Bags for solid concentrates

Abstract

The invention relates to a bag (1) made of flexible walls, equipped with an introduction fluid line for introducing dissolved water and an extraction fluid line (121, 122) for extracting the obtained solution. According to the invention, the interior of the bag has a generally V-shaped lower edge (13), the tip of the V being further from the center of the bag than the branches of the V, the extraction fluid line leading into the bag at a point closest to the tip of the V.

Description

Technical Field

[0001] The invention relates to a bag consisting of a flexible wall provided with an introduction fluid line for introducing dissolved water and an extraction fluid line for extracting the solution obtained. Background Art

[0002] Such bags are commonly used in the manufacture of hemodialysis solutions, in particular solutions based on solid concentrates, such as alkaline solid concentrates.

[0003] A hemodialysis treatment requires 120 to 240 liters of dialysis solution. For bicarbonate dialysis, the dialysis solution is produced online in an extemporaneous manner based on an acid concentrate and a base concentrate.

[0004] Acid concentrates typically consist of various electrolytes, acids, and glucose. Due to the presence of multiple components with varying dissolution rates, acid concentrates are typically supplied as liquid concentrates. If a solid acid concentrate is used, it should be completely dissolved before processing to ensure the correct composition of the liquid concentrate. The container used for the solid concentrate should therefore be large enough to dissolve the entire contents before processing begins.

[0005] This complete dissolution condition before treatment is not necessary for alkaline concentrates. In fact, alkaline concentrates are usually composed of a single component, sodium bicarbonate. The liquid concentrate is a saturated sodium bicarbonate solution that can be produced continuously throughout the entire duration of the treatment. The bag containing the solid concentrate is connected to a hemodialysis generator, which introduces water into the bag to form a saturated solution. When this condition is met, the water supply and the extraction of the saturated solution proceed simultaneously until the solid concentrate is completely dissolved.

[0006] For cost and logistical reasons, the bag should be as small as possible and the amount of bicarbonate should be as low as possible, noting that the amount of bicarbonate should be sufficient to ensure treatment with a single bag. In practice, changing bags during treatment requires time and a lot of labor.

[0007] Various bags are known from the prior art that make bicarbonate dissolution as efficient as possible. For example, the connector for connecting the bag to a hemodialysis generator can be fixed high up in the bag. Water thus flows from this height into the concentrate, while an extraction tube extracts the concentrate from the bottom of the bag. To improve salt dissolution at the end of the process, it is known to bend the lower edge of the bag so that the remaining salt falls into one of the two corners of the bag. The beveled edge has a slope effect, which forces the undissolved bicarbonate to accumulate in the smallest possible volume at the bottom of the bag. Furthermore, the extraction tube can be arranged reliably in this area.

[0008] However, a tilted bag bottom is not the optimal solution, as undissolved salt does not fall into the narrow part of the bag in a reproducible manner. If the bag size is not to be increased too much, the tilt must also be quite small. Studies have shown that the amount of undissolved salt remaining in the bag varies greatly. To ensure that there is always enough to complete the treatment, an excess of approximately 100 to 200 grams of bicarbonate should be prepared. Summary of the Invention

[0009] The object of the present invention is therefore to modify the prior art bags so as to significantly reduce the amount of solid concentrate that is excessively added to ensure that the amount of liquid concentrate is sufficient for hemodialysis, without significantly increasing the size of the bag.

[0010] This objective is achieved by providing the interior of the bag with a generally V-shaped lower edge, the tip of the V being located further from the center of the bag than the branches of the V, with the extraction fluid line being directed into the bag at a point closest to the tip of the V. By choosing two inclined edges (two branches of the V) rather than one, the slope of the lower edge can be made sufficient to ensure that the remaining solid concentrate falls under the action of gravity into the tip of the V, which constitutes the lowest point of the bag, while maintaining the bag's regular dimensions.

[0011] Preferably, the connecting area between two branches of the V is rounded. This avoids corners where salt that has not been penetrated by dissolved water could accumulate.

[0012] The two branches of the V can have the same inclination and / or the connection area between the two branches of the V can be located at the center of the lower edge. The combination of these two features makes it possible to obtain a symmetrical bag. The branches of the V are preferably obtained by welding on the bag itself.

