Method for filling membrane filters

Abstract

The invention discloses a method for filling a membrane filter of a blood treatment system, wherein the blood treatment system comprises: at least one blood treatment machine; a membrane filter, in particular a hollow fiber membrane filter, the membrane filter having a first chamber and a second chamber, the first chamber and the second chamber being separated semi-permeably by a membrane; and at least one first sub-circuit and at least one second sub-circuit, wherein the first chamber of the membrane filter is arranged in the first sub-circuit and the second chamber of the membrane filter is arranged in the second sub-circuit, wherein the first chamber of the membrane filter is filled with liquid via the first sub-circuit, while the second chamber is still filled with air, wherein a pump is arranged upstream of the membrane filter in the first sub-circuit. It is proposed that the pump is controlled according to the pressure measured in the first sub-circuit and the pressure measured in the second sub-circuit to fill the first chamber of the membrane filter via the first sub-circuit.

Description

Technical Field

[0001] The invention relates to a method for filling a membrane filter of a blood treatment system, wherein the blood treatment system comprises: at least one membrane filter, in particular a hollow fiber membrane filter, the membrane filter having a first chamber and a second chamber, the first chamber and the second chamber being separated semi-permeably by a membrane; at least one first sub-circuit and at least one second sub-circuit, wherein the first chamber of the membrane filter is arranged in the first sub-circuit and the second chamber of the membrane filter is arranged in the second sub-circuit, and wherein the first chamber of the membrane filter is filled with liquid via the first sub-circuit, while the second chamber is still filled with air. The invention also comprises a corresponding blood treatment machine and a blood treatment system. Background Art

[0002] A filling method is known from DE 10 2011 102 492 A1, in which the first chamber of the membrane filter is filled via the first partial circuit, so that air is displaced from the first partial circuit into the second partial circuit at least during a partial phase of the filling.

[0003] Furthermore, DE 10 2015 009 886 A1 discloses a method in which, after the first chamber of a membrane filter has been filled via a first partial circuit, an overpressure is exerted on the first chamber relative to the second chamber.

[0004] Furthermore, it is known from WO 2008 / 125893 A1 that, in order to fill the first subcircuit and the second subcircuit, the venous line and the arterial line of the second subcircuit are connected to the section of the first subcircuit that is downstream of the membrane filter, and a pump that is arranged in the first subcircuit downstream of the membrane filter and downstream of the connection point to the venous line and the arterial line is controlled according to the pressure in the first subcircuit and the second subcircuit. Conversely, a pump that is arranged upstream of the membrane filter is controlled in a volume-controlled manner.

[0005] For the purposes of this description, the terms "upstream" and "downstream" refer to the flow direction of how the liquid flows through the line during operation during treatment. This can be recognized, for example, by the fact that a blood leak detector can be arranged downstream of the membrane filter. The blood leak detector can be suitable for detecting blood that passes from the second sub-circuit through the membrane into the first sub-circuit during treatment. An air separation chamber can be arranged downstream. With respect to the sub-circuit that is filled with blood during operation, "upstream" can mean the line section in which a blood pump and / or an addition site for heparin are arranged. Summary of the invention

[0006] It is an object of the present invention to provide a method and a therapy machine which allow a reliable filling of a membrane filter.

[0007] This object is achieved by the method according to the invention and the treatment machine according to the invention.

[0008] The design of the present invention is described below.

[0009] The invention comprises a method for filling a membrane filter of a blood treatment system, wherein the blood treatment system comprises: at least one blood treatment machine; a membrane filter, in particular a hollow fiber membrane filter, the membrane filter having a first chamber and a second chamber, the first chamber and the second chamber being separated semi-permeably by a membrane; and at least one first sub-circuit and at least one second sub-circuit, wherein the first chamber of the membrane filter is arranged in the first sub-circuit and the second chamber of the membrane filter is arranged in the second sub-circuit, wherein the first chamber of the membrane filter is filled with liquid via the first sub-circuit, while the second chamber is still filled with air, and wherein a pump is arranged upstream of the membrane filter in the first sub-circuit. The method is characterized in that the pump for filling the first chamber of the membrane filter via the first sub-circuit is controlled according to the pressure measured in the first sub-circuit and the second sub-circuit.

[0010] A more reliable filling of the membrane filter is achieved by operating the pump according to the pressure. Thus, in some embodiments, it is possible to further reduce the number of air islands remaining in the membrane filter. In some embodiments, the filling state can be detected.

[0011] In a preferred embodiment, the first subcircuit is a dialysate circuit and / or the second subcircuit is an extracorporeal blood circuit. Therefore, the present invention particularly relates to the filling of a dialysate chamber of a dialyzer.

[0012] In a possible embodiment of the present invention, during the filling of the first chamber of the membrane filter with the liquid, the air present in the first chamber is transferred via the membrane into the second chamber of the membrane filter and thus into the second sub-circuit.

[0013] In a feasible design of the present invention, the first chamber of the membrane filter is filled from top to bottom via the first sub-circuit. Preferably, the first chamber of the membrane filter is filled via the first sub-circuit in the same flow direction in which the membrane filter is also flowed during the blood treatment.

[0014] In a preferred embodiment, the two chambers of the membrane filter are filled without an interposed rotating device of the membrane filter.

[0015] In a possible embodiment of the invention, during the blood treatment, the membrane filter is operated in countercurrent in the first subcircuit and the second subcircuit. Thus, if the first chamber of the membrane filter is filled from top to bottom via the first subcircuit, in particular in the dialysate circuit, the second chamber of the membrane filter can be filled and / or flushed from bottom to top via the second subcircuit, in particular in the blood circuit, in the flow direction also used during the blood treatment, without rotating the membrane filter. This makes it possible to safely vent the second chamber of the membrane filter.

[0016] In one possible embodiment of the invention, the volume flow generated by the pump for filling and / or the time profile and / or duration of the filling are controlled by the pump as a function of the pressure measured in the first and / or second partial circuit.

[0017] According to a first variant of the invention, the pressure in the first subcircuit and / or the transmembrane pressure on the membrane of the membrane filter is measured, wherein the pump is controlled via the first subcircuit to fill the first chamber of the membrane filter as a function of the pressure in the first subcircuit and / or the transmembrane pressure. In particular, the pressure upstream and / or downstream of the first chamber in the first subcircuit can be measured, and filling of the first chamber of the membrane filter can be achieved via the first subcircuit as a function of the pressure.

