Abstract:
A blood reservoir ( 1 ) including a venous blood filter ( 40 ) and a cardiotomy filter ( 5 ). The cardiotomy blood filter includes a first cardiotomy blood filter member ( 51 ) and a second cardiotomy blood filter member ( 52 ). The filter member ( 52 ) is equipped with a first filter portion ( 52   a ) and a second filter portion ( 52   b ). The first filter portion ( 52   a ) forms the wall portion and the second filter portion ( 52   b ) forms the bottom portion. Specifications of the first filter portion ( 52   a ) and the second filter portion ( 52   b ) are different. A guide member ( 60 ) of the blood storage tank ( 1 ) is made of a foam material. The blood from which bubbles have been removed is guided while permeating the guide member ( 60 ). Consequently, the guide member ( 60 ) can lead the blood from which bubbles are removed to a predetermined position at a suitable liquid impact speed.

Description:
TECHNICAL FIELD 
     The present invention relates a blood reservoir that has a filter member. 
     BACKGROUND ART 
     An artificial heart lung apparatus is used during conventional cardiac surgery. The artificial heart lung apparatus is mainly configured from a blood reservoir, a blood pump, a heat exchanger, a blood circuit, an oxygenator, and the like. In this type of artificial heart lung apparatus, firstly blood (venous blood) that was removed from veins of the patient and blood (cardiotomy blood) that is withdrawn from the field of operation are sent to a blood reservoir, and temporarily stored in the blood reservoir. Furthermore, blood is sent to the heat exchanger by the blood pump, and the heat exchanger adjusts the blood temperature. In the oxygenator, gas exchange (carbon dioxide removal and oxygen addition) is performed on the temperature-adjusted blood. Finally, the blood is returned to the body of the patient as arterial blood. 
     This type of artificial heart lung apparatus provides a temporary substitution for the function of the heart and lungs during cardiac surgery. In the artificial heart lung apparatus, before returning the blood to the patient, foreign material or bubbles that have become mixed in the blood during surgery must be removed. For example, JP-H5-317420 (called “Patent Document 1” hereinafter) discloses a blood reservoir (blood reservoir including a cardiotomy reservoir) that removes simultaneously bubbles and foreign matter such as bone fragments, soft-tissue fragments, or the like from blood. 
     SUMMARY 
     The conventional blood reservoir, for example, is provided with a mesh-shaped filter for removal of bubbles and foreign matter. The mesh-shaped filter may be a woven fabric, a non-woven fabric or the like (refer to Patent Document 1). For example, when a non-woven fabric is used as a filter, stable blood processing is enabled since the non-woven fabric does not tend to clog. On the other hand, when removing air bubbles of at least a specific size and over, since a non-woven fabric has low liquid permeable characteristics in comparison to a mesh fabric, blood tends to accumulate, and the permeate rate decelerates. In other words, the time until the amount of blood in the blood reservoir appears as a change of the liquid surface is increased. Therefore, when using a conventional blood reservoir, there is the problem that a clinical engineer, nurse, doctor, or the like who manages the blood reservoir has difficulty in accurately comprehending the amount of blood that has left the patient, that is to say, the blood storage amount (Problem 1). 
     A portion of the bottom portion of a conventional blood reservoir has a protruding portion that projects outwardly. A venous blood filter for removing bubbles from the venous blood is disposed above the protruding portion. Furthermore, a cardiotomy blood filter is disposed at a position adjacent to the venous blood filter, that is to say, inclining above the protruding portion. When foreign matter or bubbles are removed from cardiotomy blood by the cardiotomy blood filter, in case that the storage blood amount is low, the cardiotomy blood falls to the bottom face (non-protruding portion) that is adjacent to the protruding portion of the blood reservoir. Thus, the cardiotomy blood flows in contact with the bottom face from the non-protruding portion of the blood reservoir towards the protruding portion, and is stored in an inner space of the protruding portion. 
     In this manner, when there is a low storage blood amount in the conventional blood reservoir, since cardiotomy blood from which foreign matter and bubbles have been removed by the cardiotomy blood filter flows into an inner portion of the protruding portion while making contact with the bottom face of the blood reservoir, there is the problem that time is required for the cardiotomy blood to reach the inner space in the protruding portion. In other words, notwithstanding the fact that foreign matter and bubbles have been already removed from the cardiotomy blood by the cardiotomy blood filter, there is the problem that time is required to reflect that cardiotomy blood as a blood storage amount. Consequently, when actually using this type of blood reservoir, the medical personnel such as a clinical engineer, nurse, doctor, or the like who manages the blood reservoir have difficulty in accurately comprehending the blood storage amount during the surgical procedure. 
     In order to solve the above problem, a blood reservoir has been developed in which the cardiotomy blood filter is disposed above the protruding portion. In this type of blood reservoir, since the cardiotomy blood filter is disposed above the protruding portion, when foreign matter or bubbles are removed from the cardiotomy blood by the cardiotomy blood filter, the cardiotomy blood drops into an inner portion of the protruding portion of the blood reservoir. Therefore, when using this type of blood reservoir, cardiotomy blood from which foreign matter and bubbles have been removed by the cardiotomy blood filter is promptly reflected as a blood storage amount. However, when the blood storage amount is low, since there is an increase in the dropping distance from the position at which the cardiotomy blood from which foreign matter and bubbles have been removed starts to drop to the portion in which the blood is stored in an inner portion of the protruding portion, there is the problem that bubbles become mixed as a result of the drop (Problem 2). 
     The present invention is proposed in light of the above Problem 1, and an object of the present invention is to provide a blood reservoir that has a filter having a processing capacity that is desired by medical personnel. Furthermore, the present invention is proposed in light of Problem 2 above, and an object of the present invention is to prevent occurrence of bubbles in blood after bubble removal. In addition, a further object of the present invention is to enable accuracy comprehension of a blood storage amount by medical personnel. 
     A blood reservoir according to embodiment 1 stores venous blood and/or cardiotomy blood. The blood reservoir includes a housing and a filter means. The filter means is disposed in the housing. The filter means includes a filter member. 
