Blood components processing method

0001The present invention relates to a method for determining an interface during processing components of blood. In particular, some aspects of the invention relate to processing blood components through the use of centrifugal separation, filtration, and/or any other form of processing.

0002Whole blood consists of various liquid components and particle components. The liquid portion of blood is largely made up of plasma, and the particle components include red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes). While these constituents have similar densities, their average density relationship, in order of decreasing density, is as follows: red blood cells, white blood cells, platelets, and plasma. In terms of size, the particle constituents are related, in order of decreasing size, as follows: white blood cells, red blood cells, and platelets. Most current separation devices rely on density and size differences or surface chemistry characteristics to separate blood components.

0003Separation of certain blood components is often required for certain therapeutic treatments involving infusion of particular blood components into a patient. For example, in a number of treatments involving infusion of platelets, there is sometimes a desire to separate out at least some leukocytes and/or red blood cells before infusing a platelet-rich blood component collection into a patient.

0004For these and other reasons, there is a need to adopt approaches to processing components of blood.

0005<patcit id="pcit0001" dnum="US6039711A"><text>US 6,039,711</text></patcit> discloses a method for centrifuging blood in which the blood is centrifuged in an annular rotor comprising a diaphragm which may have pressure applied to it so as to remove the blood components from the rotor. A separate structure may be provided for controlling the flow of liquid out of the chamber.

0006<patcit id="pcit0002" dnum="WO0102037A"><text>WO 01/02037</text></patcit> also discloses an annular centrifuge chamber for use with ring type blood processing bags. Valves are used to control the flow of components from the separation bag to the component bag.

0007In the following description, certain aspects and embodiments of the present invention will become evident. It should be understood that the invention, in its broadest sense, could be practiced without having one or more features of these aspects and embodiments. It should also be understood that these aspects are merely exemplary.

0008The invention relates to a method of determining a location of at least one interface during processing of blood components, wherein the method comprises pumping at least some centrifugally separated blood components from a chamber, sensing pressure of the pumped blood components, and determining a location of at least one interface based on the sensed pressure, wherein the interface is associated with the pumped blood components. For example, the interface may be an interface between blood components and air, and/or an interface between differing blood components.

0009In another aspect, the method may further comprise passing blood components (e.g., filtered blood components) into at least one collection bag.

0010In a further aspect, the blood components in the chamber may be blood components of a buffy coat. Buffy coat blood components are generally blood components that result from a procedure where platelets and leukocytes along with some amount of red blood cells and plasma have been separated from whole blood. Alternatively, any other substance containing one or more blood components could be processed.

0011In some examples, whole blood may be processed in the method. For example, whole blood may be introduced into the chamber (e.g., from one/or more donors, and/or from one or more containers containing blood donated by one or more donors). In the processing of whole blood, any number of blood components may be centrifugally separated, filtered, and/or processed in any other way. For example, components of whole blood may be separated and pumped into separate, respective containers (optionally while being filtered via one or more filters).

0012In one more aspect, when blood components are pumped, the pumping may comprise reducing the volume of an interior of the chamber. For example, the method may comprise applying pressure to the chamber via hydraulic fluid.

0013In another aspect, the pumping may occur during rotation of a centrifuge rotor.

0014In yet another aspect, the method may comprise optically sensing pumped blood products, and controlling the pumping based on at least one of optically sensed information and sensed pressure. For example, the optically sensing may comprise optically sensing blood components in the chamber and/or optically sensing blood components in a tubing line (e.g., a tubing line in flow communication with a filter).

0015In another aspect, the method may further comprise causing at least one valving member on the centrifuge rotor to control flow of at least some of the blood components during rotation of the rotor. As mentioned above, the valving member may comprise a tubing clamp.

0016In a further aspect, the method may further comprise causing at least one sealing member on the centrifuge rotor to create a seal during rotation of the rotor. As mentioned above, the sealing member may comprise a tubing welder.

0017Aside from the structural and procedural arrangements set forth above, the invention could include a number of other arrangements such as those explained hereinafter. It is to be understood that both the foregoing description and the following description are exemplary only.

0018The accompanying drawings are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments and, together with the description, serve to explain some principles of the invention. In the drawings, <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> is a schematic cross-section view of an embodiment of a system ;</li><li><figref idref="f0002">Fig. 1A</figref> is a view similar to that of <figref idref="f0001">Fig. 1</figref> showing an alternate embodiment of the system;</li><li><figref idref="f0003">Fig. 1B</figref> is a top plan view of another alternative embodiment of the system;</li><li><figref idref="f0004">Fig. 2</figref> is a top plan view of a portion of an apparatus including a chamber and filter for use with the systems of <figref idref="f0001">Figs. 1</figref>,<figref idref="f0002">1A</figref>, and <figref idref="f0003">1B</figref>, wherein line I-I of <figref idref="f0004">Fig. 2</figref> represents the plane for the cross-section views of the chamber portion shown in <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">1A</figref>;</li><li><figref idref="f0005">Fig. 3</figref> is partially schematic view of an embodiment of an apparatus including the chamber and filter of <figref idref="f0004">Fig. 2</figref>;</li><li><figref idref="f0006">Fig. 4</figref> is an isometric view of a system including the apparatus of <figref idref="f0005">Fig. 3</figref>;</li><li><figref idref="f0007">Fig. 5</figref> is a graph showing pressure plotted over time in connection with an example involving the embodiment of <figref idref="f0003">Fig. 1B</figref>;</li><li><figref idref="f0008">Fig. 6</figref> is a top, partially schematic view of an alternative embodiment of a separation chamber;</li><li><figref idref="f0009">Fig. 7</figref> is a schematic view of an example of a controller communicating with various possible system components;</li><li><figref idref="f0010">Fig. 8</figref> is a schematic, partial cross-section view illustrating the configuration of a filter and separation chamber associated with the system embodiment of <figref idref="f0003">Fig. 1B</figref>;</li><li><figref idref="f0011">Fig. 8a</figref> is a schematic, partial cross-section view of an alternative filter configuration;</li><li><figref idref="f0011">Fig. 8b</figref> is a schematic, partial cross-section view of another alternative filter configuration;</li><li><figref idref="f0012">Fig. 9</figref> is a schematic view of a hydraulically operated pump and pressure sensor associated with the system embodiments of <figref idref="f0001 f0002 f0003">Figs. 1, 1A, and 1B</figref>;</li><li><figref idref="f0013">Fig. 10</figref> is a schematic view of an alternative embodiment of a system associated with a centrifuge;</li><li><figref idref="f0014">Fig. 11</figref> is a schematic view of an alternative embodiment of a system associated with a blood component expressor,</li><li><figref idref="f0014">fig. 12</figref> is a schematic view of an alternative embodiment of a system associated with a blood component expressor; and</li><li><figref idref="f0015">Fig. 13</figref> is a schematic view of an embodiment of a system configured to process whole blood.</li></ul>

0019Reference will now be made in detail to a few exemplary embodiments of the invention. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

0020<figref idref="f0001">Fig. 1</figref> shows an embodiment of a system for processing blood components. The system includes a centrifuge 34 in combination with an apparatus including a filter 31 and a chamber 4 in the form of a blood component separation bag having a ring shape. The centrifuge 34 has a rotor 1 including a first rotor portion defining a ring-shaped area 3 receiving the chamber 4 and a second rotor portion defining a center cavity 2 where the filter 31 and possibly also a collection container 33 (e.g., a bag used to contain blood components processed by the system) may be located during a blood component processing operation.

