APPARATUS FOR MIXING A FLUID MEDIUM Containers for a fluid medium already exist that have a suspension member at one end and a tube at the other end. When such a container is filled, the tube is also filled. Such units of container and tube can require certain tests of the medium contained and, for the test to be satisfactory, the medium in the tube must be introduced into the container and be very thoroughly mixed there before it can be re- introduced into the tube so that a sample that is suitable for testing can be extracted from the tube. Such a container arrangement is particularly suitable for blood and, for blood to be usable, it must be regularly tested. The blood is commonly contained in bags that have a suspension device at one end and a connection tube at their other end. When it becomes necessary, before a test, the blood contained in the tube is added to the blood contained in the container and is mixed very thoroughly there.

When this has been done, the blood has to be re-introduced into the tube. Hitherto, the blood from the tube has been conveyed to the container by a nurse using a pair of roller forceps to press all the blood out of the tube and into the container. This is a strenuous and cumbersome procedure.

The object of the present invention is to relieve a nurse who is preparing for a test of blood by creating an apparatus where the blood in the tube is pressed back into the container, with the aid of the apparatus, and then thoroughly mixed there, whereupon the blood can be re-introduced into the tube. The apparatus in accordance with the invention has a fixing member for the container that is so designed that it can impart different movements to the container. Further, the apparatus has a unit that is capable of compressing the tube so that the blood in the tube is conveyed back to the actual container. Thereafter, the container is subjected to movements so that thorough mixing is obtained. When this is done, the blood is re-introduced into the tube. The evacuation and filling of the tube can be performed a number of times, as required. Customary blood bags are provided with an eyelet at one end and a tube at the other end. When such blood bags are used, the blood bag can be suspended from a stand and the stand thereby constitutes the suspension member. The tube is introduced into a unit that draws the tube towards itself, thereby evacuating its contents into the container, and thereafter moves the tube back so that the same can be filled with blood again. These movements can be repeated. The unit has indicator members that sense both ends of the tube so that the unit is able to evacuate a tube completely.

Further characteristics of the present invention are disclosed in the claims set out below.

An embodiment of the present invention will be described with reference to the two accompanying drawings, in which Figure 1 show a complete apparatus in accordance with the invention and Figure 2 shows the unit for evacuating and filling the tube.

Figure 1 shows a tube-evacuating unit, placed on a shelf, more particularly at one end of said shelf. A holder member, in this case in the shape of a stand 5, is arranged at the other end of the shelf. The apparatus is intended to be utilized for bags of a rectangular shape that are provided with a tube at one end and a suspension eyelet at their other end, this eyelet being attached to an attachment point 7 on the stand. The tube is introduced into an opening in the tube-evacuating unit. The tube-evacuating unit comprises a feeder wheel 8 that co-operates with a counter wheel 9. The tube 2 is introduced into a lower tube passage 11, having tubular character, so that the tube is passed between the envelope surfaces of the two wheels 8 and 9, and thereafter expelled through the upper tube passage. A photocell is provided at each of the two tube passages to sense the ends of the tube.

In this way, the blood can be completely evacuated from the tube. The unit 1 has drive arrangements controlled by the photocells 10 and 13 so that movements back and forth are obtained. The unit further has an adjustment device so that the unit can be adapted to different tube diameters.

The apparatus shown in Figure 1 operates in the following way. A bag 3 is suspended from the attachment point 7 and the tube end is introduced into the opening of the unit 1. Thereafter, the unit is started and it will then draw the tube towards itself until the blood has been evacuated from the lower end of the tube.

Drawing the tube of the bag subjects the bag to motion, mixing the quantities of blood from the container and the tube. As the blood bag 3 is suspended from the holder 7, the movements of the tube, caused by the unit 1, will subject the container 3 to vigorous mixing movements. Obviously, an operator can impart additional movement to the container manually so that good mixing is provided. It should be evident, however, that a bag can be placed on a fixing member in one way or another such that the fixing member can impart desired motion to the bag so that

fully satisfactory mixing takes place and, further, such that the end of the bag tube can be moved towards the tube-evacuating unit 1.

It should be evident that the present apparatus, which is intended to enable control of superior mixed blood, can also be used for other mediums that require mixing and require control.