Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/02—Blood transfusion apparatus
  • A61M1/0281—Apparatus for treatment of blood or blood constituents prior to transfusion, e.g. washing, filtering or thawing
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
  • A61M1/3621—Extra-corporeal blood circuits
  • A61M1/3626—Gas bubble detectors
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/36—Other treatment of blood in a by-pass of the natural circulatory system, e.g. temperature adaptation, irradiation ; Extra-corporeal blood circuits
  • A61M1/3621—Extra-corporeal blood circuits
  • A61M1/3627—Degassing devices; Buffer reservoirs; Drip chambers; Blood filters
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/71—Suction drainage systems
  • A61M1/78—Means for preventing overflow or contamination of the pumping systems
  • A61M1/784—Means for preventing overflow or contamination of the pumping systems by filtering, sterilising or disinfecting the exhaust air, e.g. swellable filter valves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M1/00—Suction or pumping devices for medical purposes; Devices for carrying-off, for treatment of, or for carrying-over, body-liquids; Drainage systems
  • A61M1/71—Suction drainage systems
  • A61M1/79—Filters for solid matter
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
  • B01D29/111—Making filtering elements
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
  • B01D29/13—Supported filter elements
  • B01D29/23—Supported filter elements arranged for outward flow filtration
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
  • B01D29/11—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with bag, cage, hose, tube, sleeve or like filtering elements
  • B01D29/13—Supported filter elements
  • B01D29/23—Supported filter elements arranged for outward flow filtration
  • B01D29/232—Supported filter elements arranged for outward flow filtration with corrugated, folded or wound sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/08—Filter cloth, i.e. woven, knitted or interlaced material
  • B01D39/083—Filter cloth, i.e. woven, knitted or interlaced material of organic material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D39/00—Filtering material for liquid or gaseous fluids
  • B01D39/14—Other self-supporting filtering material ; Other filtering material
  • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
  • B01D39/1607—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous
  • B01D39/1623—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being fibrous of synthetic origin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/02—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by structural features of a fibrous or filamentary layer
  • B32B5/022—Non-woven fabric
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
  • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
  • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2205/00—General characteristics of the apparatus
  • A61M2205/75—General characteristics of the apparatus with filters
  • A61M2205/7536—General characteristics of the apparatus with filters allowing gas passage, but preventing liquid passage, e.g. liquophobic, hydrophobic, water-repellent membranes
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M2207/00—Methods of manufacture, assembly or production
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/04—Supports for the filtering elements
  • B01D2201/0415—Details of supporting structures
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/18—Filters characterised by the openings or pores
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2201/00—Details relating to filtering apparatus
  • B01D2201/20—Pressure-related systems for filters
  • B01D2201/204—Systems for applying vacuum to filters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
  • B01D2239/0604—Arrangement of the fibres in the filtering material
  • B01D2239/0618—Non-woven
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
  • B01D2239/0604—Arrangement of the fibres in the filtering material
  • B01D2239/0627—Spun-bonded
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
  • B01D2239/065—More than one layer present in the filtering material
  • B01D2239/0654—Support layers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
  • B01D2239/12—Special parameters characterising the filtering material
  • B01D2239/1216—Pore size
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2250/00—Layers arrangement
  • B32B2250/20—All layers being fibrous or filamentary
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/726—Permeability to liquids, absorption
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2535/00—Medical equipment, e.g. bandage, prostheses or catheter

Definitions

• the present invention relates to a filter assembly, to an appropriate use of such a filter assembly, to a container for collecting a body fluid comprising such filter assembly as well as to a method for manufacturing such a filter assembly.
• Filtering assemblies known from prior art are used to filter different types of fluids, e.g. body fluids, for removing aggregates, particles or specific cells from said fluids.
• a particular appropriate application of filter assemblies is the filtration of blood.
• Whole blood comprises three major cellular components, namely, red blood cells, leukocytes (also designated as white blood cells) and thrombocytes (also designated as platelets).
• a major non- cellular component of the blood is the blood plasma.
• Whole blood or blood components may be separated and further processed for a variety of uses, particularly for use as transfusion products.
• Filtering assemblies are also used in auto transfusion processes during surgeries procedures; i.e. blood of a patient is recovered during surgery and re-infused into the patient. This is also known as Intraoperative blood salvage, or autologous blood transfusion or cell salvage. It has been used for many years and gained greater attention over time as risks associated with allogenic (separate-donor) blood transfusion have seen greater publicity and become more fully appreciated.
• Several medical devices have been developed to assist in salvaging the patient's own blood in the perioperative setting. The procedure is frequently used in cardiothoracic and vascular surgery, during which blood usage has traditionally been high.
• Blood salvage requires a removal of blood clots, non-cellular substances, such as drugs or fluids used during surgery, bone fragments and surgery debris.
• WO 2013/1 10694 A1 describes a blood filter comprising first fibers having at least one groove extending in the longitudinal direction of the fiber.
• Filtering shed blood typically results in a foam formation in the filtered blood.
• One approach to avoid foam formation in shed blood is the use of antifoam agents in reservoirs where shed blood is collected for autotransfusion or extracorporeal circulation.
• polydimethylsiloxane (PDMS) - hydrophobed silica was widely used as antifoam.
• PDMS polydimethylsiloxane
• PDMS is leached into the blood, where it emulsifies. It is presumed that most of it will be found in the waste after the washing procedure, but it cannot excluded that part of it is found in the Red Cell Concentrate that is autotransfused to the patient.
• the filtering assemblies as for example described above are typically used in specific body fluid collecting containers, in particular blood-collecting containers.
