Abstract:
A kit for blood component processing comprising a fluid circuit into which blood is drawn, wherein the fluid circuit comprises a plurality of pathways; wherein the first pathway is configured to receive blood drawn from a blood source and leads to a separation device, wherein the separation device is configured to separate the blood into components; wherein the second pathway is configured to receive a first component from the separation device and transport at least a portion of the first component to a first processing device, wherein the first processing device may alter the first component to produce a first output; and wherein the third pathway is configured to receive a second component from the separation device and transport at least a portion of the second component to a second processing device, wherein the second processing device may alter the second component to produce a second output.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims the benefit of priority to U.S. Provisional Application Ser. No. 62/040,216, filed Aug. 21, 2014, the entire contents being incorporated herein by reference. 
     
    
     FIELD OF THE DISCLOSURE  
       [0002]    The present disclosure generally relates to fluid treatment systems and methods. More particularly, the present disclosure relates to systems and methods for separating blood into its constituents and subsequently treating the constituents. 
       BACKGROUND  
       [0003]    A variety of available blood processing systems allows for the collection and processing of particular blood components, rather than whole blood, from donors or patients. In the case of a blood donor, whole blood is drawn from the donor, a desired blood constituent isolated and collected, and the remaining blood components returned to the donor. By removing only particular constituents rather than whole blood, it takes the donor&#39;s body a shorter time period to recover to normal blood levels, thereby increasing the frequency with which the donor may donate blood. It is beneficial to increase in this manner the overall supply of blood constituents made available for health care, such as red blood cells (RBCs), leukocytes, plasma, and/or platelets, etc. 
         [0004]    In the case of a patient who requires blood therapy, for example due to blood disease, one or more blood components may be in need of treatment. Commonly treated blood components include RBCs, leukocytes, plasma, and/or platelets, etc. In such therapies, whole blood is drawn from the patient, the problematic blood component is separated and undergone a treatment phase, and the remaining blood components and treated blood component are both returned to the patient. The treatment phase of the problematic blood component can include retaining all or a portion of the component and substituting with a suitable replacement fluid, or selectively filtering out the pathogenic compounds from the blood component with or without providing a replacement fluid. 
         [0005]    Different disease states may implicate different components of blood. For example, two blood components commonly affected by various disease states include plasma and red blood cells. Examples of diseases that affect plasma and require plasma therapy include immune-mediated diseases, autoimmune diseases, neoplasia, infectious diseases, sepsis, cholesterolemia, organ transplant rejections, microcirculation disorders, and/or ischemic tissue damage, among many others. For a patient with a disease affecting plasma, the treatment phase of the problematic plasma can include retaining all or a portion of the plasma and substituting with a common replacement fluid such as saline, solution containing albumin, and/or donated fresh frozen plasma, or by selectively filtering out through adsorption the pathogenic compound associated with the disease state from the plasma and returning the pathogen-free plasma to the patient. In the case of selective filtration, a processing device, such as an adsorption device or column, can be used to filter out the pathogenic compound for different disease states. For example, low-density lipoprotein (LDL) and/or lipoprotein a (Lp(a)) may selectively be removed from the plasma in hypercholesterolemia cases; pathogenic antibodies removed in autoimmune disease or organ transplant rejection cases; and/or fibrinogen, fibrin, or C-reactive protein removed for microcirculation disorders or ischemic tissue damage cases. 
         [0006]    Examples of diseases that affect RBCs and require RBC replacement therapy include sickle cell disease, ABO-incompatible bone marrow transplant cases, multiple types of anemia, malaria, protozoal infections, and/or carbon monoxide poisoning, among other such diseases that affect the red blood cells. For a patient with a disease affecting red blood cells, the treatment phase of the problematic RBCs can be a RBC exchange procedure, which typically involves retaining a substantial portion of the RBCs and substituting with healthy RBCs originating from a donor. The replacement RBCs may join with the patient&#39;s non-RBC components (e.g., plasma, leukocytes, platelets, etc.) to re-enter the patient&#39;s bloodstream. The treatment phase of the problematic RBCs can also be a RBC depletion procedure, in which greatly elevated numbers of RBCs may be reduced by rapid removal of RBCs. RBC depletion may be appropriate for disease states such as polycythemia vera and iron overload, when it becomes necessary to reduce blood viscosity, RBC volume, and/or iron load. RBC depletion may also be accompanied by fluid substitution in which appropriate replacement fluids such as saline and/or albumin replace removed volume and therefore maintain fluid balance. 
