Abstract:
A container for use in dialysis, containing a certain amount of a salt concentrate in the form of a powder, granules or tablets or mixtures thereof, having an inlet for the water and an outlet that is connectable to a dialysis machine. Both the inlet and the outlet are situated on one side of the container, and each includes a filter therein to prevent any undissolved salt concentrate from leaving the container.

Description:
This is a nationalization of PCT/EP02/07922 filed Jul. 16, 2002 and published in German. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a container for use in dialysis containing a certain amount of a salt concentrate in the form of powder, granules or tablets or mixtures thereof, having an inlet for water and an outlet that is connectable to a dialysis machine. 
     2. Description of the Related Art 
     In dialysis systems, it has previously been customary to prepare the dialysate needed for the dialysis process just before the dialysis session. To do so, the dialysate concentrate in solid form is placed in a container; the dialysate solids are usually in the form of powders, granules or tablets, i.e., pressed tablets of powder. To form the dialysate, the solid dialysate concentrate must be dissolved in water. To do so, the container with the solid dialysate concentrate is secured in the dialysis machine and the water in which the dialysate concentrate is to be dissolved is usually introduced into the container on one side and removed again on the opposite side. This results in the problem that the solution discharged is not saturated, so the composition of the dialysate varies. 
     U.S. Pat. No. 5,385,564 describes a solution which starts with the granular form of the dialysate concentrate in a container, with the water being introduced into the container through a connection. However, the water must first be introduced completely into the container and the finished dialysate is discharged again through the same opening in the container after appropriate dissolving of the concentrate in the water. Continuous operation is impossible with this solution. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to make available a container with which it is certain that the solution prepared for the dialysis session is saturated, even when using components having a very low solubility. 
     This object is achieved according to the present invention starting from a known container by the fact that both the inlet and the outlet are situated on one side of the container, preferably in the bottom area. It is essential here for both the inlet and outlet to be situated in proximity to the dialysis concentrate, which is in the form of solids. This ensures that fresh water will flow around the dialysate concentrate particles in solid form and contribute to the most rapid possible dissolving because of the resulting turbulent flow and development of eddies. Positioning the outlet on the same side as the inlet ensures that the liquid will have the longest possible dwell time in the dialysate concentrate, which is not yet dissolved, even in continuous operation, so that saturation of the solution can be achieved here even in the case of salts having a low solubility. Because of this arrangement, the differences in density can also be compensated. 
     Preferred embodiments of the present invention are briefly described as follows. 
     Accordingly, the container may advantageously be designed in the form of a bag which is formed by two films welded together, the inlet and outlet being formed in the bottom area, whereby the inlet and outlet are preferably designed in the form of connectors which are connectable to the dialysis machine. 
     Filters having a porosity of 50 μm to 500 μm are especially advantageously provided in both the inlet and outlet. 
     The container may have one or more partitions to form different areas in the interior, but the partitions are at least perforated so that an exchange of fluid between the individual regions is possible. In this variant, the fluid passes in a labyrinthine path through the container before reaching the outlet after starting from the inlet and flowing through the solid dialysate concentrate and partially dissolving same. With an appropriate configuration of the partitions, the inlet and outlet may also be situated outside of the bottom area if it is ensured that through an appropriate configuration of the partitions, the fresh liquid is guided through the sediment of dialysate concentrate which is made up of solids. In this container, the partitions can be produced especially easily if the container is made of a bag in which the side walls of the bag are welded together at appropriate locations where the partitions are to be formed. 
     The container may be used to particular advantage when the dialysate concentrate contains sodium bicarbonate or sodium chloride, among other ingredients. 
     These and other objects of the invention, as well as many of the intended advantages thereof, will become more readily apparent when reference is made to the following description taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Additional details and advantages of this invention are explained in greater detail below on the basis of an exemplary embodiment depicted in the drawings, in which: 
         FIG. 1  is a schematic diagram of a first variant of the present invention; 
         FIG. 2  and  FIG. 2   a  present a graphic illustration of the introduction of water into a bag according to  FIG. 1 , partially enlarged; 
         FIGS. 3-8  illustrate different embodiments of the present invention in a simplified sectional diagram; and 
         FIG. 9  is a diagram showing the temperature of the liquid as a function of time. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In describing a preferred embodiment of the invention illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, the invention is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. 