• These containers serve for collecting blood during a surgical intervention of a patient. Afterwards, the blood is processed (washed) in order to remove undesired components of the blood and to increase the concentration of red blood cells in the blood. After processing the blood, it can be auto-transfused to the patient to avoid the necessity of providing the patient with blood donations.
• Prior art blood collection containers comprises a filter socket that is manually tied to the top cover of the container.
• the filter material is treated with antifoam agents that reduce the risk of foam formation in the blood.
• antifoam agents leach from the filter, into the blood and thus administered to the patient when auto-transfusing the blood to the patient (as described above).
• Blood collecting containers known from prior art are typically connected to a device that protects an undesired overfill of the blood collecting container.
• Such an overflow protection device (trap) is the only non-reusable component of the whole appliance. Its use is mandatory.
• the overflow protection device must be assembled manually to the vacuum circuit by the operator after it has been cleaned and sterilized in the hospital prior to use.
• a typical overfill protection device is a 100-ml glass with an input and an output cannula, wherein a floating element is constrained in the output cannula. In case of overflow of blood from the blood collection container into a vacuum line connected to the blood collection container, blood is drawn into the glass.
• a smoke filter is provided in the vacuum line that is used to create vacuum in the container and consequently in the cannula for drawing blood from the patient.
• This smoke filter serves for filtering surgical smoke and for preventing this smoke from clogging the antibacterial filter which protects the vacuum pump from surgical air contamination.
• Smoke filters known from prior art are stand-alone multi- or single- use disposables medical devices or accessories that are manually integrated into a vacuum line of the appliance serving for drawing blood from a patient.
• an antibacterial or antiviral filter is connected to the vacuum line and used to protect the pump from surgical air contamination. It is disposable and may be single- or multi-use. Single- use filters are typically integrated in the vacuum line. Multi-use filters are typically stand-alone
• the first and second objects are achieved by a filter assembly and a container for collecting a body fluid having the features explained in the following.
• a filter assembly comprising a prefiltering support layer.
• the prefiltering support layer in turn comprises or essentially consists of a non-woven fabric of fibers.
• the fibers are arranged such that gaps are formed between the fibers. Consequently, an average pore size of the non-woven fabric (for depth filtration) results.
• a first (woven) mesh filter layer (for surface filtration) is arranged downstream the prefiltering support layer, wherein the first mesh filter layer has a first mesh size, wherein the pore size of the prefiltering support layer is equal to or bigger than the first mesh size of the first mesh filter.
• the prefiltering support layer does not alter or limit the filtration properties of the first mesh filter layer but mainly serves for stabilizing the first mesh filter layer and keeping the first mesh filter layer in place. Some of the particles that would have been filtered by the first mesh filter layer are already filtered by the prefiltering support layer, so that the filtration load of the first mesh filter layer is reduced. Thus, the prefiltering support layer does not only stabilize the first mesh filter layer, it also serves for avoiding a premature clogging of the first mesh filter layer.
• the filter assembly further comprises a filter holder arranged downstream of the mesh filter layer.
• This filter holder contacts both the prefiltering support layer and the first mesh filter layer. In doing so, it also stabilizes the prefiltering support layer as well as the first mesh filter layer.
• the filter holder serves for keeping the prefiltering support layer and the first mesh filter layer in place; it acts as structural support.
• the filter assembly is a stand-alone filter assembly (self-sustained filter assembly) or it can be one part (overmoulded) with filter layers.
• a filter assembly comprising a prefiltering support layer as well as a mesh filter layer instead of a regular filter (made only of fibers or foam or a membrane) is connected to the effect that extremely reproducible filtering conditions can be met.
• regular filters have an average pore size with many pores being bigger or smaller than the average pore size
• a mesh filter has a clearly defined mesh size that essentially does not vary.
• a support that can be another open mesh or a continuous filament nonwoven material, such as a spunbond.
• the filter holder is made from plastic and is overmolded over a part of the prefiltering support layer and a part of the first mesh filter layer. Then, it tightly connects both layers together and serves particularly easy for a good stabilization of both layers.
• the prefiltering support layer and the first mesh layer are no separate components, but are rather integrally formed and thus build up a structural composite.
• “Structural composite” means that the prefiltering support layer and the first mesh filter layer can be made of the same material but do have a different structure (the prefiltering support layer is a non-woven fabric; the first mesh filter layer is a mesh or net).
• the first mesh layer is made of a plurality of interconnecting threads forming a screen or grid or a net.
• vertically arranged threads and horizontally arranged threads are connected to each other at connecting points so as to form a grid.
• the filter assembly comprises a second mesh filter layer.
• the second mesh filter layer has a second mesh size, wherein the second mesh size is equal to or bigger than the pore size of the prefiltering support layer.
• the prefiltering support layer is arranged in between the first mesh filter layer and the second mesh filter layer.
• the first mesh filter layer, the prefiltering support layer and the second mesh filter layer are arranged in a sandwich- like manner, wherein the prefiltering support layer is encompassed by the first mesh filter layer and the second mesh filter layer; i.e. the downstream arrangement is in the order second mesh filter - filtering support layer - first mesh filter.
• Such an arrangement serves for a particularly stable arrangement of the mesh layers and thus for a particular stable filter assembly.
• the filter holder is, in an embodiment, also overmolded over a part of the second mesh layer to also tightly connect this layer to the other two layers.
• the prefiltering support layer comprises or essentially consists of continuous filament spunbond nonwoven fabric.
