A DEVICE FOR THE SEPARATION OF A LIQUID,ESPECIALLY WHOLE BLOOD

Abstract: Device for the centrifugal separation of a liquid, especially whole blood, into fractions having different densities. Said device comprises a rotatable separation unit (5) comprising a separation chamber (5'), and a transferring element (2) in fluid communication with said chamber The transferring of said liquid and said separated fractions between a source for said liquid and said separation chamber is realized without use of rotating couplings in that one end (3) of said transferring element is held fixedly, while the other end (4) thereof, i.e. the end which is next to said separation chamber, is rotatably connected to said chamber. As well said separation unit as said transferring element thereby will perform a rotation, when said separation chamber is rotating around an axis through said one end of said transferring element. Said transferring element (2) is thereby prevented from twisting or winding. More precisely, said transferring element (2) and said separation unit (5) will rotate one revolution (secondary rotation) per revolution made by the separation unit (5) when rotating (primary rotation) around said axis through said fixedly held end (3). By suitable choice of ratio between radius (r) of said separation chamber and radius (R) of said primary rotation, i.e. the distance between said separation chamber and the axis through said fixedly held end, said secondary rotation may be used to separate said liquid already before said liquid enters into said separation chamber (5').

Description: TITLE A DEVICE FOR THE SEPARATION OF A LIQUID, ESPECIALLY WHOLE BLOOD TECHNICAL FIELD This invention relates in general to a device for the separation of a liquid into fractions having different den¬ sities. Especially, this invention relates to a device for the separation of whole blood into for example red cells and plasma. Conveniently, the present device is of the kind that is connectable to a patient to permit the whole blood to be continuously withdrawn from said patient, to be conducted through said device and then to be reinfuse into said patient. During the passage through said device said whole blood is separated into for example red cells and plasma. For example said red cells are reinfused into a patient, while said plasma is separately collected. To the above end the present device comprises a rotat- able separation unit comprising a separation chamber, and a transferring element being in fluid communication with said chamber. BACKGROUND ART To facilitate the understanding of the present inven¬ tion it may be convenient to first illustrate the nature and character of whole blood. This should however not con¬ stitute a limitation of the present invention, but should rather be taken as a convenient instrument to understand the present invention when used in one of its more especial fields of use. Whole blood is a tissue consisting of cells suspended in plasma. Said cells constitute about 45% by volume, while the remaining 55% constitutes plasma. Said suspended blood cells comprise inter alia red cells, white cells and throm- bocytes. By means of the present device it is possible not only to separate cells from plasma, but also to separate said several cells from each other into separate cell fra tions (so-called cytapheresis) if desired. Said separate fractions of said whole blood may be used independently f different purposes. For example said white cells are of p ticular concern for blood research, immunolcgical studies and for clinic use in transplantations of organs. Further more, said white cells may be used for support therapy by cancer patients, the white cells of which in one or anothe respect have been destroyed through different anti cancer drugs. The red cells as well as the plasma are of particula concern for transfusion purposes. Known devices for the separation of whole blood into different components have under favorable conditions pro- vided a sufficient separation but have, on the other han had drawbacks sometimes entailing fatal consequences for said whole blood and said separated components. The main reason has been the rotating coupling which normally is u to connect the transferring element to the rotating separ tion unit. Through the heat of fraction which is created rotating couplings in the contact surface between a stati ary and a rotating element, said whole blood has been ex¬ posed to heavy temperature increases during its passage i the separation chamber. This is also true for the separat blood fractions when said fractions have passed the rotat coupling during the flowing out of said separation unit. Even though said problem to some extent has been solved b cooling said rotating coupling with a cooling fluid, it s remains as being not completely solved. Another drawback by said known devices, which use ro ing couplings, is that blood cells may be damaged due to shear-stresses at the contact between surfaces moving rel tively to each other. The object of the present invention is therefore to provide a device of the above-mentioned kind, i.e. 