FR2814080A1 - Biological fluid filtering system, especially for blood, has at least two filtering media along flow path with space inbetween - Google Patents

Abstract

a filtering system (1), having an inlet (4) and outlet (5), consists of one or more pockets with compartments (7, 8) containing at least two filtering media (2, 3) of a non-woven porous material. The filters are located in sequence along the flow path of the fluid, with a space inbetween forming a passage (6) free of filtering medium.

Description

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The invention relates to a device for filtering a biological fluid and to a bag system comprising such a device, said system being arranged for sterile filtration and in closed circuit of the fluid.

It typically applies to the filtration of blood or blood components to retain leukocytes by filtration as well as to the separation and collection of the various constituents of leukoreduced blood in a set of satellite bags of the bag system.

Filtration devices are already known which comprise an outer envelope in which a filtering medium capable of retaining leukocytes is placed.

In such devices, illustrated for example by document EP-A-0 526 678, it is conventional to use a juxtaposition of filter layers formed of a porous nonwoven.

Indeed, in this type of so-called deep filtration, the capacity of the filtering medium to retain leukocytes is a function in particular of the amount of material traversed by the fluid, and therefore of the thickness of the filtering medium.

To improve the efficiency of this type of filtration, ie to increase the quantity of leukocytes retained by the filtering medium, we therefore thought of increasing the thickness of the filtering medium either by increasing the number of layers, or by increasing their thickness.

However, this solution has a number of drawbacks.

In particular, the increase in the thickness of the filter medium causes a significant decrease in the flow rate of fluid passing through the filter medium by gravity, and therefore increases the filtration time accordingly.

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D'autre part, le débit diminuant, la probabilité de colmatage et donc de ne pas pouvoir filtrer le fluide biologique, s'en trouve augmentée.

On the other hand, the decreasing flow rate, the probability of clogging and therefore of not being able to filter the biological fluid, is thereby increased.

Furthermore, the Applicant has found that, from a certain value, the increase in the thickness of the filter medium no longer has a positive effect on the quantity of leukocytes retained by the filter medium.

The invention therefore aims to remedy these drawbacks by proposing in particular a filtration device having an improved and modular capacity for retaining leukocytes, said device being able to be integrated in a bag system in closed circuit so as to allow, in a simple manner, separation and collection of the various constituents of leukoreduced blood.

To this end, and according to a first aspect, the invention provides a device for filtering a biological fluid, in particular blood or blood components to retain leukocytes by filtration, of the type comprising at least one inlet orifice for receiving the fluid to be filtered and at least one outlet orifice for collecting the filtrate, said device comprising at least two filter media arranged successively along the flow path of the fluid, the filter media being spaced from each other so that a fluid passage devoid of filter medium is formed between two successive filter media.

According to a second aspect, the invention provides a bag system for sterile filtration and in a closed circuit of a biological fluid, said system comprising a primary bag intended to contain the fluid to be filtered, said primary bag being connected via a first tube and at one of its outlet orifices to the inlet orifice of a filtration device as described above, and a secondary pocket intended to receive the filtrate, said secondary pocket being connected via a second tube and at one of its inlet orifices to the outlet orifice of said filtration device.

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 Other objects and advantages of the invention will appear during the description which follows with reference to the accompanying drawings. FIG. 1 represents, in front view, a filtration device in which two filter media are disposed respectively in a compartment of an external envelope provided with inlet and outlet ports, the passages devoid of filter medium being formed between the two compartments.

FIG. 2 represents, in side view and in longitudinal section, the device of FIG. 1.

FIG. 3 represents, in front view, a filtration device in which two filtering media are each arranged in an external envelope provided with an inlet orifice and an outlet orifice, a tube being connected between the orifice inlet and outlet of the two envelopes so as to form the passages devoid of filter medium.

FIG. 4 represents, in side view and in longitudinal section, the device of FIG. 3.