• Said fabrics are obtained in continuous filament nonwoven processes (meltblowing and spunbonding) that start extruding chips or pellets of raw material.
• the length of the filament is theoretically infinite, thus lowering the risks of leaching fibers (as observed in needled felt nonwoven fabrics) is essentially lower than for needled felt materials.
• the individual fibers of the prefiltering support fabric may have any desired cross-section, such as a circular, elliptic rectangular, quadratic or triangular cross-section. Mixtures of fibers having different cross sections are also possible.
• the fibers of the prefiltering support layer can also generally have any shape. However, it turned out that particularly good filtering can be achieved if the fibers, or at least a part of the fibers, comprise at least one groove extending in the longitudinal direction of the respective fiber. To give an example, the fibers may comprise three grooves each extending in a longitudinal direction of the fiber. Then, aggregates, fat and/or platelets can be particularly well filter from blood or another body fluid flowing through the filter assembly.
• At least a part of the fibers has a lobate cross-section.
• a lobate cross- section can be achieved, in an embodiment, by forming a groove in the fibers in the longitudinal direction.
• a trilobal cross-section is a particularly well suited example of a lobate structure.
• Such trilobal fibers are generally known, e.g., from WO 2013/1 10694 A1 , the entire content of which is hereby incorporated by reference.
• the fibers making up the non-woven fabric of the prefiltering support layer can be, in an embodiment, spunbond fibers or melt-blown fibers. While spunbond fibers typically have a fiber diameter that is at least 20 pm or larger, melt-blown fibers may have lower diameters of less than 20 pm.
• the fibers may be monocomponent, bicomponent or multicomponent fibers, including“island in the sea” fibers.
• the fibers may consist of one polymer or a blend of polymers. Suitable materials for the fibers are, for example, a 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 1 1 , nylon 12, cellulose acetate, cellulose acetate propionate, or a combination thereof.
• a non-hydrophobic or hydrophilic material is particularly appropriate to produce the fibers. It is also possible to increase the hydrophilicity of the material which is used to produce the fibers or to increase the hydrophilicity of the already produced fibers. Thereby, a physical treatment is more appropriate than the deposition of chemicals because such chemicals might potentially be leached from the fibers or the fabric produced therefrom during use of the filter assembly.
• the pore size of the prefiltering support layer lies in a range of between 20 and 150 pm, in particular between 30 and 140 pm, in particular between 40 and 130 pm, in particular between 50 and 120 pm, in particular between 60 and 1 10 pm, in particular between 70 and 100 pm, in particular between 80 and 90 pm. Ranges of 100 to 130 pm, 105 to 125 pm, 70 to 90 pm, 75 to 85 pm, 30 to 45 pm and 35 to 40 pm are particularly appropriate.
• the first mesh filter layer can comprise or can be entirely made of a polymer such as a 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 1 1 , nylon 12, cellulose acetate, cellulose acetate propionate, or a combination thereof.
• a non-hydrophobic or hydrophilic material is particularly appropriate to produce the mesh filter layer.
• An appropriate surface area of the mesh filter layer lies in a range of 300 to 1000 cm 2 , in particular 400 to 900 cm 2 , in particular 500 to 800 cm 2 , in particular 600 to 700 cm 2 .
• the mesh filter layer is made from the same material as the prefiltering support layer.
• the second mesh filter layer is, besides its mesh size, structurally identical to the first mesh filter layer.
• the first mesh filter layer and the second mesh filter layer are structurally very similar. This facilitates manufacturing of the filtering assembly.
• the threads or filaments of the first mesh filter layer and/or the second mesh filter layer have a circular cross-section.
• other cross sections such as an elliptic, a rectangular, a quadratic or a triangular cross-section would also be possible.
• mixtures of threads or filaments having different cross sections are also possible.
• the first mesh size of the first mesh filter layer and/or the second mesh size of the second mesh filter layer lies in a range of between 20 and 150 pm, in particular between 30 and 140 pm, in particular between 40 and 130 pm, in particular between 50 and 120 pm, in particular between 60 and 1 10 pm, in particular between 70 and 100 pm, in particular between 80 and 90 pm. Ranges of 100 to 130 pm, 105 to 125 pm, 70 to 90 pm, 75 to 85 pm, 30 to 45 pm and 35 to 40 pm are particularly appropriate, for example 1 15 pm, 120 pm or 40 pm.
• the non-woven fabric of the prefiltering support layer has areas of different pore size. This enables the prefiltering support layer to have at least two zones with different filtration capacities.
• a first zone of the prefiltering support layer might have a poresize lying in a range of 20 pm to 60 pm, in particular of 25 pm to 55 pm, in particular of 30 pm to 50 pm, in particular of 35 pm to 45 pm, in particular of 38 pm to 42 pm, i.e., around 40 pm.
• the pore size of the first area is 40 pm.
• the second area has a different pore size than the first area.
• the pore size of the second area lies, in an embodiment, in a range of 60 pm and 120 pm, in particular of 65 pm to 95 pm, in particular of 70 pm to 90 pm, in particular of 75 pm to 85 pm, in particular of 78 pm to 82 pm, i.e. around 80 pm. In an embodiment, the pore size of the second area is 80 pm.
• the prefiltering support layer has three zones or areas of different filtration capacities due to different pore sizes of the non-woven fabric.
• the first and second area as explained with respect to the preceding embodiment might be combined with a third area that has a pore size differing from the pore sizes of the first and second area.
• the pore size of the third area lies, in this embodiment, in a range of 100 pm to 140 pm, in particular of 105 pm to 135 pm, in particular of 1 10 pm to 130 pm, in particular of 1 15 pm to 125 pm, in particular of 1 18 pm to 122 pm, i.e. around 120 pm.
