FILTER ASSEMBLY AND CONTAINER FOR COLLECTING BODY FLUID - Patent application

Abstract

A filter assembly for filtering bodily fluids is disclosed, including a filter system and a filter retainer, wherein the filter system comprises at least two layers. The first layer is an anti-foaming layer formed of an open mesh fabric woven from monofilament and includes an embossed three-dimensional structure configured to trap bubbles accumulated in the bodily fluid. The second layer is a mesh filter layer positioned downstream of the anti-foaming layer. A container for collecting bodily fluids containing such a filter assembly is also disclosed.

Description

[Technical field]

[0001] [CROSS REFERENCE TO RELATED APPLICATIONS] This application claims the benefit of and priority to European Application No. 19181285.8, filed June 19, 2019, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a filter assembly, a suitable use of the filter assembly, and a container for collecting body fluids that includes the filter assembly. [Background technology]

[0003] Filter assemblies known from the prior art are used for various types of fluids, for example body fluids, for filtering aggregates, particles or specific cells from the body fluids. A particularly suitable application of filter assemblies is the filtration of blood. Whole blood or blood components can be separated and further processed for various applications, in particular for use as transfusion products.

[0004] Filter assemblies are also used in autotransfusion processes during surgical procedures, where the patient's blood is salvaged during surgery and reinfused back into the patient. This is also known as intraoperative autotransfusion (IOBS), or autologous blood transfusion or cell salvage. It has been used for many years and has received greater attention over time as the risks associated with allogeneic (separate donor) transfusion have become more widely known and better understood. Several medical devices have been developed to assist in salvaging the patient's own blood in the perioperative setting. This procedure is frequently used in cardiothoracic and vascular surgery, where blood usage is traditionally high.

[0005] Whole blood is collected during surgery, but once exposed to surgery, air, etc., it has different properties than blood collected from donors in blood banks for allogeneic transfusion. For example, blood collection requires the removal of blood clots, non-cellular material such as drugs and fluids used during surgery, bone fragments, and surgical debris.

[0006] Autologous blood recycling or salvage transfusion is often accompanied by foam formation. Blood foam formation (also called "skimming") is associated with the collection or transport of blood in large tubes (e.g., collected with a Jankauer cannula) in the presence of air and thus with turbulence during the aspiration process.

[0007] One approach to avoid the formation of bubbles in the bloodstream is to use antifoaming agents in the reservoir where the bloodstream for autotransfusion or extracorporeal circulation is collected. In the past, polydimethylsiloxane (PDMS)-hydrophobized silica was widely used as an antifoaming agent. However, PDMS may partially leach into the blood, where it emulsifies. In IOBS, it is presumed that most of it is in the waste products after washing, but it cannot be excluded that a part of it is in the red blood cell concentrates autotransfused to the patient. Although PDMS-hydrophobized silica is non-toxic, it can cause embolism and postoperative death due to capillary blockage, and is no longer used as an antifoaming agent. Therefore, today, only silica-free PDMS is used. The principle of antifoaming is the same for PDMS, but silica particles, which "destroy" the bubbles by a physical action method, are no longer applied in medical devices, but continue to be used for non-medical antifoaming. Summary of the Invention

[0008] However, there remains a need for alternative antifoam concepts.

[0009] It is an object of the present invention to provide a filter system that allows for the reduction or even prevention of foam formation in a body fluid, such as a filtered bloodstream, while at the same time reducing the risk of leaching of chemicals into the filtered body fluid.

[0010] This object is achieved by a filter assembly having the features described below.

[0011] Accordingly, there is provided a filter assembly for filtering bodily fluids that includes a filter system and a filter retainer, where the filter system and the filter retainer are in contact with or connected to one another.

[0012] The filter system is composed of at least two layers. The first layer is an antifoam layer formed by an open mesh fabric woven with monofilaments, with an embossed three-dimensional structure, specifically configured to trap foam accumulated in body fluids. The second layer is a mesh filter layer. The mesh filter layer is arranged downstream of the antifoam layer.

[0013] The terms "downstream" and "upstream" refer to the direction of flow of the fluid being filtered by the filter assembly such that the fluid being filtered first contacts the antifoam layer and then the mesh filter layer.

[0014] Such a filter assembly can be satisfactorily used to filter blood and other body fluids. The use of such a filter assembly effectively prevents foam formation in blood and other body fluids. The filter assembly of the present invention allows for the foam to be removed mechanically, thereby eliminating the need for antifoam agents and completely avoiding the risk of chemicals leaching into the filtered body fluid. The filter assembly of the present invention is particularly useful in autotransfusion reservoirs or containers.

[0015] Surprisingly, it was found that the use of an antifoam layer with an embossed 3D structure eliminated or reduced foaming. The underlying mechanism could be the trapping of foaming within the antifoam layer. The spatial 3D structure can trap air bubbles formed in the body fluid; that is, the air bubbles are trapped within the spatial structure. Another mechanism could be that the foam bubbles are blown away when passing through the downstream mesh filter.

[0016] The embossed 3D structure may be in the form of a diamond pattern with regularly-spaced protrusions and depressions of specific heights. The spatial pattern may also be described as a zigzag or pyramid-like structure.

[0017] As previously mentioned, the antifoam layer is a structured open mesh fabric.

[0018] In one embodiment, the antifoam layer comprises mesh openings of between 100 and 500 μm, particularly between 150 and 400 μm, in particular between 200 and 350 μm, more particularly between 250 and 300 μm, for example 250 μm.