FIG. 5 represents, in schematic front view, a bag system for sterile filtration and in closed circuit of an erythrocyte concentrate, said system comprising: - a primary bag intended to contain the fluid to be filtered, said primary bag being connected by means of a first tube and at one of its outlet orifices to the inlet orifice of a filtration device according to the invention; - A secondary pocket intended to receive the filtrate, said secondary pocket being connected via a second tube and at one of its inlet orifices to the outlet orifice of said filtration device; - means for collecting whole blood connected to an inlet orifice of the primary bag; and

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un ensemble de poches satellites relié à un orifice de sortie de la poche primaire par l'intermédiaire d'une troisième tubulure, de sorte à pouvoir réaliser, après recueil du sang total dans la poche primaire et centrifugation de ladite poche primaire, d'une part la filtration du concentré érythrocytaire et d'autre part le recueil du plasma riche en plaquette dans l'ensemble de poches satellites.

a set of satellite bags connected to an outlet orifice of the primary bag by means of a third tube, so that, after collection of whole blood in the primary bag and centrifugation of said primary bag, firstly the filtration of the erythrocyte concentrate and secondly the collection of platelet-rich plasma from the set of satellite bags.

FIG. 6 represents, in schematic front view, a bag system for sterile filtration and in closed circuit of whole blood, said system comprising: - a primary bag intended to contain the fluid to be filtered, said primary bag being connected by the 'through a first tube and at one of its outlet openings to the inlet opening of a filtration device according to the invention; - A secondary pocket intended to receive the filtrate, said secondary pocket being connected via a second tube and at one of its inlet orifices to the outlet orifice of said filtration device; - means for collecting whole blood connected to an inlet orifice of the primary bag; and - a set of satellite bags connected to an outlet orifice of the secondary bag by means of a third tube, so as to be able, after collecting whole blood in the primary bag, to filter the whole blood as well as the collection, after centrifugation of the secondary bag, of the various constituents of the blood in the set of satellite bags.

In Figures 1 to 4, there is shown a filtration device 1 of a biological fluid capable of retaining by filtration particles present in said fluid.

In a particular example, the fluid is blood or formed of blood components and the device 1 is capable of retaining the leukocytes by filtration.

In the embodiments represented in FIGS. 1 to 4, the filtration device 1 comprises a first and a second filtering medium 2, 3 arranged successively (upstream and downstream respectively) along the path

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d'écoulement du fluide, entre un orifice d'entrée 4 et un orifice de sorte 5 du dispositif 1, lesdits orifices 4, 5 étant agencés respectivement pour recevoir le fluide à filtrer et pour recueillir le filtrat.

fluid flow, between an inlet orifice 4 and a so orifice 5 of the device 1, said orifices 4, 5 being arranged respectively to receive the fluid to be filtered and to collect the filtrate.

encore l'efficacité de la filtration. However, more than two filter media 2,3 can be provided to improve

still the efficiency of filtration.

In the description, the terms inlet, outlet, upstream and downstream are defined with respect to the direction of circulation of the fluid in the filtration device 1 (see the arrows represented in FIGS. 1 to 4).

The two filter media 2,3 are spaced from each other so that a fluid passage 6 devoid of filter media is formed between the two filter media 2,3.

Thus, when the filtration device 1 is supplied with fluid via the inlet orifice 4, said fluid successively passes through the first filtering medium 2, the passage 6 devoid of filtering medium and then the second filtering medium 3 so that the filtrate can be collected via the outlet orifice 5.

According to one embodiment, the filter media 2,3 are each formed from one or more layers of a porous material in the form of a nonwoven, for example a hydrophilic material such as cellulose or its derivatives, for example cellulose acetate, such as a polymer or copolymer based on polypropylene, polyester, polyamide, high or low density polyethylene, polyurethane and their derivatives.

These polymeric products are generally not naturally hydrophilic and must be treated by physical and / or chemical methods, to give them said hydrophilic properties.

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 These treatments consist, for example, in the grafting of hydrophilic substituents, for example groups of the hydroxyl or carboxylic type, onto the polymer, according to known methods.

Such polymers made hydrophilic by physical and / or chemical treatment are available on the market.

The number of layers as well as the porosity of the different layers and / or their composition, which may be identical or different depending on the layers, are adapted as a function of the fluid to be treated and / or the amount of leukocytes to be eliminated.