         [0007]    The separation phase of blood components from whole blood typically takes place prior to the treatment of the problematic blood component and may be achieved through a spinning membrane or centrifugation, in which whole blood is passed through a centrifuge or membrane after it is withdrawn from the patient. To avoid contamination and possible infection of the patient, the blood is preferably contained within a sealed, sterile fluid flow system during the entire separation process. Typical blood processing systems thus may include a permanent, reusable hardware assembly containing the hardware (drive system, pumps, valve actuators, programmable controller, and the like) that pumps the blood, and a disposable, sealed and sterile fluid circuit that is mounted in cooperation on the hardware. In the case of separation via centrifugation, the hardware assembly includes a centrifuge that may engage and spin a separation chamber of the disposable fluid circuit during a blood separation step. The blood, however, may make actual contact only with the fluid circuit, which assembly may be used only once and then discarded. In the case of separation via a spinning membrane, a disposable single-use spinning membrane may be used in cooperation with the hardware assembly and disposable fluid circuit. 
         [0008]    In the case of separation via centrifugation, as the whole blood is spun by the centrifuge, the heavier (greater specific gravity) components, such as red blood cells, move radially outwardly away from the center of rotation toward the outer or “high-G” wall of the separation chamber of the fluid circuit. The lighter (lower specific gravity) components, such as plasma, migrate toward the inner or “low-G” wall of the separation chamber. Various ones of these components can be selectively removed from the whole blood by forming appropriately located channeling seals and outlet ports in the separation chamber of the fluid circuit. 
         [0009]    In the case of separation via a spinning membrane, whole blood may be spun within a disposable spinning membrane, rather than within a separation chamber of a fluid circuit. Larger molecules, such as red blood cells, may be retained within one side of the membrane, while the smaller molecules, such as plasma, may escape through the pores of the membrane to the other side of the membrane. Various ones of these components can be selectively removed from the whole blood by forming appropriately located outlet ports in the housing of the membrane column. Various types of columns with different pore sizes may be used, depending on the components to be separated. 
       SUMMARY  
       [0010]    According to an exemplary embodiment, the present disclosure is directed to a disposable kit for blood component processing. The kit may comprise a fluid circuit into which blood is drawn from a blood source, wherein the fluid circuit may comprise a first, second, and third pathway. The first pathway may be configured to receive blood drawn from the blood source and may lead to a separation device, wherein the separation device may be configured to separate the blood into two or more components. The second pathway may be configured to receive a first component from the separation device and may transport at least a portion of the first component to a first processing device, wherein the first processing device may be configured to alter the first component in at least one of volume, constitution, and composition, to produce a first output. The third pathway may be configured to receive a second component from the separation device and transport at least a portion of the second component to a second processing device, wherein the second processing device may be configured to alter the second component in at least one of volume, constitution, and composition, to produce a second output. 
         [0011]    According to an exemplary embodiment, the present disclosure is directed to a blood processing method comprising the step of receiving in a fluid circuit blood drawn from a blood source, wherein the fluid circuit may comprise a first, second, and third pathway. The blood processing method may also comprise the step of receiving in the first pathway blood drawn from the blood source, the first pathway leading to a separation device, wherein the separation device may be configured to separate the blood into two or more components. The blood processing method may also comprise the step of receiving in the second pathway a first component from the separation device, the second pathway transporting at least a portion of the first component to a first processing device, wherein the first processing device may be configured to alter the first component in at least one of volume, constitution, and composition, to produce a first output. The blood processing method may also comprise the step of receiving in the third pathway a second component from the separation device, the third pathway transporting at least a portion of the second component to a second processing device, wherein the second processing device may be configured to alter the second component in at least one of volume, constitution, and composition, to produce a second output. 