0021The chamber 4 has an interior 8 in which blood components are centrifugally separated during rotation of the rotor 34 about an axis of rotation X. As described in more detail below, at least some of the blood components centrifugally separated in the chamber 4 are passed via a tubing line 21 to a filter 31 where at least some of at least one blood component (e.g., leukocytes, platelets, and/or red blood cells) is filtered before passing the filtered blood component(s) to the collection container 33.

0022As described in more detail below, hydraulic fluid in a space 5 located beneath the chamber 4 exposes the chamber 4 to an external pressure that causes at least some centrifugally separated blood components to be pumped from the chamber 4. The centrifuge rotor 1 also has an inner lid 6 adapted to rotate along with a remainder of the rotor 1 and the separation chamber 4. The lid 6 is optionally configured to at least partially secure the chamber 4, for example, in a clamping fashion along a line 7 shown in <figref idref="f0004">Fig. 2</figref>. This may be an effective way to fix the position of the chamber 4 in the centrifuge rotor 1 and limit the stresses on the inner edge of the bag 1. The centrifuge lid 6 optionally defines a central opening 53 possibly allowing center cavity 2 to be accessible externally even when the inner lid 6 is in a closed position.

0023The centrifuge rotor 1 may include one or more supports 9, 10, 11 shown in <figref idref="f0003 f0004 f0006">Figs. 1B, 2, and 4</figref> (for example, three to five supports). (The view of <figref idref="f0001">Fig. 1</figref> shows only support 9.) Optionally, the supports extend wholly or partially in the center cavity 2 and thus may define the cavity 2. The above-mentioned clamping of the chamber 4 by the inner lid 6 may limit, through its greater contact area, the load on the inner edge of the chamber 4 and assist in preventing it from slipping over or being released in some other way from supports 8, 9, and 10 during centrifuge rotor rotation. As shown in <figref idref="f0003">Figs. 1B</figref> and <figref idref="f0004">2</figref>, e.g., the respective supports 9-11 are optionally somewhat asymmetric (e.g., about the rotational axis X), and may thus assist in defining the position of the chamber 4 and its associated tubes in the rotor 1 while holding the chamber 4 in position during centrifuging.

0024Each of the support members 9-11 may define a respective guide groove, such as groove 12 shown in <figref idref="f0001">Fig. 1</figref>, which is defined in support 9. The groove may be shaped to receive one or more different tubes passing blood components or other fluids in the system. One or more of the supports 9-11 may be configured so that the guide grooves may be selectively reduced (and/or increased) in size to clamp (and/or unclamp) tubing placed in the grooves, and thereby accomplish valving for regulating the flow of fluids in the apparatus. For example, a portion of the support 9 could be configured to move in a clamping/unclampling fashion in the direction of arrow 13 shown in <figref idref="f0001">Fig. 1</figref> so as to function as a clamp valve for tubing 21 in guide groove 12.

0025One or more of the supports 9-11 may be configured to weld and/or cut tubes extending in grooves defined in the supports 9-11. For example, electric power to perform welding via supports 9-11 may be passed to the supports 9-11 via an electrical contact between the rotor 34 and a centrifuge stand. Various different components of the centrifuge may also be supplied with power via contact(s). In the embodiment of <figref idref="f0001">Fig. 1</figref>, the electric power is conveyed via electrical slip ring connectors 14, 15 between the rotor and stand portions of the centrifuge, wherein connector 14 is a rotating part of the centrifuge and connector 15 is a secured par in the centrifuge stand. As shown in <figref idref="f0001">Fig. 1</figref>. the centrifuge 34 may include a centrifuge motor 16 coupled to the rotor 1 so as to rotate the rotor 1 about the axis of rotation X. For example, the motor 16 may be coupled to the centrifuge rotor 1 by a driving belt 47 disposed in operative communication with a motor driving pulley 48 and a centrifuge driving pulley 49. A centrifuge rotation bearing 50 may cooperate with a rotating guide 51.

0026As shown schematically in <figref idref="f0001">Fig. 1</figref>, both the collection container 33 and filter 31 may be received in the center cavity 2. The filter 31 may be disposed in the cavity 2 in any number of different fashions. In one example, shown in <figref idref="f0001">Fig. 1</figref>, the filter 31 may be arranged in the cavity 2 so that components passing through the filter flow in a direction facing generally toward the axis of rotation X. In the embodiment of <figref idref="f0002">Fig. 1A</figref>, the filter 31 is oriented to position a filter inlet 31 a above a filter outlet 31 b. Due to centrifugal forces generated during rotation of the rotor 1, substances flowing through the filter 31 of <figref idref="f0002">Fig. 1A</figref> may flow in a horizontal direction (as viewed in <figref idref="f0002">Fig. 1 A)</figref> as well as in the vertical direction.

0027As shown in <figref idref="f0002">Fig. 1A</figref>, the filter 31 is optionally disposed in a generally lateral orientation on a small ledge 32 extending into the cavity 2. A covering member such as inner lid 6 may be configured to contact and/or otherwise cover and hold filter 31 in place. For example, a projection 66 extending from the lid 6 and the ledge 32 may define a holder for the filter 31. Alternatively, the ledge 32 could be moved upwardly from the position shown in <figref idref="f0002">Fig. 1A</figref> and/or an inner part of the lid could extend slightly lower. In another alternative arrangement, the filter 31 may be positioned in the cavity 2 without being restrained, such as in the embodiment shown in <figref idref="f0001">Fig. 1</figref>.

0028<figref idref="f0003">Fig. 1B</figref> shows another embodiment including an alternative placement of filter 31. The filter 31 of <figref idref="f0003">Fig. 1B</figref> is positioned in a generally lateral orientation with the filter 31 being eccentric with respect to the axis of rotation X. In addition, the filter 31 of the embodiment of <figref idref="f0010">Fig. 8</figref> is offset slightly from the rotational axis X so that the axis X does not intersect an interior of the filter 31. The filter 31 is positioned so that substances flowing through the filter 31 flow in a direction 95 generally facing toward the axis of rotation X.

0029<figref idref="f0010">Fig. 8</figref> schematically shows an example of how the filter 31 of <figref idref="f0003">fig. 1B</figref> may be configured. (In- <figref idref="f0010">Fig. 8</figref>, the filter 31 and separation 4 are not drawn to scale.) As shown in that figure, the filter 31 has a filter inlet 31 a and a filter outlet 31 b at the respective ends of L-shaped tubing segments connected to a filter housing 31d defining an interior space containing a porous filtration medium 31c. The filter outlet 31 b is located above the filter inlet 31 a; and the filter inlet 31 a is located closer than both the filter outlet 31 b and filtration medium 31 c to the axis of rotation X. The filter housing 31d defines a filter housing inflow port 31e and a filter housing outflow port 31f above the inflow port 31e. The filter housing outflow port 31f is closer than the filter housing inflow port 31 e to the axis of rotation X. The filter housing outflow port 31f is also closer than the filtration medium 31c to the axis of rotation X.