• the pore size of the third area is 120 pm.
• the arrangement of at least three different pore size areas in the prefiltering support layer provides a pore size gradient.
• the gradient starts with a pore size of 40 pm in the first area, followed by a pore size of 80 pm in the second area and a pore size of 120 pm in the third area.
• the pore size gradient is a stepwise gradient of the pore size. Any combination of pore sizes in such a stepwise gradient are conceivable.
• the first mesh filter layer and/or the second mesh filter layer may likewise have different areas of mesh sizes, e.g., areas as explained above with respect to the prefiltering support layer.
• the areas (or gradient) of different mesh sizes are formed by establishing a gradient of mesh size within the non-woven fabric of the prefiltering support layer or within the mesh of the first mesh filter layer and/or the second mesh filter layer, respectively.
• the prefiltering support layer, the first mesh filter layer and optionally a second mesh filter layer extend over a vertical extension direction and over a horizontal extension direction.
• the vertical extension direction is vertically aligned during normal operation of the filter assembly.
• the horizontal extension direction is horizontally aligned during normal operation of the filter assembly.
• the non-woven fabric of the prefiltering support layer and/or the first mesh filter layer and/or the second mesh filter layer (if present) has a first area in a first height of the vertical extension direction and a second area in a second height of the vertical extension direction.
• the second height differs from the first height.
• the first area and the second area have different mesh sizes and exhibit different filtration capacities. Consequently, the filter assembly has a vertical gradient of filtration capacity.
• the lowest area typically has the lowest filtration capacity (it allows the lowest flow rate) but has the highest filtration performance (it filters the smallest particles).
• the topmost area typically has the highest filtration capacity but has the lowest filtration performance.
• Intermediate areas typically have intermediate filtration capacities and performances.
• the filter assembly does not comprise any anti-foaming agents.
• anti-foaming agents By avoiding the use of such anti-foaming agents the risk of leaching anti-foam chemicals into a fluid that is flowing through the filter assembly is fully prevented. This enhances the quality of the fluid filtered by the filter assembly.
• the present invention relates in an aspect to the use of the filter assembly having the features explained above for filtering a body fluid in vitro.
• the body fluid can be blood, urine, bile, tissue fluid, sperm, lymph, saliva or cerebrospinal fluid.
• Blood is a particularly appropriate body fluid to be filtered.
• the present invention relates to a method of filtering a body fluid by letting the body fluid flow through a filter assembly according to the preceding explanations.
• the flow of the body fluid can be accomplished by gravity or by applying external forces such as low pressure to the body fluid or a container into which the filter body fluid is to be drawn.
• This method can be done in vitro or ex vivo, while a patient donating the body fluid to be filtered is connected to a filter appliance in which the body fluid is filtered.
• the method is a medical method for drawing intraoperative cell salvage (ICS) from a patient in need thereof.
• ICS is typically used for patients undergoing surgery or invasive procedures and is intended to provide those patients with an autotransfusion of blood or blood components. More details on such a method are given in subsequent sections.
• the present invention relates to a container for collecting a body fluid.
• a container for collecting a body fluid.
• a container comprises a container housing with a body fluid inlet that allows a body fluid to enter an inlet section of the container housing.
• the container housing furthermore comprises a body fluid collection section and a vacuum connector for connecting a vacuum source to the container housing.
• a negative pressure can be applied to the inlet section and to the body fluid collection section.
• the vacuum source is typically connected via a vacuum line to the vacuum connector of the container housing.
• the container housing comprises a filter module that separates the inlet section from the body fluid collection section.
• the filter module is arranged between the inlet section and the body fluid collection section so that a body fluid needs to pass the filter in order to flow from the inlet section to the body fluid collection section.
• the filter module has a raw side and a clean side. The raw side faces the inlet section and the clean side faces the body fluid collection section.
• the filter module additionally comprises a filter assembly according to the preceding explanations.
• the filter assembly is arranged within the filter holder.
• the filter holder serves for supporting the filter assembly on the downstream side of the filter assembly.
• Such an arrangement is particularly appropriate for stabilizing the mesh filter of the filter assembly both from the upstream side (where the mesh filter layer is stabilized by the prefiltering support layer) and from the downstream side (where the mesh filter layer is stabilized by the filter holder). It is furthermore particularly appropriate for achieving a foam- free filtration of a body fluid such as blood.
• the container housing comprises a hydrophobic filter that is arranged between the body fluid collection section and the vacuum connector.
• the term “between” relates to a flow direction of air drawn by a vacuum source from the container (or the body fluid collection section of the container housing) during the intended operation of the container. I.e., any fluid that is drawn from the interior of the container housing (in particular air and smoke) needs to pass the hydrophobic filter prior to entering a vacuum line connected to the vacuum connector.
• the hydrophobic filter serves as protective element for a vacuum line being connected to the vacuum connector of the container housing, when vacuum is generated by a vacuum pump.
• the novel filter module and the hydrophobic filter synergistically act together so that this combination results in the effects explained in the following.
• constructing the filter module with a filter holder and a filter assembly comprising a prefiltering support layer as well as a mesh filter layer much more flexibility is given for the design of the filter holder than in case of using prefabricated filter sockets like in prior art.
• the hydrophobic filter arranged in flow direction before the vacuum connector serves both as smoke filter and as overfill protection.
• the hydrophobic filter arranged in flow direction before the vacuum connector serves both as smoke filter and as overfill protection.