         [0012]    According to an exemplary embodiment, the present disclosure is directed to a disposable kit for blood component processing comprising a fluid circuit into which whole blood may be drawn from a blood source, wherein the fluid circuit may comprise a first, second, third, fourth, fifth, and sixth tubing. The first tubing may be configured to receive blood drawn from the blood source and may lead to a separation device, wherein the separation device may be configured to separate the whole blood into substantially cell-free plasma and cellular components. The second tubing may be configured to receive the substantially cell-free plasma from the separation device and transport at least a portion of the substantially cell-free plasma to a processing device, wherein the processing device may be configured to retain and/or filter all of the substantially cell-free plasma or a portion thereof. The third tubing may be configured to receive the cellular components from the separation device and transport at least a portion of the cellular components to a container in which at least a portion thereof is retained. The fourth tubing may be configured to receive a replacement fluid from a replacement fluid container. The fifth tubing may be configured to receive from the processing device fluid of the substantially cell-free plasma that is not retained by the processing device. The sixth tubing may be configured to receive fluid from the fourth tubing and fifth tubing and transport at least a portion thereof to the blood source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Features, aspects, and advantages of the present embodiments will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
           [0014]      FIG. 1  is a perspective view of a fluid processing system, according to an exemplary embodiment; 
           [0015]      FIG. 2  is a diagrammatic view of a disposable flow circuit that may be used in combination with the fluid processing system of  FIG. 1 , according to an exemplary embodiment; 
           [0016]      FIG. 3A  is an overall schematic diagrammatic view of flow pathways that may be taken by fluid and components within a flow circuit when fluid is separated by a centrifuge, according to an exemplary embodiment; 
           [0017]      FIG. 3B  is an overall schematic diagrammatic view of flow pathways that may be taken by fluid and components within a flow circuit when fluid is separated by a membrane, according to an exemplary embodiment; 
           [0018]      FIG. 3C  is an overall schematic diagrammatic view of flow pathways that may be taken by fluid and components within a flow circuit, according to an exemplary embodiment; 
           [0019]      FIG. 3D  is an overall schematic diagrammatic view of flow pathways that may be taken by fluid and components through a flow circuit and a patient, according to an exemplary embodiment; 
           [0020]      FIG. 4  is a side elevational view, with portions broken away and in section, of the fluid processing system of  FIG. 1 , with the centrifuge bowl and spool shown in an upright position for receiving a blood separation chamber, according to an exemplary embodiment; 
           [0021]      FIG. 5  is a top perspective view of the spool of the fluid processing system of  FIG. 4  in its upright position and carrying the blood separation chamber of the flow circuit of  FIG. 2 , according to an exemplary embodiment; 
           [0022]      FIG. 6  is a plan view of the blood separation chamber of  FIG. 5 , out of association with the spool, according to an exemplary embodiment; 
           [0023]      FIG. 6A  is a perspective view of a spinning membrane that may be used as the separation device in lieu of a centrifuge, according to an exemplary embodiment; 
           [0024]      FIG. 7  is an exploded perspective view of a fluid processing cassette of the flow circuit of  FIG. 2 , according to an exemplary embodiment; 
           [0025]      FIG. 8  is a perspective view of an underside of the fluid processing cassette of  FIG. 7 , according to an exemplary embodiment; and 
           [0026]      FIG. 9  is a perspective view of a cassette holder of the fluid processing system of  FIG. 1 , according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    There are several aspects of the present subject matter which may be embodied separately or together in the devices and systems described and claimed below. These aspects may be employed alone or in combination with other aspects of the subject matter described herein, and the description of these aspects together is not intended to preclude the use of these aspects separately or the claiming of such aspects separately or in different combinations as set forth in the claims appended hereto. 
         [0028]    Some embodiments may allow the simultaneous, parallel, or concurrent performance of differing component therapies for patients with diseases that affect more than one blood component or patients with multiple diseases that cumulatively affect more than one blood component. 
         [0029]    Some embodiments may obviate the practice of patients undergoing multiple component therapies (e.g., plasma and RBC therapies) in sequence and independently, with separate disposable fluid circuits and often separate machines. 
         [0030]    Some embodiments may shorten the time that it takes to complete an entire treatment and/or decrease the required number of disposable circuit kits. 
         [0031]    Some embodiments may decrease the number of patient needle insertions and/or extracorporeal circulations of patient blood. 
         [0032]    Simultaneous treatment of two different blood components may be implemented in some embodiments while maintaining the treatment phases of these blood components in separate and/or isolated pathways for the duration of treatment. Keeping these components in separate pathways while undergoing treatment within the same disposable fluid circuit kit may be achieved by some embodiments. 
         [0033]      FIG. 1  shows an exemplary fluid processing system  10  which may be suitable for use with a centrifuge  52  ( FIG. 4 ) or spinning membrane  35  ( FIG. 6A ) used in conjunction with a disposable fluid circuit  12 . The fluid processing system  10  may have one or more features of an apheresis device, such as a system marketed as the AMICUS® separator by Fenwal, Inc. of Lake Zurich, Ill., as described in greater detail in U.S. Pat. No. 5,868,696, which is hereby incorporated herein by reference in its entirety. The system  10  can be used for processing various fluids, including, but not limited to whole blood, blood components, or other suspensions of biological cellular materials. While improved fluid circuit pathways will be described herein with reference to exemplary system  10 , it should be understood that these principles may be employed with other fluid processing systems without departing from the scope of the present disclosure. 
         [0034]    The fluid processing system  10  is used in combination with a single-use or disposable flow circuit  12 , such as the one illustrated in  FIG. 2 , to form a separation system. The flow circuit  12  includes a variety of tubing or conduits and a number of other components, only some of which will be described herein in greater detail. The flow circuit  12  of  FIG. 2  is specially configured to be used in combination with the fluid processing system  10  of  FIG. 1 , but it should be understood that the flow circuit may be differently configured if the fluid processing system is differently configured from the embodiment of  FIG. 1 . 