     More precisely, the blood reservoir includes a housing, a venous blood filter means, and a cardiotomy blood filter means. The venous blood filter means includes a venous blood filter member. The venous blood filter member removes bubbles from the venous blood. The venous blood filter member is disposed in the housing. The cardiotomy blood filter means includes a first cardiotomy blood filter member and a second cardiotomy blood filter member. The first cardiotomy blood filter member removes foreign matter and bubbles from cardiotomy blood, and is disposed in the housing. The second cardiotomy blood filter member removes foreign matter and bubbles from cardiotomy blood that has passed through the first cardiotomy blood filter member, and is disposed outside the first cardiotomy blood filter member. 
     In particular, this blood reservoir includes a filter member that removes foreign matter and bubbles from the blood that was removed from the patient. The filter member includes a first filter portion and a second filter portion. The first filter portion forms a wall portion and the second filter portion forms a bottom portion. The first filter portion and the second filter portion are formed with different specifications. 
     This type of blood reservoir is provided with a filter means, and the filter means has a filter member. As a result, a blood reservoir that responds to the requirements of medical personnel can be provided by provision of a filter member having a specification that responds to the requirements of medical personnel. 
     More specifically, the blood reservoir includes a cardiotomy blood filter means. This cardiotomy blood filter means includes a second cardiotomy blood filter member. Consequently, a blood reservoir that responds to the requirements of medical personnel can be provided by provision of a second filter having a specification that responds to the requirements of medical personnel. 
     Still more specifically, the cardiotomy blood filter means includes a first cardiotomy blood filter member. Consequently, foreign matter and bubbles having a relatively large size can be removed from cardiotomy blood flowing into the blood reservoir by the first cardiotomy blood filter member. Furthermore, when blood flows from the first cardiotomy blood filter member to the second cardiotomy blood filter member, small sized foreign matter and bubbles can be removed by the first cardiotomy blood filter member. In this manner, foreign matter can be removed from the blood that has passed through the cardiotomy blood filter means, and bubbles included in the blood that has passed through the cardiotomy blood filter means can be accurately limited to a predetermined size less or equal. 
     In particular, this blood reservoir includes a filter member that is composed of the first filter portion and the second filter portion to remove foreign matter and bubbles from the blood that has bled from the patient. The first filter portion forms a wall portion, and the second filter portion that is formed with a different specification from the first filter portion forms the bottom portion. Consequently, a filter member having the processing capacity that is required by medical personnel can be provided by separating the specification that responds to the requirements of medical personnel into the wall portion (first filter portion) and the bottom portion (second filter portion). 
     The blood reservoir includes a venous blood filter means, and the venous blood filter means includes a venous blood filter member. Consequently, a blood reservoir that enables removal of foreign matter and bubbles from cardiotomy blood and enables removal of bubbles from venous blood can be provided. 
     As described above, this blood reservoir is a blood reservoir that has the processing capacity required by medical personnel. In this manner, medical personnel managing the blood reservoir can more accurately comprehend the blood storage amount held in the blood reservoir. 
     The blood reservoir according to embodiment 2 includes the blood reservoir according to embodiment 1 in which the second filter portion is formed in a projecting shape. 
     In this configuration, since the second filter portion in the filter member, that is to say, the bottom portion, is formed in a projecting shape, the contact surface area with blood can be increased. In this manner, the blood processing capacity in the filter member can be improved. 
     The blood reservoir according to embodiment 3 includes the blood reservoir according to embodiment 1 or embodiment 2, in which the second filter portion is connected to the first filter portion to enable folding towards an inner surface of the first filter portion. When the second filter portion is folded, the second filter portion is formed in a projecting shape. 
     In this configuration, the filter member can be easily processed and manufactured since the second filter portion is connected with the first filter portion to enable folding towards an inner surface of the first filter portion. When the second filter portion is folded, the second filter portion can increase the contact surface area with blood. In this manner, the blood processing capacity in the filter member can be improved. 
     The blood reservoir according to embodiment 4 includes the blood reservoir according to any one of embodiment 1 to embodiment 3, in which the second filter portion has a specification that enables higher liquid permeable characteristics than the first filter portion. 
     In this configuration, the second filter portion in the filter member has higher liquid permeation characteristics than the first filter portion. As a result, when blood begins to flow into the inner portion of the filter member, the blood mainly flows through the second filter portion. When the blood processing capacity in the second filter portion is reduced by blocking or the like, the blood begins to mainly flow through the first filter portion. In this manner, when blood mainly flows through the second filter portion, high-speed removal of foreign matter and bubbles from the blood is enabled. Thereafter, when blood mainly flows through the first filter portion, although the blood processing speed of the second filter portion is reduced, stable removal of foreign matter and bubbles from the blood is enabled. 
     The blood reservoir according to embodiment 5 includes the blood reservoir according to embodiment 4, in which the first filter portion is formed by a non-woven fabric. Furthermore, the second filter portion is formed by a single-layer mesh fabric. 
     In this configuration, the first filter portion is formed from a non-woven fabric. Furthermore the second filter portion is formed from a single-layer mesh fabric (screen mesh). In this manner, when blood is mainly passing through the mesh fabric, high-speed removal of foreign matter and bubbles from the blood is enabled. Thereafter, when blood mainly flows through the non-woven fabric, although the blood processing speed of the mesh fabric is reduced, stable removal of foreign matter and bubbles from the blood is enabled. 
     The blood reservoir according to embodiment 6 includes the blood reservoir according to any one of embodiment 1 to embodiment 5, and is a blood reservoir that stores venous blood and/or cardiotomy blood. This blood reservoir includes a housing, a filter means, and a guide member. The housing includes a blood inflow portion and a blood outflow portion. The filter means filters blood inflowing from an inflow portion. The filter means is disposed in the housing. The guide member is disposed between the filter means and an outflow portion, and guides blood that is filtered by the filter means towards the outflow portion. The guide member is configured from a foam material. 
