TECHNICAL FIELD

The present invention refers to a blood separator which transfers blood components from a primary bag comprising centrifuged blood forming part of a set of bags to at least two secondary bags forming part of the same set of bags. The blood separator is of the type which by means of a presser arrangement acting on the primary bag transfers the blood components via tubes being possible to seal off by means of valves controlled from a microprocessor comprised in the separator. The invention makes it possible to trans- fer a predefined quantity of one or several blood compo¬ nents to preferably one of the secondary bags.

BACKGROUND ART

In order to use the blood from a blood spender in the best possible way the blood is divided into certain of its com¬ ponents so that every separate patient can be provided with exactly the blood components he or she needs. In order to make it possible to separate the blood in its components the blood is filled directly from the blood spender into a sterile blood bag made of plastic, the primary bag, which forms part of a set of bags comprising at least two addi¬ tional sterile bags, the secondary bags, which via sterile tubes are connected to the primary bag for the subsequent transfer of blood components to the secondary bags. To the primary bag an inlet tube provided with an injection needle is further connected. Blood bags of different types and de¬ signs having specific features exist.

A blood spender gives about 450 milliliter blood each time. Every time a spender gives his blood the procedure ends

with a compulsory sampling before the inlet to the primary bag is closed and the primary bag being centrifuged in or¬ der to separate the blood within the bag into its main com¬ ponents. After the centrifuge operation the primary bag is placed in a blood separating apparatus controlled by a mi¬ croprocessor. The bag is hung with the outlet directed up¬ wards on a vertical wall on the apparatus which wall raises from the rear part of the base plate of the apparatus. The wall has a flat horizontal upper part on which two hose clamps or valves, actuated individually and electrically, are arranged in which the tubes connecting the secondary bags with the primary bag are placed at the same time as the secondary bags are hung on the back side of the wall.

In the primary bag can now clearly separated main compo¬ nents be seen. Red cells at the bottom, thereafter follow white cells, leukocytes, then follow trombocytes, and at the top plasma. A plate of Plexiglas having dimensions cor¬ responding to the size of the primary bag is arranged on two pneumatically controlled arms movably arranged in the base plate of the apparatus and which by means of the pneu¬ matics can press the primary bag against the wall on which the bag is hung. The movements of the plate are controlled by the microprocessor which also one after the other opens the tube valves. At first the plasma is transferred to one of the secondary bags and after that the so called inter¬ face layer (buffy coat) which comprises trombocytes as well as white cells to the other secondary bag. An optical sen¬ sor arranged in the wall and being connected to the proces- sor indicates when the interface layer approaches the out¬ let opening of the primary bag whereby the processor seals off the valve of the "plasma bag" and opens the valve of the bag for the "interface layer". When the last mentioned valve should be sealed off can not be indicated optically on the contents of the primary bag so the processor usually calculates this time by measuring the rotation angle of the

arms carrying the Plexiglas plate which is pressed against the primary bag.

This method gives big divergencies in the quantity between different bags for the "interface layer" due to the diffi¬ culty to make exact measurements o£ angles and due to the fact that small variations in the design of the primary bag, quality and thickness of the material, influences the volume squeezed from the bag. When the interface layer is thin it is necessary to add a certain quantity of the plasma on top as well as the layer of red cells on which the interface layer is supported. It is important that these quantities could be minimized and be kept equal in all bags so that the bags will contain a uniform product. This is essential due to the fact that a significant part of the blood bags will be used in the production of pharma¬ ceuticals.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide an appa¬ ratus which decreases the drawbacks described above in con¬ nection with known blood separators and which eliminates the dependence of the filling volume of the bags due to different characteristics of different sets of bags. This object is achieved by means of an apparatus having the characterizing features according to the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described more in detail with refer¬ ence to the appended drawing on which figure 1 shows in perspective a blood separator and figure 2 shows in a plane view a common balance intended for application on the blood separator.