[0019] The mesh number (usually the number of threads per cm) of the fabric forming the defoaming layer may be between 10 and 50 n / cm, particularly between 10 and 30 n / cm, more particularly between 10 and 20 n / cm, for example 12 to 16 n / cm.

[0020] The fabric of the antifoaming layer is made of monofilament fibers having a diameter between 100 and 350 μm, particularly between 150 and 300 μm, more particularly between 200 and 300 μm, for example 200 μm, 250 μm, 300 μm. The monofilament fibers can be made of any thermoplastic material, but are preferably made of polypropylene (PP), polyethylene (PE), polyether ether ketone (PEEK), etc. Polypropylene is the most preferred.

[0021] The antifoam layer is 50 to 250 g / m 2 , especially 100-200g / m 2 , more specifically 150 to 200 g / m 2 , for example, 98 to 103 g / m 2 , 180~190g / m 2 , 156g / m 2 The weight of the sintered body may be 1.0 to 1.0 kg.

[0022] The thickness of the antifoam layer may be from 150 to 650 μm, in particular from 200 to 500 μm, in particular from 250 to 400 μm, in particular from 300 to 350 μm.

[0023] The antifoam layer may also be of a sponge-like structure formed, for example, of polyurethane or polyester foam.

[0024] In one embodiment, the first mesh layer is comprised of a plurality of interconnecting yarns forming a grid or net, such that the vertically oriented yarns and horizontally oriented yarns are connected to each other at connection points to form a grid.

[0025] In one embodiment, the threads or filaments of the mesh filter layer have a circular cross-section, although other cross-sections are possible, such as elliptical, rectangular, square, or triangular cross-sections. Similarly, a mixture of threads or filaments having different cross-sections is also possible.

[0026] In one embodiment, the mesh size of the mesh filter layer is in the range between 20 and 160 μm, in particular between 30 and 140 μm, in particular between 40 and 130 μm, in particular between 50 and 120 μm, in particular between 60 and 110 μm, in particular between 70 and 100 μm, in particular between 80 and 90 μm. The ranges from 100 to 130 μm, 105 to 125 μm, 70 to 90 μm, 75 to 85 μm, 30 to 45 μm, and 35 to 40 μm are particularly suitable.

[0027] In one embodiment, the mesh filter layer can include or be made entirely of polymers such as polyester, polyethylene, polypropylene, polybutylene, polymethylpentene, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, poly(butylene terephthalate-co-polyalkylene glycol terephthalate), nylon 6,6, nylon 6,9, nylon 6 / 12, nylon 11, nylon 12, cellulose acetate, cellulose acetate propionate, or combinations thereof. Thereby, non-hydrophobic or hydrophilic materials are particularly suitable for manufacturing the mesh filter layer. It is also possible to increase the hydrophilicity of the material used to manufacture the mesh filter layer or to increase the hydrophilicity of an already manufactured filter. Therefore, physical treatment is more suitable than deposition of chemicals. This is because chemicals may leach out of the mesh filter during use of the container.

[0028] The appropriate surface area of ​​the mesh filter layer is between 300 and 1000 cm 2 , especially between 400 and 900 cm 2 , especially 500 to 800 cm 2 , especially 600 to 700 cm 2 The range is.

[0029] In a further preferred embodiment, the filter assembly includes a pre-filter layer (depth filter) disposed downstream of the antifoam layer and upstream of the mesh filter layer, i.e. sandwiched between the antifoam layer and the mesh filter layer.

[0030] The pre-filter support layer comprises or consists essentially of a nonwoven web of fibers, whereby the fibers are arranged such that interstices are formed between the randomly deposited fibers, which interstices can be defined as openings of the average pore size, resulting in the pore size of the nonwoven web.

[0031] The pore size of the pre-filter material is smaller than that of the upstream antifoam layer, but larger than that of the downstream mesh filter material.

[0032] In one embodiment, the pre-filter layer comprises or consists essentially of a spunbond nonwoven fabric. The individual fibers of this fabric can have any desired cross-section, such as circular, elliptical rectangular, square or triangular cross-sections. A mixture of fibers having different cross-sections is also possible.

[0033] The fibers of the pre-filter layer can also generally have any shape. However, it has been found that particularly good filtration can be achieved if the fibers, or at least some of the fibers, include at least one groove extending in the longitudinal direction of the respective fiber. By way of example, the fibers can include three grooves, each extending in the longitudinal direction of the fiber. In this way, aggregates, fat and / or platelets can be particularly well filtered out of the blood or another body fluid flowing through the filter assembly.

[0034] In one embodiment, at least some of the fibers have a lobed cross section. In one embodiment, such a lobed cross section can be achieved by forming grooves in the fiber in the longitudinal direction. A trilobal cross section is a particularly suitable example of a lobed structure. Such trilobal fibers are generally known, for example, from WO2013 / 110694A1, the entire content of which is incorporated herein by reference.

[0035] The fibers making up the nonwoven fabric of the pre-filter layer may in one embodiment be spunbond or meltblown fibers. Spunbond fibers typically have a fiber diameter of at least 20 μm or greater, while meltblown fibers may have a smaller diameter of less than 20 μm.

[0036] The pre-filter layer comprises or consists essentially of a spunbonded nonwoven fabric of continuous filaments. The fabric is obtained in continuous filament nonwoven processes (meltblowing and spunbonding) where chips or pellets of raw material are extruded. The length of the filaments is theoretically infinite.

