Device for treating a medicinal liquid and medical cassette

Description

[0001] The present invention relates to a device for treating a medical fluid, which comprises a treatment machine with a coupling surface, wherein a cassette made of a hard part with fluid-conducting channels covered by a flexible film can be coupled to the coupling surface of the treatment machine. Furthermore, the present invention relates to a medical cassette made of a hard part with fluid-conducting channels covered by a flexible film, wherein the cassette can be coupled to a coupling surface of a treatment machine. Furthermore, the present invention relates to a method for coupling a cassette made of a hard part with fluid-conducting channels covered by a flexible film to the coupling surface of a treatment machine for treating a medical fluid, as well as a method for testing the leak tightness of such a medical cassette.

[0002] The treatment machine can be a blood treatment machine, such as those used in hemodialysis or peritoneal dialysis. In such a case, the medical cassette contains the blood or dialysis fluid-carrying channels and is connected to the treatment machine's actuators and sensors via the coupling surface. The medical cassette can thus be designed as a cost-effective disposable part, while the actuators for controlling the fluid flow through the cassette, as well as the sensors for level detection or pressure measurement, are integrated into the treatment machine.

[0003] Such disposable medical cassettes consist of a thin-walled, three-dimensional rigid plastic part with a flat, circumferential support edge and various recesses (chambers, webs, and channels). Medical fluids such as dialysate or blood can be conveyed through the chambers and channels formed by these three-dimensional structures of the rigid plastic part. The support surface of the cassette is sealed in a liquid-tight manner by a flexible film, advantageously a polymer film, which is connected circumferentially to the support edge of the rigid part, in particular welded and / or glued. During use, the medical cassette is pressed against the coupling surface of the treatment machine with the flexible film, so that the treatment machine's actuators and sensors rest on the polymer film.In addition, this pressure presses the flexible film onto the webs of the cassette, thus ensuring a fluid-tight separation of the fluid-carrying channels in the hard part by the webs and the flexible film.

[0004] The coupling surface of the treatment machine accordingly usually has actuators, sensors and contact force transmission surfaces. The actuators and sensors of the blood treatment machine are arranged opposite the fluid-carrying channels of the cassette when the cassette is coupled. The actuators can thereby form valves by pressing the film down, whereby the flexible film is pressed into areas of the fluid-carrying channels and closes them. The sensors measure, for example, the pressure or temperature of the fluid in the fluid-carrying channels. The contact force transmission surfaces press the flexible film against sealing webs of the hard part, which surround the fluid-carrying channels in order to seal them off from one another and from the rest of the cassette. The coupling surface is usually formed by a flat surface of a carrier element, which, for example,is made of metal, in which receptacles for the sensors and actuators are provided, and the sensors inserted flat into these receptacles.

[0005] A flexible mat, e.g. made of silicone or another elastomeric material, is usually arranged on the coupling surface of the treatment machine. This has the advantage that the sensor surfaces are protected from environmental influences and that the machine surface is liquid-tight and thus ideal for hygienic cleaning. The flexible mat represents a part of the treatment machine to which the cassette is coupled as a disposable part. The flexibility of the mat ensures the functionality of the actuators. In addition, the flexible film can be easily pressed onto the coupling surface via the flexible mat, which enables good contact with the actuators, sensors and contact force transmission surfaces. However, the treatment machine can also be operated without a flexible mat, so that the flexible film rests directly on the coupling surface and the sensors and actuators couple directly to the film.

[0006] When coupling sensors to the film surface, however, it is difficult with existing systems to achieve a good coupling in order to obtain correct measurement values. In particular, air that becomes trapped in the transmission path between the flexible film and the sensor surface when the cassette is inserted leads to a falsification of the measurement results. This applies to pressure sensors (particularly when measuring pressures lower than ambient pressure), but also to level detection and actuators such as valves. During coupling, unwanted air pockets between the outer surface of the flexible film and the contacting mat surface of the flexible mat or, if no mat is used, the contacting surface of the treatment machine must be eliminated. This is usually achieved by air extraction. However, the fluidic contact of this space is complicated.In particular, there is the problem that when the film is placed against the mat or the coupling surface, the film seals itself, leaving air islands.

[0007] From DE 101 57 924 C1 and DE 102 24 750 A1, it is therefore known to implement air transport by means of defined, integrated mat channels on the machine-side rear side of the machine mat. The air is conducted locally from the surface of the flexible film through the mat to the air channels arranged on the machine side through continuous slots in the area of ​​the mat channels. However, this only results in air transport at precisely defined points on the flexible film of the cassette, at which the air is sucked through the slots in the mat to the mat channels arranged on the machine side. These mat channels must therefore be located in the area of ​​the liquid-carrying channels of the cassette to ensure effective suction there, which can lead to safety problems. Such a machine mat with integrated mat channels and slots is also cost-intensive to manufacture and complex to clean.Furthermore, the sensor surface is no longer ideally protected from environmental influences and is no longer hermetically sealed by the mat, which also poses hygiene problems. Furthermore, there is a need to further improve the reliability of the air extraction system, as the only localized extraction through the slots can still lead to the entrapment of air pockets.

[0008] The object of the present invention is therefore to achieve a cost-effective, reliable and hygienic air extraction system.

[0009] According to the invention, this object is achieved by a device for treating a medical fluid according to claim 8. This device comprises a treatment machine with a coupling surface, and a cassette made of its hard part with fluid-conducting channels, which are covered by a flexible film, wherein the cassette can be coupled to the coupling surface of the treatment machine.

[0010] The detailed design of the device according to the invention will be described in more detail below. However, preferred embodiments will be presented first.

[0011] Preferably, when the cassette is coupled, a layer of an air-permeable, porous material is arranged between the flexible film and the coupling surface, at least in partial areas, through which air can be extracted over a wide area during the coupling process and / or when the cassette is coupled. According to the invention, air is no longer extracted only selectively through the slots in the flexible mat, as in the prior art, so that air pockets can remain, but rather across the entire area through the layer of an air-permeable, porous material. This enables the air to be extracted from the area between the flexible film and the coupling surface over the entire area, reliably preventing air pockets, which can never be ruled out with purely local extraction.In addition, the difficult-to-clean design of the flexible mat with mat channels can be dispensed with and a flexible mat with essentially no openings or no mat at all can be used.

[0012] Preferably, it is possible for air to be particularly advantageously extracted during the coupling process, in particular shortly before the coupling process is completed. When coupling the cassette, the contact pressure is increased to a maximum value. Extraction can begin as soon as the cassette is in contact with the coupling surface, but before the cassette is pressed with maximum contact force. Even during this short phase, a negative pressure can be created. In particular, the porous material or the profiling is less compressed during this phase and thus conducts air better. However, the air can also be extracted when the cassette is fully coupled.

