The present invention relates to a method and apparatus for taking blood. More specifically, the invention is concerned uiith the mixing of blood and an anticoagulant as the blood is taken. Accordingly, the present invention relates in particular to a method and an apparatus for controlling the supply of anticoagulant to a blood-collecting container so that the container in which the blood is collected contains initially sufficient anticoagulant without the blood which enters the container first becoming so diluted ωith anti- coagulant as to be harmfully impaired.

When taking blood, for example from blood donors, the blood collected must be mixed uiith an anticoagulant, e.g. an ACD- solutioπ, in order to prevent coagulation. The simplest method in this respect, and the one most often applied, is to ensure that the container in which the blood is collected contains initially the requisite amount of anticoagulant. During the blood-taking procedure, the container is rocked backwards and forwards, so as to mix the blood quickly with the anticoagulant present. One drawback with this method, however, is that the blood which enters the container first is so diluted with anticoagulant as to become impaired. Experi¬ ments have shown that this is particularly true of thrombo- cytes (low pH) and the amount of Factor VIII in plasma, the Factor VIII being of importance to persons suffering from haemophilia. It will be seen from the exposition given below that high degrees of dilution are particularly harmful, where¬ as minor over-dosages are of much smaller significance.

Other methods known to the art are based on successively supplying anticoagulant to blood during a blood-taking proce¬ dure, in pace with the blood flow. In these cases, the anti¬ coagulant is stored in a separate storage container and trans¬ ferred therefrom to the container in which the blood taken is collected, this transfer being effected by suction, or

with the aid of a pump. Blood and anticoagulant can then be mixed as the blood taken from a blood donor runs into the blood-collecting container. One drawback with such methods resides in the comparatively complicated and expensive equipment and apparatus required for storing and supplying the anticoagulant.

The invention is based on the concept that when collecting blood and mixing the same with anticoagulant held in a sufficient quantity in a blood-collecting container, a part of this anticoagulant is prevented from contacting the blood. This separation or segregation of part of the anticoagulant present is preferably effected with the aid of a mechanical influence externally of the container, such that separated anticoagulant is brought, either continuously or intermit¬ tently, into contact with the blood collected, and mixed therewith. In accordance with the invention, this affords the advantage of enabling the use of a standard container which contains from the outset a requisite amount of anti- coagulant while, at the same time, ensuring that the blood first entering the container does not become so diluted with anticoagulant as to be damaged. This enables blood to be taken in a simple and inexpensive manner, while providing high yields.

It will be understood that when practicing the method or using the apparatus according to the invention, the afore¬ said portion of the anticoagulant present in the container can be held separated from the main body of anticoagulant in a variety of ways and with the aid of a number of diffe¬ rent means. A common feature of the method and means used to separate or segregate a part of the anticoagulant, how¬ ever, is that it must be possible during a blood-taking process to supply separated or segregated anticoagulant coπ- tinuously or intermittently to that section of the container in which the blood collected is located. In other words, the quantity of anticoagulant held out of contact with the blood

collected shall decrease progressively, or intermittently, during the blood-taking process. Another common feature in- this re~gard is that this separation or blockiπg-off of part of the anticoagulant present is preferably effected by mecha- nical manipulation of the container from without, so as to avoid direct physical contact with the blood and/or the anticoagulant.

Figures 1 and 2 of the accompanying schematic drawings illustrate one embodiment of the invention, of which figures Figure 1 is a side-view of a cradle or rocker seen during an early stage of a blood-taking process, and Figure 2 is a corresponding plan view. Figures 3 and 4 illustrate a further embodiment of the invention, of which figures Figure 3 is a partial sectional view of an arrangement, seen during an early stage of the blood-taking procedure, and Figure 4 illustrates the separation of a part of the anticoagulant in an annular container.

The apparatus illustrated in Figure 1 comprises a base struc¬ ture 1 having incorporated therein a mechanical or electrical motor 2. The reference 3 identifies a motor-driven crank jour¬ nal which, via a crank web or arm 4, is operative in rocking, in a desired manner, a table 5 απ which there is placed a plastic and pliable blood-container 6 containing a given quantity of anticoagulant. Arranged over the container 5 is a stirrup structure 7, which is so mounted as to limit the volume of the container so that at a maximum it can only accαmodate the amount of blood intended. The reference 8 identifies a heavy piπch-rαller which rests on the container and* which, as a result of the weight exerted by the roller, pinches the plastic container and divides it into two sec¬ tions. The reference 9 identifies a rearward or downstream section as seen from the blood-withdrawal pipe 10, this sec- tion containing the major part of the anticoagulant at the commencement of a blood-taking procedure. The reference 11 identifies a forward or upstream container section, into