     In the variant according to  FIG. 1 , the container  10  consists of a bag made of two plastic films welded together at the sides. In the bottom area of the bag  10 , an inlet  12  and an outlet  14  are provided, these being designed as tubular connections in the exemplary embodiment depicted here, with the corresponding tubing ends  16 ,  18  (see  FIG. 2   a ) being attachable thereto by pushing onto the connection. The lower part of the bag contains the dialysate concentrate  20  comprising of powder, granules or tablets and/or mixtures thereof. In the upper area, the bag  10  has two receptacle openings  22  by means of which these bags can be suspended. Filters  24  having a porosity of 50 μm to 500 μm that can be inserted into the tube are arranged in the inlet  12  and the outlet  14 . These filters  24  are also shown in sectional view in  FIG. 2   a.    
       FIG. 2  shows the flow pattern of the water flowing in through the inlet  12 . In particular, the arrows here indicate that fluid flows through the dialysate concentrate along a comparatively broader channel and therefore turbulence is created due to this flow and also due to the density differences between more and less concentrated solution. From the upper area of the bag, the water must again flow through the entire bed of dialysate concentrate to then be removed in saturated form through the outlet  14 . The filters  24  prevent any undissolved dialysate concentrate from entering the tubing lines  16  and/or  18 . 
     On the basis of  FIGS. 3 through 8 , the different variants of the inventive container  10 , which is in the form of a bag here, can be explained. The bag shape is a simple embodiment but this shape is not necessarily stipulated according to the present invention. 
       FIG. 3  shows a section corresponding to the embodiment according to  FIGS. 1 and 2 .  FIGS. 4 through 8  differ from this simplest of variants in that partitions  26  are provided here in the interior of the bag, forming different regions in the bag. This results in a labyrinthine passage of the fresh water through the bed of dialysate concentrate. 
       FIG. 4  shows the partition  26  between the inlet  12  and the outlet  14 , serving here essentially to prevent a short-circuit flow between the inlet and the outlet. In the variant according to  FIG. 5 , two partial regions are created within the bag, these two partial regions being of very different sizes, although the inlet and outlet here are again shown in the lower region of the bag. Essentially, however, they could also be rotated by 180°. In this case, the inlet would be situated in the narrower region of the inlet. Due to the design of the partition, this ensures that fresh water is introduced into the region of the dialysate concentrate containing solids and passes through this concentrate before the saturated solution is then discharged from the outlet  14 . 
       FIG. 6  shows two symmetrical chambers  28  and  30  formed by the partition  26 . 
       FIG. 7  corresponds essentially to  FIG. 5  and leads to a bag that is similarly usable. In this case an elongated chamber is formed merely by an additional partition  27  within the bag, thus defining the inlet in relation to the outlet  14 . This chamber is designed to be even longer according to the diagram in  FIG. 8 . The variants according to  FIGS. 5 through 8  each have bags which are shaped in a triangular shape toward one side. This is appropriate in particular when the bags are rotated by 180° in comparison with the diagram here, because then the undissolved dialysate concentrate collects in the region of the tip of the triangle, i.e., in the lowest region of the bag whereby here due to the corresponding design of the chambers formed by the partitions, this ensures that the liquid also flows through this region of the bag. 
     Finally,  FIG. 9  shows a diagram which indicates that a constant saturation concentration can be achieved if a constant temperature is maintained during preparation of the dialysate. The saturation of the solution here is determined by measuring the conductivity. A constant conductivity of approximately 60 mS/cm is also measured here at a constant temperature of slightly more than 28° C., with the dialysate here being measured over a suitable period of time at the outlet  14  in an arrangement according to that shown in  FIG. 1 . 
     The foregoing descriptions and drawings should be considered as illustrative only of the principles of the invention. The invention may be configured in a variety of shapes and sizes and is not limited by the dimensions of the preferred embodiment. Numerous applications of the present invention will readily occur to those skilled in the art. Therefore, it is not desired to limit the invention to the specific examples disclosed or the exact construction and operation shown and described. Rather, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.