[0013] Advantageously, the air can be extracted through the layer of an air-permeable, porous material along the plane of the layer. This enables air to be extracted along the coupling plane, while at the same time the actuators and sensors can act perpendicular to the coupling plane. It is sufficient to fluidically contact the space between the film and the coupling surface at one or more extraction points and to connect it to an extraction device, from which the air is extracted across the entire surface of the coupling plane. If a mat is provided, the flexible mat, which otherwise has no perforations, can have openings at one or a few points for fluidically contacting the air-permeable, porous layer.

[0014] The layer of air-permeable, particularly porous, material allows the vacuum for extraction to act across the entire area of ​​the layer, enabling reliable extraction across the entire surface. The material of the layer is advantageously permeable to air both along the main plane of the layer and across the main plane. This allows air to be transported, particularly within the material layer, along its main plane, thus reliably extracting the air between the surface of the flexible film and the coupling surface.

[0015] Advantageously, the layer of an air-permeable, porous material is arranged directly on the flexible film when the cassette is coupled. This results in direct suction of air from the surface of the flexible film, enabling secure coupling.

[0016] Furthermore, the layer of air-permeable, porous material advantageously comprises a nonwoven fabric. Such a nonwoven fabric enables the air transport described above, ensuring uniform contact between the coupling surface and the film, and thus between the sensors and actuators and the film, while simultaneously ensuring surface suction in the plane between the flexible film and the coupling surface or flexible mat.

[0017] Furthermore, the layer of an air-permeable material is advantageously arranged over the entire surface of the flexible film. This provides a cost-effective and simple way to enable air extraction via a layer of an air-permeable material that covers the entire surface. However, for certain applications, it is also possible to provide such a layer of an air-permeable material only in certain areas.

[0018] Furthermore, the cassette is advantageously pressed onto the coupling surface in the coupled state, wherein the pressure transmitted during the coupling process and / or when the cassette is coupled via the layer of an air-permeable material orthogonally to its plane presses the film fluid-tightly onto the liquid-conducting channels of the hard part of the cassette, while the layer of an air-permeable porous material remains air-permeable along its plane. The layer of an air-permeable porous material can thus transmit the pressure required to seal the liquid-conducting channels through the interaction between the webs of the hard part and the film, which is pressed onto the webs. At the same time, however, it remains gas-permeable along its plane, thus ensuring surface extraction of air between the film and the coupling surface.

[0019] Furthermore, the treatment machine advantageously has a flexible mat, in particular a silicone mat, arranged on the coupling surface, and the cassette can be coupled to the coupling surface of the treatment machine via the flexible mat.

[0020] In an advantageous embodiment, the treatment machine has a flexible mat arranged on the coupling surface, wherein the cassette can be coupled to the coupling surface of the treatment machine via the flexible mat and a layer of an air-permeable material is arranged between the flexible film and the flexible mat when the cassette is coupled. The flexible mat can thus seal the coupling surface in a liquid-tight manner and thus create a particularly easy-to-clean and hygienic arrangement, while suction takes place via the air-permeable layer arranged between the flexible mat and the flexible film. Silicone or another suitable elastomer can be used as the material for the flexible mat. As already described above, a porous material layer such as a fleece can be used as the air-permeable layer.

[0021] In the present invention, however, due to the surface suction of the air along the coupling plane, it is also possible to dispense with the flexible mat between the flexible film of the cassette and the coupling surface of the treatment machine and to provide only a layer of an air-permeable porous material such as nonwoven fabric, so that the flexible film of the medical cassette lies directly on the coupling surface of the treatment machine via the layer of an air-permeable material without an intermediate mat and the air suction takes place directly between the coupling surface and the flexible film.

[0022] According to a further preferred embodiment, the flexible mat is made of an air-permeable material and is designed such that, during the coupling process and / or when the cassette is coupled, air is extracted from an area of ​​the flexible mat without any perforations, specifically along the plane of the flexible mat and / or through the flexible mat. By using a permeable mat material, an additional layer of an air-permeable material can be dispensed with, since the surface extraction takes place via the flexible mat itself. The vacuum can then be supplied via corresponding channels in the coupling surface of the treatment machine.Since thin silicone layers exhibit a certain permeability to air, the flexible mat can be molded from silicone and made very thin in the areas where air needs to be extracted, allowing air to be extracted directly through the mat by applying a sufficiently high negative pressure. This eliminates the need for slits through the mat, which would complicate cleaning. Furthermore, the coupling surface remains fluid-tight.

[0023] Alternatively or in addition to the layer made of an air-permeable porous material or the flexible mat made of an air-permeable material described above, the surface of the film or the surface of the flexible mat facing the film can also have a profile through which air can be sucked out.

[0024] According to a further preferred embodiment, the surface of the flexible film has a profile through which air can be extracted along the profile of the film during the coupling process and / or when the cassette is coupled. This also enables reliable extraction of air from the area between the film and the coupling surface or mat along the coupling plane by extracting the air through the channels formed by the profile of the film surface. The profile thus also enables surface extraction of air and thus prevents the formation of air pockets, whereby it is provided at least in the areas where air-free coupling is necessary.The profiling in the surface of the film is advantageously small enough that no or only minimal fluctuations in the contact pressure between the flexible film and the webs of the hard part occur, but large enough that the channels created by the profiling are not completely closed by the pressure between the coupling surface or mat and film, but remain air-conducting.

[0025] Profiling can be achieved by embossing the film surface. Alternatively, profiling can be applied directly during the film extrusion process.

[0026] Furthermore, it is possible to apply a profiling to the side of the flexible mat facing the film. The present invention therefore further comprises a device for treating a medical fluid, which comprises a treatment machine with a coupling surface and a flexible mat, in particular a silicone mat, arranged on the coupling surface, wherein a cassette made of a hard part with fluid-conducting channels covered by a flexible film can be coupled to the coupling surface of the treatment machine via the flexible mat. According to the invention, the surface of the flexible mat facing the flexible film has a profiling through which air can be sucked away along the profiling of the flexible mat during the coupling process and / or when the cassette is coupled.The extraction through the profiling of the surface of the flexible mat is carried out in the same way as the extraction through the profiling of the flexible film, as described above.

[0027] However, profiling the film has the decisive advantage over profiling the mat's surface facing the film: the surface of the mat facing the film can be made smooth and is therefore easy to clean. The cassette, on the other hand, is disposable anyway, so it doesn't need to be cleaned after use but can be disposed of.