[0037] The fibers of the pre-filter material can be mono-, bi- or multi-component fibers, including "islands in the sea" fibers. The fibers can consist of one polymer or a blend of polymers. Suitable materials for the fibers are, for example, polyester, polyethylene, polypropylene, polybutylene, polymethylpentene, polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, poly(butylene terephthalate-co-polyalkylene glycol terephthalate), nylon 6,6, nylon 6,9, nylon 6 / 12, nylon 11, nylon 12, cellulose acetate, cellulose acetate propionate, or combinations thereof. Thereby, non-hydrophobic or hydrophilic materials are particularly suitable for producing the fibers. It is also possible to increase the hydrophilicity of the material used to produce the fibers or to increase the hydrophilicity of already produced fibers. Thereby, physical treatments are more suitable than deposition of chemicals, since such chemicals can leach out of the fibers or the fabrics produced therefrom during use of the filter assembly.

[0038] In one embodiment the pore size of the prefilter layer is in the range between 20 and 150 μm, in particular between 30 and 140 μm, in particular between 40 and 130 μm, in particular between 50 and 120 μm, in particular between 60 and 110 μm, in particular between 70 and 100 μm, in particular between 80 and 90 μm. The ranges from 100 to 130 μm, 105 to 125 μm, 70 to 90 μm, 75 to 85 μm, 30 to 45 μm and 35 to 40 μm are particularly suitable.

[0039] As noted above, the filter system may include two layers or three layers.

[0040] In the case of a two-layer system, the first layer is an antifoam layer and the second layer is a mesh filter layer. Such a two-layer system can be used for large pore filtration. The mesh size of the mesh filter can be 120 μm, with an open transmission of 50% and a closed transmission of 34%.

[0041] In the case of a three-layer system, the first layer is an antifoam layer, the second (sandwiched) layer is a pre-filter layer (depth filtration material), and the third layer is a mesh filter layer. Such a three-layer system can be used for low pore size filtration. The mesh size of the mesh filter layer can be 40 μm and have an open permeability of 40% and a very closed permeability of 12%.

[0042] In a particularly preferred embodiment, the filter system comprises an antifoam layer with a mesh size between 200 and 300 μm, preferably 250 μm, a pre-filter layer with a pore size between 50 and 100 μm, preferably 70 μm, and a mesh filter layer with a mesh size between 30 and 50 μm, preferably 40 μm.

[0043] The filter assembly further includes a filter retainer, which contacts the filter system of the antifoam layer, the optional pre-filter layer, and the mesh filter layer. In doing so, it also stabilizes the filter system. Thus, the filter retainer helps to hold the various layers of the filter system in place. It acts as a structural support. The filter assembly can be a standalone filter assembly (self-supporting filter assembly) or one part with multiple filter layers (overmolded).

[0044] The filter holder is made of plastic and is overmolded onto at least a part of the filter system. It is preferred if the overmolding is over all filter material layers of the filter system, not just the outer layers. This can be achieved by dipping the filter material into molten plastic. When the plastic cools and hardens, it forms a holder structure (a kind of cage) that encases the filter material layers. It firmly connects the layers of the filter system together and lends itself particularly easily to a good stabilization of the layers of the filter system.

[0045] Surprisingly, it has been found that such filter assemblies can be satisfactorily used to filter blood and other body fluids. The use of such filter assemblies effectively prevents foam formation in blood and other body fluids. Antifoam agents are no longer necessary and the risk of leaching chemicals into the filtered body fluid is completely avoided.

[0046] In one embodiment, the filter assembly does not include an antifoam agent. By avoiding the use of such an antifoam agent, the risk of antifoam agent leaching into the fluid flowing through the filter assembly is completely avoided. This improves the quality of the fluid filtered by the filter assembly.

[0047] The present invention relates in one aspect to the use of a filter assembly having the characteristics described above for filtering a body fluid in vitro. The body fluid may be blood, urine, bile, tissue fluid, sperm, lymph, saliva or cerebrospinal fluid. Blood is a particularly suitable body fluid to filter.

[0048] In a further aspect, the invention relates to a method of filtering bodily fluids by forcing the bodily fluids through a filter assembly in accordance with the foregoing description. The flow of bodily fluids can be achieved by gravity or by applying an external force, such as low pressure, to a container into which the bodily fluid or the filtered bodily fluid is drawn. The method can be performed in vitro or while a patient providing the bodily fluid to be filtered is connected to a filter device through which the bodily fluid is filtered.

[0049] In one embodiment, the method is a medical method for withdrawing intraoperative cell salvage (ICS) from a patient in need thereof. ICS are typically used in patients undergoing surgery or invasive procedures, with the goal of providing those patients with autologous transfusion of blood or blood components. Details of such methods are described below.

[0050] In yet another aspect, the present invention relates to a container for collecting body fluids including a filter assembly as described in detail above as a filter module.

[0051] Such a container comprises a container housing with a bodily fluid inlet that allows bodily fluid to enter the inlet section of the container housing. The container housing further comprises a bodily fluid collection section and a vacuum connection for connecting a vacuum source to the container housing. In so doing, a negative pressure can be applied to the inlet section and the bodily fluid collection section. The vacuum source is typically connected to the vacuum connection of the container housing via a vacuum line.

