 Β1 blood flow velocity. The device according to the invention can be part of the blood treatment device or constitute a separate unit. Preferably, however, the blood treatment device already has a device according to the invention for determining the optimal dialysis fluid flow rate or blood flow rate. In addition, it is preferred that the indicated dialysis fluid flow rate or blood speed is not only proposed to the attending physician, but is also set automatically for blood treatment.
[0020] An embodiment of the invention is explained in more detail below with reference to the drawings.
[0021] And so they show:
figure 1, essential components of the device according to the invention for extracorporeal blood treatment with the device according to the invention, for determining the optimal flow rate of the dialysis fluid in a very simplified schematic view.
figure 2 clearance K (ml / min) as a function of dialysis fluid flow rate Q<sub>d</sub> (ml / min) for a specific dialyzer, for different blood flow rates Q<sub>b</sub>, figure 3 an additional amount of dialysis fluid that is necessary at different dialysis fluid flow rates Q<sub>d</sub> and blood flow velocities Q<sub>b</sub>to increase the clearance by 1 ml / min.
figure 4 a three-dimensional family of characteristics in which the optimal flow rate of dialysis fluid Q is shown<sub>dopt</sub> as a function of blood flow velocity Q<sub>b</sub> and the dialysis mass transfer coefficient, Figure 5 dialysis fluid flow rate Q<sub>d</sub> (ml / min) as a function of blood flow rate Q<sub>b </sub>(ml / min) in the method according to the invention or the device according to the invention, compared to known methods, figure 6 clearance K (ml / min) as a function of blood flow rate Q<sub>b</sub> (ml / min) in the method according to the invention or the device according to the invention, compared to known methods, figure 7, the difference in clearance K<sub>Fri.</sub> in the method according to the invention or the device according to the invention and the clearance K (A, B) in known methods as a function of the blood flow rate Q<sub>b</sub> (ml / min), figure 8 is the quotient of the optimal dialysis fluid flow rate Q<sub>dop</sub>ti blood flow velocity Q<sub>b </sub>according to the invention as a function of blood flow rate Q<sub>bi</sub> compared to known methods, figure 9 is the quotient of the optimal dialysis fluid flow rate Q<sub>dopt</sub> and blood flow velocity Q<sub>b</sub> as a function of blood flow velocity Q<sub>b</sub>, compared to known methods.
[0022] Figure 1 shows an embodiment of the blood treatment device according to the invention, which has the device according to the invention for determining the optimal fluid flow rate
EP 2 068 972 Β1 dialysis. The blood treatment device which is equipped with the device according to the invention for determining the optimal blood flow rate differs from the device described in Fig. 1 only in that according to the criteria of the invention, not depending on the blood flow rate Q<sub>b</sub> this is the dialysis fluid flow rate Q<sub>d</sub>, but depending on the dialysis fluid flow rate Q<sub>d</sub> this blood flow velocity Q is determined<sub>b</sub>at which an increase by a specific value, an increase in the characteristic size for the effectiveness of blood treatment does not fall below the lower limit of the specified value. In addition, both devices contain the same components.
[0023] In Fig. 1, for better clarity, only the essential components of the blood treatment device are shown, as the skilled person generally knows the individual components of the blood treatment device for hemodialysis or hemofiltration.
[0024] The dialysis device according to the invention has a dialyzer 1 which is divided into a blood chamber 3 and a chamber and a chamber of dialysis fluid 4 through the semi-permeable membrane 2, from which the patient carries an arterial blood line 5, into which the blood pump 6 is connected, to the inlet blood chamber 3 of the dialyzer, while while the venous blood line 7 leads to the patient from the blood chamber outlet.
[0025] Fresh dialysis fluid is provided at source 8 of dialysis fluid. From the dialysis fluid source 8 leads the dialysis fluid supply line 9 to the inlet of the dialysis fluid chamber 4 of the dialyzer 1, while the dialysis fluid drainage line 10 leads from the dialysis fluid chamber outlet to the outflow 11. Fluid pump 12 is connected to the dialysis fluid discharge line 10 dialysis.
The dialysis device is provided with a control unit 13, which via control lines 14, 15 is connected to a blood pump 6 and a dialysis fluid pump 12. The control unit 13 generates control signals for the operation of the blood pump and the dialysis fluid pump 6, 12 with pump capacity, also the marked blood flow velocity Q is set in the blood conduit 5<sub>b</sub>and the dialysis fluid flow rate marked in the dialysis fluid line Q<sub>d</sub>.