     The blood reservoir includes the guide member. The guide member is disposed between the filter means and the outflow portion, and therefore blood that has been filtered by the filter means can be accurately guided to the outflow portion at a suitable liquid impact speed. Since the guide member is configured from a foam material, blood that bubbles are removed is guided while permeating through the guide member. In this manner, the guide member can guide blood after bubble removal to a predetermined position at a suitable liquid impact speed. In other words, the guide member can prevent entry of bubbles into the blood after filtering. Furthermore, medical personnel who manage the blood reservoir can more accurately comprehend the blood storage amount stored in the blood reservoir. 
     The blood reservoir according to embodiment 7 includes the blood reservoir according to embodiment 6, and is a blood reservoir that stores venous blood and/or cardiotomy blood. This blood reservoir includes a housing, a venous blood filter, a cardiotomy blood filter, and a guide member. The housing includes a blood inflow portion and a blood outflow portion. The venous blood filter means includes a venous blood filter member for removal of bubbles from the venous blood. The venous blood filter means is disposed in the housing. The cardiotomy blood filter means includes a first cardiotomy blood filter member, and a second cardiotomy blood filter member. The first cardiotomy blood filter member removes foreign matter and bubbles from the cardiotomy blood, and is disposed in the housing. The second cardiotomy blood filter member removes foreign matter and bubbles from the cardiotomy blood that has passed through the first cardiotomy blood filter member, and is disposed outside the first cardiotomy blood filter member. The guide member is disposed between the cardiotomy blood filter means and the outflow portion, and guides blood filtered by the cardiotomy blood filter means towards the outflow portion. 
     In this configuration, the blood reservoir includes a guide member. The guide member is disposed between the cardiotomy blood filter means and the outflow portion, and ensures guiding of blood filtered by the cardiotomy blood filter means towards the outflow portion without scattering. In other words, the guide member prevents mixture of bubbles in the filtered blood. Furthermore, medical personnel who manage the blood reservoir can more accurately comprehend the blood storage amount stored in the blood reservoir. 
     The blood reservoir according to embodiment 8 includes the blood reservoir according to embodiment 6 or embodiment 7, in which the guide member is a plate shaped member which is compressed with respect to the thickness direction. 
     In this configuration, the predetermined foam material that configures the guide member is compressed with respect to a thickness direction, and therefore an elongated hole can be formed in direction that is orthogonal to the thickness direction in the guide member. In this manner, blood that is guided to permeate the guide member can be guided smoothly in a direction that is orthogonal to the thickness direction, and at the same time, bubbles do not tend to remain in the member. 
     The blood reservoir according to embodiment 9 includes the blood reservoir according to any one of embodiment 6 to embodiment 8, and the guide member is disposed at an angle of inclination that depends on the density of the material density. 
     In this configuration, the angle of inclination of the guide member is set to an angle that varies in response to the density of the material configuring the guide member. Generally, the spaces in the guide member are reduced as the density of the material configuring the guide member increases. In this manner, when the density of the material configuring the guide member increases, blood is hindered from permeating the guide member. In other words, when the density of the material configuring the guide member increases, blood does not permeate the guide member and flows on the surface of the guide member. For this reason, when the density of the material configuring the guide member increases, the speed that the blood travels over the guide member increases. 
     For the above reasons, for example, blood after bubble removal can be guided to a predetermined position at a suitable liquid impact speed by disposing the guide member so that the angle of inclination of the guide member is reduced as the density of the material configuring the guide member increases. In other words, entry of bubbles into the blood after bubble removal can be prevented by the guide member. 
     The blood reservoir according to embodiment 10 includes the blood reservoir according to embodiment 9, and the guide member is configured from a foam material that has a density in the range from 0.02 g/cm 3  to 0.05 g/cm 3 , and the angle of inclination is at least 70 degrees and over. 
     In this configuration, when the density of the material configuring the guide member is set in the range from 0.02 g/cm 3  to 0.05 g/cm 3 , and an angle of inclination is set in the range of at least 70 degrees and over, blood after bubble removal can be guided to a predetermined position at a suitable liquid impact speed. In other words, entry of bubbles into the blood after bubble removal can be prevented by the guide member. 
     The blood reservoir according to embodiment 11 includes the blood reservoir according to embodiment 9, and the guide member is configured from a foam material that has a density in the range from 0.05 g/cm 3  to 0.20 g/cm 3 , and the angle of inclination is from 65 degrees to 70 degrees. 
     In this configuration, when the density of the material configuring the guide member is set in the range from 0.05 g/cm 3  to 0.20 g/cm 3 , and an angle of inclination is set in the range from 65 degrees to 70 degrees, blood after bubble removal can be guided to a predetermined position at a suitable liquid impact speed. In other words, entry of bubbles into the blood after bubble removal can be prevented by the guide member. 
     The blood reservoir according to embodiment 12 includes the blood reservoir according to embodiment 9, and the guide member is configured from a foam material that has a density in the range from 0.20 g/cm 3  to 0.40 g/cm 3 , and the angle of inclination is less than 65 degrees. 
     In this configuration, when the density of the material configuring the guide member is set in the range from 0.20 g/cm 3  to 0.40 g/cm 3 , and an angle of inclination is set in a range less than 65 degrees, blood after bubble removal can be guided to a predetermined position at a suitable liquid impact speed. In other words, entry of bubbles into the blood after bubble removal can be prevented by the guide member. 
     In the blood reservoir according to the present invention, the first filter portion forms the wall portion and the second filter portion forms the bottom portion. The first filter portion and the second filter portion are formed with different specifications. As a result, a filter member having the processing capacity that is required by medical personnel can be provided by separating the specification that responds to the requirements of medical personnel with respect to the wall portion (first filter portion) and the bottom portion (second filter portion). In this manner, medical personnel managing the blood reservoir can more accurately comprehend the blood storage amount held in the blood reservoir. 
     The blood reservoir according to the present invention includes a guide member that is configured from a foam material. In this manner, blood from which bubbles have been removed is guided while permeating the guide member. In this manner, the guide member can guide blood after bubble removal to a predetermined position at a suitable liquid impact speed. In other words, the guide member can prevent entry of bubbles into the blood after filtering. 
