Filter Assembly and Container for Collecting a Body Fluid Containing the Same

Abstract

A filter assembly for filtering a body fluid comprising a filter system and a filter holder is disclosed, wherein the filter system consists of at least two layers. The first layer is a defoaming layer made of a monofilament woven open mesh fabric and with an embossed three dimensional structure configured for entrapping foam built up in the body fluid. The second layer is a mesh filter layer, and is arranged downstream of the defoaming layer. A container for collecting a body fluid comprising such a filter assembly is also disclosed.

Claims

1. Filter assembly for filtering a body fluid comprising a filter system and a filter holder, wherein the filter system and the filter holder are in contact with each other, wherein the filter system consists of at least two layers, wherein the first layer is a defoaming layer made of a monofilament woven open mesh fabric and with an embossed three-dimensional structure, in particular configured for entrapping foam built up in the body fluid, wherein the second layer is a mesh filter layer, and wherein the mesh filter layer is arranged downstream of the defoaming layer.

2. Filter assembly according to claim 1, characterized in that the defoaming layer comprises a mesh opening between 100-500 μm, in particular between 150-400 μm, in particular between 200-350 μm, and more particularly between 250-300 μm.

3. Filter assembly according to claim 1, characterized in that the defoaming layer is made of monofilament fibers with a diameter between 100-350 μm, in particular 150-300 μm, more particularly 200-300 μm.

4. Filter assembly according to claim 1, characterized in that the defoaming layer has a mesh count between 10-50 n/cm, in particular between 10-30 n/cm, more particularly between 10-20 n/cm.

5. Filter assembly according to claim 1, characterized in that the mesh filter layer has a mesh size in a range of 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.

6. Filter assembly according to claim 1, wherein the filter assembly further comprises a prefilter layer arranged downstream of the defoaming layer and upstream of the mesh filter layer, wherein said mesh filter layer has a mesh size of approximately 40 μm.

7. Filter assembly according to claim 1 wherein the filter assembly does not include a pre-filter, wherein said mesh filter layer has a mesh size of approximately 120 μm.

8. Filter assembly according to claim 6, characterized in that the prefilter layer comprises a spunbond nonwoven fabric.

9. Filter assembly according to claim 6, characterized in that the pore size of the prefilter layer is in a range of 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.

10. Filter assembly according to claim 1, characterized in that the filter holder is made from plastic and is over-molded over at least a part of the filter system.

11. Filter assembly according to claim 1, characterized in that the filter assembly is free of anti-foam agents.

12. Filter assembly according to claim 10 wherein said plastic is selected from ABS or polycarbonate.

13. Filter assembly of claim 1 wherein said defoaming layer has a thickness of 150-650 μm, in particular 200-500 μm, in particular 250-400 μm, in particular 300-350 μm.

14. Filter assembly of claim 1 wherein said defoaming layer includes pores distributed in a non-planar arrangement.

15. Use of a filter assembly according to claim 1 or filtering a body fluid ex vivo.

16. Use according to claim 12, characterized in that the body fluid is blood.

17. Container for collecting a body fluid, comprising a filter assembly according to claim 1 as a filter module.

18. Container according to claim 17, further comprising a container housing (2) with a body fluid inlet (4) though which body fluid can enter an inlet section (5) of the container housing (2), a body fluid collection section (9), a vacuum connector (10) for connecting a vacuum source to the container housing (2) for applying a low pressure to the inlet section (5) and the body fluid collection section (9), and the filter assembly as filter module (6) being arranged between the inlet section (5) and the body fluid collection section (9), such that the defoaming layer faces the inlet section (5) and the mesh filter layer faces the body fluid collection section (9).

19. Container for collecting a body fluid according to claim 17, characterized in that the container housing (2) additionally comprises a hydrophobic filter (11) that is arranged between the body fluid collection section (9) and the vacuum connector (10) in flow direction of air drawn by a vacuum source from the body fluid collection section (9) during intended use of the container.

Description

[0092] Further details of aspects of the present invention will be explained in the following with respect to exemplary embodiments and accompanying Figures. In the Figures:

[0093] FIG. 1 is a perspective view of an embodiment of a blood-collecting canister;

[0094] FIG. 2 is a side view onto the broad side of the canister of FIG. 1;

[0095] FIG. 3 is a detailed view of an upper part of the canister of FIG. 1 seen from the narrow side of the canister;

[0096] FIG. 4A is a schematic view of a first embodiment of the filter system according to the invention; and

[0097] FIG. 4B is a schematic view of a second embodiment of the filter system according to the invention.