which the blood taken flows. The reference 12 identifies a shaft ^" which connects the roller 8 to a spring-biased damping meaπs_ 13.* The reference 14 is a spring which strives to draw the shaft 12 into the damper 13. This movement is delayed, due to the fact that liquid in the damper is therewith forced to pass a throttle orifice 15 in a piston 16. The piston 16 is also provided with a check valve or πoπ-returπ 17 which is arranged to enable the piston to be quickly pressed-in against the bias of the spring. The reference 18 identifies a hinge means which enables the stirrup structure 7, together with the damper 13 and heavy roller 8 mounted therein, to be raised and lowered.

The arrangement has the following operational mode:

Upon commencement of a blood-taking procedure the roller 8 is withdrawn from the damper at the same time as the table 5 is tilted, so that the anticoagulant in the container col¬ lects in the bottom or at one end thereof. The stirrup- structure 7, together with the damper 13 and the roller 8, is then lowered down about the hinge means 18 so as to lie on the container 6, therewith to entrap the major part of the anticoagulant fluid in the container section 9. The blood enters the container-section 11 and the cradle is rocked with the aid of the arrangement of components 2, 3 and 4, so as to mix the blood with the minor quantity of anticoagulant which, because of the dimensioning of the cradle, could not be accomodated in the container-section 9. The spring 14 draws the roller 8 slowly towards the bottom, or end, of the container, wherewith anticoagulant is progressively forced to pass beneath the roller and into the container-section 11, where the anticoagulant is mixed with the incoming blood. Prior to having completed the blood-taking procedure, the roller 8 will have passed totally beyond the container 6 so that all the anticoagulant will have mixed with the blood.

The blood cradle according to the invention minimizes the

amount of blood exposed to overdosing, since during the first stage of the blood-taking procedure the major part of the anticoagulant is separated from that part of the container in which the blood is rocked, and since the withheld anticαa- gulaπt is supplied gradually to the blood-containing section of the container either continuously or intermittently during the blood-taking procedure.

In the described and illustrated embodiment, the major part of the anticoagulant present in the container is isolated from the incoming blood by means of a pinch roller located on top of the container. A pinch roller is known per se, for example from Swedish lay-out Print 7104975-3, although this known roller has a completely different function to that of the roller according to the invention.

Figures 1-2 illustrate an embodiment of a method and an apparatus in which the container is of an elongated, substan¬ tially rectangular configuration, and in which anticoagulant initially isolated from blood entering the container is gra¬ dually supplied continuously to said blood and mixed there¬ with during the process of taking blood. In the embodiment of the method and apparatus illustrated in Figures 3-4 the container has an annular configuration, and initially isolated anticoagulant is supplied to and mixed with the blood collec¬ ted discontiπuously. Once having understood the basic concept of the present invention and obtained an understanding as to how the method is effected, it is an easy matter for one skilled in the art to construct an arrangement according to the invention. Consequently, in order to explain the invention in the simplest and clearest possible manner, the illustration in Figure 3 lies between a functional sketch and a construc¬ tional sketch, and is not a correctly drawn construction drawing. Thus, in order to facilitate an understanding of the invention, Figure 3 shows certain details in section and others in side view, in a manner which might be considered improper from a technical drawing aspect. However, Figure 3

* ^• » *.

when taken together with the specification as a whole will enable one of normal skill in the art to carry out a method according ^' to the invention and to construct an arrangement according to the invention with ease.

In Figures 3-4 the reference 63 identifies an annular con¬ tainer for collecting blood, which passes from a blood donor through a withdrawal tube 62. The container is placed on a conical plate or dish 54. Arranged over the container is a lid 55 which has provided thereon a circular flange 64, this flange being caused to bear externally on the container so as to divide the same into two mutually concentric sections 60 and 61. The radially inner section 60 of the container rests on a circular plate 57, which is supported by a number of springs 58. A spring 56 is arranged to lift the lid 55 upon the release of a catch means 59, which is acted upon by the weight of the container section 60, via the plate 57 and the springs 58. A motor 52 is arranged to impart to the container plate, the container and other components an oscillatory, rotational movement about an axis. A balance 51 is arranged to sense the weight of the container assembly and to control in response to the weight sensed a clamping device 53, through which the withdrawal tube extends.