[0027] In order to enter various parameters for dialysis, the dialysis device has an insertion unit 16, which has, for example, an alphanumeric keypad 16A. By means of the introduction unit 16, in addition to various other quantities, for example, the blood flow velocity Q can be introduced<sub>b</sub> and the characteristic size for the efficiency of the dialyzer 1 used, especially the mass transfer coefficient kOA of the dialyzer. The introduction unit 16 is connected via a data transmission cable 17 to a control unit 13, by means of which the individual components of the dialysis device are controlled in such a way, in particular the blood pump and the dialysis fluid pump, that the dialysis treatment is carried out with the marked dialysis parameters.
[0028] The dialysis machine determines Q for the determined blood flow rate<sub>b</sub> optimal dialysis fluid flow rates Q<sub>d</sub>. For this purpose, the dialysis machine is equipped with a device 18 for determining the optimal flow rate of the dialysis fluid Q<sub>dop</sub>whose structure and mode of operation will be described in detail below.
It is assumed that dialysis treatment is carried out with the help of a specific dialyzer 11 which has a specific efficacy that can be indicated by the mass transfer coefficient kOA of the dialyzer. For the hemodialysis case, the clearance K is calculated from the blood flow velocity and the dialysis fluid flow rate and the mass transfer coefficient kOA of the dialyzer 1 according to the following equation:
EP 2 068 972 Β1 * Μ £ - ±>,
K = Q<sub>t</sub> —-Χα (i) [0029] Figure 2 shows the K clearance as a function of the dialysis fluid flow rate Q<sub>d</sub> for different blood flow velocities Q<sub>b</sub>. It turns out that at high flow rates of dialysis fluid Q<sub>d </sub>there is saturation of K clearance. At the same time, from a certain blood flow rate, increasing the flow rate of the dialysis fluid no longer makes any mention of the clearance gain. The device according to the invention, depending on the blood flow rate Q<sub>b</sub> determines the optimal flow rates of dialysis fluid Q<sub>dopt</sub> as an optimal working point for a dialysis machine. Optimal working points for different blood flow velocities are indicated in figure 2 by circles, with an additional dialysis fluid ratio per ml / min of an additional clearance of 10: 1 chosen for the working points. If, starting from each operating point, the flow rate of dialysis fluid Q increases further<sub>d</sub>, then an increase in the dialysis fluid flow rate is no longer associated with a further increase in the magnitude characteristic of dialysis treatment, especially K clearance, which exceeds a certain value. Optimal dialysis fluid flow rate Q<sub>dopt</sub> is therefore the flow rate of the dialysis fluid at which the derivative of the function shown in Fig. 2 is exceeded, which describes the relationship between the characteristic value for dialysis treatment, especially K clearance, and the dialysis fluid flow rate Q<sub>d</sub>, does not fall below the lower limit of the specified value. Thus, it is not the absolute value of the clearance but the derivative that is observed.
Figure 3 shows how much ml / min of additional dialysis fluid is needed for different blood flow rates Q<sub>b</sub> from 100 ml / min to 600 ml / min to increase the K clearance by one ml / min.
[0030] Experiments have shown that in practice the 10: 1 ratio leads to a working point at which relatively high dialysis treatment efficacy is obtained with reasonable dialysis fluid consumption. This purpose criterion of 10: 1 is indicated in figure 3 by a horizontal dashed line. Each intersection with markers for different blood flow rates represents different operating points. Since the derivative of the above-described function cannot be clearly calculated without a problem according to the dialysis fluid flow rate, the invention provides iterative approximate solutions.
[0031] In figures 2 and 3 it is clearly seen that the working point at the blood flow velocity Q<sub>b</sub> = 100 ml / min is in the saturation range. However, at the work point at Q<sub>b</sub> = 600 ml / min it could be assumed that a further increase in the dialysis fluid flow rate still leads to a relative gain in clearance. However, it should be considered that the dialysis fluid flow rate to the right of the operating point would have to be increased by more than 10 ml / min to maintain a clearance gain of only one ml / min.
[0032] Figures 2 3 show the clearance depending on the flow rate of the dialysis fluid only for a particular type of dialyzer which has a specific mass transfer coefficient kOA. In practice, different dialyzers can be used in dialysis machines that differ in different ones
EP 2 068 972 Β1 mass transfer coefficients. Figure 4 shows a three-dimensional family of characteristics with which, depending on the blood flow velocity Q<sub>b</sub> for different dialyzers, which are distinguished each time by a specific mass transfer coefficient KOA, you can determine the optimal flow rate of dialysis fluid Q<sub>dopt</sub>.