[0052] The vessel housing further includes a filter module separating the inlet section from the bodily fluid collection section. More specifically, the filter module is disposed between the inlet section and the bodily fluid collection section, and bodily fluid must pass through a filter to flow from the inlet section to the bodily fluid collection section. In other words, the filter module has a raw side and a clean side. The raw side faces the inlet section, and the clean side faces the bodily fluid collection section.

[0053] In particular, the filter assembly as a filter module is positioned between the inlet section and the bodily fluid collection section such that the antifoam layer faces the inlet section and the mesh filter layer faces the bodily fluid collection section.

[0054] In one embodiment, the container housing includes a hydrophobic filter (i.e., separate from the filter assembly) disposed between the bodily fluid collection section and the vacuum connection. The term "between" refers to the flow direction of air drawn from the container (or the bodily fluid collection section of the container housing) by the vacuum source during the intended operation of the container. That is, fluids (especially air and smoke) drawn from the interior of the container housing must pass through the hydrophobic filter before entering the vacuum line connected to the vacuum connection. Thus, the hydrophobic filter acts as a protective element for the vacuum line connected to the vacuum connection of the container housing when the vacuum is generated by the vacuum pump.

[0055] The novel filter module and the hydrophobic filter work synergistically, and thus the combination provides the following advantages: Building a filter module with a filter retainer and a filter assembly including an antifoam layer, an optional pre-filter layer and a mesh filter layer allows much more flexibility in the design of the filter retainer than using prefabricated filter sockets as in the prior art. Furthermore, the filter retainer can be manufactured together with the filter assembly in a single manufacturing step, and the connection of the co-molded filter assembly elements to the container can be easily automated. This significantly reduces manufacturing costs and improves the container's performance due to a more reliable and repeatable manufacturing process.

[0056] The additional hydrophobic filter, arranged before the vacuum connection in the flow direction, serves both as a smoke filter and an overfill prevention. It therefore combines the properties of these elements, which are used in the form of individual components according to the prior art, into a single element. This single element is thereby contained in the container housing. It therefore does not need to be connected to a separate vacuum line. The hydrophobic filter does not need to be cleaned and / or sterilized. Rather, it can be designed as disposable, to be discarded together with the entire container. This further facilitates the use of the container.

[0057] The use of a filter assembly containing an antifoam layer, an optional pre-filter layer and a mesh filter layer instead of a conventional filter (made only of fibers, foams or membranes) has the effect of fulfilling very reproducible filter requirements. Conventional filters have many pores larger or smaller than the average pore size, whereas mesh filters have a well-defined mesh size that is essentially unchanged. Furthermore, the use of an antifoam layer reduces or prevents the formation of foam.

[0058] In one embodiment, the top cover or inlet section of the container housing and the filter holder are manufactured as a single piece, i.e., they are integrally formed. This greatly facilitates the manufacturing process, since it is not necessary to manually attach the filter to the container housing. For example, the filter holder and the container housing (at least a portion thereof) can be co-molded in a single injection molding process. In doing so, the outlet of the inlet section of the container housing is integrally transformed into an inlet inside the filter holder. The bodily fluid that enters the inlet section then flows or is drawn from the inlet section of the container housing towards the interior space of the filter holder. It then has to pass through the filter assembly to reach the bodily fluid collection section.

[0059] In one embodiment, the filter retainer and the filter assembly do not contain an antifoaming agent. In the case of a normal filter, a specific antifoaming agent is required to avoid undesirable foaming of the blood, but the design of the blood flow through the filter element tends to induce only a small amount of foam formation in the blood. If an antifoaming agent is not used, there is no need to fear contamination of the corresponding body fluid, since such an agent cannot be leached into the body fluid.

[0060] In one embodiment, the filter retainer includes bars or struts that stabilize the filter material placed inside the filter retainer. Such bars can be easily manufactured, for example, by injection molding directly onto the filter material. They prevent the filter material from collapsing or remaining wet. Additionally, they can be used to support molten plastic during injection molding to create a punt at the bottom of the filter element.

[0061] In one embodiment, the inlet area of ​​the filter module is funnel-shaped. Such a funnel shape reduces the risk of foam formation in the body fluid. Therefore, the funnel shape of the inlet area can also be considered as part of the "anti-foam by design" concept, which in one embodiment is applied to the filter module. Typically, the filter holder has this particular funnel-shaped inlet area, but the filter assembly does not have to have a particular design (as long as it fits the filter holder).

[0062] In one embodiment, the bottom of the filter module is not completely flat, but rather includes a depression toward the interior space of the filter module. This depression, in one embodiment, extends over substantially the entire area of ​​the bottom of the filter module (particularly the filter retaining portion). The bottom of the filter module is concave when viewed from the outside of the filter module and convex when viewed from the inside of the filter module. Such a design of the bottom of the filter module also plays a role in the "anti-foam by design" approach adopted in one embodiment. The depression in the bottom of the filter module can also be described as shaped like a punt on a champagne bottle. This shape prevents the body fluid from spurting through the filter module and reduces the drop height of the body fluid passing through the filter module. The lower the drop height, the lower the risk of bubbles forming in the body fluid.

[0063] In one embodiment, the hydrophobic filter is integrated into the top cover of the container housing and is located at the top of the container so as to significantly reduce the risk of contact with body fluids. Furthermore, such integration into the top cover of the container allows for a compact design of the entire container.

[0064] The hydrophobic filter, in one embodiment, includes a filter housing and a filter material disposed within the filter housing. Although it is generally possible to design the hydrophobic filter as a replaceable element, in one embodiment, the hydrophobic filter is intended to be a disposable element that is discarded together with the entire bodily fluid collection container. Because the lifespan of the hydrophobic filter is generally longer than the lifespan of the bodily fluid collection container, it is generally not necessary to replace the hydrophobic filter during the intended operation of the bodily fluid collection container.