[0018] The transmembrane pressure can be determined from the pressure measured by means of a pressure sensor at the second subcircuit and the pressure measured by means of a further pressure sensor at the first subcircuit. The transmembrane pressure can be determined by means of the two pressure values ​​and a third pressure value measured by means of a pressure sensor at a third subcircuit, wherein the further pressure sensor can be arranged upstream of the membrane filter and the third pressure sensor can be arranged downstream of the membrane filter. The determination can be achieved by forming an average value of the pressures measured by means of the further pressure sensor and the third pressure sensor and subtracting the pressure in the second subcircuit therefrom, or the average value can be subtracted from the pressure in the second subcircuit.

[0019] The invention is based on the following knowledge according to the first variant: some membrane filters, in particular some dialyzers, are very sensitive to the pressure on the membrane as long as the second chamber has not yet been filled with liquid. If a certain transmembrane pressure is about to occur at the membrane filter in a certain period of time under such conditions, the liquid is transferred from the first chamber, in particular the dialysate chamber, into the second chamber, in particular the blood chamber, and it can no longer be filled formally afterwards. It should be taken into account that in a dialyzer in which the capillaries have been filled with liquid, air can no longer pass through the capillaries of the fiber wall. However, on the contrary, a certain transmembrane pressure is required in order to effectively squeeze the air from the first chamber via the membrane into the second chamber.

[0020] Since the transmembrane pressure is decisively determined by the pressure in the first subcircuit and in particular by the pressure upstream of the first chamber, the pressure in the first subcircuit and in particular upstream of the first chamber can be measured as an alternative to the transmembrane pressure and can be used or limited for control.

[0021] In a possible design solution, the filling is controlled so that the pressure in the first subcircuit and / or the transmembrane pressure does not exceed a first threshold value.

[0022] Preferably, as soon as the pressure in the first subcircuit and / or the transmembrane pressure exceeds a first threshold value, the delivery rate for filling is reduced. Reducing the filling can also include completely stopping the filling. In particular, the liquid inflow can be reduced and in particular stopped until the pressure in the first subcircuit and / or the transmembrane pressure is again below the first threshold value or the second threshold value.

[0023] In one possible design, the delivery rate of the pump during filling is reduced or the pump is stopped as soon as the pressure in the first subcircuit and / or the transmembrane pressure exceeds a first threshold value, wherein the first threshold value is, for example, at least 50 mBar, for example, at least 100 mBar, or for example, at least 200 mBar.

[0024] In a possible design, once the pressure in the first subcircuit and / or the transmembrane pressure falls below a second threshold, the delivery rate of the pump during filling is increased or the pump is restarted, wherein the second threshold is, for example, at least 50 mBar, or at least 100 mBar, or at least 150 mBar.

[0025] Preferably, the absolute value of the first threshold value is greater than the absolute value of the second threshold value. If these two threshold values ​​are the same, this may cause the pump to start and stop continuously. This is prevented by different threshold values.

[0026] In one possible embodiment, the pump is actuated such that an overpressure is at least temporarily generated in the first chamber of the membrane filter, in particular a pressure of at least 50 mBar or at least 100 mBar or at least 200 mBar.

[0027] In one possible design, a pump for filling a first chamber of a membrane filter is controlled in a volume-controlled manner, wherein the volume-controlled control is stopped or the volume flow is reduced as soon as the pressure in the first sub-circuit and / or the transmembrane pressure exceeds a first threshold value, wherein the first threshold value is, for example, at least 50 mBar, or, for example, at least 100 mBar, or, for example, at least 200 mBar.

[0028] In a possible design, once the pressure in the first subcircuit and / or the transmembrane pressure falls below a second threshold, volume-controlled control or increase of the volume flow is resumed, wherein the second threshold is, for example, at least 50 mBar, or at least 100 mBar, or at least 150 mBar.

[0029] Preferably, the absolute value of the first threshold is greater than the absolute value of the second threshold.

[0030] By limiting the pressure or flow rate according to the invention, it is possible to ensure that no air cushions are trapped in the fiber bundles of the membrane filter, which air cushions can then no longer be separated. However, the control according to the invention also ensures that sufficient pressure is applied to the first chamber in order to squeeze the air present there through the membrane into the second chamber.

[0031] In a feasible design, the first chamber of the membrane filter is filled with a pulsating volume flow, through which a pressure peak is generated in the first chamber of the membrane filter. Here, the pressure peak and the pressure drop that follows it are generated in the rhythm of the pulsating volume flow.

[0032] The pump preferably interacts with a balancing chamber arrangement, which is acted upon by the pump with liquid and whose switching causes a pulsating volume flow.

[0033] In one possible embodiment, during the filling of the first chamber of the membrane filter, liquid is at least temporarily not discharged from the system. This enables faster filling of the first subcircuit.

[0034] In particular, the fluid connection of the secondary air separator arranged downstream of the first chamber in the first sub-circuit with the outflow port can be closed during filling and / or the pump arranged there can be not operated. In particular, this can be achieved during pressure-controlled filling, in particular during the entire pressure-controlled filling.

[0035] In a possible embodiment, during the filling of the first chamber of the membrane filter, a pump arranged downstream of the membrane filter in the first dialysate circuit is at least temporarily not operated. In particular, a pump arranged downstream of the membrane filter in the first dialysate circuit can be at least temporarily not operated. In particular, one or more pumps can be arranged downstream of a secondary air separator arranged in the first subcircuit. Preferably, one or more pumps are not operated during the entire pressure-controlled filling period.

[0036] In a further variant, the pressure in the second partial circuit is measured, wherein the first chamber of the membrane filter and in particular the pump is actuated via the first partial circuit as a function of the pressure in the second partial circuit.

[0037] In this case, in a first embodiment of the invention, the measurement of the pressure in the second partial circuit can be part of the measurement of the transmembrane pressure, as has already been described above.

[0038] Alternatively or additionally, the filling of the first chamber of the membrane filter can also take place via the first partial circuit as a function of the absolute pressure and / or the pressure change in the second partial circuit.

[0039] The method control is based on the knowledge that the filling state of the first chamber of the membrane filter can be determined by measuring the pressure in the second sub-circuit. In this case, in particular, the invention utilizes the fact that when air is transferred from the first chamber through the membrane into the second sub-circuit, the pressure in the second sub-circuit increases.