0030In some examples, such as that of <figref idref="f0010">Fig. 8</figref>, the relative positioning of the filter inlet 31 a, filter outlet 31 b, housing inflow port 31 e, housing outflow port 31f, and/or medium 31 c, as well as the eccentric (and possibly also offset) positioning of the filter 31, may assist in clearing most (if not all) air from the interior of the filter, as compared to alternative filtering arrangements which might potentially cause air to be locket" therein.

0031<figref idref="f0011">Fig. 8a</figref> shows another example of a filter 31 that could be used in the system. As shown in that figure, filter outlet 31 b is located above filter inlet 31 a; and filter inlet 31 a is closer than both filter outlet 31 b and filtration medium 31c to the axis of rotation X. In this example, rather than having the L-shaped tubing segments shown in <figref idref="f0010">Fig. 8</figref>, filter housing 31d defines flow passages leading to and from filter outlet 31 b and filter inlet 31 a, respectively, such that filter housing outflow port 31 is located closer than both filter housing inflow port 31 e and medium 31 c to the axis of rotation x. In addition, outflow port 31f is above inflow port 31e.

0032<figref idref="f0011">Fig. 8b</figref> shows a further example of a filter 31 that could be used in the system. For this example, housing inflow port 31e and housing outflow port 31f are at substantially the same relative positions as filter inlet 31 a and filter outlet 31b, respectively. In contrast to the filter shown in <figref idref="f0011">Fig. 8a</figref>, filter housing outflow port 31f is closer than both filter housing inflow port 31e and filtration medium 31c to the axis of rotation X. In addition, the inlet 31a, inflow port 31e, outflow port 31f, and outlet 31 b are at substantially the same level. Further, filter outlet 31b is closer than both filter inlet 31a and filtration medium 31c to the axis of rotation X.

0033One feature in common with the filter examples of <figref idref="f0010">Fig. 8</figref>, <figref idref="f0011">8a, and 8b</figref> is that blood components flowing in an interior space containing filtration medium 31c flow in a direction 95 facing generally toward the axis of rotation X..

0034As partially shown in <figref idref="f0003">Fig. 1B</figref>, the filter 31 may be positioned at least partially in a slot 57 offset from the axis of rotation X. The slot 57 may be wholly or partially defined in lid 6. Alternatively, the slot 57 could be defined using a shelf, and projection similar to those shown in <figref idref="f0002">fig. 1A</figref>.

0035Although the embodiments of <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">1A</figref>, and <figref idref="f0003">1B</figref> show the filter positioned beneath the top surface of the rotor 34, the filter 31 could alternatively be arranged partially or completely above the rotor's top surface. In some alternate embodiments, the filter may even be positioned at a location that is not within the centrifugal field generated by rotation of the rotor 1.

0036In the embodiments of <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">1A</figref>, and <figref idref="f0003">1B</figref>, the portion of the centrifuge rotor defining the ring-shaped area 3 and the portion of the centrifuge rotor defining the center cavity 2 are positioned with respect to one another so that when the chamber 4 is received in the area 3 and the filter 31 is received in the cavity 2, the filter 31 is closer than the chamber interior 8 to the axis of rotation X, as schematically illustrated in <figref idref="f0010">Fig. 8</figref>. Such a positioning may avoid the filter 31 from being subjected to relatively high centrifugal forces while permitting substances being centrifugally separated in the chamber interior 8 to be subjected to such high forces. In some instances, it may be desired for such a reduced amount of centrifugal force to be applied to the filter 31. For example, in certain filter arrangements, exposure to relatively high centrifugal forces might cause certain potential problems associated with bursting of the filter housing, or perhaps negatively affect the filtration efficacy. For some filters, such as those that might not be significantly impacted by centrifugal forces, alternative positioning of the filter might be possible.

0037The filtration medium 31 c shown in <figref idref="f0002">Figs. 1A</figref>, <figref idref="f0010">8</figref>, <figref idref="f0011">8a, and 8b</figref> may be any form of porous medium, such as fibers combined together in a woven or unwoven form, loose fibers, foam, and/or one or more membranes, for example. The filtration medium 31 c may be configured to filter leukocytes, platelets, and/or red blood celts.

0038The filter 31 could be configured in any known form. In some embodiments, the filter 31 may be a leukoreduction filter configured to filter leukocytes from blood components including a concentration of platelets. One example of such a filter is the LRP6 leukoreduction filter marketed by the Pall Corporation of Glen Cove, New York. Another example is the Sepacell PLS-10A leukocyte reduction filter marketed by Baxter Healthcare Corp. of Deerfield, Illinois. A further example is the IMUGARD filter marketed by Terumo of Japan. It should be understood that other known leukoreduction filters could also be used and such filters optionally may be selected depending upon the process being undertaken.

0039As shown in <figref idref="f0003">Fig. 1B</figref>, the inner lid 6 includes one or more grooves 60 defined therein for receiving one or more tubing lines. A first tubing portion 21 a places the blood component separation chamber (not shown in <figref idref="f0003">Fig, 1B</figref>) and filter 31 in flow communication with one another. Tubing 21 is flow coupled to the outlet of filter 31. The tubing 21 includes a second tubing potion 21b coupled to an outlet of the filter 31 and extending in a direction facing generally away from the rotation axis X. The tubing 21 also includes a third downstream portion 21 c extending in a direction generally facing the axis of rotation X. The groove(s) 60 may be configured to receive at least some of the second and third tubing portions 21 band 21c.

0040In some embodiments, there may be lids (not shown) other than the lid 6 to account for a plurality of processes which may alternatively be performed by the system. As shown in <figref idref="f0003">Fig. 1B</figref>, the groove(s) 60 may be arranged to associate the tubing 21 with one or more other features of the embodiment. For example, the groove(s) 60 may be arranged to place the tubing 21 in cooperation/communication with the groove 12 of member 9 (and/or with an optical sensor 55 described below), among other things.

0041As shown in <figref idref="f0004">Fig. 2</figref>, the chamber 4 is optionally in the form of a bag defined by two sheets of a suitable plastic material (e.g., flexible and/or semi-rigid plastic material) joined together by circumferentially welding radially inner and outer edges 17 and 18. Between the welded edges 17 and 18, there is an open, ring-shaped chamber interior in which blood components are separated. The chamber 4 includes a central opening (e.g., aperture) 19 which primarily corresponds to the center cavity 2 opening. Such a structure may simplify access to the center cavity 2. The chamber 4 shown in <figref idref="f0004">Fig. 2</figref> has respective guide holes 109, 110, and 111 for receiving supports 9-11, respectively, and thus positioning the chamber 4 with respect to the supports 9-11. The bag material surrounding the guide holes 109, 110, and 111 may be welded to strengthen the material around the holes. The guide holes 109, 110, and 111 optionally have an asymmetric arrangement (about rotational axis X) that is like that of the optional asymmetric orientation, of the supports 9, 10, and 11 so as to facilitate orienting the chamber 4.