[0065] The hydrophobic filter may also be a mesh filter, where the mesh size is suitably from 2 to 20 μm, in particular from 3 to 19 μm, in particular from 4 to 18 μm, in particular from 5 to 17 μm, in particular from 6 to 16 μm, in particular from 7 to 15 μm, in particular from 8 to 14 μm, in particular from 9 to 13 μm, in particular from 10 to 12 μm.

[0066] The hydrophobic filter is intended to filter the air drawn by the vacuum source to collect the bodily fluids, or more precisely, from the bodily fluid collecting section of this vessel. The hydrophobic filter protects the vacuum source from smoke (especially surgical smoke), particles (such as bone and tissue fragments), and blood, and reduces the contamination load of the hydrophobic antibacterial filter associated with the pump and located downstream from the hydrophobic filter.

[0067] In one embodiment, the hydrophobic filter comprises a filter material that includes or consists of a hydrophobic polymer such as polytetrafluoroethylene (PTFE), particularly expanded PTFE (ePTFE).

[0068] In one embodiment, the hydrophobic filter comprises a filter material that includes or consists of a hydrophobic polymer, in particular a non-hydrophobic polymer such as polyester (such as PET) treated with a hydrophobic PET mesh. The contact of this element with blood is occasional and very limited in time (spurting) and by its location (top cover) the risk of the hydrophobic treatment leaching into the blood is minimized. However, the hydrophobic treatment must be biocompatible.

[0069] In one embodiment, the hydrophobic filter comprises a pleated filter material. By pleating the filter material, the effective filter surface can be increased without increasing the overall space required for the hydrophobic filter.

[0070] In one embodiment, the pleated filter material has a filter surface area that is at least 3 times, particularly at least 4 times, particularly at least 5 times, particularly at least 6 times, particularly at least 7 times, particularly at least 8 times the surface area of ​​the filter element that houses the hydrophobic filter. The surface area of ​​the filter may be 3 to 8 times, particularly 4 to 7 times, particularly 5 to 6 times the surface area of ​​the filter element that houses the hydrophobic filter. For example, when the surface area of ​​the filter element is 5 to 20 cm 2 For a total filter surface area of ​​15 to 160 cm 2 Such an arrangement therefore makes it possible to integrate a very large filter surface area in a filter element with very low space requirements, which facilitates the integration of the hydrophobic filter in the top cover of the container housing without increasing the dimensions of the top cover compared to top covers known from the prior art.

[0071] In one embodiment, the container is specifically adapted to receive blood as the body fluid, i.e. the body fluid referred to in this description is, in this embodiment, blood.

[0072] The less foam formation in the collected fluid, the better the quality or higher yield of the aggregate fluid is achieved. For blood as a fluid, less foam formation leads to less hemolysis and lower platelet activation, resulting in higher and better quality blood recovery from each individual bloodlet processing step. Mechanical stress of red blood cells is one reason for hemolysis. Foam formation can be an indicator of biological stress.

[0073] In one aspect, the present invention relates to a bodily fluid collection device comprising a vacuum source and a container according to the above description, the vacuum source being directly connected to a vacuum connection of the container via a vacuum line, and there being no components between the vacuum source and the container other than the vacuum line.

[0074] The bodily fluid collection devices known from the prior art have the following general setup: bodily fluid collection container-vacuum line-overfill protection-smoke connection-smoke filter-vacuum line-vacuum pump. Thus, a total of six connection points need to be established. If the vacuum source is directly connected to the connection as in the currently discussed embodiment of the invention, only two connection points need to be established: bodily fluid collection container-vacuum line-vacuum source. Thus, by integrating the hydrophobic filter into the container housing of the bodily fluid collection container, a separate overfill protection, a separate smoke connection, and a separate smoke filter are not required. When relying on this embodiment of the invention, three separate parts, each with two connection points, can be completely omitted. This significantly reduces the workload of medical staff preparing a ready-to-use bodily fluid collection device.

[0075] In the event of a large overflow of the bodily fluid collecting section of the container housing, the collected bodily fluid may pass through the hydrophobic filter. In that case, the bodily fluid may enter the vacuum line connected to the vacuum connection of the container housing. In one embodiment, the vacuum line includes a hydrophobic antibacterial filter to protect the pump. In that way, such a small amount of bodily fluid overflow will have no effect. Rather, some hydrophobic vacuum lines can continue to function even in the presence of accumulated contaminants and liquids. The guiding principle is to reduce the complexity of the vacuum line assembly to improve ease of use.

[0076] In one embodiment, the vacuum line includes an integrally formed antibacterial filter, such that the antibacterial filter does not represent an additional component, but is an integral part of the vacuum line.

[0077] In one embodiment, the antibacterial filter is a hydrophobic filter. In this way, it can also be used to effectively prevent liquid that has entered the vacuum line, for example due to overfilling of the body fluid collecting section of the container housing, from entering a pump arranged downstream of the antibacterial filter. It is possible to equip such an antibacterial filter with an additional chamber to accommodate contamination of the filter. In this way, such a chamber can also serve to receive excess body fluid drawn through the vacuum line due to overfilling.