PREFERRED EMBODIMENT

In figure 1 which shows a blood separator in perspective this separator is generally designated 1. The apparatus comprises a base plate 2 from the rear part of which a ver¬ tical wall 3 is raising which wall is large enough to con¬ stitute a counter part at the pressing of a blood filled so called primary bag 4 hung on the wall which by means of its outlet tube 5 and its branchings 6, 7 is connected to sec- ondary bags 8, 9 of which one bag 8 is hung on the back side of the wall 3 between the side plates of the apparatus which reaches beyond the wall 3 and of which only one hav¬ ing the designation 10 is shown.

The other secondary bag 9 is hung on a pin 12 on a common balance 14 comprising a rectangular plate 11 pivotally ar¬ ranged on a shaft 13 fixed to the side wall 10. The common balance 14 the design of which also is shown in figure 2 additionally comprises a counterweight 15 arranged adjust- able at its lower left corner and a reflective surface ar¬ ranged at the backside of the lower right corner delimited by means of an edge 16 which is directed radially relative to the shaft 13 and the passage of the vertical of which is detected by means of an optical sensor 17 in the side wall 10.

The sensor 17 is connected to a microprocessor, not shown, inside the blood separator which controls the transfer of the blood components from the primary bag to the secondary bags. The processor hereby controls the movement of the two pneumatically activated arms 18, 19 journalled in the base plate which arms carry a Plexiglas plate 20 which during the transfer of the components presses against the primary bag 4 hung on the wall 3. The contents of this bag is thereby pressed upwards and into the outlet tube 5 and its branchings 6 and 7 to the secondary bags 8, 9. On their way

to said bags the tubes on the plane horizontal top surface 21 of the wall 3 pass hose clamps or valves 22, 23 in the form of towers. A valve comprises a cylindrical core 24 ar¬ ranged in a cylindrical housing 25. The core which by means of a spring is pushed upwards inside the housing is acces¬ sible through an opening at the top of the housing. In the housing as well as the core transversal slots or groves 26 are arranged positioned in such a way that they coincide when the core 24 is pushed downwards in the housing 25 mak- ing it possible to enter sideways a tube in the slot of the valve 26. When the core 24 after placing the tube in the slot is released the tube will be squeezed and the liquid flow will be stopped. The valve which is closed when not activated could be opened manually and additionally by means of an integrated electromagnet, not shown, connected to the microprocessor.

When separating the blood components in the primary bag 4 the procedure is the same to start with as has been earlier described under the heading "Prior art", i.e. the plate of Plexiglas 20 is by means of the pneumatics pressed against the primary bag under control of the processor integrated in the apparatus in which bag the interface layer 27, clearly visible after the centrifugal process, has been in- dicated in figure 1. At the same time as the processor starts the movement of the Plexiglas plate against the pri¬ mary bag it opens the valve 22 and in doing so the tube branching 6 to the secondary bag 8. When the blood plasma on top of the interface layer 27 is pressed out through the outlet tube 5 of the primary bag 4 and further to the sec¬ ondary bag 8 the interface layer 27 will move upwards in the primary bag 4 and finally reach a level at which an op¬ tical sensor arranged in the wall 3, not shown, connected to the processor, reacts which causes the processor to close the valve 22 and to open the valve 23 and the tube

branching 7 which leads to the secondary bag 9 hung on the common balance 14.

As the bag 9 is filled the common balance is turning i.e. the plate 11 of the balance is moving to the left. By means of the counter weight 15 the balance has been adjusted for the weight of the bag and has been set in such a way that when the intended quantity of blood component has been transferred to the secondary bag 9, the edge 16 of the plate 11 passes the optical sensor 17 in the side wall 10 connected to the processor. When this happens the separa¬ tion process is stopped by means of the closing of the valve 23 and the Plexiglas plate 20 is brought back to its initial position. The bags are sealed and taken care of and the apparatus is ready to receive the next set of bags.