the centrifuge 34 shown in fig1 has a rotor 1 with a central axis of rotation 100 , and a central chamber 2 , where , for example , the final storage , product collection or satellite bags for produced or collected separated products can be located during a centrifuging operation . the central chamber has an outer wall 61 and an inner wall 63 . the satellite bags , such as bag 33 in fig9 , are connected to a ring or annularly - shaped separation vessel 4 . furthermore , a ring or separation chamber 3 is included on the rotor 1 to receive ring or separation vessel 4 . in one embodiment of the present invention , the separation chamber 3 surrounds the central chamber 2 . the area beneath the ring or separation vessel 4 in the separation chamber 3 forms a chamber 5 . the chamber 5 can be filled with a hydraulic fluid with the purpose of applying pressure or squeezing the ring or separation vessel 4 . centrifuge rotor 1 further includes a rotating inner lid 6 which includes a securing portion 7 for the ring or separation vessel 4 . a sensor for sensing component movement is included at 52 . in fig1 , ring or separation vessel 4 is shown filled with fluid 8 which is a composite fluid or composite buffy coat ( as described below ) for separation . there are three supports 9 , 10 , and 11 on the centrifuge rotor 1 . of these , only support 9 is shown in fig1 , but see also fig8 . the supports 9 , 10 , and 11 locate the position of ring or separation vessel 4 and also provide guide grooves 12 , 21 and 22 , respectively , to secure different connecting tubes or tubing or conduits between the separation vessel 4 and the satellite or product collection bags as well as a tube , tubing or conduits from the diluting fluid or buffy coat composite fluid bags as will be described below . supports 9 , 10 , and 11 may be configured such that the guide grooves 12 , 21 and 22 may be selectively reduced and / or increased in size to clamp or unclamp tubing or connecting tubes placed in the grooves . for example , a portion of the support 9 could be configured to move in the direction of arrow 13 so as to function as a clamp valve . also , one or more of supports 9 , 10 , and 11 may be configured to provide a welding function , which , when activated , seals and cuts the tubes positioned in the guide grooves 12 , 21 and 22 . the welding function on the supports requires access to electric power in the centrifuge rotor and may also receive commands from a control system of the centrifuge . any electrical connection occurs through slip ring connectors between the rotor and centrifuge stand where 14 indicates the centrifuge &# 39 ; s rotor portion and 15 indicates the centrifuge stand . on fig1 , the centrifuge motor is marked as 16 . motor 16 rotates the centrifuge rotor through driving belt 47 ; driving belt 47 is located between the motor &# 39 ; s driving pulley 48 and the centrifuge &# 39 ; s driving pulley 49 . the centrifuge &# 39 ; s rotation bearing is 50 and the centrifuge &# 39 ; s rotating guide is 51 . in the centrifuge &# 39 ; s inner lid or cover 6 , there is a central opening 53 which permits central chamber 2 to be accessible externally even when the inner lid or cover 6 is closed . ring or separation vessel 4 , as shown in fig8 , comprises two sheets of suitable plastic material joined together along the welded edges 17 and 18 . an external ring vessel for separation of a blood composite and buffy coat is formed between the welded edges 17 and 18 . besides ring welds 17 and 18 , there are additional welded points for strengthening around the holes which are intended for locating ring or separation vessel 4 on supports 9 , 10 , and 11 . all the ring or separation vessels shown in the figures are formed with a central opening , where the central opening primarily corresponds to the center chamber 2 opening when the separation vessel 4 is in the centrifuge 34 . in fig8 , this opening is designated 19 . the ring or separation vessel 4 shown in fig8 has openings 109 , 110 , and 111 for supports 9 , 10 , and 11 , respectively . input tube 20 and output tube 32 are attached to the ring or the separation vessel &# 39 ; s top and bottom sides by means of the welded sleeve couplings 24 . ports with flat securing collars 4 a and 4 b can be welded to the ring or separation vessel &# 39 ; s top and bottom sides in which the connecting tubes 20 and 32 are secured by welding . instead of being secured via the port and securing collar , the input tube 20 and output tube 32 can also be secured to each respective welded edge , i . e ., welding 17 and welding 18 in fig8 . fig9 shows the bag set for collecting blood platelets from buffy coat . this bag set includes ring or separation vessel 4 , a bag with diluting solution 23 , four connecting tubes or conduits 25 , 26 , 27 , and 28 ( the number of connecting or separation tubes can vary with the number of buffy coat collections , but generally the number is between four and six ). in use , each tube 25 , 26 , 27 , and 28 can be connected such as by welding or sterile