[0040] If the second subcircuit is open to the atmosphere, a dynamic pressure change occurs due to the flow resistance that still exists. If the second subcircuit is closed to the atmosphere, a static pressure change also occurs.

[0041] In particular, dynamic and / or static pressure changes in the second partial circuit can thus be detected and / or monitored.

[0042] In a possible embodiment of the invention, the pressure change, in particular the pressure fluctuation, of the pressure in the second subcircuit is monitored. Preferably, the time course of the filling of the first chamber is related to the detection of the pressure change, in particular the pressure fluctuation, and in particular to the time point at which the pressure change, in particular the pressure fluctuation, is detected and / or no longer detected.

[0043] In one possible embodiment of the invention, complete filling of the first chamber of the membrane filter is detected by monitoring pressure changes, in particular pressure fluctuations, wherein complete filling is preferably inferred when pressure changes, in particular pressure fluctuations, are no longer detected.

[0044] In a feasible design of the present invention, the filling of the first chamber is continued until a pressure change, especially a pressure fluctuation, is detected in the second sub-circuit. In addition, after no longer detecting a pressure change, especially a pressure fluctuation, a minimum remaining filling phase can still be performed.

[0045] In one possible embodiment of the invention, the filling of the first chamber continues until air is detected in the secondary air separator of the first subcircuit, wherein preferably a minimum residual filling phase is still carried out after air is no longer detected.

[0046] Thus, if the membrane is not already air-permeable from the outset due to the material used, or if the membrane is already completely saturated before the air is completely squeezed out of the first chamber of the membrane filter, the air is squeezed out during (further) filling of the first chamber of the membrane filter via the first subcircuit into the secondary air separator arranged downstream of the membrane filter in the first subcircuit. Thus, by monitoring the secondary air separator, it can be ensured that air is no longer pumped from the first chamber of the membrane filter into the first subcircuit, so that complete filling also occurs in this situation.

[0047] By monitoring the pressure in the second partial circuit and / or the air in the secondary air separator, it is ensured that at the end of the step the membrane is completely wetted, ie the dialyzer is filled as well as possible, ie in one embodiment without rotation.

[0048] The minimum remaining filling phase then serves as a safety buffer and for flushing the membrane filter. The minimum remaining filling phase can have a constant length.

[0049] The minimum residual filling phase can include a predetermined pump volume, a predetermined time or a predetermined number of pump strokes and / or balancing chamber switching.

[0050] Preferably, the first chamber of the membrane filter is filled with a pulsating volume flow via the first subcircuit. The pulsating volume flow can be generated by means of a diaphragm pump, for example in the form of a balancing chamber. In particular, the filling can be achieved via multiple balancing chamber switching. However, the filling can also be achieved with a constant volume flow.

[0051] In a possible embodiment of the invention, at least during the initial phase of filling the first chamber, the first subcircuit is filled with a first volume flow of a maximum of 800 ml / min, preferably a maximum of 500 ml / min. The limitation can be independent of the measured pressure. After the initial phase, it is possible to work with a greater maximum volume flow, wherein the volume flow can be controlled as a function of the measured pressure.

[0052] In a feasible design of the present invention, during the filling of the first chamber of the membrane filter via the first sub-circuit, the second sub-circuit is open to the atmosphere, that is, the second sub-circuit is connected to the atmospheric fluid. Thus, the back pressure generated by the air in the second sub-circuit is reduced and / or lowered.

[0053] In a possible embodiment of the invention, during the filling of the first chamber of the membrane filter, the second subcircuit is fluidically connected to the atmosphere via a component that generates a pressure drop. The connection to the atmosphere is preferably achieved via a filter, in particular via a hydrophobic filter and / or a sterile filter and / or a throttle and / or a valve. This maintains a certain resistance to filling the second subcircuit with air from the first chamber via the membrane, which causes a pressure change due to the filling process.

[0054] In a feasible design of the present invention, during the filling of the first chamber of the membrane filter via the first sub-circuit, liquid and / or air are squeezed out of the first chamber into a secondary air separator arranged downstream of the membrane filter in the first sub-circuit, thereby improving the filling of the first chamber and the removal of air from the first chamber.

[0055] In a feasible design, the secondary air separator is at least temporarily not connected to the liquid outflow of the system, in particular by closing the corresponding fluid connection or not running the pump. Thus, liquid does not flow out of the system, so that filling is accelerated.

[0056] In a possible design of the present invention, during the filling of the first chamber of the membrane filter via the first sub-circuit, the secondary air separator arranged downstream of the membrane filter in the first sub-circuit is at least temporarily disconnected from the atmosphere. Depending on the design of the fluid circuit, this may cause the transmembrane pressure to rise more quickly to the desired value, thereby causing a greater volume flow through the membrane.

[0057] For example, during the entire pressure-controlled filling period, the connection to the atmosphere is only established if air is detected in the secondary air separator.

[0058] The secondary air separator can have a container with an inlet and an outlet, preferably in the lower region of the container, for example in the bottom or lower third of the container, so that air collects in the upper region of the container and causes a decrease in the liquid level in the container. A decrease or increase in the liquid level can be detected by a control device of the blood treatment device by means of a liquid level sensor.

[0059] In a feasible alternative design of the present invention, during the filling of the first chamber of the membrane filter via the first sub-circuit, the secondary air separator arranged downstream of the membrane filter in the first sub-circuit is continuously connected to the atmosphere. Thus, air can also be squeezed out toward the atmosphere through the first sub-circuit. The connection to the atmosphere can exist through an opening in the upper region of the container of the secondary air separator.

[0060] In one possible embodiment of the invention, the first partial circuit is filled at least temporarily in an unbalanced manner during the pressure-controlled filling.

[0061] In this case, unbalanced filling means that different volumes of liquid are supplied to and removed from the first subcircuit. As a result, all of the liquid is supplied to the first subcircuit. In the case of balanced filling, the same volume of liquid is supplied to and removed from the first subcircuit. This results in a displacement of the liquid in the first subcircuit and, by means of the displacement of the liquid, also of the air, which can then be separated in the secondary air separator.