[0028] Advantageous profiling designs, which are applicable for both the profiling of the flexible film and the profiling of the mat surface, are described below: The profiling advantageously has a mesh structure and / or a meandering and / or linear structure. A mesh structure, particularly advantageously a honeycomb structure, allows for easy and safe extraction of air across a large area. A meandering structure, on the other hand, allows for targeted extraction in specific areas.

[0029] Furthermore, the profiling is advantageously designed to be anisotropic and / or inhomogeneous. By selecting the appropriate structure, it is possible to achieve anisotropic extraction, for example, by making the channels larger from left to right than from top to bottom. The structure can also be designed inhomogeneously across the surface. This makes it possible, for example, to achieve uniform extraction of the air across the surface, even if the space between the film and the mat is only fluidically connected to the extraction device at one point.

[0030] The aspect ratio of the resulting channels is important for the achievable extraction performance with this type of profiling. The width of the channels is advantageously smaller than their depth. Such narrow, deep channels ensure that the channels are not closed when the film and mat are pressed together, thus allowing extraction to continue. The shallower the channels, the greater the risk of sealing due to partial contact of the film with the mat. If the channels are too wide, there is also an increased risk that the compression on the smooth back of the film with the webs of the rigid part will become too inhomogeneous, leading to leaks between the fluid-carrying channels on this side.

[0031] In a further embodiment, the profiling of the film surface or the mat surface can run along the fluid-carrying channels. This allows for a smaller volume to be evacuated, thus reducing the time required for suction extraction or the time required for an initial leak test. Furthermore, the air is only extracted where an air-free connection between the film and the flexible mat is actually necessary. In areas without fluid-carrying channels, however, such an air-free connection is not necessary. The profiling can therefore advantageously extend in a meandering and / or linear pattern along the fluid-carrying channels.

[0032] However, the profiling advantageously converges in one or more areas outside the fluid-carrying channels, forming extraction points. This allows for easy connection, for example, to a suction device in these areas outside the fluid-carrying channels, while the profiling extending from the extraction point into the areas of the fluid-carrying channels ensures reliable extraction of air from these areas.

[0033] Advantageously, the profiling runs essentially perpendicular to the channel web edge at the transition from the area with fluid-conducting channels to the area outside the fluid-conducting channels. This ensures uniform compression of the film against the channel web edges without the profiling losing its air-conducting function due to the compression.

[0034] Advantageously, the profiling is spaced from the channel web edges in the areas where it does not cross the channel web edges. This allows for drainage only in the liquid-wetted film areas required for the process. In the remaining areas, however, no air extraction is necessary due to the high contact pressure between the film and the rigid part.

[0035] Advantageously, the profiling is also designed in such a way that there is no direct connection between areas of the film with different fluid-carrying channels. If the film ruptures, this has the advantage that the fluid cannot spread along the profiling across the entire cassette. In particular, ruptures in an area without fluid-carrying channels remain without consequences. Even if the film ruptures in an area with fluid-carrying channels, the fluid is only drawn along the profiling to the suction point, while leakage across the channel web edges between the fluid-carrying channels is prevented.

[0036] However, good and reliable compression and air extraction can also be achieved using a honeycomb structure, which naturally does not run along the fluid-carrying channels and whose profiling is not always perpendicular to the channel web edges. The advantage of this design is its simple and cost-effective production.

[0037] Advantageously, in the device according to the invention, the cassette is pressed with the coupling surface in the coupled state, wherein the film is pressed fluid-tight with the liquid-conducting channels of the hard part of the cassette, but the profiling along its plane allows air transport.

[0038] The device according to the invention is described in more detail below: The device according to the invention for treating a medical fluid comprises a treatment machine with a coupling surface and a flexible mat, in particular a silicone mat, arranged on the coupling surface, and a cassette made of a hard part with fluid-conducting channels covered by a flexible film, wherein the cassette can be coupled to the coupling surface of the treatment machine via the flexible mat. According to the invention, during the coupling process and / or when the cassette is coupled, air can be sucked out along a plane between the flexible film and the surface of the flexible mat facing the flexible film. This eliminates the need to equip the flexible mat with complex and difficult-to-clean mat channels and slots.Rather, the air can be extracted safely and easily between the mat surface and the flexible film. The extraction is advantageously achieved via a layer of air-permeable material arranged at least in certain areas, or via a profiled section of the flexible film or mat surface. This results in the advantages already described above.

[0039] According to the invention, air is no longer extracted at specific points through the slits in the flexible mat, as in the prior art, but across the entire plane between the film and mat. This means that it is sufficient to create fluid contact between the space between the film and mat at one or a few points and to connect it to the extraction device, from which the air is extracted across the entire plane along the coupling plane between the film and mat. This eliminates the need for the cost-intensive design of the flexible mat with mat channels. In addition, a secure, air-free connection between the film and mat is ensured without the mat having to have slits, thus once again enabling a liquid-tight and thus ideally hygienically cleanable machine surface.

[0040] The air is advantageously extracted via a structure located between the flexible film and the flexible mat. This enables air to be conducted along the coupling plane, while simultaneously allowing the actuators and sensors to act perpendicular to the coupling plane. In particular, this advantageously involves a flat structure, such as the aforementioned layer of air-permeable material or a profiling of the surface of the film or mat. This enables the entire surface of the air to be extracted from this area, reliably preventing air pockets, which can never be ruled out with purely localized extraction.

[0041] According to the invention, the device comprises at least one suction device. This suction device provides a vacuum, which is connected to the area between the flexible film and the flexible mat or coupling surface, thus enabling suction. It may be advantageous to have multiple suction devices to improve the testability of the suction device.

[0042] Furthermore, in the device according to the invention, regardless of the structure used to realize the surface suction, the air-conducting layer is fluidically connected to the suction device at one or more locations outside the area of ​​the liquid-conducting channels. Since the suction takes place along the coupling plane, it is no longer necessary in the present invention to provide a fluidic connection to a vacuum device directly in the area of ​​the liquid-conducting channels.

[0043] According to the invention, the suction is carried out through the cassette. The suction is carried out via one or more suction openings located in the hard part of the cassette, which are advantageously equipped with a hydrophobic membrane. This allows for easy fluidic contact with the air-conducting layer.

[0044] Furthermore, the device according to the invention advantageously comprises an optical sensor for detecting leaks, in particular by scattered light wetting detection. This results in simplified contactless leak detection, particularly in conjunction with a profiling of the film surface, which changes its reflective properties due to the escape of liquid, which can be detected by the optical sensor.

[0045] Furthermore, the device according to the invention advantageously comprises a control system that automatically extracts the air. The control system controls the extraction device and thus automatically ensures air-free coupling of the medical cassette.

