JP2005237791A - Method and system for filtering blood - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a system for filtering blood, capable of preventing adhesion of an outlet side flexible container to a filter element, facilitating the flow of blood, and effectively utilizing the whole filter element. <P>SOLUTION: A filter used in the method comprises the flexible containers 8 and 9 with a blood inlet and a blood outlet and the sheet-like filter element 9 for removing undesirable components from blood, and the blood inlet and the blood outlet are separated by the filter element. The blood in a blood bag is filtered with the gravity from the blood inlet side via an inlet side connection tube 3, and the blood from which the undesirable components are removed from the blood outlet side is collected in a blood collection bag via an outlet side connection tube 4. The method is characterized by filtering the blood with a space formed between the filter element and the outlet side flexible container. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a blood filtration method and blood filtration system for removing undesirable components such as aggregates and leukocytes from blood. Blood filtration using a leukocyte removal filter consisting of a flexible container for removing microaggregates and leukocytes that cause transfusion side effects from whole blood preparations, red blood cell preparations, platelet preparations, plasma preparations, etc. The present invention relates to a method and a blood filtration system.

  Whole blood collected from a donor is rarely used as a whole blood for transfusion, and is generally separated into individual components such as a red blood cell preparation, a platelet preparation, and a plasma preparation, and then transfused after storage. In addition, since microaggregates and leukocytes contained in these blood products cause various side effects of blood transfusion, leukocyte-removed blood transfusions in which these undesirable components are removed before blood transfusion are increasing. In recent years, the need for leukocyte removal has been widely recognized in recent years, and in Europe, there are countries where all blood products for blood transfusion are subjected to leukocyte removal treatment and then used for blood transfusion.

  The most common method for removing leukocytes from a blood product is to treat the blood product with a leukocyte removal filter. Conventionally, treatment of blood products with this leukocyte removal filter has often been performed at the bedside during blood transfusion operation, but in recent years, the purpose of quality control of leukocyte removal products and improvement of the effectiveness of leukocyte removal treatment For this reason, it is becoming common for leukocytes to be removed before storage at blood centers.

  To collect blood from a donor, separate it into multiple blood components, and store each blood component, typically two to four flexible bags and their connecting conduits, anticoagulants, red blood cell preservation solution A blood collection / separation set including a blood collection needle has been used for some time. A system that incorporates a leukocyte removal filter into these blood collection and separation sets is widely used as one that is preferably used for the above-mentioned “pre-storage leukocyte removal”. Names such as “closed system” or “integrated system” are widely used. It is called by. (Patent Document 1, Patent Document 2)

  Conventional leukocyte removal filters have been widely used in which filter elements made of non-woven fabric or porous material are filled in a rigid container such as polycarbonate. However, since the gas permeability of the container is low, it is widely used as a sterilization process for blood collection and separation sets. There is a problem that it is difficult to apply the high pressure steam sterilization. In addition, when a closed system is used and leukocyte removal is performed after whole blood is separated into a plurality of blood components by centrifugation, the leukocyte removal filter is also centrifuged together with the blood collection / separation set. At this time, there is a risk that the hard container damages the bag or the conduit, or that the hard container itself cannot withstand the stress during centrifugation and breaks. As a method for solving these problems, a filter in which a sheet-like filter element that separates the blood inlet side and the blood outlet side is incorporated in a flexible container having a blood inlet and a blood outlet is generally used. Has been used.

  As a method of welding the flexible container and the sheet-like filter element, the filter element is once welded to the sheet-like flexible frame, and then the frame is welded to the housing material (Patent Document 3 and Patent Document 4). , And a flexible container directly welded to the filter element (Patent Document 5 and Patent Document 6). Hereinafter, the former may be referred to as a frame welding type, and the latter may be referred to as a container welding type.