'a devi which similar to said known devices for the separation of whole blood into fractions having different densities, us a rotating separation unit comprising a separation chambe f *'- -. ___ι and a transferring element in fluid communication with said chamber. The present device, on the contrary, does not use rotating couplings to connect the separation unit to the transferring element. DISCLOSURE OF INVENTION The present device comprises a rotatable separation unit comprising a separation chamber, and a transferring element in fluid communication with said chamber. Said de- vice is characterized in that one end of said transferring element is fixedly held, while the other end of said trans¬ ferring element is rotatable together with said separation unit in a circular path around an axis through said one end. Due to the fact that said one end of said transferring element is held fixedly, i.e. is kept stationary, while said other end is rotatable together with said separation unit around an axis through said one end, the person skilled in the art realizes that said transferring element (as well as said separation unit) will rotate around said axis (primary rotation) , and also around its own longitudinal axis (secondary rotation) . Said primary and said secondary rotation thereby are so synchronized that any tending of said transferring element to be exposed to torsion or to be wound is counteracted. As regards said transferring element this fact apparently means that said transferring element will make one revolution around its own longitudinal axis per revolution around said axis through said one end of said transferring element. Preferably, said transferring element and said separation unit are firmly held together. Consequently, also said separation unit will perform a synchronized secondary rotation with said transferring element. Said firm connection between said transferring element and said separation unit is achieved preferably by means of a tubular casing comprising a closed and an open end. Said casing thereby enclose at least one inlet tube for the liquid, to be separated, and at least one outlet tube for the respective fraction of said liquid. As well said inlet as said outlet tubes are terminating at short distan from the closed end of said casing while forming a separat chamber between the respective ends of said tubes and said closed end of said casing. Preferably, said outlet tube for the heavy fraction i terminating next to said closed end of said casing, while the outlet tubes for successively lighter fractions are te minating at successively longer distance from said closed The inlet tube thereby is terminating at a longer distance from said closed end than the outlet tube for said heavies fraction, but at a shorter distance from said closed end than the outlet tube for the lightest fraction. In the separation of whole blood into for example red cells and plasma the inlet tube for said whole blood con¬ veniently is terminating into an area between the corres¬ ponding ends of the tubes for said red cells and said plas respectively. To ascertain a well balanced primary rotation the inl tube for said liquid and the outlet tube for the respectiv fraction are preferably provided in a mirror symmetric rel tion with respect to the central longitudinal axis of said casing. This means that outlet tubes for one and the same fraction are located diametrically opposite to each other within said casing. Preferably, the inlet tube is located centrally. According to another preferred.embodiment of the pres invention said tubular casing encloses two concentric tube The inlet for the liquid, to be separated, is constituted by the annular space between the innermost tube and the in termediate tube. The outlet for the heaviest fraction is i the same way formed by the annular space between said inte mediate tube and said casing, while the outlet for the lightest fraction is formed by the cavity within said inne most tube. By analogy with the first embodiment said innermost tube is terminating at a longer distance from the of said casing compared to said intermediate tube. The number of concentric tubes to be used depends in each separate case on the number of desired fractions. This preferred embodiment in general is very similar to said first embodiment and need therefore not be described in more detail . Yet it is to be noted that suitable spacers may be provided between the tubes to keep said tubes in place. For example protruding heels, frame works and similar constructions may be provided on the outer surfaces of the inner tubes to pre- vent said tubes from contacting each other and thereby clogg¬ ing said annular spaces or channels. Alternatively, said firm communication between said transferring element and said separation unit is realized by means of a tubular body comprising a closed and an open end. Said tubular body comprises at least one inlet channel (longitudinal void) for the liquid, to be separated, and at least one outlet channel (longitudinal void) for the respect¬ ive fraction of said liquid. Said channels are terminating at a distance from said closed end of said tubular body while forming a separation chamber between the respective ends of said