[0062] In a possible embodiment of the invention, the filling of the first chamber of the membrane filter via the first sub-circuit does not start in the balanced phase. Alternatively or additionally, the first chamber of the membrane filter is filled via the first sub-circuit at least until an unbalanced filling is detected. For example, the filling can be detected based on a liquid level sensor of the secondary air separator.

[0063] Conversely, in a feasible design of the present invention, the filling of the first chamber of the membrane filter via the first sub-circuit that begins in the balanced phase is followed by an unbalanced phase. In the balanced phase, air preferably moves from the first chamber to a secondary air separator that is arranged downstream of the membrane filter in the first sub-circuit.

[0064] The filling of the first chamber of the membrane filter preferably precedes the filling of the first sub-circuit. Therefore, the filling of the first chamber of the membrane filter preferably starts from a situation in which otherwise the first sub-circuit has already been filled.

[0065] In particular, the first subcircuit can be filled in a first step and the first chamber of the membrane filter can be filled only in a second step. The membrane filter can be separated from the first subcircuit for the first step and fluidically connected to the first subcircuit only for the second step.

[0066] Preferably, in a first step the first subcircuit is filled without the first chamber of the membrane filter being fluidically connected to the first subcircuit, and in a second step the first chamber of the membrane filter is fluidically connected to the first circuit in order to fill said first chamber.

[0067] For the first step, the membrane filter can be separated from the first sub-circuit via a valve and / or bridged by a bypass line.The valve is then opened and / or the bypass line is closed after filling the first sub-circuit.

[0068] The first step can be performed without a membrane filter arranged at the blood treatment device, for example, at the end of a previous treatment, for example, to flush the first subcircuit. Then, in a subsequent treatment, the first subcircuit is initially filled except for the membrane filter.

[0069] Alternatively, for the first step, instead of the membrane filter, the short-circuit can be inserted into the first subcircuit, or its ends can be directly connected to each other. For the second step, the short-circuit is subsequently replaced by a dialyzer and / or the dialyzer is inserted into the first subcircuit.

[0070] The present invention also includes a blood treatment machine, to which at least one membrane filter, in particular a hollow fiber membrane filter, can be coupled, the membrane filter having a first chamber and a second chamber, the first chamber and the second chamber being separated semi-permeably by a membrane, wherein the blood treatment machine comprises:

[0071] at least one first pump actuator of a first pump for pumping a liquid in a first sub-circuit, and at least one second pump actuator for pumping a liquid in a second sub-circuit, wherein a first chamber of the membrane filter is arranged in the first sub-circuit and a second chamber of the membrane filter is arranged in the second sub-circuit, wherein the first pump is arranged upstream of the membrane filter in the first sub-circuit,

[0072] at least two pressure sensors for measuring the pressure in the first sub-circuit and the pressure in the second sub-circuit, and

[0073] A control device which evaluates the signals of the pressure sensor and actuates actuators of the blood treatment machine.

[0074] The blood treatment machine is characterized in that the control device includes a filling program, which controls the first pump actuator to fill the first chamber of the membrane filter via the first subcircuit as a function of the pressure measured in the first subcircuit and the second subcircuit. This results in the same advantages as have been described in detail above with respect to the method according to the invention.

[0075] The membrane filter is preferably a disposable item that is coupled to a blood treatment machine to perform the treatment. The second sub-circuit is preferably also a disposable item.

[0076] Depending on the configuration of the blood treatment machine, the first partial circuit can be a disposable or a fixed component of the blood treatment machine.

[0077] In a possible embodiment of the invention, the control device for executing the filling procedure controls one or more pump actuators and / or one or more valve actuators which actuate valves of the first subcircuit and / or the second subcircuit.

[0078] In a feasible design of the present invention, the filling program is automatically completed by the control device.

[0079] In a possible design solution of the present invention, the control device is programmed to execute the method as described in detail above.

[0080] The blood treatment machine according to the invention can be, in particular, a dialysis machine, in particular a dialysis machine for hemodialysis and / or hemofiltration and hemodiafiltration.

[0081] The present invention also includes a blood treatment system consisting of the blood treatment machine and the membrane filter as described above. In addition, the blood treatment system preferably includes a first sub-circuit and / or a second sub-circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0082] The present invention will now be described in detail based on embodiments and drawings.

[0083] Here it is shown:

[0084] Figure 1 A schematic, simplified diagram showing a fluid circuit of an embodiment of a blood treatment system according to the present invention,

[0085] Figure 2 A diagram is shown in which the profile of the transmembrane pressure during the filling of the first chamber is shown for a method according to the prior art and for a method according to the invention, and

[0086] Figure 3 A diagram is shown in which the course of the pressures measured by individual pressure sensors of a blood treatment system during the filling of a first chamber in the method according to the invention is shown. DETAILED DESCRIPTION

[0087] Figure 1 A schematic simplified diagram of a fluid circuit of an embodiment of a blood treatment system according to the present invention is shown. Here, at least the components of the commonly present components of a blood treatment system that can contribute to the implementation of the present invention are shown. However, not all of the components shown and described are mandatory for the implementation of the present invention. This is derived from the description of the functions of the individual components.

[0088] The blood treatment system comprises a membrane filter 1. The membrane filter 1 comprises a first chamber 2 and a second chamber 3, which are semi-permeably separated by a membrane 50.

[0089] The blood treatment system further comprises a first sub-circuit 4 and a second sub-circuit 5. Here, the first chamber 2 of the membrane filter 1 is arranged in the first sub-circuit 4, and the second chamber 3 is arranged in the second sub-circuit 5. The first chamber 2 of the membrane filter 1 is connected to the inlet side with the inflow line 6 of the first circuit and to the outlet side with the outflow line 7 of the first circuit.

[0090] In the embodiment, the membrane filter 1 is a hollow fiber membrane filter designed as a dialysis filter. In this case, the first sub-circuit 4 is a dialysate circuit and the second sub-circuit 5 is an extracorporeal blood circuit.

[0091] The blood treatment system further comprises a blood treatment machine 40, which is only schematically shown here, comprising at least one first pump actuator of a first pump 10 for pumping liquid in the first sub-circuit 4 and at least one second pump actuator 28 of a pump for pumping liquid in the second sub-circuit 5. Here, the first pump 10 is arranged upstream of the membrane filter 1 in the dialysate circuit.