  An example of a conventional product is shown in FIG. 4, and an enlarged cross-sectional view of a filter used therefor is shown in FIG. The blood storage bag (1) is arranged upstream of the filter made of a flexible container via the inlet side connection conduit (3), and the blood collection bag (5) is connected downstream of the filter via the outlet side connection conduit (4). To do. The blood product stored in the blood storage bag (1) passes through the inlet side connection conduit (3) by gravity and enters the filter from the blood inlet (13) provided in the filter. In the center of the filter, a filter element (9) is disposed so as to separate the blood inlet (13) and the blood outlet (14), and when blood products pass through the filter element, undesirable components in the blood are removed. Is done. The blood product that has passed through the filter element exits the blood outlet and is collected in the blood collection bag (5) through the outlet-side connecting conduit. Each of the blood inlet and the blood outlet is a peripheral portion of the outer peripheral surface of the filter, and is provided at a position opposite to the filter element. Normally, when processing blood with these leukocyte removal filters, the blood storage bag is placed at a higher position than the filter, and the blood product is filtered by the action of gravity and stored in the blood collection bag. At this time, pressure loss occurs due to the resistance of the filter element during filtration, and the space on the filter inlet side becomes positive pressure. In addition, the blood collection bag is placed at a position lower than the normal filter, but the blood tends to become negative pressure on the outlet side of the filter as the blood moves through the outlet side connecting conduit on the downstream side. It becomes easy to adhere to the filter element. In other words, in a filter using a flexible container, the filter element has a strong tendency to be in close contact with the outlet-side container. It has been pointed out before that there are problems that cannot be used effectively.

  Various solutions to this problem have been proposed so far, and a method of preventing adhesion by inserting a soft PVC tube called a connecting rod between the filter element and the outlet side container (Patent Document 3), Typical methods include a method for preventing the adhesion by providing unevenness with a height difference of 0.2 to 2 mm on the inner surface of the soft container (Patent Document 4), a method for inserting a screen made of knit fiber (Patent Document 6), and the like. . However, as described in Patent Document 4, the method of inserting the connecting rod and screen has a risk of causing poor welding of the container by inserting another member, and the manufacturing process becomes complicated. There were problems such as an increase in manufacturing cost by using the. Furthermore, in the method using the connecting rod, there is a possibility that the range of the adhesion preventing effect is limited to the vicinity of the connecting rod, and the effect remains doubtful.

  Further, although the method disclosed in Patent Document 4 has been proposed as a solution to the problem of the method of inserting the connecting rod and the screen, when the container material and the filter element are to be welded directly, the inner surface of the container As a result, there is a risk that the unevenness of the film causes poor welding and decreases the pressure-resistant peelability, and its application is limited to a frame welding type filter. Furthermore, the method of preventing the adhesion by providing unevenness with a height difference of 0.2 to 2 mm on the connecting rod and the inner surface of the soft container, and the method of inserting a screen made of knit fiber, etc., lead to an increase in dead volume in the filter. For this reason, the amount of blood remaining in the filter after blood filtration increases, and there is a possibility that the amount of valuable blood collected may be reduced.

  All of these examples show how to alleviate the trouble caused by the negative pressure generated on the filter outlet side, that is, how to reduce the close contact between the outlet side flexible container and the filter element. In order to leave a space that can be a blood passage between the flexible container and the filter element, it has been studied in terms of what kind of spacer is arranged to inhibit adhesion, It was not always satisfactory, such as a decrease in the amount of blood collected, poor welding of the container, a complicated manufacturing process, and an increase in manufacturing cost due to the use of extra materials.

As a method for simply solving the above-mentioned problems encountered when gravity-filtering blood using such a filter made of a flexible container, the present inventors have made positive pressure on the outlet side of the flexible container. (Patent Document 7) and a method of preventing the close contact between the filter element and the outlet side container by applying an external force to the flexible container (Japanese Patent Application Nos. 2002-47281 and 2002-243435) ) Has already been developed and applied for a patent.
JP-A-1-320064 International Publication No. 92/20428 Pamphlet European Patent No. 0526678 JP-A-11-216179 JP-A-7-267871 International Publication No. 95/17236 Pamphlet WO 02/083200 pamphlet

  An object of the present invention is to prevent adhesion between the outlet side container of a filter made of a flexible container and a filter element without arranging a spacer, thereby preventing the flow from being hindered, and a filter. To provide a blood filtration method and a blood filtration system capable of effectively utilizing the entire element.

