Abstract:
A blood reservoir may be used in combination with other elements such as a heart lung machine (HLM), oxygenator, heat exchanger, arterial filter and the like to form an extracorporeal blood circuit that may be employed in a procedure such as a bypass procedure. The blood reservoir may be configured to receive, filter and store blood from a number of sources including vent blood (from within the heart), venous blood (from a major vein), purge blood (from a sampling line) and cardiotomy or suction blood (from the surgical field).

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to European Patent Application 11173655.9, filed Jul. 12, 2011, of which is hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The present invention relates generally to blood reservoirs for oxygenators used in blood perfusion systems. 
       BACKGROUND 
       [0003]    Blood perfusion involves encouraging blood through the vessels of the body. For such purposes, blood perfusion systems typically include the use of one or more pumps in an extracorporeal circuit that is interconnected with the vascular system of a patient. Many surgical procedures require or prefer temporary cessation of the heart to create a still operating field. Such procedures may thus rely upon a cardiopulmonary bypass (CPB) perfusion system that temporarily replaces the function of the heart and lungs. Examples of such procedures include the surgical correction of vascular stenosis, valvular disorders, and congenital heart defects. In perfusion systems used for cardiopulmonary bypass surgery, an extracorporeal blood circuit is established that includes at least one pump and an oxygenation device to replace the functions of the heart and lungs, respectively. 
         [0004]    More specifically, in cardiopulmonary bypass procedures, oxygen-poor blood (i.e., venous blood) is gravity-drained or vacuum-suctioned from a large vein entering the heart or another major vein in the body (e.g., femoral) and is transferred through a venous line in the extracorporeal circuit. The venous blood is pumped to an oxygenator that provides for oxygen transfer to the blood. Oxygen may be introduced into the blood by, for example, transfer across a membrane. Concurrently, carbon dioxide is removed across the membrane. The oxygenated blood is filtered and then returned through an arterial line to the aorta, femoral, or other artery. 
         [0005]    In many cases, an extracorporeal blood circuit includes a blood reservoir that can be used to collect, filter and de-aerate blood from a variety of different sources. For example, a blood reservoir may receive one or more of venous blood from a large vein, vent blood that is collected within the heart and cardiotomy or suction blood that is collected from outside the heart but within the surgical field. 
       SUMMARY 
       [0006]    The present invention relates to a blood reservoir that may be used in combination with other elements such as a heart lung machine (HLM), oxygenator, heat exchanger, arterial filter and the like to form an extracorporeal blood circuit. The blood reservoir, as will be described in greater detail herein, may be configured to receive, filter and store blood from a number of sources including vent blood (from within the heart), venous blood (from a major vein), purge blood (from a sampling line) and cardiotomy or suction blood (from within the surgical field). Example 1 is a dual chamber blood reservoir including an activated section and a non-activated section. The non-activated, or clean, section includes an elongate filter and a foamer that is disposed about an upper region of the elongate filter. A purgers funnel extends downwardly through the cylindrical foamer and includes a conical upper portion, a cylindrical lower portion and an intervening central portion. A venous inlet tube extends downwardly through the cylindrical lower portion of the purgers funnel to a position that is proximate a bottom surface of the elongate filter. A vent inlet tube extends downwardly through an aperture formed within the central portion of the purgers funnel to a position that is proximate the bottom surface of the elongate filter. 
         [0007]    In Example 2, the dual chamber blood reservoir of Example 1 in which blood that exits the cylindrical lower portion of the purgers funnel is able to slide down the exterior surface of the venous inlet tube. 
         [0008]    In Example 3, the dual chamber blood reservoir of Example 1 or 2 in which the central portion of the purgers funnel includes a first aperture that is configured to accommodate the vent inlet tube passing therethrough. 
         [0009]    In Example 4, the dual chamber blood reservoir of any of Examples 1, 2 or 3, further including a second vent inlet tube that extends downwardly to a position that is proximate the bottom of the elongate filter. 