[0046] Furthermore, the control system advantageously performs an automatic leak test of the medical cassette. This can be done, as described further below, by checking the negative pressure during air extraction.

[0047] Furthermore, the devices according to the invention, as already described, advantageously use a medical cassette, which is presented below.

[0048] The medical cassette according to claim 1 of the present invention comprises a hard part with fluid-conducting channels covered by a flexible film, wherein the cassette can be coupled to a coupling surface of a treatment machine. According to the invention, the medical cassette has at least one suction opening arranged in the hard part of the cassette.

[0049] Preferably, a structure is arranged on the flexible film through which air can be extracted along the plane of the film surface during the coupling process and / or when the cassette is coupled. This makes it possible, as already explained in detail with regard to the device for treating a medical fluid, to ensure safe and reliable extraction of the air between the flexible film and the mat or the coupling surface of the treatment machine. It is particularly advantageous that the structure forms part of the medical cassette, as this is a disposable part and therefore does not need to be cleaned after use. Thus, the structure for air extraction does not have to meet any special requirements regarding cleanability.

[0050] Advantageously, a layer of an air-permeable, particularly porous material is arranged on the flexible film, at least in partial areas, through which, when the cassette is connected, air can be extracted across the entire surface of the material layer. The advantages of such an arrangement have already been described above with regard to the device. The layer of an air-permeable, particularly porous material arranged on the flexible film allows for reliable and uniform, surface-wide extraction of the air.

[0051] Advantageously, the layer of air-permeable material is applied over the entire surface of the flexible film. This allows for a cost-effective and simple arrangement in which air can be extracted across the entire surface between the flexible film and the coupling surface of the treatment machine.

[0052] Advantageously, the layer of air-permeable material is welded to the cassette along a peripheral edge. This ensures that the layer of air-permeable material forms a single unit with the cassette and is securely held to it. Furthermore, the welding of the layer of air-permeable material takes place in a single step, along with the welding of the film to the rigid part. This allows for cost-effective production.

[0053] Furthermore, the welding advantageously forms a gas-tight barrier along the plane of the material layer. This ensures that air is only sucked out along the plane of the material layer in the area in which the cassette is pressed onto the treatment machine. Otherwise, air could be sucked in from the sides and thus prevent ventilation of the area between the flexible film and the treatment machine. This can be exploited because when the layer of an air-permeable material is welded onto the film, the structure of the advantageously porous material layer is changed in such a way that a gas-tight barrier is created. At this point, the flexible mat or the coupling surface is sealed against a material layer that has been made air-impermeable at this point. Advantageously, the layer of an air-permeable material is welded to the hard part of the cassette.For this purpose, the layer of an air-permeable material advantageously consists of a material that can be welded to the plastic from which the hard part of the cassette is made.

[0054] Alternatively or additionally, the hard part of the cassette can have a peripheral edge area in which the structure, in particular the layer of an air-permeable material, does not extend, so that this edge area forms a sealing ridge during compression. This sealing ridge, formed by the edge area without a structure, thus ensures that the space between the film and the mat or the coupling surface of the treatment machine can be reliably ventilated. In particular, the layer of an air-permeable material or profiling can be omitted in the edge area of ​​the cassette.

[0055] Furthermore, the flexible film is advantageously welded to the hard part of the cassette in the peripheral edge area. This peripheral edge area can thus be used, as in the prior art, both for welding to the flexible film and as a sealing strip for the structure.

[0056] Furthermore, in the present invention, the layer of an air-permeable material is advantageously connected to the film, in particular by gluing and / or spot-welding and / or lamination and / or tacking. This ensures a secure hold of the layer of an air-permeable material on the flexible film, e.g., even if the layer is not welded to the rigid part in the edge region.

[0057] Furthermore, in the medical cassette of the present invention, the pressure transmitted during the coupling process and / or when the cassette is coupled via the structure, in particular the layer made of an air-permeable material, orthogonally to its plane, presses the film fluid-tightly with the fluid-conducting channels of the hard part of the cassette. The structure, in particular the layer made of an air-permeable material, however, remains gas-permeable along its plane. This enables secure pressing of the film and hard part, in which no leaks occur between the fluid-conducting channels, while nevertheless allowing reliable air extraction via the flat structure. This is achieved by an appropriate design of the material layer, e.g., a nonwoven, or by an appropriate design of the profiling of the surface of the flexible film.

[0058] Furthermore, the layer of air-permeable material advantageously comprises a nonwoven fabric. Such a nonwoven fabric is ideal for uniform pressure transfer and suction along its plane.

[0059] In a further embodiment, the surface of the flexible film of the medical cassette of the present invention can advantageously have a profile through which, when the cassette is coupled, air can be sucked out along the plane of the film. This makes it easy to reliably remove the air from the area between the film and the mat, or between the film and the coupling surface of the treatment machine, without the formation of air pockets or air islands. The arrangement of the profile on the surface of the film is particularly advantageous because the cassette is disposed of after use anyway and therefore does not need to be cleaned.

[0060] As already described with regard to the device for treating a medical fluid, the profiling advantageously has a mesh structure and / or a meandering and / or linear structure. Furthermore, the profiling is advantageously anisotropic and / or inhomogeneous. It is also advantageous if the width of the channels formed by the profiling is smaller than their depth, as this prevents them from closing during compression with the treatment machine and still allows for uniform contact between the smooth back of the film and the webs of the rigid part.

[0061] In a further advantageous embodiment, the profiling runs along the fluid-carrying channels, particularly using a meandering and / or linear structure. This allows the volume that must be evacuated to be reduced.

[0062] Furthermore, the profiles advantageously converge in one or more areas outside the fluid-carrying channels, forming suction points. This allows for easy suction in this area, while the profiles along the fluid-carrying channels ensure air-free coupling in this area.

[0063] Advantageously, the profiling runs essentially perpendicular to the channel edge at the transition from the area with fluid-carrying channels to the area outside the fluid-carrying channels. This ensures uniform compression of the film against the channel edge while simultaneously providing good air extraction.

[0064] Advantageously, the profiling is spaced from the channel web edges in the areas where it does not cross the channel web edges. This prevents the fluid from spreading along the profiling across the entire cassette in the event of a rupture. Furthermore, better compression of the film with the channel web edges is achieved.

[0065] Advantageously, the profiling is also designed in such a way that there is no direct connection between areas of the film with different fluid-carrying channels. If the film ruptures, this has the advantage that the fluid cannot spread along the profiling across the entire cassette. In particular, ruptures in an area without fluid-carrying channels remain without consequences. Even if the film ruptures in an area with fluid-carrying channels, the fluid is only drawn along the profiling to the suction point, while leakage across the channel web edges between the fluid-carrying channels is prevented.