In order to solve the above-mentioned problems, the present inventors have conducted extensive studies focusing on providing a certain space between the inner surface of the container on the blood outlet side and the sheet-like filter element. It was found that blood flowed well by preventing the outlet side flexible container and the filter element from being adhered by the dead weight of the blood contained in the collection bag, and the present invention was made.
That is, the present invention includes the following.
(1) Blood in the blood storage bag is introduced into a filter partitioned by an inlet side flexible container and an outlet side flexible container by a filter element, and filtered by gravity by the filter element disposed in the filter. In a blood filtration method, wherein undesired components are removed from blood and blood is collected in a blood collection bag,
A blood filtration method comprising filtering blood in a state where a space is provided between the filter element and the outlet side flexible container by the blood collection bag and the gravity of the blood in the bag.
(2) including a flexible container having a blood inlet and outlet, and a sheet-like filter element for removing undesirable components from the blood, the blood inlet and outlet being separated by the filter element, In the filter constituting the inlet side flexible container and the outlet side flexible container,
A blood inlet passage connecting the blood inlet and the blood inlet opening; and a blood outlet passage connecting the blood outlet and the blood outlet opening;
The blood inlet opens near the center of the inlet-side flexible container, and a blood inlet opening is provided near the periphery of the inlet-side flexible container,
The blood outlet opens near the center of the outlet-side flexible container, and a blood outlet opening is provided near the periphery of the outlet-side flexible container,
A blood filtration filter, characterized in that the blood inlet opening and the blood outlet opening are arranged at substantially point contrast positions with respect to the center of the filter element.
(3) The blood filtration filter according to (2), wherein the blood inlet passage and the blood outlet passage of the filter are tightly fixed to the inlet side flexible container and the outlet side flexible container, respectively.
(4) A blood filtration system, wherein a blood collection bag is connected to a blood outlet of the blood filtration filter according to (2) or (3) via an outlet-side connection conduit.
(5) The blood filtration system according to (4), wherein an end of the inlet side connection conduit opposite to the filter is connected to a blood collection bag or a blood component child bag connected to the blood collection bag.

  According to the present invention, by filtering the blood in a state where a space is provided between the filter element and the outlet side flexible container due to the gravity of the blood in the blood collection bag and the blood in the bag, Without arranging a spacer between the outlet side container and the filter element, it was possible to prevent the two from sticking together, thereby preventing the flow from being hindered, and effectively using the entire filter element.

Hereinafter, the present invention will be described in detail.
One embodiment of a system for carrying out the blood filtration method according to the present invention is shown in FIG. The blood storage bag (1) is connected to the filter (2) via the inlet side connection conduit (3), and the blood collection bag (5) is connected to the filter (2) via the outlet side connection conduit (4). ing. The blood storage bag (1) stores the blood to be filtered, and the blood collection bag stores the filtered blood. The blood storage bag is disposed at a higher position than the filter (2), and therefore the filter (2) is suspended from the blood bag (1). In addition, the blood collection bag (5) is disposed at a lower position than the filter (2), and the blood collection bag (5) is suspended without contacting the floor and keeping its weight on the filter.

  FIG. 2 is an enlarged sectional view of the filter used in the present invention, and FIG. 3 is a top view of the filter. The filter (2) comprises a flat bag-like flexible container, and a blood inlet passage (6) and an outlet passage (7) are provided on the upper and lower surfaces of the container. The blood inlet passage (6) is formed as an elongated passage on the upper surface of the container so as to connect the blood inlet (13) near the center of the container and the blood inlet opening (11) near the periphery of the container. Similarly, the blood outlet passage (7) is formed as an elongated passage on the lower surface of the container so as to connect the blood outlet (14) near the center of the container and the blood outlet opening (12) near the periphery of the container. A filter element (9) is provided in the center of the inside of the container, whereby the container is divided into an inlet side flexible container (10) and an outlet side flexible container (8). An inlet side connecting conduit (3) is connected to the blood inlet, and an outlet side connecting conduit (4) is connected to the blood outlet.

  The flow of blood when using such a system configuration will be described. The blood in the blood bag passes through the filter inlet side connection conduit, the blood inlet, the blood inlet passage, and enters the inlet side flexible container from the blood inlet opening by gravity. Then, undesirable components are removed when passing through the filter element, discharged from the blood outlet opening to the outside of the outlet-side flexible container, and passed through the outlet passage, the blood outlet, and the outlet-side connecting conduit to the blood collection bag. Collected.

  When blood fills the filter, the blood flows from the blood inlet open end of the filter toward the blood outlet open end, replacing the air in the filter. As the blood in the blood collection bag increases, the weight pulls the blood outlet along with the outlet outlet connection conduit of the filter, creating a space between the outlet flexible container and the filter element.