0042At least a portion of the chamber 4 may be formed of flexible and/or semi-rigid material so that the interior of the chamber 4 has a variable inner volume. For example, the chamber 4 may be formed of material permitting external pressure to be applied to the chamber so as to reduce the inner volume of the chamber 4. In some exemplary arrangements, the chamber 4 and possibly the other parts of the apparatus 100 may be formed of material comprising inert plastic.

0043The chamber 4 includes an inlet port 4a for passing blood components to the interior of the chamber 4 and an outlet port 4b for passing at least some centrifugally separated blood components from the chamber interior. Inflow tubing 20 and outflow tubing 21 are placed in flow communication with the ports 4a and 4b, respectively, on opposite facing sides of the chamber 4 via welded sleeve couplings 24. Each sleeve coupling 24 may be a securing part in the form of a short piece of tubing with a diagonally arranged flat securing collar which may be welded to the chamber 4, while permitting the respective tubing 20 and 21 to be welded to the coupling 24. Instead of being secured via such a sleeve coupling, the tubing could alternatively be secured to (and/or in) each respective welded edge, i.e. within welded edges 17 and 18.

0044An alternative embodiment of a chamber 4 is shown in <figref idref="f0008">Fig. 6</figref>, wherein, a sort of bay 75 is positioned at the outlet port leading to tube 21. This bay 75. is defined by a gradually tapered portion formed by weld portions 61 and 62 extending in a generally radial direction from the outlet port. (The chamber 4 shown in <figref idref="f0004">Fig. 2</figref> may have a similar bay.) This type of arrangement may enable platelets to be received in a relatively non-abrupt or otherwise non-disruptive process. This may enhance the quality of the harvested platelets.

0045Referring again to <figref idref="f0008">Fig. 6</figref>, an inlet area 65 in the region of an inlet port leading from tube 20 does not have a tapered portion defined by weld portions 63, 64. This configuration may alleviate any potential capture of platelets (or some other desired product) so as to permit platelets to be available for harvesting at the outlet area 75.

0046When the chamber 4 is formed in a ring shape, as shown in the drawings, the chamber 4 and at least certain aspects of the centrifuge 34 may be configured like the separation chambers and associated centrifuges disclosed in one or more of the following patent documents: <patcit id="pcit0003" dnum="WO8706857A"><text>WO 87/06857</text></patcit>, <patcit id="pcit0004" dnum="US5114396A"><text>US 5,114,396</text></patcit>, <patcit id="pcit0005" dnum="US5723050A"><text>US 5,723,050</text></patcit>, <patcit id="pcit0006" dnum="WO9730715A"><text>WO 97/30715</text></patcit>, and <patcit id="pcit0007" dnum="WO9835757A"><text>WO 98/35757</text></patcit>, for example. Many alternative arrangements are also possible.

0047Although the embodiments shown in the drawings include a separation chamber in the form of a ring-shaped bag, it should be understood that there are many alternative forms of separation chamber configurations that could be used. For example, the separation chamber could be in the form of a bag other than a ring-shaped bag. Alternatively, the separation chamber could be in other non-bag forms, such as, for example, in the form of one of the separation vessels disclosed in <patcit id="pcit0008" dnum="US6334842B"><text>U.S. Patent 6,334,842</text></patcit>.

0048In one alternative embodiment (not shown), a filter similar to (or identical to) filter 31 could be positioned in tubing 20 to filter at least some blood components (e.g., leukocytes, platelets, and/or red blood cells) from substances being passing into the chamber 4.

0049<figref idref="f0005">Fig. 3</figref> shows an embodiment of an apparatus 100 including the chamber 4 and filter 31 shown in <figref idref="f0004">Fig. 2</figref>. This exemplary apparatus 100 is in the form of a bag set for producing platelets from a buffy coat collection. The apparatus 100 further includes a bag 23 containing diluting solution, a solution tube 30, four connecting tubes 25-28 intended to be coupled (e.g., via welding) to respective bags containing previously prepared buffy coat products (not shown), and a multi-way connector 29 connecting the tubes 25-28 and 30 to the inflow tubing 20 coupled to the inlet port of chamber 4. From the chamber 4, the tubing 21 having filter 31 in-line is coupled to an inlet 33a of collection container 33, which is in the form of a bag. In an area where the solution tube 30 is coupled to the solution bag 23, there may be a blocking switch 45 (e.g., frangible member) capable of being placed in an open, flow-permitting position by bending the tube 30 and breaking open the connection so as to initiate the addition of diluting solution to bags (not shown in <figref idref="f0005">Fig. 3</figref>) connected to tubing lines 25-28. Before the blocking switch 45 is opened, solution tube 30 may be arranged in a guide groove 12 defined by one of the supports 9-11 so as to provide a clamp valve intended for controlling the addition of diluting fluid to buffy coat bags associated with lines 25-28

0050Although four connecting tubes 25-28 are shown in <figref idref="f0005">Fig. 3</figref>, any number of tubes may be used. For example, the number of connecting tubes may be between four and six or between four and eight.

0051The system embodiments of <figref idref="f0001 f0002 f0003">Figs. 1, 1A, and 1B</figref> include a pump configured to pump at least some centrifugally separated blood components from the chamber 4 to the filter 31, and those embodiments also include a pressure sensor configured to sense pressure of the pumped blood components. As shown schematically in <figref idref="f0012">Fig. 9</figref>, a pump 80 may include a hydraulic fluid flow passage 88 passing through centrifuge rotor 1. One end of the hydraulic fluid flow passage 88 is in flow communication with a portion of ring-shaped area 3 positioned beneath the chamber 4 and separated from the chamber 4 via a flexible membrane 22. Another end of the hydraulic fluid flow passage 88 is in flow communication with a hydraulic fluid pressurizer 84 including a piston movable in a hydraulic fluid cylinder via a driver motor 82 (e.g., a stepper motor that moves a lead screw). Optionally, a hydraulic fluid reservoir 86 and associated hydraulic fluid valve 90 may be used to introduce and/or remove hydraulic fluid to/from the hydraulic fluid flow passage 88.

0052In response to a control signal from a controller 68, the driver motor 82 drives the piston of pressurizer 84 so as to pressurize or depressurize hydraulic fluid in the flow passage 88 (e.g., depending on the direction of travel of the pressurizer piston). The pressurization of the hydraulic fluid causes pressure to be applied to the chamber 4 via the hydraulic fluid pressing against membrane 22. The pressure applied to the chamber 4 causes the interior volume of the chamber 4 to become reduced and thereby pump centrifugally separated blood components from the chamber 4. Increasing the pressure of the hydraulic fluid causes an increase in the flow rate of the blood components pumped from the chamber 4. Conversely, a decrease of the hydraulic fluid pressure causes a decrease (or halting) of the pumped flow of blood components from the chamber 4.