[0092] Furthermore, a third pump actuator of a third pump 21 and a fourth pump actuator of a fourth pump 20 are provided for pumping the fluid in the first partial circuit 4 , which are both arranged downstream of the secondary air separator 18 in the dialysate circuit.

[0093] Furthermore, pressure sensors 35, 36 are provided for measuring the pressure in the first subcircuit and pressure sensors 34, 33 are provided for measuring the pressure in the second subcircuit. The blood treatment machine 40 has a control device 41, which is also only shown schematically and which evaluates the signals of the pressure sensors 33-36 and controls the actuators of the blood treatment machine.

[0094] The membrane filter 1 and the second subcircuit are preferably designed as disposables and can be coupled to a dialysis machine 40 to perform a treatment. Depending on the design of the system, the first subcircuit can also be designed as a disposable or at least partially or completely form part of the blood treatment machine 40.

[0095] Preferred features of the blood treatment system are described in detail below. However, the invention can also be implemented by means of a differently configured blood treatment system.

[0096] In the embodiment, the first pump 10 in the first subcircuit 4 forms a feed pump which pumps liquid, in the embodiment dialysate, via line 13 to the balancing chamber arrangement 11. From the balancing chamber arrangement 11 the liquid flows via lines 14, 6 to the inlet of the first chamber 2.

[0097] In the exemplary embodiment, a sterile filter 15 is provided in the lines 14 , 6 . Furthermore, a further sterile filter 16 is provided downstream of the sterile filter 15 , which forms a second filter stage for the substituate line 17 .

[0098] Upstream of the first chamber 2, a valve 42 is arranged in the inflow line 6, via which valve the inflow to the membrane filter 1 can be controlled. In addition, downstream of the first chamber 2, a further valve 44 is arranged in the outflow line 7.

[0099] The outlet of the first chamber 2 is connected to a secondary air separator 18 via an outflow line 7. The secondary air separator has a sensor 19, via which the air in the secondary air separator can be detected.

[0100] The outflow line 45 of the air separator 18 is connected to the balancing chamber device 11 via a third pump 21 designed as a dialysate pump. The used dialysate is pumped into the discharge line 23 via the dialysate pump 21 and the balancing chamber device 11.

[0101] Furthermore, an ultrafiltration pump 20 is provided as a fourth pump, which pumps the dialysate from the air separator 18 directly into the discharge line 22 , bypassing the balancing chamber arrangement 11 .

[0102] In the exemplary embodiment, the secondary air separator 18 further comprises a vent valve 43 which connects the air separator 18 to the outlet line 22 .

[0103] In the embodiment, the second sub-circuit has an inflow line 8 connected to the inlet of the second chamber 3 of the membrane filter 1 and an outflow line 9 connected to the outlet of the second chamber 3 .

[0104] In the embodiment, the inflow line 8 is part of the arterial line of the extracorporeal blood circuit 5, and the outflow line 9 is part of the venous line of the extracorporeal blood circuit. The arterial line comprises a patient-side connector 24, an arterial clamp 26, a heparin pump 27, and a pump hose section that can be inserted into a roller pump 28. The venous line has a bubble trap 29, a bubble detector 38, a venous clamp 37, and a patient-side connector 25.

[0105] The pressure sensor 33 is arranged via a filter 30, for example a hydrophobic filter and / or a sterile filter, at the venous bubble trap 29. The bubble trap is also connected to the atmosphere via the filter 30 and the throttle valve 32, wherein the connection can be opened and closed by means of a valve 46. An air pump 31 is also provided, by means of which an integrity test of the membrane 50 can be performed.

[0106] In the exemplary embodiment, pressure sensors 35 and 36 are provided, via which the pressure can be measured upstream and downstream of the first chamber of the membrane filter 1 in the first subcircuit 4. In addition, a pressure sensor 33 is provided to measure the pressure in the venous line of the second subcircuit, as well as a pressure sensor 34 to measure the arterial pressure upstream of the blocked roller pump 28.

[0107] During blood treatment, the dialysate moves in a balanced manner in the first sub-circuit 4 by the action of the feed pump 10, the dialysate pump 21 and the balancing chamber device 11. Here, the dialysate flows from the balancing chamber device 11 via the sterile filter 15 to the first chamber 2 of the membrane filter 1, and from there via the secondary air separator 19 and the dialysate pump 21 to the balancing chamber device 11. In the second sub-circuit 5, blood is pumped from the arterial connector 24 via the blood pump 28 to the second chamber, flows through the second chamber in countercurrent to the dialysate, and flows to the venous connector 25 via the bubble trap 29.

[0108] Before the treatment starts, the first sub-circuit 4, the second sub-circuit 5 and the membrane filter 1 have to be filled and optionally flushed.

[0109] An embodiment of the filling method according to the present invention is described in detail below:

[0110] In an embodiment, the first sub-circuit 4 is first filled with liquid before filling the membrane filter. For this purpose, a short-circuit piece 38 is inserted into the first sub-circuit 4 between the inlet line 6 and the outlet line 7 of the first sub-circuit 4 instead of the membrane filter 1. Filling the first sub-circuit 4 with liquid is achieved, for example, by operating a feed pump 10 for filling the balancing chamber of the balancing chamber device with fresh dialysate, which is moved from the balancing chamber into the line 14, for example, by squeezing out liquid pumped by means of a dialysate pump 21. Alternatively, liquid can also be moved by means of the feed pump 10 from a balancing chamber half of the first balancing chamber 11 that is not fluidically connected to the pump by a valve position into a second non-fluidically connected balancing chamber half of the second balancing chamber 11', and liquid is transferred from the other balancing chamber half of the second balancing chamber 11' into the line 14.

[0111] After the first partial circuit has been filled, the membrane filter 1 which has not yet been filled is inserted into the first partial circuit instead of the short-circuit piece 38. The second partial circuit 5 is likewise connected to the membrane filter 5 and, like the latter, has not yet been filled with liquid.

[0112] According to the invention, the first pump 10 is now controlled in a pressure-controlled manner to fill the first chamber 2 of the membrane filter 1 with liquid via the first subcircuit 4. Here, the pressure in the first subcircuit and / or the second subcircuit is measured, and the filling is controlled as a function of the measured pressure. The filling is preferably controlled by a filling program of the control device 41 of the blood treatment machine.