[0033] The family of characteristics shown in figure 4 could be stored as a table in the memory of the device 18 according to the invention for determining the optimal flow rate of the dialysis fluid. For reasons of disk space, the invention provides for approximation of the family of characteristics by a corresponding function. To this end, various mathematical methods are known.
[0034] In the described embodiment, the three-dimensional family of characteristics with the third degree polynomial is approximated on both axes using all possible mixed words. This leads to the following equation of the model with 4 * 4 = 16 parameters a (i, j):
<img file="PL2068972T3_D0001.tif" />
<img file="PL2068972T3_D0002.tif" />
<img file="PL2068972T3_D0003.tif" />
<sup>+ a</sup>0J <sup>+</sup>®M 'fil ^ ^ + --- ^ 00 (2) [0035] The individual parameters of the above system of equations are determined by the method of least squares, thanks to which the sum of squared deviations between the raw data and the model is minimized. In practice, it is sufficient to match the family of characteristics (surfaces) and model equations.
[0036] To perform dialysis treatment, the attending physician determines a specific blood flow rate Q<sub>b</sub>, which is entered via the 16 A keyboard into the introduction unit 16, after which the control unit 13 sets the capacity (rotational speed) of the blood pump 6 accordingly. In addition, the doctor by means of the introduction unit 16 determines which dialyzer 1 will be used for dialysis treatment and then a specific mass transfer coefficient kOA, belonging to a given type of dialyzer, which coefficient is stored in memory. It is also possible to directly enter the given mass transfer coefficient kOA of the dialyzer used.
[0037] Values for determined blood flow rate Q<sub>b</sub> and the designated mass transfer coefficient kOA receives device 18 via data transmission cable 19 from the control unit 13. Device 18 has a calculation unit 18A, which, based on the third degree equation described above, calculates the optimal flow rate of dialysis fluid Q<sub>dopt</sub>. To indicate the optimal flow rate of dialysis fluid Q<sub>dopt</sub> device 18 is equipped with an indicator unit 18B, for example in the form of a screen or display.
[0038] In addition, device 18 sends the calculated value for the optimal flow rate of dialysis fluid Q<sub>dopt</sub> [via a data transmission cable 19 to the control unit 16, which in turn sets the rotational speed of the dialysis fluid pump 12 in such a way that the dialysis fluid is transferred at the optimal dialysis fluid flow rate Q<sub>dopt</sub>.
EP 2 068 972 Β1 [0039] In a preferred embodiment, the insertion unit 16 provides for the introduction of various purpose criteria. For example, as a purposeful criterion in addition to the above ratio of
10: 1 a 5: 1 ratio can be set, i.e. 5 ml / min additional dialysis fluid for 1 ml / min additional clearance, and a 15: 1 or 20: 1 ratio.
[0040] Depending on the set mode (5: 1, 10: 1 and 15: 1 od 20: 1), the calculation unit 18A of the device 18 then calculates the optimal flow rate of dialysis fluid Q<sub>dop</sub>t · The 5: 1 ratio corresponds to the economy mode, in which the dialysis fluid is spared, but the usual clearance cannot be achieved, the 10: 1 ratio to the normal mode, and the 15: 1 or 20: 1 ratio to the intensive mode, which should particularly high clearance should be achieved, however, using more dialysis fluid.
[0041] In the event that ultrafiltration flux is also included in hemodialysis, instead of the equation (1) mentioned above, the following equation (1 ') for hemodialysis, including hemofiltration, is created:
<img file="PL2068972T3_D0004.tif" />
Equation (1 ') with
Q<sub>b</sub> blood stream
Q<sub>d</sub> dialysate stream
Q<sub>f</sub> filtrate stream, here only ultrafiltration koA mass transfer coefficient area [0042] A more general case of hemodiafiltration is described below in which hemofiltration also occurs in addition to hemodialysis. For hemodiafiltration, the flow rate relationship is described by the following more general equation (1 ") for hemodiafiltration.