• This single element is thereby included in the container housing.
• it is not necessary to connect it with a separate vacuum line.
• a top cover or an inlet section of the container housing and the filter holder are manufactured as one piece, i.e., they are integrally formed. This facilitates the manufacturing steps significantly since no manual attachment of a filter to the container housing is necessary anymore.
• the filter holder and (at least parts of) the container housing can be co-molded in one single injection molding step. Then, an outlet of the inlet section of the container housing turns integrally into an inlet of an interior of the filter holder. Any body fluid that enters the inlet section will then flow or will be drawn from the inlet section of the container housing towards an interior space of the filter holder. It has then to pass the filter assembly in order to reach the body fluid collection section.
• the filter holder and the filter assembly are free of antifoam agents. While certain antifoam agents are necessary in case of regular filters to avoid an undesired foaming of blood, the design of the blood path through the filter element tend to induce foam formation in blood only to a very low extent. If no antifoam agents are used, no such agents can be leached into body fluids so that no corresponding contamination of the body fluid needs to be feared.
• the filter holder comprises bars or struts that stabilize the filter material which is located in an interior of the filter holder.
• Such bars can be easily produced by injection molding, e.g., directly on the filter material. They prevent the filter material to collapse and to stick wet. Furthermore, they can be used during injection molding to carry molten plastics to create a punt at the bottom of the filter element.
• an inlet area of the filter module is funnel-shaped.
• Such a funnel shape reduces the risk of foam formation in the body fluid.
• the funnel shape of the inlet area can also be considered as part of the concept“defoaming by design” that is, in an embodiment, applied to the filter module.
• the filter holder typically has this specific funnel-shaped inlet area, whereas the filter assembly does not need to have any specific design (as long as it fits into the filter holder).
• the bottom of the filter module is not entirely flat, but rather comprises an indention towards an interior space of the filter module.
• this indention extends, in an embodiment, over essentially the full area of the bottom of the filter module (in particular of the filter holder).
• the bottom of the filter module has a concave shape when looked from the outside of the filter module and a convex shape when looked from the inside of the filter module.
• Such a design of the bottom of the filter module plays also a role in the“defoaming by design” approach taken in an embodiment.
• the indention of the bottom of the filter module can also be described as a shape like a champagne’s bottle punt. This shape avoids spurts of body fluid passing through the filter module and reduces the falling height of the body fluid passing through the filter module. The lower the falling height, the lower the risk of foam formation in the body fluid.
• the hydrophobic filter is integrated into the top cover of the container housing. Then, it is arranged in an upper location of the container so that the risk of getting into contact with the body fluid is significantly reduced. Furthermore, such integration in the top cover of the container still allows a compact design of the whole container.
• the hydrophobic filter comprises, in an embodiment, a filter housing and a filter material placed in the filter housing. While it would be generally possible to design the hydrophobic filter as exchangeable element, it is intended, in an embodiment, that the hydrophobic filter is a disposable element that is discarded together with the whole body fluid collecting container. The lifetime of the hydrophobic filter is generally longer than the lifetime of the body fluid collecting container so that it is generally not necessary to replace the hydrophobic filter during the intended operation of the body fluid collecting container.
• the hydrophobic filter may also be a mesh filter, wherein a mesh size of 1 to 20 pm, in particular 3 to 19 pm, in particular 4 to 18 pm, in particular 5 to 17 pm, in particular 6 to 16 pm, in particular 7 to 15 pm, in particular 8 to 14 pm, in particular 9 to 13 pm, in particular 10 to 12 pm is appropriate.
• the hydrophobic filter is intended to filter air drawn by a vacuum source from the container for collecting a body fluid, or, to be more precisely, from the body fluid collecting section of this container.
• the hydrophobic filter protects the vacuum source from smoke (in particular surgical smoke), particles (such as bone or tissue fragments), and blood and also reduces the load of contaminations of the hydrophobic antibacterial filter that is associated to the pump and thus located downstream from the hydrophobic filter.
• the hydrophobic filter comprises a filter material comprising or consisting of a hydrophobic polymer such as polytetrafluoroethylene (PTFE), in particular expanded PTFE (ePTFE).
• PTFE polytetrafluoroethylene
• ePTFE expanded PTFE
• the hydrophobic filter comprises a filter material comprising or consisting of a non-hydrophobic polymer such as polyester (such as PET) treated with a hydrophobic polymer, in particular a hydrophobic PET mesh. Since the contact with blood of this element is occasional and very limited in time (spurts) and due to the position (top cover), the risk that the hydrophobic treatment is leached into the blood is minimal. However, the hydrophobic treatment has to be biocompatible.
• the hydrophobic filter comprises a pleated filter material. By pleating the filter material, the effective filter surface can be increased while not increasing the overall space needed for the hydrophobic filter.
• the pleated filter material has a filter surface area being at least 3 times, in particular at least 4 times, in particular at least 5 times, in particular at least 6 times in particular at least 7 times, in particular at least 8 times as high as the surface area of the filter element that houses the hydrophobic filter.
• the filter surface area might be 3 to 8 times, in particular 4 to 7 times, in particular 5 to 6 as high as the surface area of the filter element that houses the hydrophobic filter.
• the total filter surface might be in a range of 15 to 160 cm 2 .
• the container is specifically adapted to receive blood as body fluid.
• body fluid referred to in the present description is, in this embodiment, blood.
• the invention relates to a body fluid collecting arrangement comprising a vacuum source and a container according to the preceding explanations.
• the vacuum source is directly connected to a vacuum connector of the container via a vacuum line. No component parts other than the vacuum line is present between the vacuum source and the container.