         [0010]    In Example 5, the dual chamber blood reservoir of Example 4, wherein the central portion of the purgers funnel includes a second aperture that is configured to accommodate the second vent inlet tube, the first and second apertures being radially spaced apart about 180 degrees. 
         [0011]    In Example 6, the dual chamber blood reservoir of any of Examples 1 to 5, further including a plurality of purge ports that are in fluid communication with the conical upper portion of the purgers funnel. 
         [0012]    In Example 7, the dual chamber blood reservoir of any of Examples 1 to 6 in which the activated section includes a suction blood filter assembly including a cylindrical suction blood filter and a defoamer layer that is disposed about the cylindrical suction blood filter. 
         [0013]    In Example 8, the dual chamber blood reservoir of any of Examples 1 to 7, further including a releasable barrier between the activated section and the non-activated section, the releasably barrier configured to be released to permit blood within the activated section to enter the non-activated section in a situation requiring additional blood. 
         [0014]    In Example 9, the dual chamber blood reservoir of Example 8, further including a porous media disposed to dissipate velocity in blood flowing from the activated section to the non-activated section. 
         [0015]    Example 10 is a dual chamber blood reservoir having a housing and a cover spanning the housing. A first vent port and a second vent port each extend through the cover. A venous port extends through the cover. A purgers port extends through the cover. The blood reservoir includes a purgers funnel that has an upper portion, a lower portion and an intervening central portion. The upper portion is in fluid communication with the purgers port. A first vent tube is in fluid communication with the first vent port and extends externally to the lower portion of the purgers funnel to a position near a lower surface of the housing. A second vent tube is in fluid communication with the second vent port and extends externally to the lower portion of the purgers funnel to a position near the lower surface of the housing. A venous tube is in fluid communication with the venous port and extends within the purgers funnel to a position near the lower surface of the housing. 
         [0016]    In Example 11, the dual chamber blood reservoir of Example 10 in which the first vent tube extends downwardly within the upper portion of the purgers funnel and passes to an exterior of the purgers funnel through a first aperture formed in the central portion of the purgers funnel. 
         [0017]    In Example 12, the dual chamber blood reservoir of Example 10 or 11 in which the first vent tube extends downwardly within the upper portion of the purgers funnel and passes to an exterior of the purgers funnel through a first aperture formed in the central portion of the purgers funnel. 
         [0018]    In Example 13, the dual chamber blood reservoir of any of Examples 10 to 12, further including an elongate filter disposed within the housing such that the vent tubes and the venous tube extend downwardly through the elongate filter. 
         [0019]    In Example 14, the dual chamber blood reservoir of Example 13 in which the elongate filter has a lower surface that is disposed near the lower surface of the housing. 
         [0020]    In Example 15, the dual chamber blood reservoir of any of Examples 10 to 14, further including a plurality of purgers ports that pass through the cover and that are in fluid communication the upper portion of the purgers funnel. 
         [0021]    Example 16 is a blood reservoir having a housing and a filtering assembly disposed within the housing. The housing has a top, a bottom, a venous inlet, a vent inlet and a purgers inlet. The filtering assembly extends from near the top of the housing to near the bottom of the housing. The filtering assembly includes a support structure, a filter membrane disposed about the support structure and a defoamer that is disposed about the filter membrane. The filtering assembly includes a purgers funnel that is in fluid communication with the purgers inlet and that extends downwardly within the filter membrane. The filtering assembly includes a venous tube that is in fluid communication with the venous inlet and that extends through an interior of the purgers funnel to a location near a bottom surface of the filtering assembly. The filtering assembly also includes a vent tube that is in fluid communication with the vent inlet and that extends partially through an interior of the purgers funnel and partially exterior to the purgers funnel to a location near the bottom surface of the filtering assembly. 
         [0022]    In Example 17, the blood reservoir of Example 16 in which the venous tube and the vent tube extend downwardly within an interior space of the filter membrane. 
         [0023]    In Example 18, the blood reservoir of Example 16 or 17 in which the purgers inlet includes a plurality of purgers ports. 