connection to bags with buffy coat , such as bags 37 , 38 , 39 , 40 in fig1 . a multi - way connector 29 is connected to the diluting solution bag 23 via tube or conduit 30 . tube 20 is further connected to the tubes 25 , 26 , 27 , and 28 through the multi - way connector 29 . tube 32 is connected from the ring or separation vessel 4 to a final storage , product collection , or satellite bag 33 . a leukoreduction filter 31 may also be included . tube 30 , which extends from diluting solution bag 23 to multi - way connector 29 , is arranged in the guide groove 22 in support 11 to provide a clamp valve function for control of the addition of diluting solution . bag 23 may also contain an optional openable closer or frangible closer at 45 . the bag set shown in fig8 and 9 is used in the apparatuses of fig2 , 3 , 4 , 5 , 6 or 7 , and , in fig1 , for buffy coat pooling . in fig1 , the centrifuge 34 is shown with an outer lid 35 open and locked in position . the centrifuge &# 39 ; s inner lid 6 has been omitted in this figure , but see fig7 . also , the centrifuge rotor 1 and the ring or separation vessel 4 are drawn in a simplified manner . the centrifuge &# 39 ; s control panel is shown schematically at 36 . furthermore , a cassette 41 mounted on the inside of the centrifuge &# 39 ; s outer lid 35 and rotatable as shown at 42 , holds blood bags 37 , 38 , 39 , and 40 which contain buffy coat . bag 23 , containing a diluting solution , is mounted via holder 44 at a level vertically higher than bags 37 , 38 , 39 , 40 . as shown in fig7 , in operation , when the bag set of fig9 is loaded on the centrifuge rotor 1 , final storage , product collection or satellite bag 33 is placed in the central chamber 2 . in the prior art fig1 , the sides 62 of the bag 33 are generally parallel to the outer wall 61 and the inner wall 63 of the central chamber . in fig2 , a removable insert 71 is provided for central chamber 2 to vary the radius of the inner wall of central chamber 2 with respect to the central axis of rotation 100 . the insert 71 includes a top side 72 , an outer side 73 , a bottom 74 , and a sloping inner side 75 . the insert 71 has a height between the top side 72 and bottom side 74 that is less than the height of the central chamber 2 . the top side of the insert 72 defines a middle portion of the inner wall of the central chamber 2 . the sloping inner side 75 of the insert 71 defines a lower portion of the inner wall of the central chamber 2 . the lower portion 75 of the inner wall has a radius with respect to the central axis of rotation 100 that decreases from its top , defined by the middle portion 72 , to its bottom , defined by the bottom of the insert 74 . the portion of the inner wall 76 above the insert 71 defines an upper portion of the inner wall of the central chamber 2 . the insert 71 fits inside the central chamber 2 to shape product collection bag 33 during centrifugation as is more fully described below . fig3 illustrates an alternative removable insert 81 with a sloping top side 82 , inner and outer sides 85 and 83 , and a bottom 84 . this insert also has a height between the highest point 87 of top side 82 and bottom 84 that is less than the overall height of the central chamber 2 . the inner side 85 defines a lower portion of the inner wall of the central chamber , and the sloping top side 82 of the insert defines a middle portion of the inner wall of the central chamber . the middle portion 82 is sloped at an angle greater than 0 degrees and less than or equal to 90 degrees with respect to the outer wall of the central chamber 61 . the portion 86 of the central chamber above the insert 81 defines an upper portion of the inner wall of the central chamber 2 . both the upper portion 86 and lower portion 85 of the inner wall have constant radii with respect to the central axis of rotation 100 . a third alternative removable insert 91 is shown in fig4 . this insert has parallel top side 92 and bottom 94 . an outer side 93 is parallel to an inner side 95 . the insert 91 has a height between the top side 92 and the bottom side 94 that is less than the overall height of the central chamber 2 . the portion 96 of the central chamber above the insert 91 defines an upper portion of the inner wall of the central chamber 2 . the inner side 95 defines a lower portion of the inner wall , and the top side 92 of the insert 91 defines a middle portion of the inner wall of the central chamber 2 . both the upper portion 96 and lower portion 95 of the inner wall have constant radii with respect to the central axis of rotation 100 . a fourth alternative removable insert 201 is shown in fig5 . the insert 201 has a bottom 204 , an outer side 203 , an inner side 205 , and a top side 202 . the insert 201 extends the length of central chamber 2 from central chamber 2 &# 39 ; s opening to its bottom . the inner side 205 of the insert 201 defines an inner wall of the central chamber 2 . the inner wall 205 is divided into portions . the portion 206 of the inner wall 205 defines an upper portion of the inner wall