[0013] In order to adapt to the deformation of the bag when it is filled and to avoid the consequent wrinkles with mechanical stress, the lower edge of the bag can be followed by an intermediate zone, opposite the tip of the V, consisting of:

[0014] a circular pit, the inclination of which at its junction with the branches of the V is less than that of the branches of the V and the inclination at its opposite ends is almost vertical, and / or

[0015] - a narrow nose which projects towards the centre of the bag to form a nose, this narrow nose being intended to slightly reduce the transverse section of the bag.

[0016] This intermediate region, in particular the circular depression, prevents the formation of vertical folds in the V-shaped portion.

[0017] In a preferred embodiment of the invention, the bag consists of two surfaces which are connected together via their outer edges, in particular by welding the edges.

[0018] In a simple embodiment, the interior of the bag of the invention comprises an upper edge, a V-shaped lower edge and two side edges, each of which connects the end of the lower edge to the corresponding end of the upper edge, if necessary with an intermediate area between the V-shaped lower edge and the side edges. The bag preferably has a substantially rectangular shape, with the tip of the V located in the center of one of the smaller sides of the rectangle, the bag extending beyond the V-shaped lower edge and on both sides of the V to an outer lower edge parallel to the upper edge (11a), the outer lower edge (11c) preferably coinciding at least partially with the lower edge (13, 132) at the tip of the V. The bag of the invention can also be produced by superimposing two rectangular faces of a sheet made of a suitable plastic material and joining them together along the side edges, the upper edge, the V-shaped lower edge and, if necessary, the outer lower edge by welding, gluing or any other suitable means, the side edges preferably being fixed (welded, glued, etc.) up to the outer lower edge.

[0019] The introduction fluid line preferably opens into the bag at a point opposite the tip of the V, which ensures that the dissolved water permeates all of the solid concentrate contained within the bag before exiting the bag through the extraction fluid line, which itself opens proximate the tip of the V.

[0020] The extraction fluid line may comprise a tube having a filter provided at a first end thereof, the tube being sized so that the filter can be placed proximate the tip of the V. The filter allows the solution to be drawn without entraining solid particles.

[0021] The bag can be provided with a connector for connecting the bag to a hemodialysis generator, the connector passing through a first section of the fluid introduction and extraction lines, the first section being extended by tubes mounted on opposite ends thereof through a filter located closest to the tip of the V, preferably located opposite the tip of the V. The connector can be inserted into the edge of the bag distal to the lower edge, preferably in the upper edge opposite the lower edge of the V. Another solution is to insert the connector into the wall of the bag at a distance from the lower edge of the V, preferably in the upper half.

[0022] The bag according to the invention is particularly suitable for hemodialysis (HD) and hemodiafiltration (HDF). It may contain bicarbonate to produce a saturated solution for dialysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention is described in more detail below with the aid of the accompanying drawings, in which:

[0024] Figure 1a is a schematic diagram of a bag at the end of the dissolution process according to the prior art;

[0025] Figure 1bis a schematic diagram of a bag at the end of the dissolution process according to the present invention;

[0026] Figure 2a is a view of the lower portion of an empty bag according to the prior art;

[0027] Figure 2b is a view of the lower portion of an empty bag according to the present invention;

[0028] Figure 3a is a side view of a filled bag according to the present invention;

[0029] Figure 3b is a front view of a filled bag according to the present invention; and

[0030] Figure 4 is a clear example of the realization of a bag according to the invention. DETAILED DESCRIPTION

[0031] For reasons of clarity, the description uses spatial references such as "below" or "above", "higher" or "lower", "vertical" or "horizontal". These references are to Figure 1a and 1b The bag is shown with the connector positioned high.