[0113] A central feature of the method approach according to the invention or of the control device according to the invention is therefore a pressure-controlled filling sequence for controlling the first pump 10 , which is intended to avoid air inclusions in the membrane filter.

[0114] If reference is made in this description to the control, starting and / or stopping of the pump 10 , this also includes the fact that, while the pump itself continues to deliver, the transport of liquid is influenced, in particular released and / or inhibited, by opening or closing one or more valves, for example valves of a balancing chamber.

[0115] Preferably, the filling program controls the filling according to the transmembrane pressure on the membrane 50 of the membrane filter 1 .

[0116] Preferably, the pressure-controlled filling continues as long as a change in the venous pressure and in particular a pressure fluctuation is observed via the pressure sensor 33 .

[0117] As an optional further condition which must be met in order to terminate the pressure-controlled filling, it can be required that no air is detected at the secondary air separator.

[0118] This can be followed by a minimum residual filling phase.

[0119] Features of a preferred embodiment of the filling procedure and the method according to the invention are described below:

[0120] In the pressure-controlled filling procedure, the blood treatment machine preferably performs a filling switch, ie the feed pump 10 conveys the liquid in the first sub-circuit 4 toward the membrane filter 1 .

[0121] For this purpose, the balancing chamber arrangement 11 has two balancing chambers 11 ′ and 11 ″ which are connected via associated valves 12 for filling switching, so that there is no balancing operation, but rather one balancing chamber drives the other balancing chamber.

[0122] The flow rate can be limited to a low first flow rate until a preset switch, in the embodiment until the 6th switch after adding the membrane filter 1. In the embodiment, this is, for example, 500 ml / min. Conversely, after the preset switch, the filling pump 10 can be operated at a higher second flow rate. The second flow rate is preferably greater than 1000 ml / min, for example 1200 ml / min.

[0123] In this case, the feed pump 10 can be operated in a volume-controlled manner.

[0124] However, during the filling process, if the pressure on the membrane 50 exceeds the first threshold, the switching is interrupted and / or the flow rate is reduced until the pressure on the membrane falls below the second threshold again. Preferably, the second threshold is lower than the first threshold in order to avoid too frequent switching.

[0125] For example, if the pressure measured by the pressure sensor 35 at the inlet of the first chamber 2 exceeds the venous return pressure measured by the pressure sensor 33 by more than 230 mmHg, the switching can be interrupted and / or the flow rate can be reduced. The interruption is maintained until the pressure difference to the venous pressure is again below 200 mmHg. Only then does the normal filling operation continue. The pressure difference across the membrane is thereby limited.

[0126] The switching of the balancing chamber can be interrupted, for example, by closing a fresh water valve 60 arranged between the feed pump 10 and the balancing chamber arrangement 11 .

[0127] Depending on the design of the method, the valve 43 can be opened so that a second flow path is present for conducting air out of the first chamber 2, or the valve 43 can be closed. When the valve is closed, the pressure difference required for displacing the air on the membrane is built up more quickly. This can speed up the filling of particularly large membrane filters.

[0128] During the pressure-controlled filling procedure, provision can be made for no transfer of liquid from the secondary air separator 18 to the discharge lines 22 and 23 to take place, ie, for the pumps 20 and 21 to be inoperative and / or for the corresponding valves to be closed.

[0129] As long as the pressure-controlled filling procedure is running, the curve of the venous pressure is monitored. As long as changes in the venous pressure and / or pressure fluctuations or air at the secondary air separator 18 are observed, the device remains in the pressure-controlled filling procedure, as has been described previously. In this case, a change in the venous pressure measured, for example, via the pressure sensor 33 is an indicator of the separation of air from the first chamber 2 into the second chamber 3 on the membrane 50 of the membrane filter 1. Air in the secondary air separator 18 is an indicator of air being squeezed out of the first chamber 2 into the outflow line 7.

[0130] If neither a pressure change in the venous pressure, for example a pressure surge, nor air in the secondary air separator 18 is detected, the membrane filter is considered to be completely filled.

[0131] However, after detecting full filling, the filling program is also provided with a minimum number of switches via the dialyzer. Preferably, the minimum number of switches is performed without pressure control. If air should be identified again during the time, the air is separated via the valve 43 at the secondary air separator.

[0132] This embodiment of the method according to the invention is described again in further detail below:

[0133] In an optional first step, the membrane filter is filled by means of normal, i.e. balanced, balancing chamber switching until air is detected in the secondary air separator 18, which must be assumed to be idling (maximum, for example, 3 switchings when air is detected by the sensor 19). However, in a possible embodiment of the invention, the first step can also be omitted.

[0134] According to the invention, the device then performs a filling switch, ie an unbalanced switch, in a pressure-controlled filling procedure according to the invention, ie the feed pump 10 delivers towards the membrane filter 1. The flow rate is limited to 500 ml / min, for example.

[0135] When filling is switched, the feed pump is delivered to the membrane filter at full power or reduced power. The pressure peaks thus generated at the membrane are first limited by the compliance and flow resistance in the system. The overpressure generated at the dialyzer membrane causes air to be transferred into the second chamber via the membrane 50 between the first chamber and the second chamber, and from there escape to the environment via the ventilation device 32. This will work as long as the dialyzer membrane is not wetted and thus air-permeable at the location where the bubbles are present.

[0136] However, if the pressure at the pressure sensor 35 (dialyser inlet) exceeds the venous return pressure by more than 230 mmHg, the switching is interrupted until the pressure difference to the venous pressure is again below 200 mmHg. The fresh water valve 60 is then opened again. The pressure difference across the membrane is thereby limited.

[0137] Limiting the flow and / or the pressure on the membrane ensures that no air cushions become entrained in the fiber bundle which can no longer be separated subsequently.

[0138] In a first alternative, valve 43 is continuously open. Thus, air and liquid from the first chamber 2 of the membrane filter 1 can additionally reach the outlet via the path. How much air escapes via what path is related to the flow resistance of the membrane, hydraulics and ventilation in the second sub-circuit.

[0139] However, as long as there is no significant dialysate outlet pressure, the valve 43 can also be closed, which can accelerate the filling, particularly in the case of very large filters.

[0140] As long as the pressure-controlled filling procedure is running, the curve of the change in venous pressure is monitored. As long as a change in venous pressure or air at the sensor 19 is observed, the device remains in the pressure-controlled filling procedure, as in the previous step. Here, a change in venous pressure is a sign that air continues to move across the membrane.

