Blood collection and separation process

#This invention relates to a method of whole-blood collection and the preparation of components therefrom following collection.

#In the conventional method of whole blood collection, a needle is placed in a vein in the donor's arm and whole blood flows by gravity into a bag which holds a quantity of anticoagulant solution, which prevents the blood from clotting. When a unit of whole blood, defined in the United States as 450 milliliters (ml), has been collected, the needle is removed from the vein and the blood bag is set aside for later transfer to the processing laboratory of the blood center.

#It should be noted that the ratio of anticoagulant to whole blood is approximately one to seven; thus the amount of anticoagulant in the bag is 63 ml. It should also be noted that, while the ratio of anticoagulant to whole blood is one to seven after a full unit has been collected, the ratio of anticoagulant to whole blood is considerably higher than one to seven at the beginning of the collection. The red cells flowing into the collection bag at the beginning of the collection are, therefore, subject to "anticoagulant shock", which has the effect of damaging some of the red cells. As the collection proceeds, the ratio decreases.

#FIG. I is a schematic of a system according to a one embodiment of the present invention.

#FIG. 2 shows a cross-section of a rotor and a chuck for holding and spinning the rotor that may be used in the present invention.

#FIG. 3 is a perspective view of FIG. 1 system.

#The separator of this invention disclosure, shown schematically in FIG. 1, consists of a sterile, closed-system disposable set in which the blood is collected and processed and a control unit 6 that interfaces with the disposable set and that controls the collection and separation process. One embodiment of the disposable set consists of a needle 72 through which blood is drawn from the donor 70 and a bag 92 containing an anticoagulant such as ACD, CPD or trisodium citrate. This bag 92 serves as the storage container for the plasma or platelet-rich plasma following the processing of the blood by the system. The disposable set also includes a second bag 91, which may contain a red cell preservative solution, and into which the red cells are directed for storage following separation. The set further includes a variable-volume rotor 2a, preferably of the type shown in FIGS. 1-4 of the above-referenced co-pending application Ser. No. 08/322,601, although other rotors shown and described in this co-pending application may be used as well, such as the rotors shown in FIG. 7, or FIG. 8A, or in FIGS. 20-22. These principal components of the system are joined by four lengths of tubing 73, two lengths of which are connected by the fitting 71 to which the needle 72 is attached, and three lengths of which are connected by a valve 81. Although, many different types of valves may be used in the present invention, one preferred embodiment of the invention uses a stopcock-type valve to direct the fluid in the desired manner. An alternative disposable set is shown in FIG. 4. In this embodiment, each of four lengths of tubing connect a valve means 82 to one of the other components of the disposable set, namely, the needle 72, the rotor 2a and the first and second containers 91, 92.

#The non-disposable portion of the system includes mechanisms for spinning the rotor 2a and applying pressure to the rotor 2a to force fluid out of the rotor 2a. FIG. 2 shows the components of a preferred arrangement for spinning and pumping. A centrifuge chuck 4a holds the rotor 2a; the chuck 4a has a clamp 8 that holds the rotor 2a securely in place in the chuck, and an 0-ring 35 that forms an air-tight seal. A drive motor 50 is connected to the chuck 4a by means of a shaft 51. In order to apply pressure to the rotor 2a to pump fluid out of the rotor, the shaft 51 has an axial hole through its center 53 and is connected to a rotary pneumatic seal 55, which in turn is connected by tubing 59 to a compressor/vacuum pump 61 and to a controllable exhaust valve 63. Holes 65 in the interior of the chuck 4a allow air to flow to and from the compressor/vacuum pump 61.

#These spinning and pumping mechanisms are preferably disposed in a control unit 6. The control unit, as shown in FIG. 3, may also incorporate a mechanism 77, such as a pump, suitable for metering the anticoagulant from the anticoagulant bag 91 into the whole blood in the proper ratio at the distal end of the needle 72 as the blood is being drawn from the donor. The anticoagulant metering mechanism 77 is also shown schematically in FIG. 1.