[0078] In one embodiment, the antibacterial filter has a pore size or mesh size small enough to filter viruses from the fluid (particularly air) drawn through the vacuum line. In such a case, the antibacterial filter also has an antiviral effect, and can be referred to as an antiviral filter.

[0079] In one aspect, the present invention relates to a method for manufacturing a container according to the above description, in which the top cover of the container housing of the container and the filter holder of the container are co-molded, i.e. they are manufactured as one piece, in other words they are integrally formed or molded. Such a manufacturing process is significantly easier than the manufacturing processes known from the prior art. It combines the steps of the previous method of manufacturing the container housing and subsequently attaching the filter to the container housing into a single manufacturing process, i.e. a co-molding process. It can be achieved, for example, by injection molding.

[0080] Although it is also possible to co-mold the filter assembly together with the filter retainer, in one embodiment of the manufacturing method, another approach is taken. More precisely, in this embodiment, the filter assembly is applied (e.g., by molding) to the filter retainer after the filter retainer is manufactured. The filter retainer itself can be co-molded with the top cover of the container housing. In that way, it is not necessary to manufacture different molds for different mesh sizes to be applied to the filter modules of the container housing. Rather, in this embodiment, only a single mold is required to manufacture a number of container housing top covers with integrally formed filter retainers, after which the filters of different filter assemblies can be applied to the filter retainers, thus resulting in container housing top covers that provide different filtering actions (especially different mesh sizes of the filter assemblies).

[0081] In one aspect, the present invention relates to a medical method for withdrawing autologous blood transfusion (ICS) from a patient in need thereof. ICS is typically used in patients undergoing surgery or invasive procedures, with the aim of providing those patients with autologous transfusion of blood or blood components. The method includes the steps described below. First, a blood suction line is connected to the blood inlet of a container for blood collection. Furthermore, a vacuum line is connected to a vacuum connection of the container and to a vacuum source, such as a vacuum pump. In this way, when the vacuum source is activated, a low pressure can be applied to the interior of the container. The container is a container according to the above description. It thus includes a container housing with a blood inlet that allows blood to enter the inlet section of the container housing. The container housing further includes a blood collection section. The vacuum source is typically connected to the vacuum connection of the container housing via a vacuum line.

[0082] The container housing further includes a filter module that separates the inlet section from the blood collection section. More specifically, the filter module is disposed between the inlet section and the blood collection section such that blood drawn from the patient must pass through a filter to flow from the inlet section to the blood collection section. In other words, the filter module has a raw side and a clean side. The raw side faces the inlet section and the clean side faces the blood collection section.

[0083] Once all elements are assembled, the vacuum source is activated, causing blood to be drawn from the patient (e.g., during a surgical intervention) through the blood suction line and into the receiving section of the blood collection canister. It then passes through a filter to reach the blood collection section. It can then be withdrawn from the blood collection container for further processing and / or autotransfusion into the patient.

[0084] In one aspect, the present invention relates to a method for manufacturing a filter assembly according to the foregoing description. As already mentioned, such a filter assembly includes a filter retainer, an antifoam layer, optionally a pre-filter layer and a mesh filter layer.

[0085] The filter retainer is disposed downstream of a mesh filter layer, which in turn is disposed downstream of an antifoam layer and an optional pre-filter layer.

[0086] The method is characterized in that a filter retainer (made of plastic) is overmolded onto the antifoam layer and optionally the pre-filter layer and part of the mesh filter layer, contacting the filter layers of the filter system and stabilizing them. Thus, only one manufacturing step is required to place the filter retainer around the layer of filter material, since the filter retainer is manufactured in situ. This significantly facilitates the manufacture of the filter assembly compared to the filtration devices known from the prior art. The filter retainer can also form the ground area of ​​the filter assembly. It thus forms the base of the filter assembly, and at the same time, a filter material layer can be embedded near the base in order to fix the filter material layer.

[0087] In one embodiment, the various layers of the filter system first form a flat ribbon. This flat ribbon is then brought to the desired shape of the filter assembly. This desired shape can be, for example, the shape of a cylinder jacket, where the cylinder has a circular ground area, an elliptical ground area, a rectangular ground area, or a square ground area. The free ends of the shaped ribbons are then connected to each other. In one embodiment, the connection of the free ends of the shaped ribbons can be achieved by a welding process. Alternatively, the connection can be formed as a non-welded joint. The predetermined shape is fixed by partially overmolding the layers of the filter system with a filter retainer. This manufacturing method of the filter assembly according to one aspect of the invention is significantly easier than the manufacturing techniques applied according to the prior art. More precisely, in the prior art, it is usually necessary to cut the arrangement of the tubular filter made of two welded ribbons. Such a manufacturing process is very difficult, since welding and cutting the two tubular ribbons generates particles that can leach into the fluid passing through the filter, increasing the risk of particle contamination.

[0088] All of the described embodiments of the filter assemblies can be combined in any desired manner and transferred to the described applications, the described containers for collecting bodily fluids and the described methods, and vice versa in each case.

[0089] Further details of aspects of the invention are described below with respect to exemplary embodiments and the accompanying figures. [Brief description of the drawings]

[0090] [Figure 1] FIG. 1 is a perspective view of one embodiment of a blood collection canister.

[0091] [Diagram 2] FIG. 2 is a side view of the broad side of the canister of FIG. 1.

[0092] [Diagram 3] FIG. 2 is a detailed view of the top of the canister of FIG. 1, taken from the narrow side of the canister.

[0093] [Figure 4A] FIG. 1 is a schematic diagram of a first embodiment of a filter system according to the invention.