         [0035]    The illustrated flow circuit  12  is a “two needle” system, which includes a pair of blood source access devices  14  and  14   a  (e.g., phlebotomy needles) for fluidly connecting a blood source (e.g., donor, patient, blood bag, etc.) with the flow circuit  12 . The blood source access devices  14  and  14   a  are connected by tubing to a left cassette  16 . A cassette may comprise a case made of plastic or other material configured to facilitate the flow of fluid therethrough. One of the blood source access devices  14  of the flow circuit  12  accesses blood from the blood source and is connected to the left cassette  16  by a y-connector  18 . The other leg of the y-connector  18  is connected to tubing  20  which leads to a middle cassette  16   a.  The tubing  20  is connected, through the middle cassette  16   a,  to additional tubing  22 , which includes a container access device  24  (e.g., a sharpened cannula or spike connector) for accessing the interior of an anticoagulant container (not illustrated). During a blood treatment operation, anticoagulant from the anticoagulant container may be added to the blood from the blood source at the y-connector  18  prior to entering the left cassette  16 . 
         [0036]    The other blood source access device  14   a  may be used to deliver or return blood, a blood component, and/or some other replacement fluid to the blood source and is also connected to the left cassette  16  by a y-connector  26 . The other leg of the y-connector  26  is connected to tubing  28  connected at its other end to a container access device  30 . Although not illustrated, the container access device  30  may be associated with a container having an amount of fluid (e.g., saline) to be used to prime the flow circuit  12  and/or be delivered to the blood source via the blood source access device  14  or  14   a.    
         [0037]    The left cassette  16  also includes tubing  32  which is connected to a blood separation chamber  34  of the flow circuit  12  (in a centrifugation system) or to a spinning membrane  35  (in a spinning membrane system) for flowing anticoagulated blood thereto. The blood separation chamber  34  or spinning membrane  35  separates the blood into its constituent parts and returns the blood components to other portions of the flow circuit  12 . In one embodiment, cellular blood components, such as RBCs, are returned to a right cassette  16   b  of the flow circuit  12  from the blood separation chamber  34  or spinning membrane  35  via tubing  36  and y-connector  37 , while substantially cell-free plasma is returned to the same right cassette  16   b  of the flow circuit  12  from the blood separation chamber  34  or spinning membrane  35  via tubing  38 . The cellular blood components may be pumped through right cassette  16   b  to container  44 , via tubing  46 , where they are retained. The substantially cell-free plasma may be pumped through the right cassette  16   b  and into tubing  42 , which may lead to a processing device  43  that selectively filters out designated pathogenic compounds from the plasma and/or may retain a portion of the plasma volume. The processing device  43  may be a plasma reduction container, or any device such as a column described in greater detail in International Publication No. WO 2012/141697 and U.S. Pat. No. 6,569,112, each of which is hereby incorporated by reference herein in its entirety, although any suitable processing device may be used. In the event that the treatment phase of plasma includes plasma reduction, substitution with a common replacement fluid such as saline or solution containing albumin or fresh frozen plasma drawn from container access devices  51  or  61  may be provided as part of the processing. 
         [0038]    As used throughout this disclosure, the term processing includes, for example, altering plasma volume, constitution, and/or composition. A volume alteration, for example, may comprise any change in the plasma volume before and after processing. Plasma reduction is one example of a volume alteration, in which the plasma volume before processing may be less than that after processing. Plasma reduction followed by substitution with a replacement fluid is an example of an alteration in constitution and/or composition, in which the plasma subsequent to processing may have a different constitution and/or composition from the plasma prior to processing. 
         [0039]    Although in the embodiment presented, both the cellular blood components and the substantially cell-free plasma are returned to the right cassette  16   b  of the flow circuit  12  via their respective tubings  36  and  38 , their pathways within the cassette  16   b  may remain separate and independent. This may be achieved by a predetermined layout of open and closed valves configured to provide separate and/or independent pathways within cassette  16   b.  Referring to  FIG. 2 , while the cellular blood components enter the right cassette  16   b  via tubing  36  and y-connector  37 , valves V 1  and V 2  of cassette  16   b  and valve V 7  of cassette  16   a  remain closed while valves V 6  and V 3  remain open, ensuring that the only pathway available for the cellular blood components is the pathway leading to container  44 . At the same time, while the substantially cell-free plasma enters the same right cassette  16   b  via tubing  38 , valves V 9 , V 5 , V 7 , V 1 , and V 2  remain closed while valves V 8 , V 10 , and V 4  remain open, ensuring that the only pathway available for the plasma is the pathway leading to processing device  43  and/or container  45  via tubing  42 . While in this particular embodiment, a specific valve arrangement and cassette  16   b  are disclosed, a different cassette or cassettes and/or a different valve arrangement may serve a similar purpose. 