channels and said closed end of said tubular body. Again, this alternative embodiment is very similar to said first embodiment and therefore need not be described more in detail. Still another embodiment of the present invention com- prises a separation unit in the form of a separate hollow body in firm communication with said transferring element. Said hollow body is preferably molded and comprises cavities in communication with tubes or channels in said transferring element. As well said molded separation unit as said trans- ferring element are conveniently encapsulated within a tubu¬ lar housing comprising a closed and an open end. The princip¬ al difference between this embodiment and the embodiments described hereabove is that the separation chamber in this case is formed by cavities in an individual molded hollow body, while the corresponding chambers in the preceding embodiments are formed by the space between said transferr ing element and said closed end of said enclosing casing. Neither this embodiment should need to be discussed more i detail. Although not necessary, said separation unit convenie ly is carried in a rotatable support casing which is adapt to be rotated together with said separation unit around sa axis through said fixedly held end of said transferring element. Thereby is a smooth and vibration free primary ro tation ascertained. As an extra matter of safety against vibrations and possible unbalances during said primary rot tion said support casing is preferably driven by means of separate driving means which in turn are adapted to be dri synchronically to the secondary rotation of said transferr element. Said driving means are preferably coupled to the motor that provides for the primary rotation of said trans ferring element. Preferably, said transferring element is provided in curved path and supported in this position by means of suitable supporting means. As well said support casing as said separation unit may be manufactured from transparent material making it possible to visually (for example by means of a stroboscope) watch the separation of whole blood within said separation chamber. Finally, said transferring element may comprise flowi channels for a cooling liquid, for example salt solution, which is adapted to withdraw heat that may be generated through shearing in said transferring element due to bendi of tubes in said secondary rotation. The present invention will be described in more detai with reference to the accompanying drawings, wherein Fig. 1 is a schematic view of the present device to¬ gether with suitable accessories, Figs. 2-4 are cross-sections of preferred transferrin elements according to the present invention, fϋRE OMP . • ■ ^__ WIP r Fig. 5 is a schematic illustration, partly in section, of a preferred transferring element in firm communication with a separation unit, Figs. 6-8 are cross-sections of the transferring element and the separation unit of Fig. 5 along lines VI-VI, VII-VII and VIII-VIII in Fig. 5, Fig. 9 is a schematic illustration, partly in section, of a second preferred transferring element in communication with an individual separation unit, taken along lines IX-IX in Figs. 10-15, Figs. 10-15 are cross-sections of the separation unit and the transferring element of Fig. 9, taken along lines X-X, XI-XI ... XV-XV, Fig. 16 is a schematic view, partly in section, of a further transferring element according to the present in¬ vention, taken along lines XVI-XVI in Figs. 17-19, and wherein Figs. 17-19 are cross-sections of the transferring element of Fig. 16, taken along lines XVII-XVII, XVIII-XVIII and XIX-XIX in Fig. 16. As is shown in Fig. 1, the present device, generally designated 1, comprises a transferring element 2 which at its one end 3 is held fixedly and at its other end 4 is connected to a separation unit 5 comprising a separation chamber 5 ' . Said separation unit 5 is preferably carried in a support casing 6 which is rotatable around its own longitu¬ dinal axis by means of a bearing 7, 8. Between its two ends 3 and 4 said transferring element 2 is provided in a curved path and kept in this position by means of a stand 9 and suitable support bearings 10, 11 being attached to said stand and permitting said transferr¬ ing element 2 to rotate freely around its own longitudinal axis. Said stand 9 is carried on a stationary support plate 12 and is rotatable around an axis through said fixedly held end 3 of said transferring element. Said axis is de¬ signated I-I in Fig. 1. The rotation around said axis I-I is provided by means of a not shown drive motor via a drive shaft 9c which is carried in a bearing 9a in a supporting means 9b. To the right part (not shown) of said stand 9 in Fig a counter-weight may be provided to balance said trans- ferring element 2 and said separation unit 5, when said stand 9 is rotating. Thereby, vibrations due to asymmetri weight distribution are avoided. Said separation unit 5 as well as said support casin 6 are preferably transparent. Thereby it is possible to visually (for example by means of a stroboscope) watch th separation and, if necessary, to control the rotation spe so that the best possible separation is