Furthermore, a pre-filter and / or a post-filter, for example formed of a porous membrane and / or of one or more layers of specific nonwoven, can be placed against the filtering medium 2,3, respectively upstream and downstream thereof, so as to improve the depletion of leukocytes in the fluid.

In a first embodiment, the two filter media 2,3 are identical, the first filter medium 2 retaining part of the leukocytes and the second filter medium 3 another part.

In a second embodiment, the two filter media 2,3 are different, for example by the nature of the materials that compose them and / or by their porosity.

In particular, the second filter medium 3, located downstream, can have a porosity lower than that of the first filter medium 2 so as to be able to retain in the second filter medium 3 leukocytes of smaller sizes without risking clogging the first filter medium 2 .

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A first advantage of the filtration device 1 is to be able to use identical and / or different filter media 2, 3 so as to obtain, by combining their effects, an adjustable filtration as a function of the desired results.

In particular, it can be provided that the first filter medium 2 has a retention rate of 5 log (that is to say that the quantity of leukocytes is divided by 105 while passing through the first filter medium 2) and that the second filter medium 3 has a retention rate of 2 log, so that the filtration device 1 has a retention rate of 7 log.

Furthermore, in the filtration device 1, the filter media 2,3 are not placed side by side so that the thickness of the filter medium is reduced compared to those of the prior art.

The Applicant has found that this embodiment allows better retention of leukocytes in whole blood or in a fluid containing blood components such as an erythrocyte concentrate, while limiting the clogging of the filtering medium.

This better filtration makes it possible in particular to have a simpler filtration protocol, by allowing a longer period between the collection and filtration of the blood.

A first embodiment of the filtration device 1 is described below, in relation to FIGS. 1 and 2, and, in relation to FIGS. 3 and 4, a second embodiment of the said device 1.

In the first embodiment, the first and second filter media 2, 3 are disposed respectively in a first and a second compartment 7, 8 formed in an outer casing 9, said casing 9 being provided with inlet orifices 4 and exit 5.

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Dans le mode de réalisation représenté, l'enveloppe extérieure 9 est souple et formée par l'assemblage de deux feuilles de matière plastique souple 10, 11 assemblées mutuellement, par exemple par soudage, sur leur périphérie.

In the embodiment shown, the outer casing 9 is flexible and formed by the assembly of two sheets of flexible plastic material 10, 11 assembled together, for example by welding, on their periphery.

The compartments 7, 8 are separated by a weld line 12 so as to communicate with each other only by means of an orifice 13 in which a portion of tubing 14 is arranged so as to form the passage 6 devoid of filter medium. .

Each filter medium 2,3 is held in its respective compartment 7,8 by means of a flexible and sealed frame 15 so as to define two chambers 16-19, respectively of inlet and outlet for each compartment 7.8.

The inlet chamber 16 of the first compartment 7 communicates with the outside of the filtration device 1 via the inlet orifice 4 in which an inlet pipe 20 is arranged.

The outlet chamber 19 of the second compartment 8 communicates with the outside of the filtration device 1 via the outlet orifice 5 in which an outlet pipe 21 is arranged.

The outlet chamber 17 of the first compartment 7 communicates with the inlet chamber 18 of the second compartment 8 via the portion of tubing 14.

In the second embodiment shown in Figures 3 and 4, the first and second filter media 2,3 are arranged respectively in a first and a second outer casing 22,23.

In the embodiment shown, the outer envelopes 22, 23 are identical, flexible and formed by the assembly of two sheets of flexible plastic material 24, 25 assembled together, for example by welding, on their periphery.

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 Each outer casing 22, 23 is provided with an inlet port 4, 4a and an outlet port 5a, 5. Each filter medium 2.3 is held in its respective casing 22, 23 by means of a frame 15 flexible and waterproof so as to define two chambers 26-29, respectively of inlet and outlet for each envelope 22,23.

The inlet chamber 26 of the first envelope 22 communicates with the outside of the filtration device 1 via the inlet orifice 4 in which an inlet pipe 20 is arranged.

The outlet chamber 29 of the second casing 23 communicates with the outside of the filtration device 1 via the outlet orifice 5 in which an outlet pipe 21 is arranged.