     The blood reservoir according to the present invention includes a guide member that is disposed between the filter means and the outflow portion, and guides blood that is filtered by the filter means towards the outflow portion at a suitable liquid impact speed. In other words, the guide member can prevent entry of bubbles into the blood after filtering. Furthermore, medical personnel managing the blood reservoir can more accurately comprehend the blood storage amount held in the blood reservoir. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an external view of a blood reservoir according to a first embodiment of the present invention. 
         FIG. 2  is a exploded perspective view of a second support member in a filter support unit. 
         FIG. 3  is a perspective view of a filter retaining member that configures the second support member. 
         FIG. 4  is a perspective view of a bottom member that configures the second support member. 
         FIG. 5  is a sectional view of the blood reservoir. 
         FIG. 6  is a side view of the second cardiotomy blood filter member before mounting (First View). 
         FIG. 7  is a side view of the second cardiotomy blood filter member before mounting (Second View). 
         FIG. 8  is a view illustrating the relationship between the angle of inclination of the guide member and the density of the material configuring the guide member. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the present invention, venous blood denotes blood that has bled from a blood vessel of a patient through a cannula, and cardiotomy blood denotes blood (vented blood or suction blood) that is withdrawn from outside or inside the heart in the surgical field (the field of operation). Furthermore, foreign material in the present invention denotes a substance other than blood that has the possibility of inclusion in cardiotomy blood such as fat globule, soft-tissue fragments, bone fragments, denatured protein, platelet clump, or the like. 
       FIG. 1  is an external view of a blood reservoir  1  according to a first embodiment of the present invention.  FIG. 2  is a partial perspective view of a second support member  22  in a filter support unit  20 .  FIG. 3  is a perspective view of a filter retaining member  222  that configures the second support member  22 .  FIG. 4  is a perspective view of a bottom member  322  that configures the second support member  22 .  FIG. 5  is a sectional view of the blood reservoir  1 .  FIG. 6  and  FIG. 7  are side views of the second cardiotomy blood filter member  52  before mounting.  FIG. 8  is a view illustrating the relationship between the angle of inclination of the guide member and the density of the material configuring the guide member  60 . 
     The blood reservoir  1  includes a housing  10 , a filter support unit  20 , a blood guiding pipe  30 , a venous blood filter means  40 , a cardiotomy blood filter means  50 , and a guide member  60 . 
     As shown in  FIG. 1 , the housing  10  includes a housing main body  11  and a cover  12 . As shown in  FIG. 5 , a storage space S that stores blood is formed in the housing  10 . The storage space S is a space inside the housing  10  that is formed by mounting the cover  12  onto the housing main body  11 . 
     The housing main body  11  forms a box shape in which a portion has an opened configuration. The opening in the housing main body  11  is formed substantially in an oval shape, or substantially in a quadrilateral shape. As shown  FIG. 1  and  FIG. 5 , the housing main body  11  includes a box portion  11   a  and a protruding portion  11   b . The box portion  11   a  forms the storage space S on the blood inflow side, that is to say, forms an upper storage space Sa. The protruding portion  11   b  forms the storage space S on the blood outflow side, that is to say, forms a lower storage space Sb. The protruding portion  11   b  is a portion of the bottom portion of the box portion  11   a  that projects outwardly, and is integrally formed with the box portion  11   a . A pipe-shaped blood outflow port  11   c  communicating from the storage space S to the outside is provided on the bottom portion of the protruding portion  11   b . For example the blood outflow port  11   c  is connected to a tube of the blood line in the external blood recirculation path. 
     As used herein, one side face of the box portion  11   a  and one face of the protruding portion  11   b  are formed on the same surface. A scale (not shown) is provided on the above surface to confirm the blood storage amount. The bottom portion of the box portion  11   a  and the bottom portion of the protruding portion  11   b  face the opening of the housing main body  11 . 
     As shown in  FIG. 1  and  FIG. 5 , the cover  12  is fitted and mounted on the housing main body  11  to cover the opening of the housing main body  11 . A first blood input port  12   a  and a second blood inflow port  12   b  are provided in the cover  12 . The first blood input port  12   a  for example is connected to a tube of a blood extraction line for venous blood in the external blood recirculation path. The second blood input port  12   b  for example is connected to a tube of the cardiotomy blood line in the external blood recirculation path. The first blood input port  12   a  and the second blood inflow port  12   b  communicate from an external portion to the storage space S, for example, the upper storage space Sa when the cover  12  is mounted on the housing main body  11 . 
     An air bleed port (not shown) allowing entry and exit of air depending on fluctuation in the amount of blood in the blood reservoir  1  is provided in the cover  12 . Air after defoaming or air after foam breaking is discharged to the outside from the air bleed port. 
     The constituent material used in the housing main body  11  and the cover  12  is for example polycarbonate, acrylic resin, polystyrene, polyvinyl chloride, or the like. The housing main body  11  formed from such a material is preferably substantially transparent in order to enable visual confirmation of the blood storage amount stored in an inner portion of the blood reservoir  1 , and the state of the blood in the inner portion. 
     The filter support unit  20  supports the venous blood filter means  40  and the cardiotomy blood filter means  50 , and is mounted on the housing  10 , for example, on the cover  12 . As shown in  FIG. 2  to  FIG. 5 , the filter support unit  20  is configured from a first support member  21  and a second support member  22 . The first support member  21  supports the venous blood filter means  40 , for example, the venous blood filter member  41  as described hereafter. The first support member  21  has a frame structure, and is mounted onto the inner surface of the cover  12 . 
     As shown in  FIG. 2  to  FIG. 5 , the second support member  22  supports the cardiotomy blood filter means  50 , for example, the first cardiotomy blood filter member  51  and the second cardiotomy blood filter member  52  as described hereafter. The second support member  22  is mounted onto the inner surface of the cover  12 . More specifically, the second support member  22  includes a frame  122 , a filter retaining member  222  that retains the second cardiotomy blood filter member  52  with the frame  122 , and a bottom member  322  that supports the bottom portion of the second cardiotomy blood filter member  52 . 