achieved. Alterna ively, said separation may be controlled by controlling t introducing and/or withdrawing of liquid in said differen inlet and outlet tubes. For example, if whole blood is to be separated into plasma.and red cells and the volume of plasma within said separation chamber apparently is too big, then said volume may be reduced by either increasing the withdrawing of plasma or by reducing the withdrawing red cells. Polyvinylchloride (PVC) is a suitable transpar material. A further way of controlling said separation compris the choice of a suitable rotation radius R from said axis Depending on the liquid, to be separated, it may be convenient to use a larger or smaller ratio between radiu of said separation chamber 5 ' and radius R of the primary rotation of said separation chamber 5*, i.e. the distance between said axis I-I and said separation unit 5. In the separation of whole blood into red cells and plasma, said ratio conveniently is between 30:1 and 15:1. In this way influence of the secondary rotation of said separation un on said separation may be more or less used and thereby t separation be initiated already prior to entering into sa separation chamber 5 * . To avoid unbalances due to vibrations of said suppor casing 6, said casing may be driven separately by means o schematically shown drive means, generally designated 13, which are synchrcnically driven by the not shown " ~ &\- ( drive motor for said stand 9. In Figs. 2-4 suitable cross-sections are shown, which may be used for said transferring element 2. In Fig. 2 said transferring element consists of a tubu- lar body 2a having perforating holes or channels 14a, 14a', 15a, 15', 16a, 16a 1 and 17a. As is shown in Fig. 2 said channels are preferably mirror symmetrically provided to the central longitudinal axis of said tubular body 2a. In the separation of whole blood said channels 14a, 14a' constitute inlet channels for said whole blood, while said channels 15a, 15a' and 16a, 16a' constitute outlet channels for the red blood cells and the plasma, respectively. The central channel 17a may either form a third inlet channel for said whole blood, or a separate flowing channel for cooling liquid, if necessary. In Fig. 3 said transferring element consists of a tubular housing 2b enclosing six individual tubes 14b, 14b', 15b, 15b', 16b, 16b" . Said tubes are mirror symmetrically provided around the central longitudinal axis of said casing and attached to each other to maintain the shown position. Said tubes form in pairs inlet and outlet tubes for the whole blood and the separated fractions, respectively. For example, said tubes 14b, 14b' are inlet tubes for said whole blood, while the tubes 15b, 15b' and 16b, 16b" are outlet tubes for red blood cells and plasma, respectively. The space 17b between said tubes and said casing 2b forms flowing channels for a cooling liquid, for example isotonic 0.9% NaCl solution. In Fig. 4 said transferring element consists of an outer tubular casing 2c enclosing concentric tubes 16c, 18c. Said casing 2c and said tubes 16c and 18c thereby form annular spaces or channels 14c, 15c. Said annular space 15c between said casing 2c and the intermediate tube 18c forms prefer¬ ably outlet channel for the heaviest fraction (red blood cells) , while the annular space 14c between said intermediate tube 18c and the innermost tube 16c forms preferably inlet tube for said whole blood. The cavity in the innermost tube 16c consequently forms outlet channel for said plasma. As mentioned before the number of concen tubes, to be used, may vary from case to case and is depe ing on the number of fractions that is desired. To maintain the concentric arrangement of said casin 2c and said tubes 16c and 18c, said intermediate tube 18c may be provided with protruding heels 19c abutting the in surface of said casing 2c and the outer surface of the in most tube 16c, respectively. Thereby is avoided that said tubes will contact each other and clog the annular spaces 14c and 15c, when said transferring element is rotating aro said axis I-I. As well said tubular body 2a as said casings 2b and are manufactured from a flexible material. A preferred example of such material is silicon rubber which is also sufficiently firm to withstand shearing due to the primar rotation of said transferring element. The transferring element and the separation unit sho in Figs. 5-8 correspond generally to the transferring ele ment shown in Figs. 1 and 4. The same reference numbers a those in Figs. 1 and 4 have therefore been used, except f the addition of the letter "d" instead of the letter "c". In Fig. 5 said separation unit is designated 5d, said sep ration chamber is designated 5d' and said transferring el ment (including said tubular casing) is designated 2d. Reference is also made to the above description in connec tion with Fig. 4. The transferring element and the separation unit of Figs. 9-15 differ fromthe construction shown in Fig. 5 primarily in that said separation unit 5e is formed as a separate molding unit. Said transferring element 2e has i general the same cross-section as that of Fig. 3. For sim lar parts, the same reference numbers have therefore