• Body fluid collecting arrangements known from prior art have the following general setup: body fluid collecting container - vacuum line - overfill protection - smoke connector - smoke filter - vacuum line - vacuum pump. Thus, six connection points need to be established in total. If the vacuum source is directly connected to the connector like in the currently discussed aspect of the present invention, only two connection points need to be established: body fluid collecting container - vacuum line - vacuum source. Thus, the integration of the hydrophobic filter into the container housing of the body fluid collecting container renders a separate overflow protection, a separate smoke connector and a separate smoke filter superfluous. Three separate parts each having two connecting points can be fully skipped when relying on this aspect of the present invention. This significantly reduces the workload for medical staff preparing a body fluid collecting arrangement ready to be used.
• the vacuum line comprises a very hydrophobic antibacterial filter to protect the pump. Then, such overflow of small amounts of body fluids will not have any consequences. Rather, some hydrophobic vacuum lines are able to keep working also in the presence of accumulation of contaminations or liquids.
• the guiding principle is to reduce complexity of assembly of the vacuum line to enhance usability.
• the vacuum line comprises an integrally formed antibacterial filter.
• this antibacterial filter does not represent an additional component part, but rather is an integral part of the vacuum line.
• the antibacterial filter is a hydrophobic filter. Then, it can also be used to effectively prevent any liquid that has entered the vacuum line, e.g., due to overfill events of the body fluid collection section of the container housing, from entering into the pump being arranged downstream of the antibacterial filter. It is possible to equip such an antibacterial filter with an additional chamber to accommodate any contaminations of the filter. Then, such chamber can also serve for receiving excessive body fluid drawn through the vacuum line due to an overfill event.
• the antibacterial filter has a pore size or mesh size that is sufficiently small to also filter viruses out of the fluid (in particular air) drawn through the vacuum line.
• the antibacterial filter has also anti-viral properties. Then, it can be denoted as anti-viral filter.
• the present invention relates to a method for manufacturing a container according to the preceding explanations.
• a top cover of a container housing of the container and a filter holder of the container are co-molded. I.e., they are manufactured as one piece or, expressed in other words, they are integrally formed or integrally molded.
• Such a manufacturing process is significantly easier than the manufacturing processes known from prior art. It combines the previous method steps of producing a container housing and subsequently attaching a filter into the container housing into one single manufacturing step, namely a co-molding step. It can be accomplished, e.g., by injection molding.
• the filter assembly is applied (e.g., by molding) into the filter holder after the filter holder has been produced.
• the filter holder itself may be co-molded with the top cover of the container housing. In doing so, it is not necessary to produce different molds for different mesh sizes to be applied for a filter module of the container housing.
• container housing top covers with an integrally formed filter holder, wherein afterwards different filter assemblies filters can be applied into the filter holder, thus resulting in container housing top covers providing different filter properties (in particular different mesh sizes of the filter assembly).
• the present invention relates to medical method for drawing intraoperative cell salvage (ICS) from a patient in need thereof.
• ICS is typically used for patients undergoing surgery or invasive procedures and is intended to provide those patients with an autotransfusion of blood or blood components.
• This method comprises the steps explained in the following.
• a blood suction line is connected to a blood inlet of a container for collecting blood.
• vacuum line is connected to a vacuum connector of this container and to a vacuum source, such as a vacuum pump.
• a vacuum source such as a vacuum pump.
• the container is a container according to the preceding explanations.
• it comprises a container housing with the blood inlet that allows blood to enter an inlet section of the container housing.
• the container housing furthermore comprises a blood collection section.
• the vacuum source is typically connected via a vacuum line to the vacuum connector of the container housing.
• the container housing comprises a filter module that separates the inlet section from the blood collection section.
• the filter module is arranged between the inlet section and the blood collection section so that the blood drawn from the patient needs to pass the filter in order to flow from the inlet section to the blood collection section.
• 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.
• the vacuum source is activated. Then, blood is drawn from a patient (e.g., during a surgical intervention) through the blood suction line into the receiving section of the blood-collecting canister. It then passes the filter and reaches the blood- collecting section. Afterwards, it can be drawn from the blood-collecting container in order to be further processed and/or auto-transfused to the patient.
• the present invention relates to a method for manufacturing a filter assembly according to the preceding explanations.
• a filter assembly comprises a filter holder, mesh filter layer and a prefiltering support layer.
• the prefiltering support layer comprises a non-woven fabric of fibers.
• the non-woven fabric has a first mesh size.
• the filter holder is arranged downstream the first mesh filter layer.
• the first mesh filter layer is arranged downstream of the prefiltering support layer.
• the first mesh filter layer has a second mesh size, wherein the first mesh size is equal to or bigger than the second mesh size.
• the method is characterized in that the that the filter holder (which is made from plastic) is overmolded over a part of the prefiltering support layer and a part of the first mesh filter layer so that it contacts and stabilizes both the prefiltering support layer and the first mesh filter layer.
• the filter holder can also form the ground area of the filter assembly. Thus, it may form the base of the filter assembly and at the same time embeds the filter material layers near the base to fix them.
• the first mesh filter layer and the prefiltering support layer initially form a flat ribbon.
• This flat ribbon is then brought into the desired shape of the filter assembly.
• This desired shape can be, e.g., the shape of a cylinder jacket, wherein the cylinder has a circular ground area, an elliptic ground area, a rectangular ground area or a quadratic ground area.
• the free ends of the shaped ribbon are then connected to each other.