         [0024]    Example 19 is an extracorporeal blood circuit that includes a heart lung machine, an oxygenator, a sampling line downstream of the oxygenator and a blood reservoir. The blood reservoir includes a vent blood inlet, a venous blood inlet and a purgers port configured to accept blood from the sampling line. The blood reservoir is configured to accommodate blood from the sampling line without causing excessive gaseous microembolic activity within the blood from the sampling line. 
         [0025]    In Example 20, the extracorporeal blood circuit of Example 19 in which the blood reservoir includes a purgers funnel that is in fluid communication with the purgers port, with the venous blood inlet extending downwardly through an interior of the purgers funnel such that blood from the sampling line is permitted to flow downwardly along an exterior surface of the venous blood inlet. 
         [0026]    While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a schematic illustration of an extracorporeal blood circuit in accordance with an embodiment of the present invention. 
           [0028]      FIG. 2  is a partially cross-sectioned perspective view of a blood reservoir in accordance with an embodiment of the present invention. 
           [0029]      FIG. 3A  is a cross-sectional view of the blood reservoir of  FIG. 2 . 
           [0030]      FIG. 3B  is a partially cross-sectioned perspective view of a blood reservoir in accordance with an embodiment of the present invention. 
           [0031]      FIG. 3C  is a cross-sectional view of the blood reservoir of  FIG. 3B . 
           [0032]      FIG. 4  is a perspective view of a purgers funnel in accordance with an embodiment of the present invention. 
           [0033]      FIG. 5  is a perspective view of a filtering assembly in accordance with an embodiment of the present invention. 
           [0034]      FIG. 6  is a cross-sectional view of the filtering assembly of  FIG. 5 . 
           [0035]      FIG. 7  is a perspective view of a portion of the filtering assembly of  FIG. 5 . 
           [0036]      FIG. 8  is a perspective view of a filtering assembly in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0037]      FIG. 1  is a schematic illustration of an extracorporeal blood circuit  10 . As illustrated, the extracorporeal blood circuit  10  includes an HLM  12 , an oxygenator  14 , a sampling device  16  and a blood reservoir  18 . The HLM  12  is in fluid communication with a patient  20  and as such can receive blood from the patient  20  and moreover can return blood and other fluids to the patient  20 . The sampling device  16  may be a port or similar structure that permits blood to be withdrawn from the extracorporeal blood circuit  10  for lab work and/or additional testing done in the surgical arena. Blood in the sampling device  16  may flow into the blood reservoir  18  through a sampling line  22 . 
         [0038]      FIG. 2  is a partially cross-sectioned perspective view of a blood reservoir  24  that may be used as the blood reservoir  18  in the extracorporeal blood circuit  10  of  FIG. 1 . The blood reservoir  24  includes a clean (i.e., non-activated) section  26  and a dirty (i.e, activated) section  28 . In this, “clean” and “dirty” are relative terms pertaining to an expected level of solid particles or air bubbles within the blood entering each section. For example, vent blood and venous blood, which are usually fairly clean, may be processed within the non-activated section  26 , while suction blood, which tends to contain relatively more debris, may be processed within the activated section  28 . 
         [0039]    As shown in  FIG. 2 , the blood reservoir  24  includes a housing  30  and a cover  32 . A number of blood inlets, as will be described, extend through or are otherwise disposed within the cover  32 . The housing  30  includes a blood outlet  34  that may, in some embodiments, be in fluid communication with the HLM  12 . The housing  30  tapers to a bottom  46 . The cover  32  accommodates a venous inlet port  36 , one or more vent inlet ports  38  (only one is visible in this view) and a purgers inlet  40  having one or more purgers ports  42 . The cover  32  also accommodates a suction inlet  44 . In some embodiments, one or more of the venous inlet port  36 , the vent inlet port(s)  38 , the purgers inlet  40  or the suction inlet  44  may pass through the cover  32  such that they can rotate relative to the cover  32 . 