[0094] [Figure 4B] FIG. 2 is a schematic diagram of a second embodiment of a filter system according to the invention.

[0095] FIG. 1 is a perspective view of a blood collection canister 1 that serves as a container for collecting bodily fluids. The blood collection canister 1 comprises a canister housing 2 having a top cover 3. Three different blood inlets 4 are disposed on the top cover 3. Typically, only one of these blood inlets 4 is used to connect a blood suction line to the blood collection canister 1 in order to draw blood from a patient into the interior of the canister housing 2. The right-most blood inlet 4 (with reference to FIG. 4) is designed as a 3 / 8 inch connection. The middle blood inlet 4 is designed as a Luer inlet, and the left-most blood inlet 4 is designed as a suction line connection sized to accommodate a typical blood suction line.

[0096] Each of the blood inlets 4 is fluidly connected to a blood-receiving section 5 disposed inside the top cover 3. The blood-receiving section 5 is in fluid communication with the interior of a filter module 6 (functioning as a filter assembly) that includes a skeletal structure 7 that functions as a filter holder.

[0097] Disposed within skeletal structure 7 are material layers of filter system 8. Filter material or filter system 8 includes an antifoam layer made of medical grade mesh and a mesh filter layer. Blood enters receiving section 5 of blood collection canister 1 through blood inlet 4 and flows or is drawn into the interior of filter module 6. It then passes through filter material 8 and arrives at blood collection section 9 of canister housing 2.

[0098] The blood collection canister 1 includes a vacuum connection 10 at the top section 3 of the canister housing 2 that is connected to a vacuum line and, via the vacuum line, to a vacuum pump that functions as a vacuum source. Air or other gas present in the blood collection section 9 that is drawn through the vacuum connection 10 into the connected vacuum line must pass through a hydrophobic filter 11 located between the blood collection section 9 and the vacuum connection 10.

[0099] The blood collection canister 1 further comprises a safety valve 12 that limits the amount of negative pressure that can be achieved within the interior of the canister housing 2. The safety valve 12 thus helps to reduce the risk of the blood collection canister 1 imploding due to undesirably low negative pressure within the interior of the canister housing 2.

[0100] Viewed from the outside, the bottom 13 of the filter module 6 has a concave shape, i.e. with a depression towards the inside of the filter module 6 .

[0101] Blood that enters the canister housing 2 through the blood inlet 4 and passes through the filter material 8 is collected in the blood collection section 9. It is then withdrawn from the blood collection canister 1 through the blood outlet 14 for further processing and / or autotransfusion into the patient.

[0102] Figure 2 shows the blood collection canister 1 of Figure 1 in a side view of the broad side of the blood collection canister 1. The same reference numbers are used for the same elements. Reference is made to the explanation given with respect to Figure 1. In Figure 2 the connection between the filter module 6 and the blood receiving section 5 of the canister housing 2 can be seen. As is evident from Figure 2, blood can only enter from the blood receiving section 5 into the interior of the filter module 6 and then has to pass through the filter material 8 to reach the blood collecting section 9 of the canister housing 2. The filter module 6 thus separates the blood receiving section 5 from the blood collecting section 9.

[0103] Figure 3 shows a partial cutaway view from the narrow side of the blood collection canister 1 of Figure 1. The same reference numbers are used again for the same elements. Reference is again made to the above description.

[0104] In the depiction of FIG. 3, it can be seen that a funnel-shaped inlet 15 is disposed in the inlet region of the filter element. Blood entering the filter module 6 from the blood receiving section 5 must pass through this funnel-shaped inlet 15. The funnel-shaped inlet 15, together with the filter material 8 and the concave bottom 13 of the filter module 6, helps to reduce bubble formation in the blood passing through the filter module 6. This reduction in bubble formation results in better quality blood than foamy blood, resulting in a higher collection yield due to a lower rate of hemolysis.

[0105] 3, it can be seen that the hydrophobic filter 11 comprises a pleated filter material. This folding of the filter material significantly increases the effective surface area of ​​the filter. By way of example, the filter material of the hydrophobic filter 11 may be approximately 60 cm 2 The hydrophobic filter itself has a total filter surface area of ​​approximately 10 cm2 in the top cover 3 of the canister housing 2. 2 Thus, by folding the filter material, the effective filter surface area is made six times larger than the surface area required by the hydrophobic filter element 11.

[0106] 4A shows a first embodiment of a filter system 8 according to the invention, which comprises an antifoam layer 8a and a mesh layer 8b.

[0107] The antifoam layer 8a is made of an open mesh fabric with a three-dimensional (3D) embossed structure for trapping foam. For the embodiment shown in FIG. 4A (and FIG. 4B), the spatial structure of the antifoam layer is a diamond pattern with regularly spaced protrusions and depressions of constant height. This structure or weave pattern is also known as Gauffree Diamond. The depressions form cells for trapping the formed biofluid bubbles.

[0108] The antifoam layer 8a may have a thickness greater than that of the downstream pre-filter layer 8c or mesh layer 8b. In one embodiment, the antifoam layer 8a may have a thickness greater than the thickness of 2 to 3 filaments. The three-dimensional structure and thickness of the antifoam layer means that the pores of the fabric do not all lie in the same plane.

[0109] The fiber material of the antifoaming layer is polypropylene (PP) with a fiber diameter of 200-300 μm, for example, 200 μm, 250 μm, 300 μm. The mesh number is between 12 and 16 n / cm. The mesh size or opening is between 250 and 300 μm.