         [0040]    At a time point in close proximity to the retention of the cellular blood components in container  44 , donated healthy red blood cells or an appropriate replacement fluid such as saline or albumin, may be drawn by container access device  51  or container access device  61 . In an embodiment in which the healthy RBCs or appropriate replacement fluid are drawn by container access device  51 , the donated RBCs or replacement fluid enters the middle cassette  16   a  via tubing  53  and are led by another predetermined layout of open and closed valves into tubing  40 , this time a layout in which valves V 7 , V 1 , V 2 , V 9 , and V 5  are closed, and valves V 8 , V 10 , and V 4  are open. Meanwhile, treated plasma that has not been retained by the processing device  43  and/or treated plasma that has been filtered through processing device  43  may enter tubing  47 . Both the healthy RBCs or replacement fluid from tubing  40  and the treated plasma from tubing  47  then may join pathways as treated whole blood at tubing  49  to jointly enter the left cassette  16 . While in this particular embodiment, a specific valve arrangement and cassette  16   a  are disclosed, a different cassette or cassettes and/or a different valve arrangement may serve a similar purpose. 
         [0041]    Inside the left cassette  16 , another predetermined layout of open and closed valves may ensure that the pathway of the treated whole blood back to the blood source remains separate and independent from the untreated whole blood that is entering the same left cassette  16  from tubing  15  and blood source access device  14 . In one embodiment, valves V 1 , V 2 , V 4 , V 5 , and V 9  remain closed while valves V 3 , V 6 , V 7 , V 8 , and V 10  remain open to provide two separate and independent pathways for outgoing treated and in-coming untreated whole blood. The treated whole blood may leave the left cassette  16  via tubing  15 a to blood source access device  14 a, where it may re-enter the blood source as healthy whole blood. 
         [0042]      FIGS. 3A and 3B  are overall schematic diagrams of one embodiment of the flow pathways of untreated whole blood, untreated plasma, untreated cellular blood component, donor RBCs or replacement fluid, treated plasma, and treated whole blood. For simplicity, only open valves are shown. While in this particular embodiment, a specific valve arrangement and cassette  16  are disclosed, it should be contemplated that a different cassette or cassettes and/or a different valve arrangement may serve a similar purpose. Referring to  FIGS. 3A and 3B , one of the blood source access devices  14  of the flow circuit  12  accesses blood from the blood source and is connected to the left cassette  16 . The other blood source access device  14   a  may be used to deliver or return blood, a blood component, and/or some other replacement fluid to the blood source and is also connected to the left cassette  16 . The left cassette  16  is connected to a blood separation chamber  34  of the flow circuit  12  (in a centrifugation system in  FIG. 3A ) or to a spinning membrane  35  (in a spinning membrane system in  FIG. 3B ) for flowing blood thereto. The blood separation chamber  34  or spinning membrane  35  separates the blood into its constituent parts. In one embodiment, cellular blood components, such as RBCs, are returned to a right cassette  16   b  of the flow circuit  12  from the blood separation chamber  34  or spinning membrane  35 , while substantially cell-free plasma is returned to the same right cassette  16   b  of the flow circuit  12  from the blood separation chamber  34  or spinning membrane  35 . The cellular blood components may be pumped through right cassette  16   b  to container  44 , where they may be retained. The substantially cell-free plasma may be pumped through the right cassette  16   b,  which may lead to a processing device  43  that selectively filters out designated pathogenic compounds from the plasma and/or may retain a portion of the plasma volume. In the event that the treatment phase of plasma includes plasma reduction, substitution with a common replacement fluid such as saline or solution containing albumin or fresh frozen plasma drawn from container access devices  51  may be provided. 
         [0043]    Although in the embodiment presented, both the cellular blood components and the substantially cell-free plasma are returned to the right cassette  16   b  of the flow circuit  12 , their pathways within the cassette  16   b  may remain separate and independent. This may be achieved by a predetermined layout of open and closed valves configured to provide separate and/or independent pathways within cassette  16   b.    
         [0044]    At a time point in close proximity to the retention of the cellular blood components in container  44 , donated healthy red blood cells or an appropriate replacement fluid such as saline or albumin, may be drawn by container access device  51 . The donated RBCs or replacement fluid enters the middle cassette  16   a.  Meanwhile, treated plasma that has not been retained by the processing device  43  and/or treated plasma that has been filtered through processing device  43  may join pathways with the healthy RBCs or replacement fluid. Both the healthy RBCs or replacement fluid and the treated plasma may jointly enter the left cassette  16  as treated whole blood. 