j βθ> Qsa -7
<img file="PL2068972T3_D0005.tif" />
Equation (1 ")
EP 2 068 972 B1
<img file="PL2068972T3_D0006.tif" />
ρ = ν + (ΐ-σ) · (ΐ - /) · ρ<sub>Ρ</sub> _1_
Pe exp (Pe) -l where σ reflection coefficient (0 <σ <1), for example for urine σ = 0 and the index for inflow (inflow) by the index for outflow (outflow)
Q<sub>f</sub> total filtration intensity, sum of ultrafiltration intensity Q<sub>UF</sub> and substitution intensity Qs Qf ~ Quf <sup>+</sup> qs
Q<sub>di</sub> the stream that adheres to the dialyzer input usually corresponds to the dialysate stream Q<sub>D</sub>on the machine
Q<sub>Down</sub> stream that adheres to the dialysate dialyzer output
Qo »~ Qdi Qf
Q<sub>bi</sub> stream that adheres to the dialysis blood inlet
Qai ~~ Qb <sup>+</sup> f'Qs with the factor f for predilution or post-dilution, f = 0 for post-dilution, f = 1 for predilution, or between 0 and 1 in the case of mixed-dilution
Q<sub>Because</sub> stream that adheres to the blood outlet of the dialyzer
Q & A> <sup>=</sup> Qbi - Qf
EP 2 068 972 Β1
Q<sub>b</sub> the blood stream which in the extracorporeal blood circulation adheres before the arterial infusion site corresponds to the user-set blood stream [0043] The differences of the method according to the invention will be described below in comparison to known methods for determining a given dialysis fluid flow rate, with reference to figures 5 to 9. In figures 5 to 9, "A" indicates a known method in which a constant dialysis fluid flow rate of 500 ml / min is set for the blood flow rate Q<sub>b</sub> up to 300 ml / min and constant flow rate of dialysis fluid Q<sub>d</sub> of 800 ml / min for blood flow rate Q<sub>b</sub> more than 300 ml / min. A known method in which the dialysis fluid flow rate is calculated by multiplying the blood flow velocity Q<sub>b</sub> by a factor of 1.2, it is denoted by "B". Figure 5 shows the dialysis fluid flow rate Qd as a function of blood flow rate Q<sub>b</sub> for the method according to the invention, compared to the known methods "A" and "B", while figure 6 clearance K as a function of blood flow for the method according to the invention and the known methods "A" and "B".
[0044] Figure 7 shows the difference between the Ko clearance<sub>Fri.</sub>obtained by the method of the invention at the optimal dialysis fluid flow rate Q<sub>dopt</sub> and the clearance K<sub>AND</sub> or K<sub>B</sub>, obtained using known methods as functions of blood flow rate Q<sub>b</sub>to make clearer the differences between the method of the invention and the known methods with respect to the change in clearance. Compared to the known method "A", the method according to the invention saves a relatively large amount of dialysis fluid, although the clearance has been reduced only by a relatively small amount. Although the "B" method saves even more dialysis fluid compared to the A method, this also leads to a greater reduction in clearance.
[0045] Figures 8 and 9 show for selected "intentional criteria" of 10: 1 (figure 8) and 5: 1 (figure 9) normalized to blood flow velocity optimal flow rate of dialysis fluid Q<sub>dopt</sub> according to the method of the invention for three different dialyzers. It can be recognized that for the selected target criterion 10: 1 a factor of 1.5 in the working range between Q<sub>b</sub> = 200 and 400 is understood only as the first approximation for different dialyzers. However, the 1.2 ratio for the 10: 1 target criterion is too low. The state of affairs changes, however, when 5: 1, i.e. 5 ml / min dialysis fluid for 1 ml / min clearance is chosen as the targeted criterion. Here, it can be seen that the factor 1.2 represents a better approximation. By means of the substance according to the invention, a compromise can be found between methods A and B, whereby the user gets at the same time the quantified working points at which he has a direct orientation on the effects of increased flux on the effectiveness of the treatment.
8 priority claims, no other members on record
Priority claims8
| Document | Office | Kind | Date |
|---|---|---|---|
| 102006045437 | Germany | A | |
| 102006045437 | Germany | A | |
| 07818382 | European Patent Office (EPO) | A | |
| 2007008297 | European Patent Office (EPO) | W | |
| 2007008297 | European Patent Office (EPO) | W | |
| DE20061045437 | – | – | – |
| EP20070818382 | – | – | – |
| WO2007EP08297 | – | – | – |
Numbers
- Publication, DOCDB
- 2068972
- Publication, EPODOC
- PL2068972T
- Application
- 818382
- Application, DOCDB
- 07818382
- Application, EPODOC
- PL20070818382T
Titles2
- English
- DEVICE AND METHOD FOR DETERMINING A DIALYSIS FLUID FLOW RATE OR BLOOD FLOW RATE FOR EXTRACORPOREAL BLOOD TREATMENT
- Polish
- Urządzenie i sposób oznaczania natężenia przepływu płynu fluidyzacyjnego lub prędkości przepływu krwi dla pozaustrojowej obróbki krwi
Classification
- CPC, 7
- A61M1/16
- A61M1/1613
- A61M1/1615
- A61M2205/50
- A61M1/3607
- A61M2205/3331
- A61M2205/3334
- IPC, 1
- A61M1 16