     The frame  122  is mounted onto the inner surface of the cover  12 . The frame  122  includes two opposed plate portions  122   a , a connecting member  122   b  connecting the two plate portions  122   a , and a mesh portion  122   c  formed on an inner face of each plate portion  122   a . The second support member  22  is mounted on the inner surface of the cover  12  in the two plate portions  122   a . The second cardiotomy blood filter member  52  covers the plate portion  122   a  and the connecting member  122   b . The second cardiotomy blood filter member  52  engages the plate portion  122   a  and is mounted onto the plate portion  122   a.    
     The filter retaining member  222  is mounted on the inner surface of the cover  12 . The filter retaining member  222  is formed in a box shape along the outer shape of the frame  122 . An opening is formed on the upper portion, the central portion and the lower portion of the filter retaining member  222 . The upper portion of the opening  222   a  is a portion for inserting the frame  122 . The central opening  222   b  is a through hole. The through hole is a passage of blood that has passed through a first filter portion  52   a  of the second cardiotomy blood filter member  52 , for example, a non-woven fabric. The lower opening  222   c  is a through hole. The through hole is a passage of blood that has passed through a second filter portion  52   b  of the second cardiotomy blood filter member  52 , for example, a mesh fabric (screen mesh). The filter retaining member  222  is mounted on the cover  12  with the second cardiotomy blood filter member  52  covered by the frame  122 . 
     The bottom member  322  is mounted on the filter retaining member  222 . More specifically, the bottom member  322  is mounted on the opening  222   c  formed in the filter retaining member  222 . The bottom member  322  is formed to enable passage of cardiotomy blood into an inner portion in a supported configuration. In the supported configuration, the bottom member  322  supports the bottom portion (the second filter portion  52   b  described below) of the second cardiotomy blood filter member  52 . The bottom member  322  is formed from a support portion  322   a  that supports the bottom portion of the second cardiotomy blood filter member  52 , and a passage  322   b  that enables passage of cardiotomy blood from the cardiotomy blood filter means  50 . The support portion  322   a  is formed in a plate shape, and is placed in abutment with the bottom portion of the second cardiotomy blood filter member  52  to thereby support the bottom portion of the second cardiotomy blood filter member  52 . 
     The passage  322   b  is formed as a rectangular tube. In other words, the passage  322   b  is formed as a hollow beak shape. The opening  322   c  is provided on the opposed side face on the passage  322   b . In this manner, cardiotomy blood that passes through the passage  322   b  flows out from the opening  322   c  in addition to the distal tip of the passage  322   b.    
     Furthermore, when the bottom member  322  is mounted on the filter retaining member  222 , the passage  322   b  is set to a predetermined angle of inclination a with reference to the horizontal plane (refer to  FIG. 5 ). More specifically, the bottom member  322  is mounted on the filter retaining member  222  so that the angle of inclination α of the passage  322   b  relative to the horizontal plane is approximately 65 degrees. 
     Furthermore, when the bottom member  322  is mounted on the filter retaining member  222 , the distal tip of the passage  322   b  of the bottom member  322  is disposed on an inner portion of the protruding portion  11   b . In this manner, cardiotomy blood after filtering is guided from the upper portion of the protruding portion  11   b  into an inner portion of the protruding portion  11   b.    
     The statement “a inner surface of the cover  12 ” as used herein means the surface opposite the side on which the first blood input port  12   a  and the second blood input port  12   b  are mounted on the cover  12 . Furthermore, the statement “the top surface of the cover  12 ” as used herein means the surface opposite the inner surface of the cover  12 . In other words, “the top surface of the cover  12 ” means the surface on the side on which the first blood input port  12   a  and the second blood input port  12   b  are mounted on the cover  12 . 
     The blood guiding pipe  30  includes a venous blood guiding pipe  31  for guiding venous blood from the first blood input port  12   a  into an inner potion the housing  10 , and a cardiotomy blood guiding pipe  32  for guiding cardiotomy blood from the second blood input port  12   b  into the housing  10 . 
     The venous blood guiding pipe  31  is mounted on the inner surface of the cover  12  at the position of the first blood input port  12   a . The venous blood guiding pipe  31  is formed as a pipe, and is inserted into an inner portion of the frame structure of the first support member  21 . When the cover  12  is mounted on the housing main body  11 , one end of the venous blood guiding pipe  31  is mounted onto the inner surface of the cover  12 , and the other end is positioned in an inner portion of the protruding portion  11   b . In other words, when the cover  12  is mounted on the housing main body  11 , the venous blood guiding pipe  31  is disposed in the housing  10  extending from the first blood input port  12   a  of the cover  12  in an inclined configuration towards the protruding portion  11   b  of the housing main body  11 . 
     The cardiotomy blood guiding pipe  32  is mounted on the inner surface of the cover  12  at the position of the second blood input port  12   b . More specifically, the cardiotomy blood guiding pipe  32  is formed as a pipe, and is mounted on the inner surface of the cover  12  at the position of the second blood input port  12   b  between the second support member  22  and the cover  12 . When the cover  12  is mounted on the housing main body  11 , one end of the cardiotomy blood guiding pipe  32  is mounted onto the inner surface of the cover  12 , and the other end is located above the protruding portion  11   b . In other words, when the cover  12  is mounted on the housing main body  11 , the cardiotomy blood guiding pipe  32  is disposed in the second support member  22 , for example, in an inner portion of the frame  122  with extending from the second blood input port  12   b  of the cover  12  downwards towards the protruding portion  11   b  of the housing main body  11 . 
     Although an example is described herein in which the cardiotomy blood guiding pipe  32  is mounted on the inner surface of the cover  12  at the position of the second blood input port  12   b , the cardiotomy blood guiding pipe  32  may be integrally formed with the inner surface of the cover  12  at the position of the second blood input port  12   b.    
     The venous blood filter means  40  is mounted in the housing  10 . The venous blood filter means  40  includes a venous blood filter member  41 . The venous blood filter member  41  removes bubbles from venous blood guided from the first blood input port  12   a  through the venous blood guide pipe  31  into the housing  10 . For this reason, it is preferred that the hole diameter of the venous blood filter member  41  is approximately 20-40 μm. 