[0066] Furthermore, the hard part of the medical cassette according to the invention advantageously has containment ribs that connect the channel edge sealing ribs and form compression-tight, sealed areas. Advantageously, the suction point is located in such a compression-tight, sealed area, so that in the event of a film rupture, the leaking fluid only reaches this area, preventing direct contact between the individual fluid-carrying areas.

[0067] As already described above, the medical cassette according to the invention has at least one suction opening located on the hard part of the cassette. This suction opening allows fluid to be drawn into contact with the space between the film and the mat or coupling surface for suction. This allows the flexible mat on the machine side to be designed to be continuous and thus ideally cleanable.

[0068] Advantageously, the suction opening is located outside the area of ​​the cassette's fluid-carrying channels. This increases safety, as a weld failure only results in contamination of the suction device or the hydrophobic membrane arranged in the suction channel if a film ruptures at a channel location or a sealing bar simultaneously fails.

[0069] Advantageously, the flexible film is welded to the hard part of the cassette around the suction opening.

[0070] The ring weld seam around the extraction opening is advantageously profiled to prevent the weld seam from impeding air extraction. This is particularly important when the film surface is profiled and can be achieved, for example, by appropriately structuring the welding die.

[0071] Alternatively or additionally, the weld seam area can also be lowered relative to the cassette's contact surface. This can also prevent the weld seam from interfering with air extraction. This is particularly advantageous when using a layer of air-permeable material.

[0072] Furthermore, a hydrophobic filter is advantageously arranged at the suction opening. Advantageously, the suction opening(s) are sealed in a liquid-tight manner with one or more hydrophobic filters. Hydrophobic filters are both liquid-tight and gas-permeable.

[0073] In the following, non-claimed methods for coupling a cassette to a treatment machine, which enable a safe, air-free coupling, are described.

[0074] A method for coupling a cassette made of a hard part with fluid-conducting channels covered by a flexible film to the coupling surface of a treatment machine for treating a medical fluid can comprise the following steps: coupling the medical cassette to the coupling surface of the treatment machine, and suctioning air between the flexible film and the coupling surface of the treatment machine during the coupling process and / or with the cassette coupled, wherein the suctioning takes place over a surface area of ​​a layer of an air-permeable, porous material arranged at least in partial areas between the flexible film and the coupling surface. The coupling and suctioning steps can be carried out either one after the other or at least partially simultaneously, by starting the suctioning during the coupling process.

[0075] Alternatively, the extraction can also be carried out along a profile of the surface of the flexible film and / or along a profile of a surface of a flexible mat facing the flexible film, via which the cassette is coupled to the coupling surface. This results in the advantages already described with regard to the device, in particular, reliable extraction of air from the area between the flexible film and the coupling surface of the treatment machine.

[0076] Furthermore, a method for coupling a cassette made of a hard part with liquid-conducting channels, which are covered by a flexible film, to the coupling surface of a treatment machine for treating a medical liquid, comprising the steps of: coupling the medical cassette to the coupling surface of the treatment machine via a flexible mat arranged on the coupling surface, suctioning off air between the flexible film and the flexible mat during the coupling process and / or when the cassette is coupled, wherein the suctioning takes place in areas of the flexible mat without openings, namely along the plane of the flexible mat and / or through the flexible mat, for which purpose the mat is made of an air-permeable material.

[0077] A further method for coupling a cassette made of a hard part with fluid-carrying channels covered by a flexible film to the coupling surface of a treatment machine for treating a medical fluid can comprise the following steps: coupling the medical cassette to the coupling surface of the treatment machine via a flexible mat, in particular a silicone mat, arranged on the coupling surface, and suctioning out air between the flexible film and the flexible mat during the coupling process and / or when the cassette is coupled, wherein the suctioning takes place along the plane between the flexible film and the surface of the flexible mat facing the flexible film. This also results in the advantages already described above. In particular, the flexible mat can be designed to be inexpensive and easy to clean.

[0078] The method uses a medical cassette and / or a device for treating a medical fluid, as already described above.

[0079] A method for checking the tightness of a medical cassette made of a hard part with fluid-carrying channels covered by a flexible film, in particular before filling the medical cassette, can comprise the following steps: coupling a medical cassette to a coupling surface of a treatment machine, suctioning out air between the flexible film and the coupling surface of the treatment machine during the coupling process and / or with the cassette coupled, in particular surface suctioning, checking the tightness of the medical cassette based on the resulting negative pressure, wherein the tightness check takes place during and / or after coupling the cassette. Since no vacuum can build up when the air is suctioned out in the event of a film leak, it is possible according to the invention to determine and indicate an excessively high leakage rate via the negative pressure monitoring and negative pressure evaluation of the air suction.This allows for detection of any leakage in the disposable film – especially before filling the disposable and before treatment begins. This allows the defective disposable to be replaced with an intact one. Continuous evacuation thus provides the opportunity to detect leaks in the film and replace defective disposables.

[0080] This is particularly facilitated by the surface suction of the present invention. Without surface suction, however, self-sealing would occur between the film and the mat, which would make inspection more difficult. Such a method utilizes a medical cassette and / or a device for treating a medical fluid, as described above.

[0081] The present invention will now be described in more detail with reference to exemplary embodiments and drawings. In the drawings: Figure 1: a device for treating a medical fluid according to the prior art, Figure 2: a device for treating a medical fluid according to a first embodiment of the present invention, Figure 3: a device for treating a medical fluid according to a second, unclaimed embodiment, Figure 4: a plan view and a sectional view of a profiling according to a third embodiment of the present invention, in which, however, not all features of the invention are shown, Figure 5a: a plan view of a medical cassette according to a fourth embodiment of the present invention, in which, however, not all features of the invention are shown, Figure 5b: a sectional view through a profiling in an area with sealing webs, Figure 5c: a sectional view through an embodiment of a suction opening according to the invention,and Figure 6: a device for treating a medical fluid according to a fifth, unclaimed embodiment of the present invention. ,

[0082] Figure 1 shows a device for treating a medical fluid, such as is used in the prior art, for example, for hemodialysis or peritoneal dialysis. However, such devices can also be used in a variety of other applications, in which a disposable cassette, also referred to as a disposable device, is used and coupled to sensors and actuators of a treatment machine via a coupling surface.

[0083] The treatment machine 1 has a coupling surface 10 on which, for example, a sensor 11 is arranged. The cassette 2 comprises a hard part 20 with a fluid-conducting channel 21, which is covered by a flexible film 25. The fluid-conducting channel is separated in a fluid-tight manner within the cassette by laterally arranged sealing webs 22, which are pressed onto the flexible film 25. The sensor 11 is located opposite the fluid-conducting channel 21, which thus forms a measuring chamber, or in the case of a pressure sensor, a pressure measuring chamber.