[0032] The bag (1) according to the invention, like the bag (9) of the prior art, consists of two rectangular lower edges of a flexible plastic sheet. For use in the dialysis field, the bag can be made of low-density polyethylene (PEBD), a mixture of polyamide and low-density polyethylene (PA / PEBD), or a mixture of low-density polyethylene and high-density polyethylene (PEBD / PEHD), or even a double-layer material. The two lower edges are fixed together by their outer edges so that the empty bag is flat at least in its lower part. This fixing is preferably achieved by welding, but other fixing methods such as gluing are also conceivable. For reasons of clarity, the term "welding" will no longer be used in the following process, although it does not represent a limiting feature and any other fixing method compatible with the use of the bag (in particular gluing) is also applicable to the present invention. In the example presented here, the bag has two side edges (11b, 11d, 91b, 91d), an outer lower edge (11c, 91c) and an upper edge (11a, 91a). The side edges, the outer lower edge and the upper edge are essentially straight when the bag is empty. Instead of using two hems welded and superimposed at their outer edges, it is also possible to use a tubular wall closed at its two ends, for example by welding, or even a sheet folded in half and closed at its superimposed edges, in particular by welding. The overall shape of the bag (here rectangular) and the number of edges are not important. It is conceivable that the bag may have an overall shape of a trapezoid, a triangle, or even a circle.

[0033] The extraction device (12, 92) is placed in one of the edges (11a, 91a) of the bag, or in a wall of the bag at a distance from the edge. Typically, these extraction devices include two fluid lines, one for introducing water to dissolve the sodium bicarbonate, and the other for extracting the obtained solution contained in the bag. In the example herein, the extraction device is composed of a connector (12, 92) of the type disclosed in patent application EP 1 344 550 A1. It is advantageous to combine the extraction device with a connection device connected to a hemodialysis generator. The connector (12, 92) is inserted into the upper edge (11a, 91a). Of course, any other type of extraction device can also be envisioned without having to assume the additional function of the connection device. Other possible implementation examples are two separate tubes inserted into the upper edge (11a, 91a) as disclosed in US 4 561 110. These tubes can be inserted into two different edges, in particular two opposite edges. It is also conceivable to have a single fluid line for introducing dissolved water and extracting the completed solution.

[0034] The two fluid lines of the connectors (12, 92) lead to the upper part of the bag (1, 9). The extraction fluid line of the connectors (12, 92) is equipped with a hose (121, 921) at the end of which is a filter (122, 922). The length of the hose is selected so that the filter is placed in the lower part of the bag. Dissolved water is thus introduced into the upper part of the bag, permeates the solid concentrate to saturate it, and the saturated solution passes through the filter and the hose and is extracted into the lower part.

[0035] To ensure that the solid concentrate accumulates in as little space as possible at the end of the process, the transverse cross-section of the lower portion of the bag is reduced. In the prior art bag (9), this reduction is achieved by implementing an inclined weld (93) located between one of the two corners (91e) of the lower portion of the bag and the opposite side edge (91d). The inclined weld has two sections with different slopes: the first section (931) near the lower corner (91e) has a smaller slope than the second section (932) near the side edge (91d) opposite the lower corner (91e). In the example presented here, the first section is inclined at approximately 20 degrees relative to the horizontal plane (or the outer lower edge 91c), and the second section is approximately 38 degrees. The 20-degree slope allows the tube to conform to its radius of curvature and allows the filter to end in the corner of the bag, while the 38-degree slope allows the powder to fall as it dissolves. The filter (922) fixed to the end of the hose is located on the first section and its end is also as close as possible to the lowest point (94). The second section is a compromise. In fact, the greater the slope, the easier it is for the concentrate to slide down the inclined weld, but the wasted space (933) between the inclined weld and the second corner (91f) of the lower part of the bag will also be greater. Alternatively, in order to compensate for the wasted space while maintaining the same available space, the height of the bag should be increased.

[0036] Furthermore, when the bag of the prior art is filled with solid concentrate and undergoes a dissolution process, it tends to deform asymmetrically, so that a kind of wrinkle appears in the wall of the bag. In order to ensure that the filter is located on the first section (931) of the inclined weld and its end is at the lowest point (94) of the bag, it is necessary to fix the tube (921) to the fluid line of the connector (92) opposite the corner (91e) where the lowest point is located, otherwise there is a risk that the filter will not be located at the lowest point after the bag is deformed.