         [0045]    Inside the left cassette  16 , another predetermined layout of open and closed valves may ensure that the pathway of the treated whole blood back to the blood source remains separate and independent from the untreated whole blood that is entering the same left cassette  16  from tubing  15  and blood source access device  14 . The treated whole blood may leave the left cassette  16  to blood source access device  14   a,  where it may re-enter the blood source as healthy whole blood. 
         [0046]    Referring to  FIG. 3D , yet another embodiment is shown in which patient whole blood may be separated into components and undergo different therapies. The components may be plasma and red cells, as in the embodiment in  FIG. 3D . The components may be separated and treated. In this particular embodiment, RBC exchange takes place for the RBCs in one pathway, and a plasma treatment is executed in another pathway. The treated RBCs and the treated plasma then may join as treated whole blood back to the patient. 
         [0047]    As an alternative to an embodiment in which healthy RBCs or replacement fluid and treated plasma join pathways as treated whole blood, treated RBCs and treated plasma may separately be collected in respective containers  40   a  and  47   a,  as depicted in  FIG. 3C . Such an alternative may be suitable when treated blood components are needed for future use for the donor and/or another patient. 
         [0048]    Turning to the fluid processing system of  FIG. 4 , an embodiment is shown in which the separation method is centrifugation. However, it should be understood that the centrifuge components may be replaced with a spinning membrane and its accompanying hardware or other separation devices. An exemplary spinning membrane and hardware is disclosed in greater detail in PCT Patent Application No. PCT/US2012/28492, which is incorporated herein by reference in its entirety, although any suitable membrane assembly may be used. The fluid processing system  10  of  FIG. 4  includes a centrifuge  52  used to centrifugally separate blood components. An exemplary centrifuge is disclosed in U.S. Patent Application Publication No. 2014/0045671, which is incorporated herein by reference in its entirety, although any suitable centrifuge may be used. The centrifuge  52  comprises a bowl  54  and a spool  56 , which are pivoted on a yoke  58 . The centrifuge  52  is housed within the interior of the fluid processing system  10 , so a door  60  is provided to allow access to the centrifuge  52  for loading and unloading the blood separation chamber  34 . The door  60  remains closed during operation to protect and enclose the centrifuge  52 . 
         [0049]    When in a loading or unloading position, the spool  56  can be opened by movement at least partially out of the bowl  54 , as  FIG. 4  shows. In this position, the operator wraps the flexible blood separation chamber  34  about the spool  56  (see  FIG. 5 ). Closure of the spool  56  and bowl  54  encloses the chamber  34  for processing. 
         [0050]      FIG. 6  shows a representative embodiment of a blood separation chamber  34  which may be used in connection with a suitable centrifuge. The chamber  34  shown in  FIG. 6  allows for either single- or multi-stage processing. When used for multi-stage processing, a first stage  62  separates whole blood into first and second components. Depending on the nature of the separation procedure, one of the components may be transferred into a second stage  64  for further processing, although the present disclosure focuses on the first stage  62 . 
         [0051]    As  FIGS. 5 and 6  show, there may be three ports  66 ,  68 , and  70  associated with the first stage  62 . Depending on the particular blood processing procedure, the ports may have different functionality but, in one embodiment, the port identified at  70  may be used for conveying blood from a blood source into the first stage  62  via tubing  32  of the flow circuit  12 . The other two ports  66  and  68  may serve as outlet ports for passing separated blood components from the first stage  62  to the flow circuit  12  via tubing  36  and  38 , respectively. More particularly, the first outlet port  68  may convey a low density blood component from the first stage  62 , while the second outlet port  66  may convey a high density blood component from the first stage  62 . 
         [0052]    As best shown in  FIG. 5 , a tubing umbilicus  48  of the flow circuit  12  is attached to the ports  66 ,  68 ,  70 ,  72 , and  74 . The umbilicus  48  interconnects the first and second stages  62  and  64  with each other and with the components of the flow circuit  12  positioned outside of the centrifuge  52 . 
         [0053]    As  FIG. 6  shows, a first interior seal  82  is located between the low density or plasma outlet port  68  and the high density or red cell outlet port  66 . A second interior seal  84  is located between the high density outlet port  66  and the blood inlet port  70 . The interior seals  82  and  84  form a fluid path or passage  86  (an outlet for high density blood components) and a low density collection path or region  88 . The second seal  84  also forms a fluid passage  90 , which in this embodiment allows for a blood inlet. 
         [0054]    Blood entering the blood separation chamber  34  is pumped thereinto by one or more pumps  92  of the fluid processing system  10  ( FIGS. 1 and 2 ) acting upon one or more of the tubing loops  50  extending from the cassettes  16 - 16   b  of the flow circuit  12  ( FIG. 2 ). An exemplary cassette  16  is illustrated in greater detail in  FIGS. 7 and 8 , while the pumps  92  and associated cassette holder  94  are shown in greater detail in  FIG. 9 . 