• the connection of the free ends of the shaped ribbon can be accomplished, in an embodiment, by a welding process. Alternatively, the connection can be formed as a non-welded joint.
• the given shape is fixed by partially overmolding the prefiltering support layer and the first mesh filter layer with the filter holder.
• This manufacturing method of a filter assembly according to an aspect of the present invention is significantly easier than manufacturing techniques applied according to prior art.
• a tubular filter arrangement made of two welded ribbons needs to be cut.
• the according manufacturing steps are significantly more difficult and increase the risk of particle contamination since welding and cutting two tubular ribbons may generate particulates that can be leached into a fluid that passes the filter.
• All embodiments of the described filter assembly can be combined in any desired way and can be transferred to the described use, the described container for collecting a body fluid and the described methods, and vice versa in each case.
• Figure 1 is a perspective view of an embodiment of a blood-collecting canister
• Figure 2 is a side view onto the broad side of the canister of Figure 1 ;
• Figure 3 is a detailed view of an upper part of the canister of Figure 1 seen from the narrow side of the canister;
• Figure 4A is a schematic depiction of a manufacturing process of an embodiment of a filter assembly
• Figure 4B is an enlarged detailed view of the area in Figure 4A that is encircled and marked with the letters AA;
• Figure 5A is a partially cut depiction of another embodiment of a filter assembly
• Figure 5B is an enlarged detailed view of the area figure 5A that is encircled and marked with the letter T;
• Figure 6 is a schematic depiction of the microstructure of a prefiltering support layer and an mesh filter layer of an embodiment a filter assembly
• Figure 7 is a schematic depiction of another embodiment of a filter assembly.
• FIG. 1 is perspective view of a blood-collecting canister 1 that serves as container for collecting a body fluid.
• the blood-collecting canister 1 comprises a canister housing 2 having a top cover 3.
• Three different blood inlets 4 are arranged in the top cover 3. Typically, only one of these blood inlets 4 is used for connecting a blood suction line with the blood-collecting canister 1 in order to draw blood from a patient into the interior of the canister housing 2.
• the most right blood inlet 4 is designed as a 3/8 inch connection.
• the middle blood inlet 4 is designed as Luer inlet, wherein the most left blood inlet 4 is designed as suction line connector sized for accommodating typical blood suction lines.
• Each of the blood inlets 4 is fluidly connected with a blood receiving section 5 that is arranged on an inner side of the top cover 3.
• This blood receiving section 5 is in fluid communication with an interior of a filter module 6 (serving as filter assembly) that comprises a skeletal structure 7 that serves as filter holder. Inside the skeletal structure 7, two layers of filter material 8 are arranged.
• the filter material 8 comprises a prefiltering support layer as well as a mesh filter layer made of a medical grade mesh. If blood enters through the blood inlet 4 into the receiving section 5 of the blood-collecting canister 1 , it flows or it is drawn into the interior of the filter module 6. Afterwards, it passes the filter material 8 and reaches a blood collection section 9 of the canister housing 2.
• the blood-collecting canister 1 comprises in the top section 3 of the canister housing 2 a vacuum connector 10 that is intended to be connected to a vacuum line and, via the vacuum line, with a vacuum pump that serves as vacuum source. Air or any other gases being present in the blood-collecting section 9 that are drawn through the vacuum connector 10 into a connected vacuum line need to pass a hydrophobic filter 1 1 that is arranged between the blood-collecting section 9 and the vacuum connector 10.
• the blood-collecting 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 serves for reducing the risk of the blood-collecting canister 1 to implode due to an undesired low negative pressure in the interior of the canister housing 2.
• a bottom 13 of the filter module 6 When seen from the outside, a bottom 13 of the filter module 6 has a concave shape, i.e., it comprises an indention towards the interior of the filter module 6.
• Blood that has entered the canister housing 2 through the blood inlet 4 and has passed the filter material 8 collects in the blood-collecting section 9. It can then be drawn through a blood outlet 14 out of the blood-collecting canister 1 in order to be further processed and/or auto- transfused to the patient.
• FIG 2 shows the blood-collecting canister 1 from Figure 1 in a side view onto the broad side of the blood-collecting canister 1.
• Figure 2 shows the blood-collecting canister 1 from Figure 1 in a side view onto the broad side of the blood-collecting canister 1.
• the same numeral references for the same elements are used. Reference is made to the explanations given with respect to Figure 1 .
• a connection between the filter module 6 and the blood receiving section 5 of the canister housing 2 can be seen. It is apparent from Figure 2 that blood can enter from the blood receiving section 5 only the interior of the filter module 6 and then needs to pass the filter material 8 in order to reach the blood-collecting section 9 of the canister housing 2.
• the filter module 6 separates the blood receiving section 5 from the blood-collecting section 9.
• Figure 3 shows a partially cut view from the narrow side onto the blood-collecting canister 1 of Figure 1 .
• a funnel-shaped inlet 15 is arranged in an inlet area of the filter element can be seen. Blood entering the filter module 6 from the blood receiving section 5 needs to pass needs to pass this funnel-shaped inlet 15.
• the funnel-shaped inlet 15 serves - together with the filter material 8 and the concavely shaped bottom 13 of the filter module 6 for a reduced foam formation in the blood that passes through the filter module 6. Such a reduced formation of foam leads to blood having better quality than foamed blood and to a higher collection yield due to a lower hemolysis rate.
• the hydrophobic filter 1 1 comprises a pleated filter material. Due to this folding of the filter material, the effective filter surface area is significantly increased.
• the filter material of the hydrophobic filter 1 1 has an overall filter surface area of approximately 60 cm 2 .