been used, except for the addition of the letter "e". The chann in said separation unit 5e have therefore been designated in the same way as the corresponding tubes in the trans¬ ferring element 2e, except for the addition of double prim and triple prim. The transferring element 2f (including the separation unit 5f) of Fig. 16 is the simplest possible realization of said transferring element having the cross-section shown in Fig. 3. The same reference numbers as those in Fig. 3 have therefore been used, except for the addition of the letter "f". Thus, the transferring element comprises only three • tubes, designated 14f, 15f, 16f. The inlet tube for the liquid,, to be separated, is designated 14f, while the outlet tubes for the red cells and the plasma are designated 15f and 16f, respectively. In connection with Fig. 5 the operation of the present device will be described when used in the separation of whole blood. Said whole blood, to be separated into red blood cells and plasma, is introduced through the annular space 14d between the innermost tube 16d and the intermediate tube 18d. Due to the secondary rotation of said transferring element, shown by the arrow to the left of Fig. 5, said whole blood will be exposed to preseparation prior to entering in¬ to said separation chamber 5d* in such a manner that said plasma tends to concentrate towards the longitudinal axis of said transferring element 2d, while the heavier red blood cells correspondingly tend to concentrate away from said longitudinal axis within said space 14d. The so partly se¬ parated whole blood enters into said separation chamber 5d' , where the proper separation occurs. Due to the centrifugal forces the heavier red blood cells will be concentrated peripherially outwardly (to the left of Fig. 5) , while the lighter plasma will be concentrated towards the centre and will enter into the cavity in said outlet tube 16d. The flowing conditions for said whole blood, said red cells and said plasma are shown by arrows in Fig. 5. Due to the fact that whole blood is continuously introduced into said space 14d the separated red blood cells and the plasma correspond¬ ingly are continuously withdrawn through the annular space 1HJR- £ A7 15d and the cavity in sa'id outlet tube 16d, respectively. Since neither the way in which said whole blood is intro¬ duced into said transferring element 2d and said separati unit 5d or the way in which the separated fractions are wi drawn from said unit constitute any essential part of the present invention, no further description thereof is ther fore needed. Briefly, the arrangement 20 of Fig. 1 corre¬ sponds in general to the construction of Figs. 9-15. The same reference numbers for similar parts have therefore b used, yet without the addition of any letter. Even if the present invention has been described wit particular reference to the separation of whole blood, it is to be understood that the present invention is as well applicable to other liquids, containing fractions of different densities, which are to be separated into said fractions. INDUSTRIAL APPLICABILITY As is realized from the above description, the prese device is especially, though not exclusively, useful in t separation of whole blood into for example red blood cell and plasma. Said whole blood is thereby continuously intr duced into said device from an outer source, for example patient, and is separated under the influence of centrifu forces in a rotatable separation unit. The separated frac tions, red blood cells and plasma, are withdrawn from sai separation chamber within said separation unit through in vidual tubes and are reinfused into said patient or are collected selectively. Due to the fact that one end of sa transferring element is held fixedly, while the other end thereof (i.e. the end which is in fluid communication wit said separation chamber) is rotatably connected to said chamber, rotating couplings are thereby avoided, which du to heat of friction may expose said blood and the separat fractions to excessive and detrimental temperature increa and/or detrimental shear stresses. OM

Claims: CLAIMS 1. A device for the separation of a liquid, especially whole blood, into fractions having different densities, said device comprises a rotatable separation unit (5) comprising a separation . chamber (5') / and a transferring element (2) in fluid communication with said chamber, characterized in that one end (3) of said transferring element (2) is held fixedly, while the other end (4) thereof is rotatable to- gether with said separation unit (5) in a circular path around an axis (I-I) through said one end (3) . 2. A device in accordance with claim 1, characterized in that said transferring element (2) and said separation unit (5) are firmly connected to each other. 3. A device in accordance with claim 1 or 2, characterized in that said transferring element (2) and said separation unit (5) are connected to each other by means of a tubular casing (2b; 2f) having a closed and an open end and enclosing at least one inlet tube (14b, 14b 1 ; 14f) for the liquid, to be separated, and at least one outlet tube (15b, 15b', 16b, 16b'; 15f, 16f) for the respective frac¬ tion of said liquid, wherein said tubes are terminating at a distance from said closed end of said casing while forming a separation chamber (5f') between the respective ends of said tubes and said closed end of said casing (for example Figs. 3 and 16-19) . 