         [0055]    Before beginning a given blood processing and collection procedure, the operator may load various components of the flow circuit  12  onto the sloped front panel  96  and centrifuge  52  of the centrifuge system  10 . The blood separation chamber  34  and the umbilicus  48  of the flow circuit  12  are loaded into the centrifuge  52 , with a portion of the umbilicus  48  extending outside of the interior of the fluid processing system  10 , as shown in  FIG. 4 . The sloped front panel  96  of the fluid processing system  10  includes at least one cassette holder  94  (three in the illustrated embodiment), each of which is configured to receive and grip an associated cassette  16 - 16   b  of the flow circuit  12 . 
         [0056]    Each cassette  16 - 16   b,  one of which is shown in  FIGS. 7 and 8 , may include an injection molded body  98  that is compartmentalized by an interior wall  100  ( FIG. 8 ) to present or form a topside  102  ( FIG. 7 ) and an underside  104  ( FIG. 8 ). For the purposes of description, the topside  102  is the side of the cassette  16  that, in use, faces away from the centrifuge system  10 , while the underside  104  faces towards the centrifuge system  10 . A flexible diaphragm  106  may overlie and peripherally seal the underside  104  of the cassette  16 . A generally rigid upper panel  108  may overlie the topside  102  of the cassette  16  and may be sealed peripherally and to the raised channel-defining walls in the cassette  16 . 
         [0057]    In one embodiment, the cassette  16 , the interior wall  100 , and the upper panel  108  may be made of a rigid medical grade plastic material, while the diaphragm  106  may be made of a flexible sheet of medical grade plastic. The upper panel  108  and the diaphragm  106  may be sealed about their peripheries to the peripheral edges of the top- and undersides  102 ,  104  of the cassette  16 , respectively. 
         [0058]    As shown in  FIGS. 7 and 8 , the top- and undersides  102 ,  104  of the cassette  16  contain preformed cavities. On the underside  104  of the cassette  16  ( FIG. 8 ), the cavities form an array of valve stations  110  and an array of pressure sensing stations  112 . On the topside  102  of the cassette  16  ( FIG. 7 ), the cavities form an array of channels or paths  114  for conveying liquids. The valve stations  110  communicate with the liquid paths  114  through the interior wall  100  to interconnect them in a predetermined manner. The sensing stations  112  also communicate with the liquid paths  114  through the interior wall  100  to sense pressures in selected regions. The number and arrangement of the liquid paths  114 , the valve stations  110 , and the sensing stations  112  can vary but, in the illustrated embodiment, the cassette  16  may provide nineteen liquid paths  114 , ten valve stations  110 , and four sensing stations  112 . 
         [0059]    The valve and sensing stations  110 ,  112  resemble shallow wells open on the cassette underside  104  ( FIG. 8 ). Upstanding edges  116  rise from the interior wall  100  and peripherally surround the valve and sensing stations  110 ,  112 . The valve stations  110  are closed by the interior wall  100  on the topside  102  of the cassette  16 , except that each valve station  110  includes a pair of through holes or ports  118  in the interior wall  100 . The ports  118  each open into selected different liquid paths  114  on the topside  102  of the cassette  16 . 
         [0060]    The sensing stations  112  are likewise closed by the interior wall  100  on the topside  102  of the cassette  16 , except that each sensing station  112  includes three through holes or ports  120  in the interior wall  100  ( FIG. 8 ). The ports  120  open into selected liquid paths  114  on the topside  102  of the cassette  16 . These ports  120  channel liquid flow among the selected liquid paths  114  through the associated sensing station  112 . 
         [0061]    In one embodiment, the flexible diaphragm  106  overlying the underside  104  of the cassette  16  is sealed by ultrasonic welding to the upstanding peripheral edges  116  of the valve and sensing stations  110 ,  112 . This isolates the valve stations  110  and sensing stations  112  from each other and the rest of the system. In an alternative embodiment, the flexible diaphragm  106  can be seated against the upstanding edges  116  by an external positive force applied by the cassette holder  94  against the diaphragm  106 . The positive force, like the ultrasonic weld, peripherally seals the valve and sensing stations  110 ,  112 . 
         [0062]    The localized application of additional positive force (referred to herein as a “closing force”) upon the intermediate region of the diaphragm  106  overlying a valve station  110  serves to flex the diaphragm  106  into the valve station  110 . Such closing force is provided by the cassette holder  94 . The diaphragm  106  seats against one of the ports  118  to seal the port  118 , which closes the valve station  110  to liquid flow. Upon removal of the closing force, fluid pressure within the valve station  110 , the application of a vacuum to the outer surface of the diaphragm  106 , and/or the plastic memory of the diaphragm  106  itself unseats the diaphragm  106  from the port  118 , opening the valve station  110  to liquid flow. 