The outlet chamber 27 of the first envelope 22 communicates with the inlet chamber 28 of the second envelope 23 by means of a tube 30 connecting the orifices 5a, 4a so as to form the passage 6 of fluid devoid of medium filter.

A description will now be given, with reference to FIGS. 1 to 4, of the assembly of the filtration device 1 in the two embodiments described.

The flexible frames 15 are formed by an assembly of two sheets 31, 32, for example plasticized, between which is placed the filtering medium 2,3.

These two sheets 31, 32 are perforated in their central part and each comprise at least one opening 33 allowing the passage of the biological fluid to be filtered.

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The two sheets 31, 32 are fixed to each other preferably at the periphery of the filter medium 2, 3, for example by a weld bead, produced through the filter medium 2, 3, ensuring both the fixing of the medium filter 2, 3 but also sealing.

The welding of the sheets 31, 32 through the filter medium 2,3 causes compression, forming a tight bead 34 around the filter medium 2, 3.

The periphery of the flexible frame 15 is also welded with the outer sheets 10, 11, 24, 25 forming the outer envelope 9, 22, 23, mutually over their entire periphery and at their periphery, thus ensuring sealing.

To prevent the filtering medium 2,3 from sticking against the outer casing 9, 22, 23, and thus hampering the flow of the biological fluid, two spacer rods 35, 36 are placed inside the outlet 17,19, 27, 29, between the filtering medium 2,3 and the outer casing 9,22, 23.

These two rods 35, 36 release the outlet chambers 17, 19, 27, 29 from the filter medium 2.3 and thus prevent the filter medium 2.3 from pressing against the inner wall of the outer sheet.

The rods 35, 36 can be produced from flexible tubes welded, for example at the level of the inner wall of the sheet of the outer envelope 9, 22, 23, for example at the level of the peripheral weld.

It goes without saying that the number of spacing rods 35.36 can vary, depending for example on the dimensions of the filtration device 1.

For example, it is conceivable to provide a single spacer ring 35 folded back so as to form a loop inside the outlet chambers 17, 19, 27, 29.

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 Furthermore, in the first embodiment, the same spacer ring 35 can be provided for the outlet chambers 17, 19 of the two compartments 7, 8, for example the ring 35 can pass through the weld line 12 in leaktight fashion. .

Preferably, flexible rods 35, 36 are used, so as not to hinder the possibilities of folding the filtration device 1.

In another embodiment (not shown), the outer envelopes 9, 22, 23 are rigid, for example made of rigid plastic material such as polycarbonate.

We will now describe, in relation to FIGS. 5 and 6, a first and a second embodiment of a bag system for sterile filtration and in closed circuit of a biological fluid, said system comprising a filtration device 1 such as described above.

To this end, the bag systems comprise a primary bag 37 intended to contain the fluid to be filtered, said primary bag 37 being connected by means of a first tube 38 and at one of its outlet orifices 39 to the inlet orifice 4 of the filtration device 1 and a secondary pocket 40 intended to receive the filtrate, said secondary pocket 40 being connected by means of a second tube 41 and at one of its orifices inlet 42 to the outlet orifice 5 of said filtration device 1.

In the first embodiment (FIG. 5), the bag system further comprises means 43 for collecting whole blood connected to an inlet orifice 44 of the primary bag 37 and a set of satellite bags 45, 46 connected to an outlet orifice 47 of the primary pocket 37 by means of a third tube 48.

This system makes it possible, after sterilization, to carry out the following stages successively in closed circuit:

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- recueil du sang total dans la poche primaire 37 ; - centrifugation de ladite poche primaire 37 ; - filtration du concentré érythrocytaire ; - recueil du plasma riche en plaquette dans l'ensemble de poches satellites
45, 46.

- collection of whole blood in the primary pocket 37; - centrifugation of said primary bag 37; - filtration of the erythrocyte concentrate; - collection of plasma rich in platelets in the set of satellite bags
45, 46.