     The venous blood filter member  41  is formed as a bag with a portion thereof in an opened configuration, and is disposed in the housing  10 . More specifically, the venous blood filter member  41  is formed as a bag with an upper portion thereof in an opened configuration, and is mounted on an outer surface of the first support member  21  of the filter support unit  20 . Still more specifically, the venous blood filter member  41  is mounted on the first support member  21  of the filter support unit  20  to enclose the frame structure of the first support member  21  of the filter support unit  20 . In this manner, when the cover  12  is mounted on the housing main body  11 , the venous blood filter member  41  is disposed in the housing  10  to extend from the first blood inflow port  12   a  of the cover  12  inclining towards the protruding portion  11   b  of the housing main body  11 . 
     The cardiotomy blood filter means  50  is mounted in the housing  10 . The cardiotomy blood filter means  50  includes the first cardiotomy blood filter member  51  and the second cardiotomy blood filter member  52 . 
     The first cardiotomy blood filter member  51  removes relatively large foreign matter and bubbles from cardiotomy blood guided from the second blood inflow port  12   b  through the cardiotomy blood guide pipe  32  to the inner portion of the housing  10 . 
     The first cardiotomy blood filter member  51  is formed in a hat shape with a portion thereof in an opened configuration, and is disposed in the housing  10 . The first cardiotomy blood filter member  51  is mounted onto the inner surface of the cover  12 . More specifically, the first cardiotomy blood filter member  51  includes a flange portion  51   a  and an concave portion  51   b . Still more specifically, the concave portion  51   b  of the first cardiotomy blood filter member  51  is fitted to the cardiotomy blood guide pipe  32 , and the flange portion  51   a  is mounted on the inner surface of the cover  12 . The flange portion  51   a  of the first cardiotomy blood filter member  51  is supported by the second support member  22  mounted on the cover  12 . More specifically, the flange portion  51   a  of the first cardiotomy blood filter member  51  is supported by a claw portion  122   c  provided on the frame  122  of the second support member  22 . 
     Foam urethane is used in the first cardiotomy blood filter member  51 . A defoaming agent, such as silicone that defoams bubbles when coming into contact with bubbles, is coated on an inner surface of the first cardiotomy blood filter member  51 , for example, on the inner surface of the concave portion  51   b . For that reason, when the cardiotomy blood comes into contact with the inner surface of the first filter member  51  before cardiotomy blood passing through the first cardiotomy blood filter member  51 , the bubbles contained in the cardiotomy blood are burst by the defoaming agent. After the cardiotomy blood passes through the first cardiotomy blood filter member  51 , bubbles of more than a predetermined size corresponding to the size of the cavities in the first cardiotomy blood filter member  51  are removed from the cardiotomy blood. Furthermore, when the cardiotomy blood passes through the first cardiotomy blood filter member  51 , foreign matter is also removed from the cardiotomy blood. For example, foreign matter having a size that is larger than the cavities of the first cardiotomy blood filter member  51  is removed from the cardiotomy blood. 
     The second cardiotomy blood filter member  52  removes foreign matter and bubbles from cardiotomy blood that has passed through the first filter member, that is to say, from cardiotomy blood from which relatively large foreign matter and bubbles have been removed by the second cardiotomy blood filter member  52 . It is preferred that the hole diameter of the second cardiotomy blood filter member  52  is approximately 20-200 μm. 
     The second cardiotomy blood filter member  52  is formed as a bag with a portion thereof in an opened configuration, and is disposed in the housing  10 . More specifically, the second cardiotomy blood filter member  52  is formed as a bag with an upper portion thereof in an opened configuration. In addition, the second cardiotomy blood filter member  52  is mounted on the second support member  22  of the filter support unit  20  that is disposed on an outer side of the first cardiotomy blood filter member  51 . For example, the second cardiotomy blood filter member  52  is covered by the plate portion  122   a  and the connecting member  122   b , and is engaged and mounted on the plate portion  122   a . In this configuration, the filter retaining member  222  is mounted on the frame  122 . The bottom member  322  is mounted in the through hole  222   c  that is formed in the filter retaining member  222 . In this manner, the second cardiotomy blood filter member  52  is supported on the filter support unit  20  with the bottom portion folded inwardly. Furthermore in this configuration, the first cardiotomy blood filter member  51  is disposed on an inner portion of the second cardiotomy blood filter member  52 . 
     More specifically, as shown in  FIG. 6  and  FIG. 7 , the second cardiotomy blood filter member  52  includes the first filter portion  52   a  and the second filter portion  52   b.    
     The first filter portion  52   a  forms a wall portion in the bag-shaped second cardiotomy blood filter member  52 , that is to say, an upstream wall portion on a upstream side in the direction of the inflow of blood. The first filter portion  52   a  is configured from a two substantially trapezoid sheet-shaped mesh members. More specifically, the first filter portion  52   a  is formed by press fitting or welding the two side edges (the edges excluding the upper edge and the lower edge) of the two mesh members. The first filter portion  52   a  is formed for example from non-woven fabric. The first filter portion  52   a  is mounted on the frame  122  on the edge forming the upper opening. 
     The statement “substantially trapezoid” as used herein means a “trapezoid having a lower edge that projects outwardly”, or “a trapezoid that has a lower edge that bends outwardly”. 
     The second filter portion  52   b  forms a bottom portion on a downstream side in the direction of the inflow of blood. The second filter portion  52   b  is configured from a two substantially trapezoid sheet-shaped mesh members. More specifically, the substantially trapezoid sheet-shaped mesh members  52   b  for the second filter portion are formed so that the height H 2  (height of the trapezoid) of the substantially trapezoid sheet-shaped mesh members  52   b  for the second filter portion is smaller than the height H 1  (height of the trapezoid) of the substantially trapezoid sheet-shaped mesh members  52   a  for the first filter portion. More specifically, the substantially trapezoid sheet-shaped mesh members  52   b  for the second filter portion are preferably formed so that the height H 2  of the substantially trapezoid sheet-shaped mesh members  52   b  for the second filter portion is approximately ⅓ of the height H 1  of the substantially trapezoid sheet-shaped mesh members  52   a  for the first filter portion. 