[0098] 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 right-most (with reference to FIG. 1) blood inlet 4 is designed as a ⅜ 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.

[0099] 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.

[0100] Inside the skeletal structure 7, the material layers of the filter system 8 are arranged. The filter material or filter system 8 comprises a defoaming layer and 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.

[0101] 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 11 that is arranged between the blood-collecting section 9 and the vacuum connector 10.

[0102] 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. Thus, 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.

[0103] 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.

[0104] 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.

[0105] FIG. 2 shows the blood-collecting canister 1 from FIG. 1 in a side view onto the broad side of the blood-collecting canister 1. Thereby, the same numeral references for the same elements are used. Reference is made to the explanations given with respect to FIG. 1. In FIG. 2, 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 FIG. 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. Thus, the filter module 6 separates the blood receiving section 5 from the blood-collecting section 9.

[0106] FIG. 3 shows a partially cut view from the narrow side onto the blood-collecting canister 1 of FIG. 1. Thereby, once again the same numeral references are used for the same elements. Reference is made once again to the explanations given above.

[0107] In the depiction of FIG. 3, 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.

[0108] It can be furthermore seen in the depiction of FIG. 3 that the hydrophobic filter 11 comprises a pleated filter material. Due to this folding of the filter material, the effective filter surface area is significantly increased. To give an example, the filter material of the hydrophobic filter 11 has an overall filter surface area of approximately 60 cm.sup.2. Thereby, the hydrophobic filter itself takes only approximately 10 cm.sup.2 space in the top cover 3 of the canister housing 2. Thus, by folding the filter material, the effective filter surface area is made six times as big as the surface area needed by the hydrophobic filter element 11.

[0109] FIG. 4A shows a first embodiment of the filter system 8 according to the invention. It shows that the filter system 8 is made a defoaming layer 8a and a mesh layer 8b.

[0110] The defoaming layer 8a is made of an open mesh fabric with a three-dimensional (3D), embossed structure for foam entrapment. In the case of the embodiment shown in FIG. 4A (and also in FIG. 4B) the spatial structure of the defoaming layer is a diamond pattern with regularly arranged protrusions and depressions of a certain height. This structure or weave pattern is also known as Gauffree Diamond. The depressions form cells for capturing the formed foam of the biological fluid.

[0111] Defoaming layer 8a may have a thickness greater than the thickness of the downstream pre-filter layer 8c or mesh layer 8b. In an embodiment, defoaming layer 8a may have a thickness greater than the thickness of 2 to 3 filaments. The three-dimensional structure and thickness of the defoaming layer means that the pores in the fabric are not all within the same plane.

[0112] The fiber material of the defoaming layer is polypropylene (PP) with fiber diameters between 200-300 μm, such as 200, 250, 300 μm. The mesh count is between 12-16 n/cm. The mesh size or opening is between 250-300 μm.

[0113] The mesh filter layer 8b is made of interconnecting threads forming a grid or a net. The mesh size of mesh filter material 8b is between 40 μm and 120 μm and thus smaller than the mesh size of the defoaming layer. In case of the embodiment shown in FIG. 4A wherein the filters system consists only of the defoaming layer and the mesh filter layer the mesh size of the mesh filter material may be 120 μm. Such a filter system is applicable for large pore size filtration.

[0114] The filter system as shown in FIG. 8B consists of three layers: defoaming layer 8a, mesh filter layer 8b and a prefilter layer 8c arranged (or sandwiched) between defoaming layer 8a and mesh filet layer 8b.

[0115] The prefilter layer 8c consists of non-woven fibers with a trilobal cross-section, whereas the mesh filter layer 8b consists of a regularly formed medical grade mesh.

[0116] In case of the embodiment shown in FIG. 4B wherein the filters system consists three layers (defoaming layer 8a, prefilter layer 8c and mesh filter layer 8b) the mesh size of the mesh filter material may be 40 μm. Such a filter system is applicable for low pore size filtration.

[0117] As depicted in both FIGS. 4A and 4B the blood flow enters the filter system 8 through the defoaming layer 8a. The foam bubbles contained in the blood are entrapped within the 3D structure of the defoaming layer 8a and are thus prevented to enter the downstream prefilter layer 8c and the mesh filter layer 8b. The blood flow leaving the filter system on the mesh filter side is foam free.

[0118] The pressure depends on the pore size of the material used and from its basis weight. The pressure is determined by Capillary flow porometry. This method allows for determining the pore size of the filter material (MFP, Mean Flow Pore).