In the second embodiment (Figure 6), the bag system further comprises means 43 for collecting whole blood connected to an inlet orifice 44 of the primary bag 37 and a set of satellite bags 45,46 connected to an outlet orifice 49 of the secondary pocket 40 via a third tube 48.

This system makes it possible, after sterilization, to carry out successively in a closed circuit the following steps: - collection of whole blood in the primary bag 37; - filtration of whole blood; - centrifugation of the secondary bag 37; - collection of the various constituents of the blood in the set of satellite bags 45, 46.

As a variant, the tubes 38, 41, 48 are flexible, breakable and weldable so that, after filtration and before centrifugation, they can dissociate the filtration device 1 from the bag system.

Claims (10)

 1. A filtration device (1) for a biological fluid, in particular blood or blood components for retaining leukocytes by filtration, of the type comprising at least one inlet orifice (4) for receiving the fluid to be filtered and at least an outlet orifice (5) for collecting the filtrate, characterized in that it comprises at least two filter media (2, 3) arranged successively along the fluid flow path, the filter media (2,3) being spaced from each other so that a fluid passage (6) devoid of filter medium is formed between two successive filter media (2,3). 2. A filtration device according to claim 1, characterized in that the filtering media (2) are formed from one or more layers of a porous material in the form of a nonwoven, for example a hydrophilic material such as cellulose or its derivatives, for example cellulose acetate, such as a polymer or copolymer based on polypropylene, polyester, polyamide, high or low density polyethylene, polyurethane and their derivatives, rendered hydrophilic by physical or chemical treatment . 3. A filtration device according to claim 2, characterized in that the different layers forming a filtering medium (2,3) are of porosities and / or of compositions different from each other. 4. A filtration device according to any one of claims 1 to 3, characterized in that the filtering media (2,3) are different by the number of layers which form them, the nature of the materials which compose them and / or their porosity. 5. A filtration device according to claim 4, characterized in that each filter medium 3 has a porosity lower than the porosity of the filtration medium 2 located upstream. <Desc / Clms Page number 14> 6. Device according to any one of claims 1 to 5, characterized in that each filtering medium (2, 3) is arranged in a compartment (7, 8) of an outer casing (9) provided with inlet openings (4) and outlet (5), the passages (6) devoid of filter medium being formed between the successive compartments (7,8). 7. Device according to any one of claims 1 to 5, characterized in that each filtering medium (2,3) is arranged in an outer envelope (22,23) provided with an inlet orifice (4,4a) and an outlet (5.5a), a tube (30) being connected between the inlet (4, 4a) and the outlet (5.5a) of two envelopes (22,23 ) successive so as to form the passages (6) devoid of filter medium. 8. Pouch system for sterile filtration and in closed circuit of a biological fluid, characterized in that it comprises a primary pocket (37) intended to contain the fluid to be filtered, said primary pocket (37) being connected by l 'through a first tube (38) and at one of its outlet openings (39) to the inlet opening (4) of a filtration device 1 according to any one of claims 1 7, and a secondary pocket (40) intended to receive the filtrate, said secondary pocket (40) being connected by means of a second tube (41) and at one of its inlet orifices ( 42) to the outlet orifice (5) of said filtration device (1). 9. bag system according to claim 8, characterized in that it further comprises means for drawing (43) whole blood connected to an inlet orifice (44) of the primary bag (37) and a set of satellite bags (45,46) connected to an outlet orifice (47) of the primary bag (37) by means of a third tube (48), so as to be able to produce, after collection of whole blood in the bag primary (37) and centrifugation of said primary pocket (37), on the one hand the filtration of the erythrocyte concentrate and on the other hand the collection of platelet-rich plasma in the set of satellite bags (45, 46). <Desc / Clms Page number 15> 10. Bag system according to claim 8, characterized in that it further comprises means for drawing (43) whole blood connected to an inlet orifice (44) of the primary bag (37) and a set of satellite bags (45,46) connected to an outlet orifice (49) of the secondary bag (40) by means of a third tube (48), so that after collection of whole blood can be carried out in the bag primary (37), the filtration of whole blood as well as the collection, after centrifugation of the secondary bag (40), of the various constituents of the blood in the set of satellite bags (45, 46).