0053The pressure of the hydraulic fluid is related to the pressure of blood components being pumped from the chamber 4. As shown in <figref idref="f0012">Fig. 9</figref>, a pressure sensor 70 is configured to monitor the pressure of the hydraulic fluid in the hydraulic fluid flow passage 88. Due to the relationship between the pressure of the hydraulic fluid and the pressure of the pumped blood components, the hydraulic fluid pressure sensed by the pressure sensor 70 reflects the pressure of the blood components pumped from the chamber 4. In other words, the pressure sensed by the pressure sensor 70 of <figref idref="f0012">Fig. 9</figref> is essentially the same as (or at least proportional to) the pressure of-the pumped blood components.

0054The hydraulic fluid may be any suitable substance. For example, the hydraulic fluid may be a fluid having a density slightly greater than that of packed red blood cells. One example of such a substance is Glycol. The hydraulic fluid may alternatively comprise oil.

0055A number of different pumping and/or blood component pressure sensing arrangements other than those shown in <figref idref="f0012">Fig: 9</figref> are possible. For example, the amount of current needed to drive the driver motor 82 associated with the hydraulic fluid pressurizer 84 may indicate the pressure of both the hydraulic fluid and the blood components. In other examples, the pressure of the blood components could be sensed more directly (e.g., not via hydraulic fluid) using any type of pressure sensor.

0056The pump 80 may be controlled based at least partially on the pressure sensed by the pressure sensor 70. In the embodiment of <figref idref="f0012">Fig. 9</figref>, the controller 68 could be configured to control the driver motor 82 based at least partially on the pressure sensed by the pressure sensor 70. For example, the controller 68 could be configured such that the controller 68 calculates a difference between pressures sensed by the pressure sensor 70 in at least one time interval while blood components are pumped by the pump 80, determines when the calculated difference is at least a predetermined amount, and controls the pump 80 in response to at least the determination that the calculated difference is at least the predetermined amount. Such an arrangement could enable a feedback control of the pump 80, for example, when the pump is initially operated via a volume flow rate command.

0057As explained in more detail below, in a procedure attempting to collect a maximum number of platelets and a minimum number of white and red blood cells, the control of the pump 80 based at least partially on the sensed pressure may be used to stop the pumping of the blood components from the chamber 4 in response to an increased pressure reflecting that relatively viscous red blood cells are entering the filter 31 and causing an occlusion of flow through the filter 31.

0058The pressure sensed by the pressure sensor 70 enables a determination of the location of one or more interfaces associated with separated blood components being pumped from the chamber 4. For example, the pressure sensed by the pressure sensor 70 could indicate the location of an interface between blood components and air present in the system at the start-up of a blood component processing procedure. In such an example, an increase in pressure might reflect that an air-blood component interface is near (or at) a radially outward portion of a fluid flow path (e.g., in <figref idref="f0003">Fig. 1B</figref>, the location F₀). In another example, the pressure could provide an indication of the location of an interface between blood components having differing viscosities. For example, an increase of the pressure sensed by the pressure sensor 80 during the filtering of at least some blood components via the filter 31 could provide an indication that a blood component interface (e.g., between a first phase including primarily liquid (i.e., plasma and possibly one or more liquid additives) and platelets, and a second phase including primarily red blood cells and white blood cells) is located near (or at) the filter 31, and/or a particular location in the flow path leading to or from the filter 31, and/or a particular location in the chamber 4.

0059The pressure sensed by the pressure sensor 70 could reflect a "fingerprint" of the operation of the system. For example, the sensed pressure could reflect one or more of the following: a kinking of fluid flow lines; a leak (e.g., rupture) of the membrane 22, chamber 4, and/or flow path leading to and from the filter; an increased likelihood of platelet activation (e.g., a high pressure might reflect forcing of platelets through the filter 31); a defect and/or clogging associated with the filter 31; and/or a possible need for maintenance (e.g., an indication that the membrane 22 is worn).

0060The pressure sensed by the pressure sensor 70 could also be used to optimize (e.g., reduce) the time for processing (e.g., separation) of blood components. For example, when the pressure sensed by the pressure sensor 70 indicates a location of particular blood components, the pump 80 could be controlled to use differing flow rates for differing blood components (e.g., use a faster flow rate for pumping certain blood components, such as plasma).

0061In addition to pressure sensor 70, embodiments of the system may also include one or more optical sensors for optically sensing blood components, and the pumping of the blood components may also be controlled based on at least information sensed by the optical sensor(s). As shown schematically in <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">1A</figref>, a first optical sensor 52 is positioned in the centrifuge rotor 1 adjacent the chamber 4 to optically sense blood components in the chamber 4. (Although not shown in <figref idref="f0003">Fig. 1B</figref>, the embodiment of <figref idref="f0003">Fig. 1B</figref> also includes such a sensor.) In addition, as shown in <figref idref="f0003">Fig. 1B</figref>, the system also may include a second optical sensor 55 positioned to optically sense blood components flowing through the tubing line 21 at the second tubing portion 21b, located downstream from the filter 31.

0062The optical sensors could be configured in the form of any type of optical sensor used in association with blood components. One-example of an optical sensor may include a photocell. The first and second optical sensors 52 and 55 may be configured to detect a change of color of blood components. Such a change of color may be indicative of the location of an interface between differing blood component phases, such as an interface where one of the phases that defines the interface includes red blood cells.

0063The first optical sensor 52 may be located at a particular radial position on the centrifuge rotor 1 so as to sense when an interface has moved to that location in the chamber 4. For example, the pumping of blood components from the chamber 4 could be slowed 9 (e.g., via a reduction of hydraulic pressure with the arrangement of <figref idref="f0012">Fig. 9</figref>) in response to the first optical sensor 52 detecting an interface (e.g., an interface partially defined by red blood cells) approaching a radially inward location. Similarly, the second optical sensor 55 may detect the presence of an interface (e.g., an interface partially defined by red blood cells) along the flow path leading from the chamber 4. In some examples, the controller 68 could be configured so as to halt pumping of blood components from the chamber 4 in response to the second sensor 55 sensing an interface (e.g., an interface partially defined by red blood cells) and/or in response to a determination that the difference between pressures sensed by the pressure sensor 70 is at least a predetermined amount.

0064<figref idref="f0009">Fig. 7</figref> shows a schematic view of an example of the controller 68 that may be used to at least partially control certain features of the system. The controller 68 communicates with various system components. For example, the controller 68 could communicate with the pump 80, centrifuge motor 18, pressure sensor 70, first optical sensor 52, second optical sensor 55, valving structure 72 (e.g., the valves defined by supports 9, 10, 11), and a control panel 36. The controller 68 may be configured to cause rotation of the centrifuge rotor 1 during filtering of at least some blood components (e.g., leukocytes, platelets, and/or red blood cells) via the filter 31 received in the cavity 2. In some embodiments, this may enable centrifugal separation in the chamber 4 and filtering via the filter 31 to occur at least partially simultaneously in a somewhat on-line fashion, as compared to some other approaches where filtering takes place a period of time after initial centrifugal separation and removal of a separation chamber and possibly also a filter from a centrifuge rotor. Alternatively (or additionally), the controller 68 may be configured so that filtering via the filter 31 takes place at least some time after at least an initial separation of blood components in the chamber 4.