[0084] A flexible silicone mat 15 is also arranged on the machine side between the film 25 and the coupling surface 10 of the treatment machine 1 to protect the sensor surfaces of the sensor 11 from environmental influences. Furthermore, this makes the machine surface hermetically sealed and thus ideal for hygienic cleaning.

[0085] When coupling sensors to the disposable film 2, however, it is difficult to couple the film 25 to the sensor surface of the sensor 11 in such a way that correct measurement values ​​are obtained. In particular, air trapped in the transmission path between the disposable film 25 and the sensor surface when inserting the cassette leads to falsified measurement results. This applies to pressure sensors, but also, for example, to level detection and actuators such as valves, which control the fluid flow within the cassette by pressing the flexible film 25 into the fluid-carrying channels 21 of the hard part 20.

[0086] A first embodiment of the present invention is now shown in Figure 2shown. A flat structure between the film 25 and the mat 15 enables flat air extraction along the coupling plane. This ensures that the space between the film 25 and the mat 15 is reliably ventilated without trapping air pockets due to the self-sealing effect of the film 25 being applied to the mat 15, which could distort the measurement results.

[0087] In the Figure 2 In the embodiment shown, the surface suction is achieved by inserting a layer 30 of an air-permeable, particularly porous material, in this case a nonwoven layer, between film 25 and mat 15. Such a nonwoven layer is porous due to its structure, meaning that air can flow across the surface of this layer, even if the entire composite of film 25, nonwoven 30, and mat 15 is strongly compressed, e.g., by the sealing webs 22.

[0088] This results in a liquid-tight pressed connection between film 25 and hard part 20, whereby the layer 30 made of an air-permeable, particularly porous, material nevertheless remains permeable to air. Thus, it is sufficient to fluidically contact the space between film 25 and mat 15 at a single point via a suction opening 28 with a vacuum system 13 in order to reliably and extensively vent the entire space between film 25 and mat 15. This allows a multitude of sensors 11 or actuators to be coupled to film 25 safely and without air. In this way, the connection of the fleece space to the vacuum system can also be used for a film tightness test directly after pressing, which would not be possible without such an air-conducting layer.

[0089] According to the invention, the suction opening 28 is integrated into the hard part 20 of the cassette and has a hydrophobic membrane 24 in the suction channel, which is also integrated into the hard part. This prevents contamination of the machine in the event of a film rupture. When the cassette is inserted into the treatment machine, the suction opening 28 in the hard part 20 of the cassette is connected via a sealing element 14 to suction channels integrated in the machine door 12, which in turn are connected to a vacuum system 13. The film has a circumferential weld to the hard part around the suction opening 28. The area of ​​the circumferential weld is lowered compared to the contact plane of the cassette, so that the weld between the fleece layer 30 and the hard part does not represent a barrier to air extraction.

[0090] The fluidic contact of the fleece space takes place outside the liquid-carrying areas of the channel structure 21. Thus, a failure of the weld between the film and the hard part around the suction opening only results in contamination of the hydrophobic membrane 24 if there is a simultaneous film rupture at a channel point or a simultaneous failure of a sealing web 22.

[0091] In Figure 3an unclaimed embodiment is shown in which the fluidic contact does not occur from the hard part 20, but from the mat side. In this case, an opening is provided in the mat 15, which is connected to the vacuum system 13 via a valve 16. Here, too, the contact with the air-conducting layer 30 occurs outside the region of the liquid-conducting areas of the channel structure 21. The hard part 20 has a plunger 29, which opens the valve 16 when the cassette is inserted into the treatment machine. The cassette has a circumferential sealing web 27, on which no fleece layer 30 is provided, so that an outwardly closed space is created between the film 25 and the mat 15, from which the air can be sucked out without leakage air flowing in from the outside.

[0092] Alternatively to the Figure 3In the arrangement shown, excessive penetration of leakage air into the system can also be prevented by other designs of a circumferential sealing edge. For example, it can be exploited that when the fleece 30 is welded to the film 25, the fleece structure is changed in such a way that a gas-tight barrier is created. Thus, at this point, a fleece 30 that has been rendered air-impermeable can be pressed airtight with the silicone mat 15. Ideally, this welding takes place in a single step together with the welding of the film to the rigid part 20. For this purpose, it is advantageous to manufacture the fleece 30 from a material that can be welded to the rigid part 20, e.g., PP.

[0093] Another possibility is to cut the fleece smaller than the film, allowing a seal to be created all the way around the film and the silicone mat. In this case, the fleece 30 can be attached to the film, for example, by gluing and / or spot welding and / or lamination and / or tacking. It is also possible to bond the film and fleece in a first step and then create the connection to the rigid part in a second step.

[0094] As an alternative to using the nonwoven fabric shown in the first and second embodiments, air transport in the desired plane can be achieved by profiling the surface of the film 25 in such a way that an air-conducting layer is created within the film itself. This can be achieved, for example, by embossing a structure into the film.

[0095] In a third embodiment, for which not all features of the invention will be described again, a grid-like structure is pressed into the film, creating a network of channels in the film that are separated from each other by areas of thicker material. Various geometries are conceivable, whereby Figure 4 This shows an example of a honeycomb structure. By choosing a suitable structure, it is also possible to achieve anisotropic extraction, for example, by making the channels larger from left to right than from top to bottom. The structure can also be inhomogeneous across the surface. The structure can also be meandering.

[0096] The geometry of the resulting channels is important for the achievable suction performance. Narrow, deep channels are not closed off by the silicone mat during compression, so that suction through the channels remains possible. The shallower the channels, the higher the risk of sealing due to the film partially adhering to the mat in the channels. If the channels are too wide, there is an increased risk that the compression on the smooth side of the film (towards the blood side and the hard part) will become too inhomogeneous and leaks will occur on this side. In addition to embossing, other manufacturing processes are available for producing the profiling of the film surface. For example, a structure can be introduced into the film surface directly during extrusion.

[0097] Alternatively, such a profiling could also be arranged on the surface of the mat 15 facing the film 30. This would also enable reliable air extraction. A disadvantage of such an arrangement, however, is that the surface of the mat is then no longer smooth, thus making cleaning the mat surface more difficult.

[0098] Alternatively, it is also possible to dispense with the silicone mat 15 when using a fleece 30 or a profiling of the film surface, so that the fleece 30 is arranged directly between the film 25 and the coupling surface 10 of the treatment machine or the profiled surface of the film 25 lies directly against the coupling surface 10 of the treatment machine.