The method illustrated by means of Figures 3-4, and the apparatus shown at least in part in Figure 3, function in the following manner. A blood container 63 is placed concent¬ rically on the plate 54. As a result of the coπicity of the plate the anticoagulant present in the container collects at the periphery or the outer part of the container. The lid

55, which has a stub axle 65 arranged thereon, is placed on top of the container and pressed down against the spring

56, until the catch means 59 locks the stub axle 65 in posi¬ tion. This causes the flange 64 to press externally against the container so as to divide the container into an inner section 60 and an outer section 61. The lid 55 and the flange 64 are so formed that when the lid is pressed down a desired

volume of anticoagulant is squeezed from the outer part, or periphery, of the container to the inner part thereof and when ^" tne container is divided remains in the inner section. The main part of the anticoagulant, however, is kept separa¬ ted from the inner section by the flange in combination with the plate 54, and remains in the outer section 61 when the lid is pressed down. The container is connected to a blood donor via the tube 62, whereafter the motor 52 is started in order to commence the blood taking procedure. This results in oscillating rotatory movement of the container, such as to mix the blood entering the section 60 with the anticoa¬ gulant present therein.

When a predeterminated quantity of blood has entered section 60, the section becomes so heavy that the plate 57 on which it rests under the action of the springs 58 releases the catch means from the stub axle 65. Once the stub axle has been released, the spring 56 is able to lift the lid 55 so that the flange 64 In combination with the plate 54 no longer divides the container into two sections, thereby enabling the entire container to be filled with blood and the blood mixed with the entire quantity of anticoagulant present. When the required quantity of blood has been withdrawn, the balance 51 activates the clamping device 53 so that no more blood is withdrawn into the container. The balance also controls a signalling device (not shown) arranged to produce « signal indicating that the blood-taking procedure has been terminated.

The invention is not restricted to methods and apparatus involving the use of a motor-driven rocker in accordance with the embodiment of Figures 1-2 or an oscillating plate in accordance with the embodiment of Figure 3. The manner in which the blood collected is mixed into the aπticoagu- lant is of subordinate significance, provided that it does not prevent or restrict the separation or blocking-off of a part of the anticoagulant from contact with the blood in

accordance with the invention. It will also be understood that the invention is not limited to methods and apparatus in wh_ich said separation is effected by means of a pressure or pinch roller arranged to pass over a bag on a cradle table in accordance with Figures 1 -2 or by means of a flange on a lid placed over a container in accordance with Figures 3-4. For example, the pressure roller can be replaced with pressure slats or bars arranged for movement towards and away from one another, these bars, far example, being capable of compressing one or more portions of the bag therebetween, these portions dividing the bag into two or more sections which are totally isolated from one another. The anticoagu¬ lant can also be separated, for example, by suspending the bag aver a narrow horizontal supporting roller, so as to form a bag-section on each side of the crest of the roller. This bag-supporting roller can also be arranged to co-act with an overlying pressure roller and be slowly turned clock¬ wise or anticlockwise around its axis to effect progressive transfer of withheld coagulant to the bag-section receiving the incoming blood. It will be understood that many methods and procedures are conceivable for separating anticoagulant from the blood in the container. Neither is. the invention restricted to bags of elongated, generally rectangular configuration according to Figures 1-2, or to the annular bag of the Figure 4 embodiment, but can be applied with bags of any suitable configuration which will enable a major part of the anticoagulant to be held separated in accordance with the invention. Finally, it is conceivable, in accordance with the invention, to supply the initially separated aπti- coagulant discontinuously, in several stages, instead of all at once according to Figures 3-4. In this respect the contai¬ ner can be divided into more than two sections by means of externally applied influences.

0

0PTIMATI0N OF ANTICOAGULANT ADDITION WHEN TAKING BLOOD

Blood, from a normal person was taken in a random sequence in small tubes containing varying amounts of anticoagulant. The blood was mixed immediately and cεntrifuged to plasma, which was analysed with respect to Factor VIII. Corrections were made to compensate for the varying degrees of plasma dilution. Anticoagulant = CPD with current percent admix¬ ture, 12 _/ . in the case of donated blood.

% CPD Factor VIII rel.

5 90

7 104 10 107 12 100 20 102 40 76 60 42 80 .24

Blood from another normal person was taken in a random sequence in small tubes containing varying amounts of anti¬ coagulant. The blood was mixed immediately and centrifuged to plasma, which was analysed in respect of Factor VIII. Corrections were made to compensate for varying degrees of plasma dilution. Anticoagulant = CPD with current percent admixture, 12% in the case of donated blood.

% CPD Factor VIII rel

5 91

7 97 10 103 12 100 20 91 40 60 60 31 80 20