4. A device in accordance with claim 3, characterized in that said outlet tube (15b, 15b' ', 15f) for the heaviest fraction is terminating next to said closed end of said casing (2b; 2f) and in that the outlet tubes (16b, 16b'; 16f) for successively lighter fractions are terminating at successively longer distances from said closed end, wherein the inlet tube (14b, 14b'; 14f) is terminating at a longer distance from said closed end than said outlet tube (15b, 15b'; 15f) for said heaviest fraction, but at a shorter distance from said closed end than said outlet tube (16b, 16b 1 ; 16f) for said heaviest fraction. 5. A device in accordance with claim 3 or claim 4, characterized in that said inlet tube (14b, 14b') for sai liquid and/or said outlet tubes (15b, 15b 1 , 16b, 16b') fo the respective fraction are mirror symmetrically provided to the central longitudinal axis of said casing (2b) (for example Fig. 3) . 6. A device in accordance with any one of claims 3-5 characterized in that the space (17b) between said tubes (14b, 14b', 15b, 15b » , 16b, 16b') within said casing (2b) forms flow channels for cooling liquid, for example salt solution. 1. A device in accordance with claim 3, characterize in that said tubular casing (2c; 2d) encloses two concent tubes (16c, 18c; 16d, 18d) , wherein the inlet for the liq is constituted by said annular space (14c; 14d) between t innermost tube (16c; 16d) and the intermediate tube (13c; 18d) , wherein said outlet for the heaviest fraction pre¬ ferably is constituted by said annular space (15c; 15d) between said intermediate tube (18c; 18d) and said casing (2c; 2d) , and wherein said outlet for the lightest fracti preferably is constituted by the cavity in the innermost tube (16c; 16d) (for example Figs. 4 and 5) . 8. A device in accordance with claim 7, characterize in that the innermost tube (16c; 16d) is terminating at a longer distance from said closed end of said casing (2c; than said intermediate tube (18c; 18d) . 9. A device in accordance with claim 2, characterize in that said transferring element (2) and said separation unit (5) are connected to each other by means of a tubula body (2a) comprising a closed and an open end and compris at least one inlet channel (14a, 14a 1 ) for the liquid, to be separated, and at least one outlet channel (15a, 15a', 16a, 16a') for the respective fraction of said liquid, wherein said channels are terminating at different distan from said closed end of said tubular body (2a) while form a separation chamber between the respective ends of said channels and said closed end of said tubular body (for example Fig. 2) . 10. A device in accordance with claim 9, characterized in that said outlet channel (15a, 15a') for said heaviest fraction is terminating next to said closed end of said tubular body (2a) and in that said outlet channels (16a, 16a') for successively lighter fractions are terminating at successively longer distances from said closed end, wherein said inlet channel (14a, 14a') is terminating at a longer distance from said closed end than said outlet channel (15a, 15a') for said heaviest fraction, but at a shorter distance from said closed end than said outlet channel (16a, 16a') for said lightest fraction. 11. A device in accordance with claim 9 or 10, characterized in that said inlet channel (14a, 14a') for said liquid and said outlet channels (15a, 15a', 16a, 16a') for the respective fractions are mirror symmetrically pro¬ vided to the central longitudinal axis of said tubular body (2a) . 12. A device in accordance with any of claims 7-11, characterized in that said tubular body (2a) comprises one or more flow channels (17a) for a cooling liquid, for example salt solution. 13. A device in accordance with claim 2, characterized in that said separation unit (5e) is formed as an individual hollow body in firm connection to said transferring element (2e) (for example Fig. 9) . 14. A device in accordance with any one of claims 1-13, characterized in that said separation unit (5) is carried in a rotatable support casing (6) . 15. A device in accordance with claim 14, characterized in that said support casing (6) is adapted to be driven by means of separate driving means (13) which in turn are adapted to be synchronically driven in relation to the secondary rotation of said transferring element (2) . 16. A device in accordance with claim 15, characterized in that said transferring element (2) is provided in a curved path and carried in this position by means of suitable support means (10, 11) . 17. A device in accordance with claim 16, characteri in that as well said support casing (6) as said separatio unit (5) are manufactured from transparent material. ' B R __QMP WΪP ■ N

Inventors: BOBERG N, GULLBERG C, LARSSON L, STENBERG K
Applicants: BOBERG N, GAMBRO AB, GULLBERG C, LARSSON L, STENBERG K
Application year: 1979
Main classification: B04B5
IPC codes: A61M1, B04B5