         [0063]    Upstanding channel sides or edges  122  rise from the interior wall  100  to peripherally surround and define the liquid paths  114 , which are open on the topside  102  of the cassette  16 . The liquid paths  114  are closed by the interior wall  100  on the underside  104  of the cassette  16 , except for the ports  118 ,  120  of the valve and sensing stations  110 ,  112  ( FIG. 8 ). The rigid panel  108  overlying the topside  102  of the cassette  16  is sealed by ultrasonic welding to the upstanding peripheral edges  122 , sealing the liquid paths  114  from each other and the rest of the system. 
         [0064]    In the illustrated embodiment, ten pre-molded tube connectors  124  extend out along opposite side edges  126 ,  128  of each cassette  16 . The tube connectors  124  are arranged five on one side edge  126  and five on the other side edge  128 . The other side edges  130  of the cassette  16 , as illustrated, are free of tube connectors. The tube connectors  124  are associated with external tubing ( FIG. 2 ) to associate the cassettes  16  with the remainder of the flow circuit  12 , as described above. 
         [0065]    The tube connectors  124  communicate with various interior liquid paths  114 , which constitute the liquid paths of the cassette  16  through which a fluid enters or exits the cassette  16 . The remaining interior liquid paths  114  of the cassette  16  constitute branch paths that link the liquid paths  114  associated with the tube connectors  124  to each other through the valve stations  110  and sensing stations  112 . 
         [0066]    Turning now to the cassette holders  94  ( FIG. 9 ), each may receive and grip one of the cassettes  16 - 16   b  along the two opposed sides edges  130  in the desired operating position. The cassette holder  94  includes a pair of peristaltic pump stations  92 . When the cassette  16  is gripped by the cassette holder  94 , tubing loops  50  extending from the cassette  16  ( FIG. 2 ) make operative engagement with the pump stations  92 . The pump stations  92  are operated to cause fluid flow through the cassette  16 . 
         [0067]    The flexible diaphragm  106  covering the underside  104  of the cassette  16  is urged into intimate contact with a valve and sensor array or assembly  132  by the cassette holder  94 . The valve assembly  132  acts in concert with the valve stations  110  and sensing stations  112  of the cassette  16 . The valve assembly  132  illustrated in  FIG. 9  includes ten valve actuators  134  and four pressure sensing transducers  136 . The valve actuators  134  and the pressure sensing transducers  136  are mutually arranged in the same layout as the valve stations  110  and sensing stations  112  on the underside  104  of the cassette  16 . When the cassette  16  is gripped by the cassette holder  94 , the valve actuators  134  align with the cassette valve stations  110 . At the same time, the pressure sensing transducers  136  mutually align with the cassette sensing stations  112 . 
         [0068]    In one embodiment, each valve actuator  134  includes an electrically actuated solenoid pin or piston  138 . Each piston  138  is independently movable between an extended position and a retracted position. When in its extended position, the piston  138  presses against the region of the diaphragm  106  that overlies the associated valve station  110 . In this position, the piston  138  flexes the diaphragm  106  into the associated valve station  110 , thereby sealing the associated valve port  118 . This closes the valve station  110  to liquid flow. When in its retracted position, the piston  138  does not apply force against the diaphragm  106 . As before described, the plastic memory of the diaphragm  106  may be such that the removal of force is sufficient for the diaphragm to unseat from the valve port  118 , thereby opening the valve station  110  to liquid flow. Alternatively, a vacuum may be applied to the diaphragm  106 , for example by the vacuum port  140  illustrated in  FIG. 9 , to actively unseat the diaphragm  106  from the valve port  118 . 
         [0069]    The pressure sensing transducers  136  sense liquid pressures in the sensing stations  112  of the cassette  16 . The sensed pressures are transmitted to a controller of the centrifuge system  10  as part of its overall system monitoring function. If provided, the vacuum port  140  of the cassette holder  94  may provide suction to the diaphragm  106  of the cassette  16 , drawing it into close contact with the transducers  136  for more accurate pressure readings. 
         [0070]    The embodiments disclosed herein are for the purpose of providing a description of the present subject matter, and it is understood that the subject matter may be embodied in various other forms and combinations not shown in detail. While described with reference to a blood component processing device, the subject matter presented herein may be applied to other fluid processing devices and medical devices. In some embodiments, the teachings herein could be used on any medical device that involves the parallel processing or treatment of fluid components. Therefore, specific embodiments and features disclosed herein are not to be interpreted as limiting the subject matter as defined in the accompanying claims.