[0110] The mesh filter layer 8b is made of interconnecting threads forming a grid or net. The mesh size of the mesh filter material 8b is between 40 μm and 120 μm, and is therefore smaller than the mesh size of the antifoam layer. For the embodiment shown in FIG. 4A, where the filter system consists only of an antifoam layer and a mesh filter layer, the mesh size of the mesh filter material can be 120 μm. Such a filter system is applicable to large pore filtration.

[0111] The filter system shown in Figure 8B is composed of three layers: an antifoam layer 8a, a mesh filter layer 8b, and a pre-filter layer 8c disposed (or sandwiched) between the antifoam layer 8a and the mesh filter layer 8b.

[0112] The pre-filter layer 8c is made of non-woven fabric having a trilobal cross-section, while the mesh filter layer 8b is made of a regularly shaped medical grade mesh.

[0113] In the embodiment shown in Figure 4B, where the filter system consists of three layers (antifoam layer 8a, pre-filter layer 8c and mesh filter layer 8b), the mesh size of the mesh filter material can be 40 μm. Such a filter system is applicable for low pore size filtration.

[0114] As shown in both Figures 4A and 4B, blood flow enters the filter system 8 through antifoam layer 8a. Foam bubbles contained in the blood are trapped within the 3D structure of antifoam layer 8a and are therefore prevented from entering the downstream pre-filter layer 8c and mesh filter layer 8b. The blood flow exiting the filter system at the mesh filter side is bubble-free.

[0115] The pressure depends on the pore size of the material used and its basis weight. The pressure is determined by capillary flow porometry. This method allows the pore size of the filter material (MFP, Mean Flow Pore Size) to be determined.

Claims

1. A filter assembly for filtering a body fluid, comprising a filter system and a filter retainer, The filter system and the filter holder are in contact with each other, The filter system is disposed inside the filter holder, The filter system is comprised of at least two layers; a first layer formed of an open mesh fabric woven from monofilaments, the first layer being an antifoaming layer having an embossed three-dimensional structure configured to trap foam accumulated in said bodily fluid; The second layer is a mesh filter layer; The filter assembly, wherein the mesh filter layer is disposed downstream of the antifoam layer.

2. 10. The filter assembly of claim 1, wherein the anti-foam layer comprises mesh openings between 100-500 μm, or between 150-400 μm, or between 200-350 μm, or between 250-300 μm.

3. 3. A filter assembly according to claim 1 or claim 2, wherein the antifoam layer is formed by monofilament fibres having a diameter between 100 and 350 μm, or between 150 and 300 μm, or between 200 and 300 μm.

4. 4. The filter assembly according to claim 1, wherein the antifoam layer has a mesh number between 10 and 50 n / cm, or between 10 and 30 n / cm, or between 10 and 20 n / cm.

5. 5. The filter assembly of claim 1, wherein the mesh filter layer has a mesh size in the range of between 20 and 150 μm, or between 30 and 140 μm, or between 40 and 130 μm, or between 50 and 120 μm, or between 60 and 110 μm, or between 70 and 100 μm, or between 80 and 90 μm.

6. 6. The filter assembly of claim 1, further comprising a pre-filter layer disposed downstream of the antifoam layer and upstream of the mesh filter layer, the mesh filter layer having a mesh size of about 40 μm.

7. 6. The filter assembly of claim 1, wherein the filter assembly does not include a pre-filter and the mesh filter layer has a mesh size of about 120 μm.

8. The filter assembly of claim 6 , wherein the pre-filter layer comprises a spunbond nonwoven.

9. 9. A filter assembly according to claim 6 or claim 8, wherein the pore size of the pre-filter layer is in the range between 20 and 150 μm, or between 30 and 140 μm, or between 40 and 130 μm, or between 50 and 120 μm, or between 60 and 110 μm, or between 70 and 100 μm, or between 80 and 90 μm.

10. The filter assembly of claim 1 , wherein the filter retainer is made of plastic and is overmolded onto at least a portion of the filter system.

11. The filter assembly of claim 1 , wherein the filter assembly is free of an antifoam agent.

12. The filter assembly of claim 10, wherein the plastic is selected from ABS or polycarbonate.

13. 13. The filter assembly of any one of the preceding claims, wherein the antifoam layer has a thickness of 150 to 650 μm, or 200 to 500 μm, or 250 to 400 μm, or 300 to 350 μm.

14. 14. The filter assembly of claim 1, wherein the anti-foam layer comprises pores distributed in a non-planar arrangement.

15. A container for collecting body fluids, comprising as a filter module a filter assembly according to any one of claims 1 to 14.

16. the container housing (2) having a body fluid inlet (4) through which body fluid can enter an inlet section (5) of the container housing (2), a body fluid collection section (9), a vacuum connection (10) for connecting a vacuum source to the container housing (2) for applying an underpressure to the inlet section (5) and to the body fluid collection section (9), and a filter assembly as a filter module (6) disposed between the inlet section (5) and the body fluid collection section (9); Container according to claim 15, wherein the antifoam layer faces the inlet section (5) and the mesh filter layer faces the bodily fluid collection section (9).

17. Container for collecting bodily fluids as described in claim 16, wherein the container housing (2) further comprises a hydrophobic filter (11) arranged between the bodily fluid collection section (9) and the vacuum connection (10) in the flow direction of air drawn by a vacuum source from the bodily fluid collection section (9) during intended use of the container.

Images