[0037] As dissolution continues, the amount of solid concentrate in the bag decreases. Under the influence of gravity, the solid concentrate tends to accumulate in the lower part of the bag. However, experience has shown that at the end of the process, a portion of the solid concentrate hangs on the inclined weld seam (93) on the wall of the bag, as shown in FIG. Figure 1aAs shown schematically. It forms a kind of groove in the accumulated solids so that the dissolved water can no longer penetrate the solid concentrate. Some studies carried out on hemodialysis bags have shown that at the end of the process, 2.1% to 21.6% of solid concentrate (bicarbonate) remain, these values varying with the initial volume of the solid concentrate and the dissolution rate. This groove effect is particularly due to the fact that the dissolved water is introduced from the filter essentially vertically, which is not conducive to bringing the solid concentrate to the lowest point where the filter is located. The presence of the tube (921) along a portion of the inclined weld also facilitates the retention of solids. In order to compensate for this part of the retained product, it is necessary to provide more solid concentrate than theoretically required. This large range observed (2.1% to 21.6%) demonstrates how the amount extracted is non-renewable. Therefore, the excess product should be sufficient to obtain the nominal volume of solution in any case. In practice, the excess portion is between 100 grams and 200 grams, depending on the size of the bag.

[0038] The bag according to the invention has been developed to significantly reduce the amount of excess product that must be added to the bag to ensure the nominal volume of solution. The lower edge of the bag (1) according to the invention is V-shaped, with the tip of the V facing the upper edge (11a) and forming the lowest point (14) of the bag. The two edges (13) forming the branches of the V are formed by two inclined welds (13) extending between approximately the middle of the outer lower edge (11c) and one of the side edges (11b, 11d). At the junction between the two branches of the V, the two inclined welds (13) are separated by a circular, in particular arc-shaped, junction area (132). This junction area forms the lowest point (14) of the bag. By moving this lowest point of the corner (91e) of the bag to the center of the lower edge (11c) and by choosing two inclined welds (13) instead of one (93), it is possible to choose a greater inclination while keeping the wasted space (131) between the inclined welds (13) and the corresponding lower corner (11e, 11f) relatively small. Of course, the material forming the wasted space (131) can also be cut, but this additional step is not necessary. It is simpler to use two rectangular hems and weld not only the edges (11a, 11b, 13, 132, 13, 11d) that strictly form the bag, but also the outer lower edge (11c), then the side edges up to the outer lower edge (11c) to form the lower corners (11e, 11f). This avoids the hem being empty at the wasted space (131). In addition, the welding of the corners stiffens these parts so that they do not tend to fold in half unhelpfully. Figure 2b It can be seen that the lower portion of the outer lower edge (11c) and the joining area (132) forming the tip of the V coincides with the lowest point of the bag.

[0039] In addition, since the bag is symmetrical, it will not be as difficult to move as the bags in the prior art (see Figure 1a ) does not deform asymmetrically. The length of the tube (121) can be chosen so that only the filter is located at one of the inclined welds (13) on the wall of the bag. The tube (121) thus does not allow solids to recede along the weld as in prior art bags.

[0040] The angle (α) between the two branches ( 13 ) of the V is preferably between 65° and 75°.

[0041] In order to follow the natural deformation of the bag when it is filled and to avoid the formation of wrinkles and the resulting tension areas, an intermediate area (15) can be provided between the apex of the two branches (13) of the V and the side edges (11b, 11d). Figure 1b and 2b In the example presented, this intermediate region is formed by a recess (151) and a narrow nose (152), the recess preferably being in the shape of a circular arc. The slope of the recess, which meets the vertex of the inclined weld (13), increases regularly until it is essentially vertical. Here, the width of the bag edge is at least equal to the general width of the side edges (11b, 11d) outside this intermediate region. The recess (151) thus leaves room for the narrow nose (152), which continues to be concave again in the lower part by diverging towards the center of the bag until the nose (152'). From this nose, the bag edge diverges again from the center of the bag. The length of the edge between the junction with the recess (151) and the nose is preferably shorter than the length between the nose and the junction with the side edges (11b, 11d), that is, the first portion is more inclined (relative to the vertical) than the second portion. If the outer contour of the empty bag is rectangular, the width of the bag edge in this narrow nose (152) increases more gently up to the nose before decreasing again, until it returns to the width of the side edges (11b, 11d). The pit (151) and the beginning of the narrow nose (152) together form a cavity (153). The narrow nose does not need to extend to the upper edge (11b). It is sufficient for it to start a few centimeters from the apex of the branch of the V. When the bag is filled with dry sodium bicarbonate, but mainly salt and dissolved water, the bag expands by about 3 to 4 centimeters, which puts pressure on the weld edge. The presence of the cavity (153) and the narrow nose (152) helps to better distribute the stresses and pressures on the weld edge. The rounded shape of the cavity (153) also reduces the risk of leaks, for example, in the corners.