0065The controller 68 may control the rotational speed of the rotor 1. In addition, the controller 68 may control the pump 80 and/or valving structure 72 to control the pumping of substances flowing to and from the chamber 4 and the filter 31. The controller 68 may include a processor having programmed instructions provided by a ROM and/or RAM, as is commonly known in the art. Although a single controller 68 having multiple operations is schematically depicted in the embodiment shown in <figref idref="f0009">Fig. 7</figref>, the controlling may be accomplished by any number of individual controllers, each for performing a single function or a number of functions.

0066The controller 68 may be configured to pump hydraulic fluid at a specified flow rate. This flow rate may cause a blood component flow rate with a resultant pressure. The controller 68 may then take readings from the pressure sensor 70 and change the flow rate based on those reading so to control flow rate as a function of pressure measured.

0067A number of different pumping and/or blood component pressure sensing arrangements other than those shown in <figref idref="f0012">Fig. 9</figref> are possible. In addition, there are a number of alternative ways in which the pumping of blood components from the chamber 4 could be controlled.

0068<figref idref="f0013">Fig. 10</figref> schematically illustrates an embodiment where blood components are pumped from chamber 4 via a pump 80 positioned downstream from the filter 31 at a location outside of the centrifugal field generated by rotation of centrifuge rotor 1. Such a pump 80 could be configured in the form of a peristaltic pump or any other type of pump suitable for pumping blood components.

0069As shown schematically in <figref idref="f0013">Fig. 10</figref>, the pressure sensor 70 could directly sense the pressure of pumped blood components (rather than via hydraulic fluid) from a location on the centrifuge rotor 1. Alternatively (or additionally) the pressure of the blood components could be sensed directly by a pressure sensor 70' located outside of the centrifugal field caused by rotation of the rotor 1. Similarly, a filter 31' In place of (or in addition to) filter 31 could be located at a location outside of the centrifugal field of the rotor 1. Additionally, the collection container 33 may be located outside of the centrifugal field. In a further modification, the system might be modified so that there is no filter.

0070In other embodiments, at least some structural features might not be part of a centrifuge structure. For example, <figref idref="f0014">Fig. 11</figref> schematically shows an embodiment in the form a blood component expressor including a pump 80 configured to pump blood components from a chamber 4. The pump 80 of <figref idref="f0014">Fig. 11</figref> includes a pair of clamping plates 92 and 94 that apply pressure to chamber 4 when a clamp driver 96 moves the clamping plates 92 and 94 together. A controller 68 controls the pump 80 based at least partially on pressure of pumped blood products sensed directly via the sensor 70. The chamber 4 could be a chamber that has been removed from a centrifuge rotor after blood components in the chamber 4 have been previously stratified in a centrifuging procedure.

0071<figref idref="f0014">Fig. 12</figref> schematically shows an embodiment similar to that of <figref idref="f0014">Fig. 11</figref>, but substituting a pump 80 like that shown in <figref idref="f0013">Fig. 10</figref>.

0072The following provides a discussion of an exemplary blood processing method that could be practiced using the system embodiments shown in <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">1A</figref>, <figref idref="f0003">1B</figref>, <figref idref="f0004 f0005 f0006 f0008 f0009 f0010 f0011 f0012">2-4, and 6-9</figref>. Although the exemplary method is discussed in connection with the structure shown in those figures, it should be understood that the exemplary method could be practiced using alternative structure. (in addition, the structure shown in those figures could be used in alternative methods.)

0073<figref idref="f0006">Fig. 4</figref> shows certain components of the apparatus shown in <figref idref="f0005">Fig. 3</figref>, but some of those components are drawn to a smaller scale or are not visible in <figref idref="f0006">Fig. 4</figref>. As shown in <figref idref="f0006">Fig. 4</figref>, centrifuge 34 is shown standing with its outer lid 35 completely open and locked in that position. The centrifuge inner lid 6 (see <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">1A</figref>) has been omitted to show other parts more clearly. Also, the centrifuge rotor 1 and chamber 4 have, to a certain extent, been drawn in a simplified manner. The centrifuge control panel 36 is also shown schematically.

0074<figref idref="f0006">Fig. 4</figref> illustrates four blood bags 37-40 containing buffy coat suspended in a cassette 41, which is mounted on the inside of the centrifuge outer lid 35. Buffy coat bags 37-40 have individual output lines connected by sterile welding to tube connectors 25-28 (see <figref idref="f0005">Fig. 3</figref>). The fluid content of the bags is introduced into the chamber 4 via the tubes 25-28 and connecting tube 20. After (or before) that, the buffy coat bags 37-40 may be supplied with washing fluid and/or diluting solution from diluting solution bag 23 suspended from a holder 44. The diluting solution contained in the bag 23 may be plasma or any other standard diluting solution. An example of a conventional diluting solution is a PAS (platelet additive solution), such as, e.g., T-Sol. Diluting solution bag 23 is suspended sufficiently high above bags 37-40 to allow the diluting solution to be added in sufficient amounts to these bags as soon as blocking switch 45 in tube 30 and a clamp valve in support 11, through which tube 30 is passed, are opened. Communication between bags 37-40 and chamber 4 proceeds via tube 20 which in turn passes through a clamp valve in support 10, for example, for controlling fluid communication. After the addition of diluting solution in sufficient amounts to bags 37-40, a motor (not shown) connected with the cassette 41 may be started and operated to move the cassette 41 back and forth in a curved pendulum movement 42 (or alternatively a complete (or substantially complete) rotational movement) until all the concentrate substance in the buffy coat bags 37-40 is resuspended.

0075Various arrangements may cause the agitation movement of the cassette 41. For example, the motor driving the cassette movement may be associated with a gear box, or there may be a crank function or control of the motor. It may also be theoretically possible to use a hydraulic motor, but it might have a slower shaking speed and longer mixing time.

0076Then, the built-in clamp valve in the support member 10 may be opened so as to cause flow of substantially all of the substance from the bags 37-40 to the chamber 4 via the tubing 20. The tube 20 in support 10 may then be sealed by sterile welding provided by the support 10 so as to block fluid communication through the tube 20, and thereafter (or substantially simultaneously therewith) the support 10 may cut the tube 20, so that the empty bags 37-40 and bag 23 with any possible solution and/or concentrates from the buffy coat diluting solution mixture may be disposed. If desired, the flushing out of the buffy coat bags 37-40 could be carried out in one, two, or several consecutive flushing operations. After flushing out the buffy coat bags, cassette 41 and holder 44 may then be removed from the centrifuge lid 35 and thereafter the centrifuge lid 35 may then be closed and a centrifuging operation may be carried out.

0077Before centrifuging, the chamber 4 is placed in the ring-shaped area 3 {see <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">1A</figref>) and the collection container 33 (see <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">1A</figref> and <figref idref="f0005">3</figref>) and filter 31 are placed in the center cavity 2 (see <figref idref="f0001 f0002 f0003">Figs. 1, 1A, and 1B</figref>). During centrifuging, the centrifuge rotor 1 is rotated about the axis of rotation X, thereby causing the blood platelet product to be separated from the other buffy coat components (e.g., red and white blood cells) in the chamber 4. Then, after (or in some embodiments, during) that separation, at least some of the platelet product may be pumped to the collection container 33 by increasing the pressure of hydraulic fluid passed into the ring-shaped area 3 under the membrane 22 shown in <figref idref="f0012">Fig. 9</figref>, and thereby applying external pressure to the chamber 4 that causes a reduction of the volume of an interior of the chamber 4. As is understood in the art, such a pressure applied by hydraulic fluid may occur during continued centrifugation (continued rotor spinning). It otherwise may be applied before rotor rotation has begun or even after rotation has halted.