In addition, although it is desirable that a filter is near horizontal with respect to a floor surface, it is not necessarily limited to it.
Moreover, the blood bag in which the blood to be filtered is stored may be connected upstream of the filter in a state where the blood has already been stored, or may be stored in advance after being connected upstream of the filter.

The blood as used in the present invention includes whole blood products and blood products such as erythrocyte products and platelet products from which components are separated.
The unfavorable components contained in blood as used in the present invention are at least one or more of leukocytes, fine aggregates, viruses, bacteria, prions and pathogens. Depending on the type of blood product, it may contain platelets.

  As described above, the filter in the present invention includes a flexible container having an inlet and an outlet for blood and a sheet-like filter element for removing undesirable components from the blood. Are leukocyte removal filters separated by the filter element. The shape of the filter element may be flat, square, or round.

Examples of the sheet-like filter element include fiber aggregates such as nonwoven fabrics and porous bodies such as sponges. These may be used in a single layer or in combination of a plurality of layers. The filter element may be coated with a specific polymer on the substrate for the purpose of improving blood wettability, blood compatibility, and selective separation, or may be physically modified.
When the filter element is a fiber assembly, examples of the material include synthetic fibers, semi-synthetic fibers such as regenerated cellulose, natural fibers such as cotton, and inorganic fibers. Among these, synthetic fibers, for example, polyester fibers such as polyethylene terephthalate and polybutylene terephthalate, and fibers such as nylon, polypropylene, and polyacrylonitrile are preferable. These fiber diameters are preferably 0.01 μm to 20 μm.
When the filter element is a porous body, any material such as polyacrylonitrile, polysulfone, cellulose acetate, polyvinyl formal, polyester, polyacrylate, polymethacrylate, and polyurethane is suitable for the present invention. The average pore diameter of the porous body is preferably 1 μm or more and less than 30 μm.

  The material of the flexible container, conduit, or bag is not limited. For example, a conventionally known flexible thermoplastic resin as described in Patent Documents 5 and 6 is used, and a soft vinyl chloride resin is used. Styrene-ethylene-butylene copolymers and thermoplastic elastomers containing these as main components are preferred.

The blood inlet passage referred to in the present invention is a passage connecting the inner surface of the inlet-side flexible container and the outside. Similarly, the blood outlet passage is a passage connecting the inner surface of the outlet-side flexible container and the outside. Point to.
The blood inlet opening is an opening into the blood vessel provided in the peripheral edge of the upper surface of the inlet side flexible container. Similarly, the blood outlet opening is the lower peripheral edge of the outlet side flexible container. This is an opening for discharging blood from the inside of the container.
The blood inlet, the blood inlet passage, and the blood inlet opening are arranged substantially in a point contrast with those on the outlet side and the center in the container.
The adhesion and fixation of these flexible containers and filter elements and the adhesion and fixation of the blood inlet / outlet passage to the flexible container are preferably welding without using an adhesive. The welding may be any of external heating welding by heat sealing, internal heating welding by a high frequency welder, and ultrasonic welding. Further, the welding method may be performed by dividing all the above members at the same time or by dividing them into a plurality of times.

  The blood collection bag may function as the blood storage bag of the present invention, and refers to a bag in which a blood collection needle is connected to the bag via a conduit and an anticoagulant is sealed inside. The blood component child bag is connected to the blood collection bag via a conduit, and a component preservation solution may be enclosed in advance.

  Hereinafter, although the blood filtration method and the blood filtration system of the present invention will be described in detail based on examples, the scope of the present invention is not limited by these.