[0042] As Figure 4By way of a non-limiting example, for a bag with a height of 280 mm and a width of 122 mm, the general width of the welded edges (11a-d, 13, 132, 151) is approximately 4 mm (slightly larger at the nose of the narrow nose), the circular joint area forms the tip of a V with a width of approximately 15 mm, the welded edge (13) (or the outer lower edge 11c) having an inclination of approximately 55° with respect to the horizontal, i.e. the angle (α) between the branches (13) of the V is 70°. In the following description of the example, reference is made to a rib of 0 mm corresponding to the bottom of the joint area. The lowest point of the bag (14) is the oblique weld. The oblique weld extends between the end of the joint area, 7.5 mm from the center of the lower edge (11b), and the 50 mm rib, 42 mm from the center of the lower edge (11b). Between the 50 mm rib and the 120 mm rib, the oblique weld (13) leaves room for a weld forming an intermediate area (15) between the oblique weld (13) and the welds of the side edges (11b, 11d). This intermediate area begins with a circular pit (151) that extends to the 64 mm rib, 56 mm from the center of the lower edge. This is followed by a narrow nose (152) in which the width of the bag edge increases to a nose (152') at the 75 mm rib, before continuing to decrease again to the 120 mm rib. At a position 54 mm from the center of the lower edge, the thickness of the 120 mm rib is the same as the rest of the side edge, i.e., about 4 mm. The radius of curvature of the cavity (153) is 14 mm.

[0043] The weld seam (11b, 152, 151, 13, 132, 13, 151, 152, 11d) forming the lower part of the bag is realized so that it describes a continuous track inside the bag without corners that could easily allow solid product to fall back, disrupt the flow of liquid and / or cause deformation of the bag.

[0044] exist Figure 1b and 2b In the example shown, the tip of the V (132) is located at the center of the outer lower edge (11c) of the bag (1), and therefore at the center of the V-shaped edges (13, 132). The bag is symmetrical, so it is not necessary to orient the connector (12) so that the filter (122) is located at a specific point, as is required in bags of the prior art. In some cases, the tip of the V can be moved away from the center of the outer lower edge (11c), rather than having to be positioned at one of the corners (11e, 11f).

[0045] Studies conducted on bags according to the invention filled with bicarbonate for hemodialysis have shown that only 1.2% and 5.2% of the solid product remain undissolved at the end of the process. Due to the large angle of the oblique weld seam (13) relative to the horizontal (55° in the example presented, as opposed to 38° in bags according to the prior art), the excess product to be provided in the bag to ensure the nominal volume of solution can be significantly reduced. In the example of a bag for hemodialysis, 50 g of bicarbonate are saved for 500 g and 600 g bags, while 100 g of bicarbonate are saved for a 900 g bag. This represents a 50% reduction in losses. Not only due to the geometry of the reduction, but also due to the smaller amount of bicarbonate contained in the bag, the size of the bag and, in particular, its height can be reduced. In the case presented here, the height of the bag according to the invention is 4 cm less than that of the bag according to the prior art for the same width. This not only saves on the material used to make the bag, but also on storage space for the empty bag before filling and for the bag ready for use.

[0046] List of reference numerals:

[0047] [Table 1]