0078The pumped blood components are removed from the chamber 4, optionally filtered by the filter 31, and then conveyed to collection container 33. As shown in <figref idref="f0003">Fig. 1B</figref>, arrows F show flow through portions of the filter 31 and the tubing line 21 (which passes through the second sensor 55 and support member 9) and thence into collection container 33. The flow path of material out of chamber 4 begins through first tubing portion 21 a upstream from filter 31. Flow through tubing portion 21 a emanates first from chamber 4, then travels through or near the axis of rotation X where the centrifugal forces are the lowest (zero or very near thereto) of any point in the system. The application of hydraulic pressure (and/or the centrifugal force) continues to then push the flow into the filter 31. As shown in <figref idref="f0003">Figs. 1B</figref> and <figref idref="f0010">8</figref>, the blood components may flow in an interior space of the filter housing 31 d in a direction 95 facing generally toward the axis of rotation X. After exiting the filter housing, the blood components flow in a direction generally facing away from the axis of rotation X, through the second tubing line portion 21 b, radially outwardly and through the second optical sensor 55. Then, the flow reaches its radially outermost point of travel, here indicated as point F₀, relative to the axis of rotation X. Flow then proceeds roughly inward via third tubing portion 21c, while passing through the support member 9, and the valving and/or sealing mechanism therein. The flow then proceeds to the container 33 disposed in the central cavity 2.

0079The filter 31 (e.g., a leukoreduction filter) may be configured to filter at least some undesired components. For example, where the desired product is platelets, the filter 31 may filter leukocytes and/or red blood cells. The filtration may occur substantially simultaneously with the removal (e.g., pumping) of components from the chamber. 4, and also may be performed at least partially during rotation of the centrifuge rotor 1.

0080The exemplary method further includes optical sensing of blood components via the first and second optical sensors 52 and 55. In the exemplary method, the flow rate at which blood components are pumped from the chamber 4 may be reduced when the first optical sensor 52 senses that an interface (e.g., an interface between desired lighter substance (e.g., platelets) and a darker non-desired concentrate product (e.g., red blood cells and/or leukocytes)) is approaching a radially inward location (e.g., a location at or near the tubing 21). For example, such a reduction of the flow rate might be achieved by reducing the hydraulic pressure applied to the membrane 22 shown in <figref idref="f0012">Fig. 9</figref>.

0081The pumping of blood components from the chamber 4 may be interrupted or halted when the second optical sensor 55 senses an interface (e,g., an interface defined at least partially by red blood cells).

0082The exemplary method also includes sensing the pressure of blood components pumped from the chamber 4. In the embodiment shown in <figref idref="f0012">Fig. 9</figref>, the pressure of the pumped blood components is sensed via sensing of the pressure of the hydraulic fluid used to pump the blood components from the chamber 4.

0083<figref idref="f0007">Fig. 5</figref> illustrates an exemplary graph showing pressure sensed by the pressure sensor 70 of <figref idref="f0012">Fig. 9</figref> relative to time during the processing of blood components in the exemplary method. Prior to a time T₀, there is relatively little (or no) sensed pressure because there is some initial time that may be dedicated to mere centrifugation/rotation of the centrifuge rotor 1 to effect the separation of the blood components into stratified layers before much hydraulic pressure is added to pump the blood products (in some alternative examples, pressure may be added sooner (or later) and perhaps even from the beginning of the rotation). At time T₀, the pressure of the hydraulic fluid is increased to begin pumping of blood components from the chamber 4. In some examples, the controller 68 could provide a relatively constant volume flow rate of hydraulic fluid, and, as described below, the hydraulic fluid flow could be altered based on sensed pressure feedback.

0084The initial pumping of blood components from the chamber 4 pushes an interface defined by the blood components and air initially present in the system at the beginning of the centrifugation. An increased amount of hydraulic pressure (and corresponding increase in pressure of the pumped blood components) occurs up until there is a peak of pressure P₁ at a time T₁. The pressure peak at time T₁ provides an indication that the air-blood component interface (e.g., interface between air and platelet rich plasma) has reached a particular location in the flow path defined by the system. For example, the pressure peak at time T₁ may represent that the air-blood component interface is located in the filter 31. Alternatively, the pressure peak at time T₁ may represent a form of "siphon" effect associated with pumping the air-blood component interface to the radially outermost flow path point F₀ shown in <figref idref="f0003">Fig. 1B</figref>. After reaching the point F₀. substances may encounter a bit of resistance due to centrifugal forces (which also contribute to keeping heavier phase materials at further radii from the axis of rotation) encountered when flowing back inwardly toward a lesser radius (which describes all points in the flow other than point F₀). Thus, a sort of back pressure may be built up.

0085After the air-blood component interface has been pumped past the location identified by the pressure peak at time T₁, the pressure reaches a reduced pressure level P₂ at time T₂. In a time period from T₂ to T₃, the pressure remains substantially constant at level P₂ while blood components (e.g., plasma, possible additive solution(s), and platelets) are pumped from the chamber 4, through the filter 31, and into the collection container 33. In the example represented by the graph of <figref idref="f0007">Fig. 5</figref>, the controller 68 has reduced the hydraulic pressure level to P₃ at time T₃ in response to the first optical sensor 52 sensing an interface defined at least partially by red blood cells in the chamber 4. The reduction of the hydraulic pressure causes a corresponding reduction of the pressure of the pumped blood components as well as a reduction of the flow rate of the pumped blood components (as compared to that in the time interval from T₂ to T₃). The reduction of the flow rate of the pumped blood components may reduce the likelihood that a substantial number of red and white blood cells will pass into the collection container 33. Additional flow rate reductions may also be possible for alternative

examples.

0086The sensed pressure remains relatively constant at pressure P₃ immediately after time T3 and then the sensed pressure increases somewhat rapidly. The increased pressure represents that an interface defined between a phase of relatively low viscosity blood components (e.g., primarily liquid (i.e., plasma and possible liquid additives)) and platelets) and a phase of relatively high viscosity blood components (e.g., primarily red blood cells and white blood cells) is beginning to enter the filter 31. The relatively high viscosity blood cells (e.g., red blood cells) are unable to pass through the filter 31 as easily as liquids and other relatively low-viscosity components. As the relatively viscous blood components continue to enter the filter 31, they become "packed" in the filter 31 and cause an increasing back pressure sensed by the pressure sensor 70.