[0099] When the entire surface of the cassette film is structured or by creating a full-surface drainage layer between the film level and the coupling level, the entire film area of ​​the cassette up to the circumferential film weld seam A or up to the outer circumferential sealing bar B (created on the cassette side or machine side) is made passable for gases and liquids across all regular channel edge sealing bars C. During the initial integrity test, the entire area must therefore be evacuated, and the tightness of the circumferential sealing bar must also be ensured parallel to the actually desired tightness of the channel edges so that treatment can be approved. The amount of air that must initially be extracted for this purpose and the time required for this are thereby increased, and the detection reliability for the relevant film ruptures is reduced.

[0100] In Fig. 5aTherefore, a fourth embodiment of the present invention is shown, for which not all features of the invention will be described again. In this embodiment, an internal structuring of the profiled surface of the film is used. With the internal structuring, only the liquid-wetted film areas required for process engineering purposes are made drainable. The compression between the film's outer surface and the coupling plane is significantly lower than the compression on the channel edge sealing webs and in the non-liquid areas G and H. In these latter areas, the cassette has flat, dense bases parallel to the film.While the channel edge sealing strips are designed in such a way that the liquid cannot normally overflow, the areas G and H are designed in such a way that any liquid that has penetrated finds no space, since the compression of the rubber mat causes the film to be almost completely pressed against both the cassette level and the sunken rubber level.

[0101] Since the compression between the film and the rubber mat in the liquid-wetted inner areas S1, S2, and S3 is significantly lower than the compression in all other areas of the film area, a significantly less pronounced drainage structure is sufficient in this area to ensure both complete film coupling and complete coverage of the relevant film area with regard to potential ruptures. Therefore, a safety distance E of the structuring D of approximately up to 1 mm can be provided for the internal structuring to the channel web edges C.

[0102] Areas G and H are also included in the sterilization process and hermetically sealed from the outside world. If a rupture occurs in area G during treatment, i.e., after an unremarkable initial integrity test, this generally has no consequences for the treatment, as the relevant areas S are not affected and there is no possibility of fluid entering area G. If a rupture occurs at a channel sealing web and beyond, as outlined by F, the self-sealing functions are activated by the high compression between the smooth film and the smooth rubber mat, as well as the additional compression at the peripheral edge. If a rupture occurs in the inner areas S during treatment, the leaking fluid penetrates the space between the film and the rubber mat, further reducing the compression, and is finally forced along the anisotropic structure D to the suction point K.Even the collection area H is only insignificantly filled with leakage fluid, since the path via the targeted pathways I to the suction point K offers the lowest flow resistance.

[0103] The internal structuring offers shorter detection times and higher detection accuracy during integrity testing prior to filling with treatment fluid. The internal structuring provides redundant passive leak protection in the event of a film rupture during treatment. The internal structuring significantly reduces the surface area of ​​film and rubber mat that can be wetted in the event of a film rupture and contribute to contamination of the treatment surface with the treatment fluid and vice versa. The internal structuring can increase reliability and reduce the detection time of a film rupture during treatment, thus increasing safety against contamination and cross-contamination. The internal structuring can prevent the likelihood and extent of potential fluid leaks to the outside.

[0104] Furthermore, there is the possibility of anisotropic structuring: Anisotropic foil structuring or anisotropic design of intermediate drainage layers means locally varying the intensity, direction, functionality, and absence of the drainage effect. This already includes the previously described internal structuring with an unstructured edge area towards the channel sealing webs.

[0105] The next possibility is the deliberate creation of separate structural areas S1...S3 with a minimized number of crossings I of the channel edge sealing web areas. I also shows how, through optimized structuring, a minimum volume must be extracted or wetted during the initial test and in the event of a leak.

[0106] The sectional view Fig. 5bshows the optimizing effect of linear structures that vertically cross the channel edge sealing bars. This arrangement allows for optimum grouting tightness on the fluid side to be combined with optimal retention of drainage structure depth on the machine side. The figure shows the two fundamentally negative structuring configurations, namely partial squeezing U of the structuring channels D and a disrupted grouting V at the channel edge sealing bars C due to inhomogeneous force transmission, with extreme exaggeration. Structuring parallel or diagonally crossing the sealing bars would penetrate the bar and the rubber mat more deeply, thus further reducing the drainage and grouting effects.

[0107] It should also be considered that in certain locations, for example, for optical measurement of fluid turbidity or at ultrasound transmission points, it may be necessary for the film to remain smooth and / or transparent. In this case, a window is created by omitting any structuring or drainage layers.

[0108] Further possibilities arise from the use of containment bars: If connecting bars J are inserted between the channel edge sealing bars at suitable locations in the channel and chamber layout, new, sealed areas H are created. If the drainage structures converge in this area, then this area H, together with the fluid areas S1...S3, forms the overall area, which is detected for film rupture before and during treatment and which has a passively sealed, sealed channel edge as the area boundary for any possible leakage fluid or for any possible contamination and cross-contamination. Every leak must ultimately reach this area H, and this is the preferred location for suction points K with leak detectors and hydrophobic protective membranes.

[0109] Furthermore, containment webs provide the opportunity to slightly reduce the grouting tightness effect at the points where the drainage structures cross the canal sealing edges in favor of a better drainage effect (for example by widening the canal edge sealing web), without reducing the effect of the secure grouting tightness towards the outside.

[0110] Furthermore, the present invention creates the possibility of non-invasive blood leak detection: The decision to cover the coupling plane of the machine with a closed protective layer, such as rubber, requires the implementation of a leak detector for the early detection of film ruptures during treatment as a non-invasive device. This is possible, for example, through a thin rubber mat using capacitive sensors, ultrasonic sensors, or by detecting the vacuum that collapses in the event of a leak. On the side of the counter-coupling plane (on the non-film side of the cassette), this is possible using optical sensors with a reflex arrangement. For example, a color sensor can distinguish whether blood has leaked out or whether it is normal moisture. The structuring of the film can be exploited here to set up scattered light wetting detection.When the film is dry, scattered light is reflected off the pattern, which is absent when the pattern is wetted with liquid. With such an arrangement on the non-rubber mat side, there is no need for a special sensor-sensitive rubber mat.

[0111] Furthermore, possibilities arise through specially structured weld seams and rubber mats: In particular at the extraction point K, the required annular weld seams around the hydrophobic membrane and around the hydrophobic membrane or extraction hole recess in the film create the problem that both the structuring of the film and the welding of an overlying drainage layer (e.g. made of fleece) are leveled by an annular weld seam and thus form annular barriers between the areas H and K.