of the central chamber 2 . the portion 207 of the inner wall 205 defines a lower portion of the inner wall 205 of the central chamber 2 . both the upper portion 206 and the lower portion 207 of the inner wall have decreasing radii with respect to the central axis of rotation 100 from the top of the central chamber 2 to the bottom of the central chamber 2 . a fifth alternative removable insert 301 is shown in fig6 . the insert 301 has a bottom 304 , an outer side 303 , an inner side 305 , and a top side 302 . the insert 301 extends the length of central chamber 2 from central chamber 2 &# 39 ; s opening to its bottom . the inner side 305 of the insert 301 defines an inner wall of the central chamber 2 . the inner wall 305 is divided into portions . the portion 306 of the inner wall 305 defines an upper portion of the inner wall of the central chamber 2 . the portion 307 of the inner wall 305 defines a lower portion of the inner wall 305 of central chamber 2 . both the upper portion 306 and the lower portion 307 of the inner wall have increasing radii with respect to the central axis of rotation 100 from the top of the central chamber 2 to the bottom of the central chamber 2 . as described , the inserts 71 , 81 , 91 , 201 and 301 fit inside the central chamber 2 permitting the central chamber 2 to have an inner wall with a varied radius , shaping the product collection bag 33 during centrifugation . the product collection bag 33 , when received , is positioned in the central chamber 2 adjacent to both the upper portions 76 , 86 , 96 , 206 , 306 and the lower portions 75 , 85 , 95 , 207 , 307 of the inner wall of the central chamber 2 . the upper portions 76 , 86 , 96 , 206 of the inner wall have a radius greater than any radius of the lower portions 75 , 85 , 95 , 207 of the inner wall with respect to the central axis of rotation 100 . however , the upper portion may have a greater radius than the lower portion of the inner wall such as in fig6 and still accomplish the goal of reducing the surface area for platelets to sediment on . an insert consistent with such a configuration is shown in fig6 ; insert 301 has a lower portion 307 of the inner wall 305 with a radius with respect to the central axis of rotation 100 greater than any radius of the upper portion 306 of the inner wall 305 . in the case that the upper portion of the inner wall has a greater radius than the lower portion of the inner wall , then the middle portion of the inner wall will be sloped at an angle greater than or equal to 90 degrees and less than or equal to 180 degrees with respect to the outer wall of the central chamber . fig2 , 3 , 4 , 5 , and 6 describe removable inserts . however , as shown in fig7 , the central chamber inner wall 171 can be manufactured having a varied radius without an insert . as shown in fig7 , the upper portion 176 of the inner wall has a constant radius from the central axis of rotation 100 greater than any radius of the lower portion 175 of the inner wall . a middle portion 172 divides the upper portion 176 of the inner wall from the lower portion 175 of the inner wall . a bottom of the lower portion of the inner wall is shown at 174 . as shown in fig7 , under centrifugal forces , a portion of product collection bag 33 extends adjacent to both the lower portion 175 of the inner wall and the upper portion of the inner wall 176 . although only a wall configuration similar to fig2 is shown in fig7 , it is understood that wall configurations similar to fig3 , 4 , 5 , and 6 could be used to define the inner wall of the central chamber 2 rather than using an insert . before the buffy coat is separated into its components , the buffy coat in bags 37 , 38 , 39 , 40 must be loaded into the separation vessel 4 . as ring or separation vessel 4 is loaded on the centrifuge rotor 1 , the product collection bag 33 is loaded into the central chamber 2 for product collection . also , tube or conduit 30 is placed in groove 22 in support 11 , tube or conduit 20 is placed in groove 21 in support 10 and tube or conduit 32 is placed in groove 12 in support 9 . to begin the process of transferring or loading the buffy coat into the ring or separation vessel 4 , a small amount of diluting solution will be flowed through tube 30 after opening the valve in support 11 and optional frangible 45 , through multi - way connector 29 , and through tubes 25 , 26 , 27 , 28 into bags 37 , 38 , 39 , 40 , respectively . after the addition of diluting solution in sufficient amounts to bags 37 , 38 , 39 , 40 , a motor operatively connected to cassette 41 is actuated to oscillate cassette 41 forward and backwards in a pendulum movement , shown as 42 , until all remaining concentrate substance in the buffy coat bags 37 , 38 , 39 , 40 is suspended in the diluting solution . after sufficient agitation for suspension , the valve in support 10 on the rotor is opened through which tubing 20 passes from the multi - way connector 29 to drain or load the buffy coat into separation vessel 4 . the process of adding diluting solution to bags 37 , 