[0141] The above-mentioned monitoring ensures that the membrane is completely wetted at the end of the step (or, for example, when the membrane is gas-impermeable, air can no longer escape via the dialysate outlet), ie the membrane filter is filled as well as possible (without rotation).

[0142] After testing the filter thus filled, a minimum number of switching operations are also performed via the membrane filter. If air is detected again during this time, the air is separated via valve 43 via a pressure-controlled filling procedure.

[0143] Compared to the curve of the mean dialysis fluid pressure as line 70 in the method according to the prior art, ie without pressure control, Figure 2The course of the mean dialysate pressure in the method according to the invention, ie during pressure control, is shown as line 71. The mean dialysate pressure is calculated as the average of the pressures at the inlet of chamber 1 (pressure sensor 35) and at the outlet of chamber 1 (pressure sensor 36).

[0144] During the balanced filling phase 74 used in both methods, no significant dialysate pressure is yet applied, since liquid or air is only moved in the first subcircuit. However, according to the invention, in an alternative embodiment, the balanced filling phase 74 can also be omitted.

[0145] During the unbalanced, pressure-controlled filling phase 75, the maximum achievable dialysate pressure initially increases with each balancing chamber switchover. In the first phase 72, the pressure peak has not yet reached the first threshold value 77, so that the pressure control does not intervene. In this case, the dialysate pressure is therefore limited only by the compliance of the hose set, as is already known from the prior art.

[0146] In contrast, in the second phase 73, the pressure peak exceeds the first threshold value 77. If this is detected by the control device, it stops the inflow of dialysate until the transmembrane pressure and / or the dialysate pressure again falls below a second, lower threshold value 78. Normal filling is then recorded again until the first threshold value is exceeded again. Thus, in the exemplary embodiment, a plurality of pressure peaks are generated per balancing chamber switch.

[0147] As a comparison with the prior art directly shows, operation is thus performed at a significantly lower maximum dialysate pressure than according to the prior art. The pressure limitation prevents the transfer of dialysate from the first chamber into the second chamber during the filling of the first chamber.

[0148] After the end of the pressure-controlled filling phase 75 , a flushing phase 76 takes place, in which the pressure drops again.

[0149] Figure 3 The pressure curves at the individual pressure sensors during the just described phases of filling according to the invention are now shown in detail. The individual lines show the following:

[0150] 80 Pressure at the pressure sensor 35 (pressure at the inlet of the first chamber 2)

[0151] 81 Pressure at the pressure sensor 36 (pressure at the outlet of the first chamber 2)

[0152] 82 Pressure at pressure sensor 33 (pressure in venous line / second chamber 3)

[0153] 83 Transmembrane pressure

[0154] 84 Filling status of the first chamber

[0155] It can be clearly seen that at the beginning of the pressure-controlled filling phase 75, the pressure 82 in the venous line or in the second chamber 3 fluctuates during the cycles of the balancing chamber switching due to the air that is squeezed out of the first chamber into the second chamber via the membrane. However, after a certain number of balancing chamber switchings, the pressure fluctuations disappear again, because the membrane is now soaked and air can no longer be squeezed out via the membrane. As a result, the dialysate pressure 81 downstream of the first chamber also increases.

[0156] According to the invention, the pressure 82 on the blood side can be used in order to detect the complete filling of the membrane filter or the complete soaking of the membrane and / or to manipulate the time course and / or duration of the filling procedure, as described in detail above. In particular, after the pressure fluctuation of the detection pressure 82, a minimum remaining filling phase is carried out, in which the first chamber is further filled.

[0157] The transmembrane pressure is limited to a certain value, for example 200 mBar or 250 mBar, by a pressure-controlled filling procedure. This prevents the dialysate from flowing into the second chamber, especially in the minimum residual filling phase, in which a high transmembrane pressure could occur without such a pressure limitation.

[0158] In an embodiment, the pressure-controlled filling procedure works directly with the transmembrane pressure, which is compared with a threshold value. However, in an alternative design, the average dialysate pressure and / or the pressure at the inlet of the first chamber can also be compared with a threshold value and limited, since the pressure on the dialysate side and in particular the pressure at the inlet of the first chamber is inherently significantly greater than the pressure on the blood side and thus strongly determines the transmembrane pressure.

[0159] After the first chamber is filled, the second chamber can be filled according to one of the methods known from the prior art. The filling can be achieved, for example, by liquid via the membrane 50 and / or by an alternative line.

Claims

1. A method for filling a membrane filter of a blood treatment system, wherein the blood treatment system has: at least one blood treatment machine; A membrane filter, wherein the membrane filter is a hollow fiber membrane filter, the membrane filter having a first chamber and a second chamber, the first chamber and the second chamber being semi-permeably separated by a membrane; and at least one first subcircuit and at least one second subcircuit, wherein the first chamber of the membrane filter is arranged in the first subcircuit and the second chamber of the membrane filter is arranged in the second subcircuit, wherein the first chamber of the membrane filter is filled with liquid via the first subcircuit, while the second chamber remains filled with air, wherein the first subcircuit is a dialysate circuit and / or the second subcircuit is an extracorporeal blood circuit, and wherein a pump is arranged upstream of the membrane filter in the first subcircuit, It is characterized in that actuating the pump to fill the first chamber of the membrane filter via the first subcircuit according to the pressure measured in the first subcircuit and / or the transmembrane pressure, so that during the filling of the first chamber of the membrane filter with liquid, air present in the first chamber is transferred via the membrane into the second chamber of the membrane filter and thus into the second subcircuit, and / or preventing the dialysate from transferring from the first chamber into the second chamber during the filling of the first chamber, wherein the delivery rate of the pump during filling is reduced or the pump is stopped as soon as the pressure in the first subcircuit and / or the transmembrane pressure exceeds a first threshold value, and In this case, the delivery rate of the pump during filling is increased or the pump is restarted as soon as the pressure in the first subcircuit and / or the transmembrane pressure does not exceed a second threshold value. 2 . The method according to claim 1 , wherein the volume flow generated by the pump for filling and / or the time profile and / or duration of the filling by the pump are controlled as a function of the pressures measured in the first and second subcircuit.