[0112] To remove these blocking options, Fig. 5cA combination of four possible measures. A dent Q in the rubber mat reduces the sealing compression against the ring weld seam, as does a dent R in the cassette surface. Another similar effect is achieved by the local structuring S of the rubber mat in the area of ​​the dent, with grooves and patterns that radially bridge the weld seam at several points, effectively providing drainage.

[0113] Both rubber mat measures have the disadvantage of impaired cleanability of the rubber mat. The counterpart to structuring the rubber mat in the area of ​​the extraction point is structuring the ring weld seam. For this purpose, the welding stamp is designed so that it is ring-shaped, but this ring is more conical than the associated welding surface of the cassette. Furthermore, the ring surface M is equipped with radially arranged drainage ribs, which leave a common structuring of the cassette base and film during welding. Due to the conicity of the ring surface assignment, this has a jagged ring surface after welding with line structures pointing radially outwards into the unwelded film areas. Together with the radial structures already present there, this overall structure is no longer interrupted by the ring-shaped seal welding zone.

[0114] Figure 6now shows a fifth, unclaimed embodiment of the device for treating a medical fluid of the present invention, in which the suction is not carried out by an additional fleece between the flexible film 25 and the flexible mat 15 or by a corresponding profiling of the surfaces, but rather by the suitable choice of the mat material via the flexible mat 15 itself. For this purpose, the flexible mat consists of an air-permeable material (e.g., silicone), so that the air between the flexible mat 15 and the flexible film 25 can be sucked out directly through the mat 15 itself via the vacuum applied to the suction channels 40. The large-scale distribution of the vacuum takes place via the air channels 40 in the machine plate, while the permeable mat then enables surface suction over the entire surface. This surface design also virtually eliminates the possibility of the suction being completely blocked.

[0115] In this embodiment, a previously known medical cassette 2 consisting of a hard part 20 with fluid-carrying channels 21 can be used, which are sealed by the flexible film 25. For this purpose, as in known systems, the medical cassette 2 is pressed onto the flexible mat 15 of the treatment machine, so that the sealing webs 22 ensure a seal. However, according to the invention, a surface suction is now possible, which takes place on the machine side via the vacuum channels 40 and the permeable mat material.

[0116] The mat material is advantageously permeable to air but liquid-tight to prevent contamination of the coupling surface and to facilitate cleaning.

[0117] The ability to continuously extract air from between the flexible film 25 and the coupling surface 10, according to the invention, also makes it possible to detect leaks in the film. Due to the surface evacuation, no vacuum can be built up after the door has been pressed shut in the event of a sufficiently large film leak. Consequently, air is constantly sucked from the still-unfilled disposable into the space between the film and the mat or coupling surface. The excessive leak rate can then be detected and recorded via the vacuum monitoring and vacuum evaluation. The leak test can be performed during and / or after coupling to the cassette.

[0118] This makes it possible to detect any leakage in the disposable film, especially before filling the disposable and before treatment begins. This allows the defective disposable to be replaced with an intact one.

[0119] Without the area-wide suction, such a test would be less reliable, as a self-sealing effect can develop between the film and the mat, and in areas with trapped air pockets, film leaks could still exist that would not be detected by the negative pressure monitoring and evaluation. In principle, however, the leak test according to the invention can be performed with any type of evacuation.

Claims

1. Medical cassette (2) made of a hard part (20) having liquid-conducting passages (21) which are covered by a flexible film (25), wherein the cassette (2) can be coupled to a coupling surface (10) of a treatment machine (1), characterized in that the medical cassette (2) comprises at least one suction opening (28) arranged in the hard part (20) of the cassette, via which opening the space between the flexible film (25) of the medical cassette (2) and the coupling surface (10) of the treatment machine (2) can be fluidically contacted for suctioning-off in the coupled state of the cassette (2).

2. Medical cassette according to claim 1, wherein the suction opening (28) is arranged outside the region of the liquid-conducting passages (21).

3. Medical cassette according to claim 1, wherein the flexible film (25) is welded to the hard part (20) of the cassette (2) around the suction opening (28), wherein the annular weld seam preferably has a structuring around the suction opening and / or wherein the region of the weld seam is preferably lowered with respect to the pressing plane of the cassette (2).

4. Medical cassette in accordance with claim 1, wherein a hydrophobic filter (24) is arranged at the suction opening.

5. Medical cassette in accordance with any one of the claims 1 to 4, wherein the suction opening (28) is located opposite the coupling surface (10) of the treatment machine (1) in the coupled state of the cassette.

6. Medical cassette in accordance with any one of the claims 1 to 5, wherein the suction opening (28) comprises a suction passage which passes through the hard part (20).

7. Medical cassette in accordance with claim 6, wherein the suction passage of the medical cassette (2) is connectable to a suction channel of the treatment machine (1), wherein preferably the end of the suction passage of the medical cassette (2) connectable to the suction passage of the treatment machine (1) is arranged on the rear side of the medical cassette.

8. Apparatus for treating a medical liquid, comprising a medical cassette in accordance with any one of the preceding claims and a treatment machine (1) with a coupling surface (10) and a flexible mat (15), in particular a silicone mat arranged on the coupling surface, wherein the cassette (2) can be coupled to the coupling surface (10) of the treatment machine (1) by means of the flexible mat (15), wherein the apparatus comprises at least one suction device (13), using which a vacuum is made available, which vacuum is connected to an area between the flexible film (25) and the flexible mat (15) and thus enables a suctioning, characterized in that air can be sucked-off along a plane between the flexible film (25) and the surface of the flexible mat (15) facing the flexible film, during the coupling process and / or with a coupled cassette (2), wherein the suction takes place via one or more suction openings (28) arranged in the hard part (20) of the cassette.

9. Apparatus in accordance with claim 8, wherein the air-guiding layer is in communication with the suction device (13) at one of multiple points outside the region of the fluid-carrying passages (21).

10. Apparatus in accordance with claim 8 or 9, wherein the apparatus comprises suction ducts in communication with the suction device (13), wherein the suction ducts are configured in such a way that the suction opening (28) in the hard part (20) of the cassette, upon insertion of the cassette (2) into the treatment machine (1) is connected to the suction ducts via a sealing element (14), wherein the suction ducts are preferably integrated into a machine door (12) of the apparatus.

11. Apparatus in accordance with any one of the preceding claims, comprising an optical sensor for the recognition of leaks, in particular by scattered light wetting detection.

12. Apparatus in accordance with any one of the preceding claims, comprising a control unit which carries out an automatic suctioning of the air.

13. Apparatus in accordance with claim 12, wherein the control unit carries out an automatic check of the leaktightness of the medical cassette (2).