     The two side edges (the edges excluding the upper edge and the lower edge) of the two mesh members are press fitted or welded to thereby form the second filter portion  52   b . The lower edge of the second filter portion  52   b  (the respective lower edges of the two mesh members that configure the second filter portion  52   b ) are press fitted or welded to the upper edge (the respective upper edges of the two mesh members that configure the first filter portion  52   a ) to thereby form the second cardiotomy blood filter member  52  (refer to  FIG. 6 ). In this configuration, the second filter portion  52   b  is supported on the bottom member  322 , and is formed into a projecting shape on an upstream side with reference to the inflow of blood (refer to  FIG. 5 ). 
     When the second cardiotomy blood filter member  52  is disposed between the frame  122  and the filter retaining member  222 , and the bottom member  322  is mounted onto the lower portion of the filter retaining member  222 , the second filter portion  52   b  is folded towards an inner surface of the first filter portion  52   a  on the connecting member  52   c  (press fitted portion or welded portion) with the first filter portion  52   a  (refer to  FIG. 5  and  FIG. 7 ). Consequently, the second filter portion  52   b  is supported on the support portion  322   a  of the bottom member  322 . Thus, the second filter portion  52   b  is maintained in a projecting shape on the upstream side in the direction of the inflow of blood in the housing  10 . In this configuration, when cardiotomy blood passes through the second filter portion  52   b , the cardiotomy blood passes through the passage  322   b  of the bottom member  322 . 
     The second filter portion  52   b  has a different specification from the first filter portion  52   a . For example, the second filter portion  52   b  is formed from a material that has higher liquid permeation characteristics than the first filter portion  52   a . More specifically, the second filter portion  52   b  is formed from a mesh fabric (screen mesh). 
     The term “specification” as used herein includes at least any one of structure, material, property, or the like. Herein, an example of the term “specification” in relation to structure will be described. 
     When the cardiotomy blood passes through the second cardiotomy blood filter member  52 , foreign matter that could not be removed by the first cardiotomy blood filter member  51  is removed. Furthermore, at this time, bubbles that could not be removed by the first cardiotomy blood filter member  51  are removed from the cardiotomy blood. In other words, foreign matter and bubbles of a predetermined size that corresponds to the size of the cavities (minute holes) of the second cardiotomy blood filter member  52  are removed from the cardiotomy blood. For example, foreign matter and bubbles of at least 40 microns are removed from the cardiotomy blood as a result of the cardiotomy blood passing through the second cardiotomy blood filter member  52 . 
     As shown in  FIG. 5 , the guide member  60  is disposed between the cardiotomy blood filter means  50  and the blood outflow port  11   c , and is a member that guides the blood that has been filtered by the cardiotomy blood filter means  50  towards the blood outflow port  11   c . More specifically, as shown in  FIG. 4 , the guide member  60  is mounted on the second support member  22 , that is to say, on the bottom member  322 . Still more specifically, the guide member  60  is formed in a plate shape, and is inserted and mounted in an inner portion of the passage  322   b  of the bottom member  322 . 
     The guide member  60  is configured from a foam material compressed with respect to a direction of thickness. A material is used in the guide member  60 , the material has a density D that corresponds to the angle of inclination α of the bottom member  322 , for example, that corresponds to the angle of inclination α of the passage  322   b  of the bottom member  322 . For example, the guide member  60  is configured from a material that has a density D within a range of 0.12 g/cm 3  to 0.16 g/cm 3 . In this example, the guide member  60  is configured from a material that, has a density D of 0.13 g/cm 3 . 
     Foam urethane for example is used in the guide member  60 . More specifically, compressed foam urethane in which foam urethane has been compressed is used in the guide member  60 . The compressed foam urethane used in this example is a foam urethane having a thickness of 2 mm that is formed by compressing a foam urethane having a thickness of 10 mm. 
     For example, when commercially available foam urethane having a density of 26-30 kg/m 3  is compressed in the above manner, compressed foam urethane with a density of 0.13 to 0.15 g/cm 3  is obtained. 
     Generally, the spaces in the guide member  60  are reduced in size as the density D in the material configuring the guide member  60  increases. As a result, permeation of blood into the guide member  60  is hindered as a result of an increase in the density D of the material in the guide member  60 . In other words, when the density D of the material in the guide member  60  increases, blood tends to flow across the surface of the guide member  60  without permeating the guide member  60 . As a result, when the density D of the material in the guide member  60  increases, the speed of flow of blood through the guide member  60  tends to increase. Due to this reason, for example, it is desirable to dispose the guide member  60  so that the angle of inclination α of the guide member  60  is reduced as the density D of the material in the guide member  60  increases. 
       FIG. 5  shows an example in which the density D of the material in the guide member  60  is 0.13 g/cm 3 . However, due to the above reasons, when the angle of inclination a of the bottom member  322  is varied, it is desirable to vary the density D of the material. 
     As shown in  FIG. 8 , when the angle of inclination α is 70 degrees and over, it is desirable to use a porous material with a density D in the range of 0.02 g/cm 3  to 0.05 g/cm 3 . Furthermore, when the angle of inclination α is at least 65 degrees and less than 70 degrees, it is desirable to use a porous material with a density D in the range of 0.05 g/cm 3  to 0.20 g/cm 3 . Yet furthermore, when the angle of inclination α is less than 65 degrees, it is desirable to use a porous material with a density D in the range of 0.20 g/cm 3  to 0.40 g/cm 3 . 
     The blood storage features of the blood reservoir  1  will be described below. 
     When venous blood reaches the blood inflow port, that is to say, the first blood inflow portion  12   a , connected to the tube on the blood-extraction line for venous blood in the external blood recirculation path, the venous blood is guided into the housing  10  through the venous blood guide pipe  31 . Since the distal end of the venous blood guide pipe  31  (referred to above as the other end) extends into an inner portion of the protruding portion  11   b  of the housing  10 , the venous blood is guided into proximity with the bottom portion of the venous blood filter portion member  41 . In this manner, the venous blood commences to accumulate from the bottom portion upwardly in the inner portion of the venous blood filter member  41 . Thus, when the venous blood passes through the venous blood filter member  41 , bubbles contained in the venous blood are defoamed by the member  41 . In this manner, the venous blood is filtered by the venous blood filter member  41 , that is to say, by the venous blood filter means  40 , and is stored in the blood reservoir  1 . 