         [0040]    As shown, the non-activated section  26  includes a filtering assembly  48 , while the activated section  28  includes a filtering/defoaming assembly  50 .  FIG. 3A  is a cross-sectional view taken along line  3 - 3  of  FIG. 2  and provides greater detail pertaining to the filtering assembly  48  and the filtering/defoaming assembly  50 . The blood reservoir  24  includes a movable or releasable valve  52  that, when in place as illustrated, keeps blood within the activated section  28  from entering the non-activated section  26 . In some cases, there may be a need for more blood than is available from the non-activated section  26  and thus the valve  52  may be lifted, rotated or otherwise moved to permit blood to pass from the activated section  28  to the non-activated section  26 . 
         [0041]    In some embodiments, the housing  30  may include a shield  54  that directs blood from the activated section  28  towards the bottom  46 . The shield  54  may be shaped and positioned to minimize turbulence within the blood flow. While relative blood levels may vary during use in the non-activated section  26  and the activated section  28  (when the valve  52  is closed), in some embodiments, the blood level within the non-activated section  26 , indicated by a line  56 , may be relatively lower than the blood level within the activated section  28 , as indicated by a line  58 . In some embodiments, the blood level within the non-activated section  26  may instead be higher than the blood level within the activated section  28 . 
         [0042]    In the activated section  28 , the suction filtering/defoaming assembly  50  includes several components. Blood from the suction inlet  44  may pass into a collection funnel  60  and may then slide or otherwise flow down a diverter  62  that is configured to minimize turbulence in the blood flow. The blood then passes through a cylindrical filter  64  and a defoamer  66  that is disposed about the cylindrical filter  64 . Blood thus filtered then collects within the activated section  28 , where it is stored until it is either needed or subsequently discarded through an exit port  68 . 
         [0043]    In the non-activated section  26 , the filtering assembly  48  includes several components, not all of which are visible in  FIG. 3A . The filtering assembly  48  includes an elongate cylindrical filter  70  having a lower surface  72 . A venous inlet tube  74  that is in fluid communication with the venous inlet port  36  extends downwardly through an interior of the elongate cylindrical filter  70  and terminates at a position that is near the lower surface  72  of the elongate cylindrical filter  70 . A cylindrical defoamer  76  is disposed about an upper region of the elongate cylindrical filter  70 . 
         [0044]    The filtering assembly  48  also includes a purgers funnel  78  that extends downwardly through the cylindrical defoamer  76  and into the elongate cylindrical filter  70 . The purgers funnel  78  is in fluid communication with the purgers inlet  40 . The venous inlet tube  74  extends downwardly through the purgers funnel  78 . In some embodiments, the venous inlet tube  74  has an outer diameter that is less than an inner diameter of the purgers funnel  78  such that purgers blood collected within the purgers funnel  78  may exit the purgers funnel  78  by sliding down an exterior of the venous inlet tube  74 . In some embodiments, this reduces turbulence in the flow of purgers blood, thereby reducing or even eliminating the formation of gaseous microembolic activity in the purgers blood. In some embodiments, the purgers funnel  78  may include fingers (not shown) that form an interference fit with the exterior of the venous inlet tube  74  yet permit blood to flow down the exterior of the venous inlet tube  74 . In some embodiments, any entrained air within the blood in the non-activated section  26  may travel up into the cylindrical defoamer  76 . 
         [0045]      FIG. 3B  is a partially cross-sectioned perspective view blood reservoir  25  that may be used as the blood reservoir  18  in the extracorporeal blood circuit  10  of  FIG. 1 . In some embodiments, the blood reservoir  25  is similar in at least some constructional aspects to the blood reservoir  24 , and thus similar elements share reference numbers therebetween. The blood reservoir  25  includes a clean (i.e., non-activated) section  26  and a dirty (i.e, activated) section  28 . In this, “clean” and “dirty” are relative terms pertaining to an expected level of solid particles or air bubbles within the blood entering each section. For example, vent blood and venous blood, which are usually fairly clean, may be processed within the non-activated section  26 , while suction blood, which tends to contain relatively more debris, may be processed within the activated section  28 . 