0087The controller 68 receives signals indicative of the pressure sensed by the pressure sensor 70. In the exemplary time interval from T₃ to T₄, the controller 70 calculates the difference between maximum and minimum pressures sensed by the pressure sensor 70, and the controller 70 determines when that calculated difference exceeds a predetermined amount. Then, in response to such a determination, the controller 70 controls the system so as to cause a significant reduction of hydraulic pressure and corresponding halting or ending of the pumping of blood components from the chamber 4 (e.g., the piston of pressurizer 84 could be retracted and/or valve 90 shown in <figref idref="f0012">Fig. 9</figref> could be opened).

0088In the example shown in <figref idref="f0007">Fig. 5</figref>, at time T₄, the pressure reaches a peak at P₄ sufficient to cause a pressure difference ΔP (the difference between P₄ and P₃) indicating that the location of the interface defined by the viscous blood components has been pumped to (and possibly slightly beyond) the filter 31. In response to that pressure difference ΔP being determined by the controller 68, the controller 68 discontinues the pumping of blood components from the chamber 4 so that an excessive number of the viscous blood components will not be passed to the collection container 33. Accordingly, the pressure after T₄ reflects that hydraulic pressure is no longer applied to the chamber 4.

0089In some alternative examples, the system may be configured so that in response to a sufficient pressure difference, the pressure of the hydraulic flow may be altered (increased or decreased) to continue pumping of blood components at a different flow rate. This could, happen multiple times during a single processing procedure.

0090For the example shown in <figref idref="f0007">Fig. 5</figref>, the pressure difference ΔP may be about 0.2 bar. Many other differentials could be used depending on a number of factors.

0091The generally flat portions of the pressure diagram (e.g., between T₂ and T₃ or between T₃ and T₄) indicate that there are no significant discrete phases of blood components passing from the chamber 4. Those flat portions might be interpreted as an indication of a desired flow rate. Such a flow rate may be determined in advance of a blood processing procedure and used as a form of feedback control so that when the desired flow rate is reached (as measurable by a discrete sensor (not shown)), the pressure may be leveled as shown and maintained, before encountering a pressure difference indicating a possible condition where it might be desire to cease (or otherwise alter) hydraulic pressure.

0092In some instances, the actual level of relatively steady pressure sensing (e.g., e.g., between T₂ and T₃ or between T₃ and T₄) might not be the same or even nearly the same value from one run to another. Thus, the interpretation of the pressure difference may not be determined by any particular pressure point, but rather may be expressed as and/or be dependent upon a certain minimum change in pressure regardless of the starting or ending pressure level.

0093The sensing of the pressure to determine the location of interfaces between phases could be used even in some blood component processing procedures that do not include centrifugation separation and/or filtration. For example, in a procedure that includes centrifugation, but not filtration, the sensing of pressure might be used to determine when an interface reaches a radially outermost position (similar to the position F₀ shown in <figref idref="f0003">Fig. 1B</figref>.

0094After an identification of the location of a blood component interface via the pressure sensing and/or the optical sensing (e.g., whichever detects the interface first), there could be a time delay before the pumping of blood components from the chamber 4 is discontinued. For example, in a procedure where platelets are being collected, at least a slight time delay might maximize a platelet collection while presenting a relatively low risk of causing a significant number of red and white blood cells to be collected along with the platelets.

0095When the pumping of blood components has been discontinued, the tubing 21 may be clamped shut (via the optional clamp associated with one or more of supports 9-11) and possibly also sealed and cut via sterile welding supplied by one or more of the supports 9-11 (e.g., support 9). Thereafter, the chamber 4 containing non-desired concentrates of particular blood components (e.g., red blood cells, etc.), may be removed from the centrifuge and disposed.

0096Systems and methods in accordance with the invention may be used in the processing of whole blood. For example, <figref idref="f0015">Fig. 13</figref> schematically illustrates an embodiment of a system configured to process whole blood. As shown in that figure, whole blood from a whole blood source 100 (e.g., one/or more donors, and/or one or more containers containing blood donated by one or more donors) may be introduced into a chamber 4', which may be configured at least similar to the chamber 4 discussed above. For example, the chamber 4' may include a variable volume interior that may be reduced via hydraulic pressure so as to pump centrifugally separated blood components from the chamber 4'. As discussed in some of the above examples, alternative pumps may also be used. The pumping may optionally be controlled based on pressure sensing and/or optical sensing in a manner at least similar to that discussed above in connection with <figref idref="f0001">Figs. 1</figref>, <figref idref="f0002">1A</figref>, <figref idref="f0003">1B</figref>, <figref idref="f0007">5</figref>, <figref idref="f0009">7</figref>, and <figref idref="f0012 f0013 f0014">9-12</figref>.

0097The chamber 4' may include a single outlet or more than one outlet. In the example shown in <figref idref="f0015">Fig. 13</figref>, separate outlets may be associated with removal of particular blood components from the chamber 4'. In addition, a plurality of collection containers 33', 33", and 33"' may be respectively flow coupled to those outlets so as to collect separate blood components separated in the chamber 4'. For example, the collection container 33' may be used to collect a platelet product, collection container 33" may be used to collect a plasma product, and collection container 33"' may be used to collect a red blood cell product. One or more of the containers 33', 33", and 33"' may be either received in centrifuge rotor 1 or positioned at a location outside of the centrifugal field.

0098One or more of filters 31', 31", and 31"' may be associated with each of the respective flow paths leading from the chamber 4' to the containers 33', 33", and 33"'. The filters 31', 31", and 31"' may be configured at least similar to filter 31 discussed above. One or more of the filters 31', 31". and 31"' may either be received in a portion of the centrifuge rotor 1 or located outside of the centrifugal field. Although <figref idref="f0015">Fig. 13</figref> shows a separate, respective filter 31', 31", 31 "' associated with each of the flow paths leading from the chamber 4', many other arrangements are possible. For example, one or more of the filters 31', 31", and/or 31"' (e.g., filter 31 ") may be omitted, and/or the filter outlets may be coupled to more than one collection container, and/or a single filter may be used for multiple flow paths.

0099In the embodiment of <figref idref="f0015">Fig. 13</figref>, one or more controllable clamps associated with one or more the supports 9, 10, 11 may be used to control flow of substances to and/or from the chamber 4'. One or more welders associated with one or more of the supports 9, 10, and 11 may be used to seal tubing lines leading to the containers 33', 33", and 33"'. For example, such clamps and welders may be operated during rotation of the rotor 1.

0100In some alternative embodiments, other optional components, accessories and/or methods may be used in addition or in lieu of certain features described hereinabove. An example is a leukoreduction system, involving an LRS® chamber described in numerous publications including various U.S. and foreign patents (e.g., <patcit id="pcit0009" dnum="US5674173A"><text>US Pat. No. 5,674,173</text></patcit>., among others). Other potential accessory devices may include sampling devices of numerous types including, for example, bacteria screening devices referred to as Bact-T Alert® devices.

0101In addition, an adapted database associated with a barcode reader may be utilized to make all the blood products processed by the system directly traceable and that database may also contain all control criteria for feasible blood product processing stages of the system.

0102It will be apparent to those skilled in the art that various modifications and variations can be made to the structure and methodology described herein. Thus, it should be understood that the invention is not limited to the subject matter discussed in the specification. Rather, the present invention is intended to cover modifications and variations.