[0048] 1. Bag of the present invention

[0049] 11a-d Side edges of bag

[0050] 11e-f lower corner

[0051] 12 Extraction device

[0052] 121 hose

[0053] 122 filters

[0054] 13 Beveled Edge

[0055] 131 Wasted Space

[0056] 132 junction area

[0057] 14 bags of low points

[0058] 15 Middle Area

[0059] 151 Pit

[0060] 152 Nose

[0061] 152' Nose tip of nose piece

[0062] 153 cavity

[0063] The angle between the branches of α V

[0064] 9 Bags in the prior art

[0065] 91a-d Side edges of bags in the prior art

[0066] 91e First lower corner from which the inclined edge originates

[0067] 91f Second lower corner

[0068] 92 Extraction Device

[0069] 921 hose

[0070] 922 filter

[0071] 93 Slanted Edge

[0072] 931 The first section with the smallest inclination

[0073] 932 The second section with the largest inclination

[0074] 933 Wasted Space

[0075] 94 bags of low points

Claims

1. A bag (1) consisting of flexible walls, equipped with an introduction fluid line for introducing dissolved water and an extraction fluid line for extracting the obtained solution, characterized in that The interior of the bag has a generally V-shaped lower edge (13, 132), the tip (132) of the lower edge being further away from the center of the bag than the branches (13) of the lower edge, the extraction fluid line leading to a position in the bag closest to the tip (132, 14) of the lower edge, Characterized in that the lower edge (13, 132) is followed by an intermediate region (15) after each branch (13) and opposite the tip (132) of the lower edge, the intermediate region being composed of: a dimple (151) having a slope smaller than that of the branch (13) at a location where the dimple joins the branch (13) of the lower edge and having a slope close to vertical at opposite ends thereof, and A narrow nose (152) bulges toward the center of the bag to form a nose.

2. The bag (1) according to claim 1, characterized in that The joining area (132) between the two branches (13) of the lower edge is circular.

3. The bag (1) according to claim 1 or 2, characterized in that The two branches (13) of the lower edge have the same inclination and / or the joining area (132) between the two branches (13) of the lower edge is located in the center of the lower edge (13, 132).

4. The bag (1) according to claim 1 or 2, characterized in that The angle between the two branches (13) of the lower edge is between 65° and 75°.

5. The bag (1) according to claim 1 or 2, characterized in that The branches (13) of the lower edge are obtained by welding the bag itself.

6. The bag (1) according to claim 1 or 2, characterized in that The bag consists of two hems joined together by their outer edges.

7. The bag (1) according to claim 6, characterized in that The two hems are connected together by welding their outer edges.

8. The bag (1) according to claim 1 or 2, characterized in that The interior of the bag has an upper edge (11a), a V-shaped lower edge (13, 132) and two side edges (11b, 11d) each connecting an end of the lower edge to a corresponding end of the upper edge.

9. The bag (1) according to claim 8, characterized in that An intermediate region (15) is interposed between the lower edge (13, 132) of the V-shape and the side edges (11b, 11d).

10. The bag (1) according to claim 9, characterized in that The bag is generally rectangular, with the tip of the lower edge located in the middle of one of the small sides of the rectangle, and the bag extends on both sides of the lower edge, over the lower edge of the V shape to an outer lower edge (11c) parallel to the upper edge (11a).

11. The bag (1) according to claim 10, characterized in that The outer lower edge (11c) at least partially coincides with the lower edge (13, 132) at the tip (132) of the lower edge.

12. The bag (1) according to claim 11, characterized in that The side edges (11b, 11d) extend up to the outer lower edge (11c).

13. The bag (1) according to claim 1 or 2, characterized in that The incoming fluid line opens into the bag at a location opposite the tip of the lower edge.

14. The bag (1) according to claim 1 or 2, characterized in that The extraction fluid line comprises a tube (121) equipped at a first end with a filter (122), the tube being sized to allow the filter to be placed closest to the tip (132) of the lower edge.

15. The bag (1) according to claim 1 or 2, characterized in that The bag is provided with a connector (12) for connecting it to a hemodialysis generator, through which pass the first sections of the introduction fluid line and the extraction fluid line, the first sections being extended by tubes (121) provided at their opposite ends with filters (122), the filters being located closest to the tip (132) of the lower edge.

16. The bag (1) according to claim 15, characterized in that A first section of the extraction fluid line is located opposite the tip of the lower edge.

17. The bag (1) according to claim 16, characterized in that The connector (12) is inserted into the edge of the bag at a distance from the lower edge (13, 132) of the V-shape, or the connector is inserted into the wall of the bag at a distance from the lower edge (13, 132) of the V-shape.

18. The bag (1) according to claim 17, characterized in that The connector (12) is inserted into the upper edge (11a) opposite the lower edge of the V-shape.

19. The bag (1) according to claim 1 or 2, characterized in that The bag contains bicarbonate which is used to make a saturated solution for dialysis.

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