         [0046]    As shown in  FIG. 3B , the blood reservoir  25  includes a housing  30  and a cover  32 . A number of blood inlets, as will be described, extend through or are otherwise disposed within the cover  32 . The housing  30  includes a blood outlet  34  that may, in some embodiments, be in fluid communication with the HLM  12 . The housing  30  tapers to a bottom  46 . The cover  32  accommodates a venous inlet port  36 , one or more vent inlet ports  38  (only one is visible in this view) and a purgers inlet  40  having one or more purgers ports  42 . The cover  32  also accommodates a suction inlet  44 . In some embodiments, one or more of the venous inlet port  36 , the vent inlet port(s)  38 , the purgers inlet  40  or the suction inlet  44  may pass through the cover  32  such that they can rotate relative to the cover  32 . As shown, the non-activated section  26  includes a filtering assembly  48 , while the activated section  28  includes a filtering/defoaming assembly  50 . 
         [0047]      FIG. 3C  is a cross-sectional view taken along line  3 ′- 3 ′ of  FIG. 3B  and provides greater detail pertaining to the filtering assembly  48  and the filtering/defoaming assembly  50 . The blood reservoir  25  includes a movable or releasable valve  52  that, when in place as illustrated, keeps blood within the activated section  28  from entering the non-activated section  26 . In some cases, there may be a need for more blood than is available from the non-activated section  26  and thus the valve  52  may be lifted, rotated or otherwise moved to permit blood to pass from the activated section  28  to the non-activated section  26 . 
         [0048]    In some embodiments, the housing  30  may include a shield  55  that directs blood from the activated section  28  towards the bottom  46 . The shield  55  may be shaped and positioned to minimize turbulence within the blood flow. In some embodiments, as illustrated, the shield  55  may include a frame portion  57  and a porous media portion  59 . The frame portion  57  supports the porous media portion  59  and helps to anchor the shield  55  within the housing  30 . The porous media portion  59  slows blood passing through the shield  55 . 
         [0049]    While relative blood levels may vary during use in the non-activated section  26  and the activated section  28  (when the barrier  52  is closed), in some embodiments, the blood level within the non-activated section  26 , indicated by a line  56 , may be relatively lower than the blood level within the activated section  28 , as indicated by a line  58 . In some embodiments, the blood level within the non-activated section  26  may instead be higher than the blood level within the activated section  28 . 
         [0050]    In the activated section  28 , the suction filtering/defoaming assembly  50  includes several components. Blood from the suction inlet  44  may pass into a collection funnel  60  and may then slide or otherwise flow down a diverter  62  that is configured to minimize turbulence in the blood flow. The blood then passes through a cylindrical filter  64  and a defoamer  66  that is disposed about the cylindrical filter  64 . Blood thus filtered then collects within the activated section  28 , where it is stored until it is either needed or subsequently discarded through an exit port  68 . In some embodiments, blood stored within the activated section  28  may be released into the non-activated section  26  by opening the valve  52 . 
         [0051]    In the non-activated section  26 , the filtering assembly  48  includes several components, not all of which are visible in  FIG. 3A . The filtering assembly  48  includes an elongate cylindrical filter  70  having a lower surface  72 . A venous inlet tube  74  that is in fluid communication with the venous inlet port  36  extends downwardly through an interior of the elongate cylindrical filter  70  and terminates at a position that is near the lower surface  72  of the elongate cylindrical filter  70 . A cylindrical defoamer  76  is disposed about an upper region of the elongate cylindrical filter  70 . 
         [0052]    The filtering assembly  48  also includes a purgers funnel  78  that extends downwardly through the cylindrical defoamer  76  and into the elongate cylindrical filter  70 . The purgers funnel  78  is in fluid communication with the purgers inlet  40 . The venous inlet tube  74  extends downwardly through the purgers funnel  78 . In some embodiments, the venous inlet tube  74  has an outer diameter that is less than an inner diameter of the purgers funnel  78  such that purgers blood collected within the purgers funnel  78  may exit the purgers funnel  78  by sliding down an exterior of the venous inlet tube  74 . In some embodiments, this reduces turbulence in the flow of purgers blood, thereby reducing or even eliminating the formation of gaseous microembolic activity in the purgers blood. In some embodiments, the purgers funnel  78  may include fingers (not shown) that form an interference fit with the exterior of the venous inlet tube  74  yet permit blood to flow down the exterior of the venous inlet tube  74 . In some embodiments, any entrained air within the blood in the non-activated section  26  may travel up into the cylindrical defoamer  76 . 