A hole (blood inlet opening) was made in the portion of the flexible sheet that would be the periphery of the filter, and a blood inlet passage made of flexible resin was welded at high frequency. At that time, the blood inlet passage was tightly fixed to the flexible sheet so as to have the above-mentioned hole and an opening (blood inlet) in the center of the filter, thereby forming an inlet-side flexible container. Similarly, an outlet side flexible container was prepared. The peripheral edge of the filter was high-frequency welded in the order of the inlet side flexible container, the filter element, and the outlet side flexible container to prepare a leukocyte removal filter. At that time, the holes on the inlet side opened in the filter peripheral part were arranged so as to be located in the peripheral part in the opposite direction to the hole on the outlet side.
An inlet-side connecting conduit having a length of 0.5 m was inserted into the blood inlet of the filter and adhered using a solvent, and the inlet-side connecting conduit was connected to a blood containing bag containing blood to be filtered. In addition, an outlet-side connecting conduit having a length of 0.5 m was inserted into the blood outlet of the filter and adhered using a solvent, and the outlet-side connecting conduit was connected to a blood collection bag.
The flexible sheet, flexible resin blood inlet / outlet passage, blood storage bag, and blood collection bag were made of soft polyvinyl chloride resin. A tube made of a soft vinyl chloride resin having an inner diameter of 2.9 mm and an outer diameter of 4.2 mm was used for the inlet side connecting conduit and the outlet side connecting conduit.
The filter element is a nonwoven fabric made of polyester from the blood inlet to the outlet, with an average fiber diameter of 12 μm, a basis weight of 30 g / m ² , a thickness of 0.21 mm, four sheets, an average fiber diameter of 1.7 μm, a basis weight of 66 g / m ² , One sheet having a thickness of 0.4 mm, average fiber diameter of 1.2 μm, basis weight of 40 g / m ² , 25 sheets having a thickness of 0.2 mm, average fiber diameter of 1.7 μm, basis weight of 66 g / m ² , thickness One of 0.4 mm ones, an average fiber diameter of 12 μm, a weight per unit area of 30 g / m ² , and a thickness of 0.21 mm laminated in order of 4 sheets were used.

The blood bag containing the blood to be filtered is fixed at a height of 160 cm, and the entire system comprising the inlet side connection conduit, the filter, the outlet side connection conduit, and the blood recovery bag is arranged so that the blood recovery bag does not contact the floor surface. Hanging. Blood containing blood to be filtered after adding 0.025% of calligraphy ink to polyvinylpyrrolidone (molecular weight 390,000) aqueous solution prepared to have a viscosity of 21.8 mPa · s (22.8 ° C.) as a liquid to be filtered 350 g was poured into the bag and allowed to flow using gravity at room temperature. The time (min) required for the blood bag containing the blood to be filtered to be emptied was measured, and 350 g was divided by the value to calculate the processing speed (g / min).
Furthermore, after the liquid to be filtered in the filter was sufficiently recovered by gravity, the recovered amount (g) was measured, and the filter was separated from the inlet side connecting conduit and the outlet side connecting conduit. Next, the filter was disassembled and the filter element was removed. Each non-woven fabric laminated as a filter element was arranged in order from the liquid inflow side to the filtrate outflow side, and the density of the calligraphy ink colored on the filter element was qualitatively examined. The test results at that time are shown as follows.
Diffusion is present = Only the vicinity of the filtrate outlet is colored with the calligraphy ink, and the liquid to be filtered seems to have flowed in that area.
No drift = The entire surface of the filter is evenly colored with calligraphy ink until the filtrate outflow side.
When the shape of the filter outlet side container during the liquid treatment for filtration was observed, a space was formed between the outlet side flexible container and the filter element. As a result of observing the degree of coloration of the filter element, no drift was observed. The results are shown in Table 1 together with the results of the following comparative examples.

Comparative Example 1

The system and filter configuration used in this comparative example are shown in FIGS. However, in this comparative example, the blood collection bag was tested away from the floor, and thus differs from FIG.
A hole was made in the portion of the flexible sheet that would be the periphery of the filter, and a blood inlet passage made of flexible resin was welded at high frequency. At that time, the blood inlet passage was tightly fixed to the flexible sheet so as to have the above-mentioned hole and an opening outside the filter peripheral edge further than the hole, thereby forming an inlet-side flexible container. Similarly, an outlet side flexible container was prepared. Except for these, the same operations and evaluation as in Example 1 were performed.
When the filter shape at the time of processing was observed, the outlet side flexible container and the filter element were in close contact. The treatment flow rate was lower than that in Example 1, and as a result of observing the degree of coloration of the filter element, drift was observed.

Comparative Example 2

The same operation and evaluation as in Example 1 were performed except that a half of the plane area of the blood collection bag was brought into contact with the floor.
When the filter shape at the time of processing was observed, the outlet side flexible container and the filter element were in close contact. The treatment flow rate was lower than that in Example 1, and drift was observed in the observation results of the filter element.