3. A method according to claim 1, wherein the pressure in the first sub-circuit and / or the transmembrane pressure on the membrane of the membrane filter is determined, and the pump is controlled to fill the first chamber of the membrane filter via the first sub-circuit according to the pressure in the first sub-circuit and / or the transmembrane pressure. The method according to claim 1 , wherein the first threshold is at least 50 mBar, or at least 100 mBar, or at least 200 mBar. 5 . The method according to claim 1 , wherein the second threshold value is at least 50 mBar, or at least 100 mBar, or at least 150 mBar. The method according to claim 1 , wherein an absolute value of the first threshold is greater than an absolute value of the second threshold.

7. The method according to claim 1, wherein the pump is controlled such that an overpressure is at least temporarily generated in the first chamber of the membrane filter, wherein the overpressure is at least 50 mBar, or at least 100 mBar, or at least 200 mBar.

8. The method according to any one of claims 1 to 7, wherein the pump is operated in a volume-controlled manner to fill the first chamber of the membrane filter, wherein once the pressure in the first sub-circuit and / or the transmembrane pressure exceeds a first threshold value, the volume-controlled operation is stopped or the volume flow is reduced, and / or wherein once the pressure in the first sub-circuit and / or the transmembrane pressure does not exceed a second threshold value, the volume-controlled operation is resumed or the volume flow is increased.

9. A method according to any one of claims 1 to 7, wherein the first chamber of the membrane filter is filled with a pulsating volume flow, a pressure peak is generated in the first chamber of the membrane filter by the pulsating volume flow, wherein the pump acts together with a balancing chamber device, the balancing chamber device is loaded with liquid by the pump, and the switching of the balancing chamber device causes a pulsating volume flow.

10. A method according to any one of claims 1 to 7, wherein liquid is at least temporarily not discharged from the blood treatment system while the pump is controlled to fill the first chamber of the membrane filter based on the measured pressure and / or transmembrane pressure in the first sub-circuit, and / or wherein during the filling of the first chamber of the membrane filter, a pump arranged downstream of the membrane filter in the first dialysate circuit is at least temporarily not operated.

11. A method according to any one of claims 1 to 7, wherein the pressure is measured in the second sub-circuit and the first chamber of the membrane filter is filled via the first sub-circuit according to the pressure in the second sub-circuit, wherein dynamic and / or static pressure changes in the second sub-circuit are detected and / or monitored.

12. A method according to claim 11, wherein pressure fluctuations of the pressure in the second sub-circuit are monitored, wherein the time course of the filling is related to the detection of the pressure fluctuations, and / or wherein complete filling of the first chamber of the membrane filter is identified by monitoring the pressure fluctuations, wherein complete filling is inferred when pressure fluctuations are no longer detected.

13. The method according to any one of claims 1 to 7, wherein the filling is continued until a pressure fluctuation in the second sub-circuit is detected.

14. The method according to any one of claims 1 to 7, wherein during the filling of the first chamber of the membrane filter via the first sub-circuit, the second sub-circuit is connected to the atmospheric fluid.

15. The method according to any one of claims 1 to 7, wherein during the filling of the first chamber of the membrane filter, the second sub-circuit is fluidically connected to the atmosphere via a member generating a pressure drop.

16. The method according to any one of claims 1 to 7, wherein during filling of the first chamber of the membrane filter via the first sub-loop, liquid and / or air are squeezed out of the first chamber into a secondary air separator arranged downstream of the membrane filter in the first sub-loop.

17. A method according to any one of claims 1 to 7, wherein the first sub-loop is filled at least temporarily in an unbalanced manner while the pump is controlled to fill the first chamber of the membrane filter based on the measured pressure and / or transmembrane pressure in the first sub-loop, wherein the filling of the first chamber of the membrane filter via the first sub-loop is started without a balancing phase, and / or the filling of the first chamber of the membrane filter via the first sub-loop is carried out unbalancedly at least until the filling is detected.

18. The method according to claim 13, wherein a minimum remaining filling phase is still performed after pressure fluctuations are no longer detected, wherein the minimum remaining filling phase comprises a predetermined pump volume, or the minimum remaining filling phase comprises a predetermined time or a predetermined number of pump strokes and / or a predetermined number of balancing chamber switches.

19. The method of claim 16, wherein the secondary air separator is at least temporarily disconnected from a liquid drain of the blood treatment system.

20. A blood treatment machine, to which at least one membrane filter can be coupled, the membrane filter being a hollow fiber membrane filter, the membrane filter having a first chamber and a second chamber, the first chamber and the second chamber being semi-permeably separated by a membrane, wherein the blood treatment machine comprises: - at least one first pump actuator of a first pump for pumping a liquid in a first sub-circuit, and at least one second pump actuator of a second pump for pumping a liquid in a second sub-circuit, wherein the first chamber of the membrane filter is arranged in the first sub-circuit and the second chamber of the membrane filter is arranged in the second sub-circuit, wherein the first pump is arranged upstream of the membrane filter in the first sub-circuit, at least one pressure sensor for measuring the pressure in the first sub-circuit, and / or at least one first pressure sensor arranged at the first sub-circuit and at least one second pressure sensor arranged at the second sub-circuit, the first pressure sensor and the second pressure sensor being used to measure the transmembrane pressure, and a control device which evaluates the signal of the pressure sensor and actuates actuators of the blood treatment machine, It is characterized in that The control device comprises a filling program, which controls the first pump actuator to fill the first chamber of the membrane filter via the first subcircuit as a function of the pressure measured in the first subcircuit and / or the transmembrane pressure, so that during the filling of the first chamber of the membrane filter with liquid, the air present in the first chamber is transferred via the membrane into the second chamber of the membrane filter and thus into the second sub-circuit, and / or during the filling of the first chamber, the dialysate is prevented from transferring from the first chamber into the second chamber, reducing the delivery rate of the first pump during filling or stopping the first pump as soon as the pressure in the first subcircuit and / or the transmembrane pressure exceeds a first threshold value, and As soon as the pressure in the first subcircuit and / or the transmembrane pressure does not exceed a second threshold value, the delivery rate of the first pump during filling is increased or the first pump is started again.

21. A blood treatment machine according to claim 20, wherein the control device controls one or more pump actuators and / or one or more valve actuators to perform the filling procedure, the one or more valve actuators operate valves of the first sub-circuit and / or the second sub-circuit, and / or wherein the filling procedure is automatically completed by the control device.

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