38 , 39 , 40 , agitating , and draining the mixture of buffy coat and diluting solution through multi - way connector 29 and into tube 20 can be repeated until there is no remaining buffy coat in bags 37 , 38 , 39 , 40 . the buffy coat and diluting solution flow through tube 20 to ring or separation vessel 4 . after the buffy coat and diluting solution have been drained or loaded into ring or separation vessel 4 , tubes 20 and 30 can be cut and sealed in guide grooves 21 and 22 , respectively , by the welding function in supports 10 and 11 . cassette 41 , holder 44 , bags 37 , 38 , 39 , 40 and 23 , and all associated tubing are removed from the centrifuge lid whereby the centrifuge is closed for the centrifugation operation . the rotor 34 is rotated at 1800 rpm or at a sufficient rpm that the less dense platelets separate from the denser red blood cells ( rbc ) and leukocytes of the buffy coat . the built - in valve in guide groove 12 in support 9 can be opened and separation vessel 4 can be squeezed using the hydraulic fluid in chamber 5 to permit the less dense platelets and any plasma or diluting solution to be transferred through tube 32 to product collection bag 33 to be collected . while being expressed or passed from the separation vessel 4 to the product collection bag 33 , the platelets can be pushed through the optional filter 31 , shown on fig9 , and collected into the product collection bag 33 . the transfer of the platelets and any plasma continues until a sensor 52 indicates the interface between the platelets and rbcs / leukocytes . after the final expression of platelets , tube 32 is sealed by sterile welding using the welding function on support 9 . the platelets in bag 33 will continue to be subjected to centrifugal force until the centrifuge slows to a stop . during centrifugation , the surface area is reduced for the collected platelets to contact the product collection bag and platelets are prevented from contacting the entire inner wall . product collection bag 33 is extended adjacent to both the upper and lower portions of the inner wall and is shaped by the contour of central chamber 2 &# 39 ; s inner wall during centrifugation . the inner wall of the central chamber has a varying radius with respect to the central axis of rotation 100 shaped either by an insert 71 , 81 , 91 , 201 or 301 shown in fig2 , 3 , 4 , 56 or by the use of the central chamber inner wall 171 of fig7 . the product collection bag is shaped by the centrifugal force to conform to the shape of the inner wall of the central chamber 2 . thus , the radius of the product collection bag is also varied by the shaping . when subjected to the centrifugal force , the platelets will form a layer farthest from the central axis of rotation 100 due to their sedimentation velocity . decreasing or increasing the inner wall radius of the central chamber from top to bottom of the chamber either by manufacture 171 as shown in fig7 or by using an insert 71 , 81 , 91 , 201 or 301 in fig2 , 3 , 4 , 5 or 6 reduces surface area for the platelets to form a layer by preventing the platelets from contacting the entire inner wall . as shown in fig2 , 3 , 4 , 5 and 6 , adding an insert 71 , 81 , 91 , 201 or 301 or using of the central chamber inner wall 171 of fig7 to vary the radius of the central chamber between the central axis of rotation 100 and the inner wall permits the platelets to pack or sediment out along the portion of the wall with the greatest radius , including upper portions 76 , 86 , 96 , 206 or 176 of the inner wall or , alternatively , the lower portion 307 of the inner wall . this is because the platelets will sediment out faster than any remaining less dense plasma or diluting fluid . the denser platelets under centrifugal force that have been expressed tend to move to form a layer farthest from the rotation axis . if the layer forms only in the upper portions 76 , 86 , 96 , and 206 or , alternatively , the lower portion 307 , of the inner wall , there will be fewer numbers of platelets contacting the surface area of the bag 33 than if the platelet layer extended along the entire height of the bag parallel to the central axis of rotation 100 , as in the prior art fig1 . platelets in plasma have a lower sedimentation velocity generally than platelets that are stored in a platelet additive solution ( pas ). generally , platelets in such an additive solution have a higher sedimentation velocity and thus may be more likely to form a film on the bag wall over its height . thus , using the configurations of fig2 , 3 , 4 , 5 , 6 and 7 reduce the ability of platelets in pas to form such a film .
the present invention relates generally to the field of extracorporeal blood processing methods and apparatus which are particularly useful in blood component collection , and more specifically , the present invention relates to methods and apparatus for centrifugally separating buffy coat that reduce the surface available for separated buffy coat components to sediment on by varying the radius of the product collection bag .