• the hydrophobic filter itself takes only approximately 10 cm 2 space in the top cover 3 of the canister housing 2.
• the effective filter surface area is made six times as big as the surface area needed by the hydrophobic filter element 1 1.
• FIG 4A shows an exemplary manufacturing process of a filter module 6 that can be used as filter module for the blood-collecting canister shown in Figure 1.
• a flat ribbon 80 of a co- molded spunbond prefilter (serving as prefiltering support layer) and a mesh filter (serving as mesh filter layer) is provided.
• This flat ribbon 80 is shaped into the desired shape in subsequent manufacturing steps 100, 101 , 102 and 103.
• the flat ribbon 80 becomes shaped filter material 8 that has, in this embodiment, the shape of a cylinder jacket with an elliptical ground area.
• free ends 81 and 82 of the ribbon that are not yet connected in manufacturing step 102 are connected to each other to form a connection line 83 in manufacturing step 103.
• the connection line 83 can be realized in form of seam like a welded seam or in form of a seamless joint, i.e., a non-welded joint.
• this filter material 8 can then be inserted into a skeletal structure 7 of the bare filter module 6 so as to form a complete filter module 6 including the filter material 8.
• the skeletal structure 7 is overmolded over the shaped filter material, e.g., by injection molding. Thereby, it partly embeds the individual layers of the shaped filter material (in particular at their bottom portion that is oriented towards the elliptical ground area) and serves for connecting them tightly together.
• the skeletal structure can also overmold a seamless joint between the free ends of the shaped filter material 8 to also serve for a tight connection of the shaped filter material 8 between its free ends (i.e., along a vertical extension direction that is vertically aligned during normal operation of the assembled filter module 6).
• Figure 4B shows an enlarged detailed view of the area of the ribbon 80 that is encircled and marked with the letters AA in step 101 of Figure 4A.
• This enlarged view shows that the ribbon 80 is made up of a prefiltering support layer 84 and a mesh filter layer 85.
• the structure of these two layers 84, 85 is also schematically depicted in Figure 4B.
• the prefiltering support layer 84 consists of non-woven fibers with a trilobal cross-section
• the mesh filter layer 85 consists of a regularly formed medical grade mesh.
• FIG 5A shows another embodiment of the filter module 6 that can be used in connection with the blood-collecting canister shown in Figure 1.
• the filter material 8 of this embodiment of the filter module 6 is partially cut.
• the area that is encircled and marked with the letter T is depicted in an enlarged detailed view in Figure 5B.
• the filter material 8 comprises a prefiltering support layer 84 made up of non-woven fibers having a trilobal cross-section and a first mesh filter layer 85 that is arranged on the side of the prefiltering support layer 84 that faces the skeletal structure 7 of the filter module 6.
• the filter material 8 of this embodiment comprises a second mesh filter layer 86 that is arranged on the opposite side of the prefiltering support layer 84 than the first mesh filter layer 85.
• the prefiltering support layer 84 is encompassed between the first mesh filter layer 85 and the second mesh filter layer 86 and thus forms a sandwich-like structure together with the first mesh filter layer 85 and the second mesh filter layer 86.
• Figure 6 shows a depiction of the microstructure of the filter material 8 based on an electron microscopic picture of individual fibers that make up the prefiltering support layer 84.
• the individual grid elements that make up the mesh filter layer 85 are highly ordered and are arranged horizontally and vertically so as to form an ordered grid. In doing so, a highly repetitive and reproducible structure of the mesh filter layer 85 results.
• FIG. 7 shows another embodiment of a filter module 6 that can be used as filter module for the blood collection canister shown in Figure 1 .
• the filter module 6 of Figure 7 comprises a skeletal structure 7 and a filter material 8.
• This filter material 8 comprises three zones of differing filtration capacity that are arranged one above another in a vertical extension direction of the filter module in which the filter module 6 is vertically aligned during normal operation.
• the lowest zone 87 has a mesh size of 40 pm so as to allow only particles having a size smaller than 40 pm to pass.
• An intermediate zone 88 has a mesh size of 80 pm and has a somewhat lower filtration capacity then the lowest zone 87 but and enables a higher volume to pass in the same time then the first zone 87.
• All three zones extend along the whole circumference of the filter module 6, i.e., along the whole circumference in a horizontal extension direction which is horizontally aligned during normal operation of the filter module 6.
• the topmost zone 89 has a mesh size of 120 pm and allows an even higher blood flow through the filter material 8 than the intermediate zone 88 if the blood level in the filter material 8 is so high that blood can flow through the topmost zone 89.
• the filter material 8 has, in this embodiment, a vertical gradient of mesh size that efficiently prevents an overflow of the filter module 6 since it allows higher volumes of blood to pass the filter material 8 in dependence on the level or the amount of blood being present in the interior of the filter module 6.
• the topmost zone 89 can also be seen as a safety zone that allows proper functioning of the filter module 6 even in cases of a high blood inflow. As a side effect, the filtration effect is reduced in cases of such high blood inflow into the filter module 6, since the filtration capacity of the topmost zone 89 is significantly lower than the filtration capacity of the lowest zone 87.
• the differing filtration capacities of the individual zones 87, 88 and 89 of the filter material 8 are achieved, in the embodiment of Figure 7, by combining meshes having different mesh sizes onto one and the same prefiltering support layer. This significantly facilitates the manufacturing of the filter material 8 and does not necessitate an adjustment of the structure of the non-woven fibers making up the prefiltering support layer (which is not visible in the drawing of Figure 7).

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• 2018
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