         [0053]      FIG. 4  is a perspective view of an embodiment of the purgers funnel  78 . In the illustrated embodiment, the purgers funnel  78  includes an upper portion  80 , a lower portion  82  and a tapered central portion  84  between the upper portion  80  and the lower portion  82 . In some embodiments, the upper portion  80  may be conical or otherwise tapered in shape. In some cases, the lower portion  82  may be cylindrical in shape. In the illustrated embodiment, the central portion  84  of the purgers funnel  78  includes a first aperture  86  and a second aperture  88 . The first aperture  86  and the second aperture  88  may be configured to permit first and second vent tubes (illustrated in a subsequent Figure) to pass therethrough. In some embodiments, the first aperture  86  and the second aperture  88  may be radially spaced about  180  degrees apart. 
         [0054]      FIG. 5  is a perspective view of the filtering assembly  48 . The filtering assembly  48  includes, as shown in  FIG. 3A , the elongate cylindrical filter  70  and the cylindrical defoamer  76 . The elongate cylindrical filter  70  includes a filter membrane  90  and a support structure  92 . As illustrated, the filter membrane  90  is disposed inside of the support structure  92 . In some embodiments, the filter membrane  90  may instead be disposed about the support structure  92 . The support structure  92  may provide sufficient support to the filter membrane  90  to hold the filter membrane  90  in a desired configuration against the fluid pressures to which the filter membrane  90  may be exposed during operation of the blood reservoir  24 . 
         [0055]      FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5  and illustrates a blood flow path for purgers blood. As indicated by arrows  94 , purge blood may enter the blood reservoir  24  through the purgers ports  42 . The purgers blood then travels down through the purgers funnel  78  as indicated by arrows  96 , and exits through a bottom  98  of the purgers funnel  78 . As indicated by arrows  100 , the blood then slides or otherwise flows down the exterior surface of the venous inlet tube  74 . 
         [0056]      FIG. 7  is a perspective view of a portion of the filtering assembly  48 , illustrating the venous inlet tube  74 , a first vent tube  102  and a second vent tube  104 . The venous inlet tube  74 , the first vent tube  102  and the second vent tube  104  extend downwardly from the cover  32  through an interior of the elongate cylindrical filter  70 . As shown in  FIG. 4 , the first vent tube  102  may pass through the first aperture  86  and the second vent tube  104  may pass through the second aperture  88 . The first vent tube  102  may be considered as extending within the purgers funnel  78  above the first aperture  86  but exterior to the purgers funnel  78  below the first aperture  86 . Similarly, the second vent tube  104  may be considered as extending within the purgers funnel  78  above the second aperture  88  but exterior to the purgers funnel  78  below the second aperture  88 . In some embodiments, the venous inlet tube  74 , the first vent tube  102  and the second vent tube  104  each extend downwardly to a position that is proximate or near to the lower surface  72  of the elongate cylindrical filter  70 . As a result, in some embodiments, turbulence and resulting blood cell damage may be reduced or eliminated. 
         [0057]      FIG. 8  is a perspective view of an embodiment of the filtering/defoaming assembly  50 . In some embodiments, the filtering/defoaming assembly  50  includes a plastic frame  150  that supports the filtering/defoaming assembly  50  and provides the filtering/defoaming assembly  50  with an annular or ovoid shape. A foam cylinder such as a polyurethane foam cylinder  152  is disposed within the plastic frame  150  and at least partially defines an internal sliding surface  154 . An outer surface of the foam cylinder  152  is at least partially wrapped in a polyester felt  156 . In some embodiments, the polyester felt  156  has a pore size of about 40 microns. 
         [0058]    Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the above described features.