     When venous blood reaches the blood inflow port, that is to say, the second blood inflow portion  12   b , connected to the tube on the blood-extraction line for cardiotomy blood in the external blood recirculation path, the cardiotomy blood is guided into the housing  10  through the cardiotomy blood guide pipe  32 . In this manner, the cardiotomy blood commences to accumulate in the first cardiotomy blood filter member  51 . Thus, when the cardiotomy blood passes through the first cardiotomy blood filter member  51 , relatively large foreign matter contained in the cardiotomy blood, for example, bone fragments, soft tissue fragments, and the like, are removed by this filter member. Furthermore, when the cardiotomy blood passes through the first cardiotomy blood filter member  51 , relative large bubbles contained in the cardiotomy blood are defoamed or broken by the filter member. 
     In this manner, cardiotomy blood passing through the first cardiotomy blood filter member  51  starts to accumulate in the second cardiotomy blood filter member  52 . When the cardiotomy blood passes through the second cardiotomy blood filter member  52 , foreign matter contained in the cardiotomy blood is removed by the second cardiotomy blood filter member  52 . Furthermore, when the cardiotomy blood passes through the second cardiotomy blood filter member  52 , bubbles contained in the cardiotomy blood are defoamed by this filter member. 
     More specifically, when the cardiotomy blood that has passed through the first cardiotomy blood filter member  51  commences to accumulate in the second cardiotomy blood filter member  52 , firstly foreign matter and bubbles contained in the cardiotomy blood are removed by the mesh fabric (first filter portion  52   a ) of the second cardiotomy blood filter member  52 . Then, when the blood processing capacity of the mesh fabric is reduced by blocking or the like, foreign matter and bubbles contained in the cardiotomy blood are removed by the non-woven fabric (second filter portion  52   b ) of the second cardiotomy blood filter member  52 . In this manner, the cardiotomy blood is filtered by the first cardiotomy blood filter member  51  and the second cardiotomy blood filter member  52 , that is to say, by the cardiotomy blood filter means  50 . 
     In this manner, the blood that has been filtered by the cardiotomy blood filter means  50  is guided towards the blood outflow port  11   c  by the guide member  60 . More specifically, the blood guided by the guide member  60  accumulates in the protruding portion  11   b  of the housing  10 . In this manner, the cardiotomy blood is filtered by the cardiotomy blood filter means  50 , and accumulated in the lower storage space Sb of the blood reservoir  1 . 
     The characteristics of the blood reservoir  1  will be described below. 
     In the present embodiment, the cardiotomy blood filter means  50  includes the second cardiotomy blood filter member  52 . In the second cardiotomy blood filter member  52 , the bottom portion (second filter portion  52   b ) is formed as a projecting shape with respect to the upstream side in the direction of blood inflow. In this manner, the blood processing capacity in the filter member can be improved. 
     Furthermore the second cardiotomy blood filter member  52  can be easily processed and manufactured by connection to the wall portion so that the bottom portion (second filter portion  52   b ) in the second cardiotomy blood filter member  52  can be folded inwardly towards the wall portion (first filter portion  52   a ) in the second cardiotomy blood filter member  52 . 
     In addition, the wall portion (first filter portion  52   a ) in the second cardiotomy blood filter member  52  is formed from a non-woven fabric. Furthermore, the bottom portion (second filter portion  52   b ) in the second cardiotomy blood filter member  52  is formed from mesh fabric. Consequently, when blood starts to flow into the inner portion of the second filter member, the blood mainly passes through the mesh fabric (bottom portion). Then when the blood processing capacity of the mesh fabric is reduced by blocking or the like, the blood starts to pass through the non-woven fabric (wall portion). In this manner, when the blood is mainly passing through the mesh fabric, foreign matter and bubbles can be removed from the blood at a high speed. Thereafter, when the blood is mainly passing through the non-woven fabric, although the blood processing capacity of the mesh fabric is reduced, foreign matter and bubbles can be stably removed from the blood. 
     In the present embodiment, the blood reservoir  1  includes the cardiotomy blood filter means  50 . The cardiotomy blood filter means  50  includes the second cardiotomy blood filter member  52 . Thus the blood reservoir  1  according to the present embodiment obtains the same effect as the effect of the second cardiotomy blood filter member  52 . In this manner, medical personnel who manage the blood reservoir  1  can more accurately comprehend the blood storage amount accumulated in the blood reservoir  1 . 
     Modified Example 
     (a) In the above embodiment, although an example was described in which cardiotomy blood was filtered by the cardiotomy blood filter means  50  in the blood reservoir  1 , the feature of filtering cardiotomy blood is not limited thereby, and may take any configuration. For example, the cardiotomy blood filter means  50  may be separated, and a cardiotomy reservoir may be additionally provided. The cardiotomy blood filter means  50  may be provided in such a cardiotomy reservoir. In this configuration, venous blood is filtered in the filter means (venous blood filter means  40 ) of the blood reservoir, and cardiotomy blood is filtered in the filter means (cardiotomy blood filter means  50 ) of the cardiotomy reservoir. In this manner, the same effect as the above embodiment is obtained even when blood is filtered in the blood reservoir  1  and the cardiotomy reservoir. 
     INDUSTRIAL APPLICABILITY 
     Use is possible in relation to a blood reservoir for storing venous blood and/or cardiotomy blood. 
     REFERENCE SIGNS LIST 
     
         
           1  BLOOD RESERVOIR 
           10  HOUSING 
           11   c  BLOOD OUTFLOW PORT 
           40  VENOUS BLOOD FILTER MEANS 
           41  VENOUS BLOOD FILTER MEMBER 
           50  CARDIOTOMY BLOOD FILTER MEANS 
           51  FIRST CARDIOTOMY BLOOD FILTER MEMBER 
           52  SECOND CARDIOTOMY BLOOD FILTER MEMBER 
           52   a  FIRST FILTER PORTION 
           52   b  SECOND FILTER PORTION 
           60  GUIDE MEMBER 
         α ANGLE OF INCLINATION