実施例１においては、出口側可撓性容器の内表面とフィルター要素との間に空間を形成することにより、出口側容器の張り付きがなく、流路の閉塞から生じる偏流、すなわちフィルター要素の一部しか有効利用されない状態を防ぐことができ、その結果濾過部が完全に有効利用され、良好な流速を得ることができたと考える。一方、比較例１、２では、出口側可撓性容器の内表面とフィルター要素とが密着し、流路の閉塞による偏流が生じ、そのため流速低下を生じたと考えられる。
また、本発明において定量的に確認することは困難であるが、本発明者らが推察するに従来技術である比較例では図５に示すように使用時に血液はフィルター上部から下部に向かってフィルター内部へ入っていくため血液入口側空間のエア抜けが悪くなることも考えられる。ところが、本願のごとく血液出入口の位置を工夫したことにより使用時には図２のようにフィルタ下部から上部へ向けて血液が流れるためエア抜けもよくなってフィルターの有効濾過面積が比較例に比べて広がり、このような要因も加味されて処理速度が早くなった可能性も考えられる。

In the first embodiment, by forming a space between the inner surface of the outlet side flexible container and the filter element, there is no sticking of the outlet side container, and the drift caused by the blockage of the flow path, that is, one of the filter elements. It is possible to prevent a state where only the portion is effectively used, and as a result, the filtration portion is completely effectively used, and a good flow rate can be obtained. On the other hand, in Comparative Examples 1 and 2, it is considered that the inner surface of the outlet side flexible container and the filter element are in close contact with each other, causing a drift due to the blockage of the flow path, resulting in a decrease in flow velocity.
In addition, although it is difficult to confirm quantitatively in the present invention, in the comparative example which is the prior art as inferred by the present inventors, blood is filtered from the upper part of the filter toward the lower part during use as shown in FIG. It is conceivable that air leaks out of the blood inlet side space because it enters the inside. However, by devising the position of the blood inlet / outlet port as in the present application, the blood flows from the lower part of the filter toward the upper part as shown in FIG. It is also possible that the processing speed has increased due to such factors.

  The present invention is a leukocyte removal filter comprising a flexible container for removing microaggregates and leukocytes that cause transfusion side effects from blood, particularly whole blood preparations for blood transfusion, erythrocyte preparations, platelet preparations, plasma preparations and the like. A blood filtration method and a blood filtration system useful in filtering blood.

It is a schematic diagram which shows an example of the filtration method and system of this invention. It is an expanded sectional view of the filter shown in FIG. It is a top view of the filter shown in FIG. It is a schematic diagram which shows an example of the filtration method and system of a prior art example. It is an expanded sectional view of the filter shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blood storage bag 2 Filter 3 Inlet side connection conduit 4 Outlet side connection conduit 5 Blood collection bag 6 Blood inlet passage 7 Blood outlet passage 8 Outlet side flexible container 9 Filter element 10 Inlet side flexible container 11 Blood inlet opening 12 blood outlet opening 13 blood inlet 14 blood outlet

Claims (5)

Blood in the blood storage bag is introduced into a filter partitioned into an inlet side flexible container and an outlet side flexible container by a filter element, and filtered by gravity using the filter element disposed in the filter. In the blood filtration method of removing undesirable components from the inside and collecting blood in a blood collection bag,
A blood filtration method comprising filtering blood in a state where a space is provided between the filter element and the outlet side flexible container by the blood collection bag and the gravity of the blood in the bag. A flexible container having a blood inlet and outlet, and a sheet-like filter element for removing undesirable components from the blood, the blood inlet and outlet being separated by the filter element, respectively In the filter constituting the flexible container and the outlet side flexible container,
A blood inlet passage connecting the blood inlet and the blood inlet opening; and a blood outlet passage connecting the blood outlet and the blood outlet opening;
The blood inlet opens near the center of the inlet-side flexible container, and a blood inlet opening is provided near the periphery of the inlet-side flexible container,
The blood outlet opens near the center of the outlet-side flexible container, and a blood outlet opening is provided near the periphery of the outlet-side flexible container,
A blood filtration filter, characterized in that the blood inlet opening and the blood outlet opening are arranged at substantially point contrast positions with respect to the center of the filter element.   3. The blood filtration filter according to claim 2, wherein a blood inlet passage and a blood outlet passage of the filter are fixed to the inlet side flexible container and the outlet side flexible container, respectively.   4. A blood filtration system, wherein a blood collection bag is connected to a blood outlet of the blood filtration filter according to claim 2 through an outlet-side connection conduit. The blood filtration system according to claim 4, wherein an end of the inlet side connection conduit opposite to the filter is connected to a blood collection bag or a blood component child bag connected to the blood collection bag.

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