WO2010108289A1

WO2010108289A1 - Infusion device

Info

Publication number: WO2010108289A1
Application number: PCT/CH2010/000054
Authority: WO
Inventors: Jean-Denis Rochat
Original assignee: Jean-Denis Rochat
Priority date: 2009-03-24
Filing date: 2010-03-03
Publication date: 2010-09-30

Abstract

The invention relates to an infusion device including a cylindrical body (1), one end of which is closed and the other end of which is open so as to receive a plunger (2), and comprising a means for inserting therein a flexible bag (12) of liquid to be infused that comprises a passage for dispensing through the closed end thereof. Said dispensing passage is controlled by a valve (15), the opening of which is selected so as to respond to a predetermined positive pressure inside the bag and caused by the plunger, the wall of the flexible bag having a thickness less than 150 μm such that the bag wall contacting the side wall of the cylindrical body folds up in an accordion-like fashion in an annular area adjacent to the side wall under the pressure exerted by the plunger so that the volume of the flexible bag has a predetermined correlation with the axial position of the plunger in the cylindrical body.

Description

INFUSION DEVICE

The present invention relates to an infusion device comprising a cylinder in which a piston is slidably mounted, this cylinder having an opening for receiving a flexible bag containing the liquid to be infused.

Devices of this type are known which are used especially in chemotherapy for oncological treatments. These devices are containers containing an elastomeric wall bag provided with a filling opening and a dispensing conduit. The bag is filled with the volume of liquid to be infused and the liquid is then flushed through the dispensing conduit by the force of the elastic wall of the bag. Then the device is discarded. Since an oncological treatment usually involves the infusion of 12 doses for a patient, this treatment requires 12 disposable devices.

Moreover, it is not possible with such a device to modulate in time the flow rate of the infusion, the latter being given by the force exerted on the liquid by the elastic wall of the bag and by the pressure drop in a calibrated glass restriction.

The use of disposable flexible bags poses the problem of distributing almost all the product contained in the flexible pouch. Indeed, the volume of the folded pocket is generally significant because of the thickness of its wall and residual liquid volumes remaining between the folds.

Attempts were made to fold the flexible pouch sidewall on itself, which would allow it to be almost completely emptied. Unfortunately, tests have shown that this ideal folding is not feasible and that the side wall folds more or less accordion. This poses two problems, that of the volume infused with respect to the volume of liquid contained in the pocket. If this volume is significant, for example more than 1 to 2%, the patient has not received a significant part of his treatment. The second problem is that of the elimination of the flexible bags, when they still contain a significant amount of product, taking into account the dangerousness of the oncological treatment products, for example cytotoxic. Also known are devices called syringe pushers used to perform injections or infusions using disposable syringes actuated by an engine drive device to push the piston of the syringe at a rate controlled by the drive motor pro - grammable.

Such devices are especially used for anesthesia, several devices being programmed to operate syringes containing different anesthetic products. Such systems pose congestion problems. An anesthesia station may have several syringe pumps connected to a common infusion line, so that such a station occupies a significant place. In addition, the volume of waste and the amount of material generated by the empty syringes are important. The object of the present invention is to overcome, at least in part, these disadvantages.

For this purpose, the present invention relates to an enteral or parenteral infusion device such as that defined by claim 1. This invention also relates to a flexible bag for use in this device.

The main advantage of this device lies in the fact that the side wall of the pocket is folded into accordion in regular folds, occupying a very small volume. With this control of the folding of the wall of the flexible bag, the volume of the flexible bag has a determined correlation with the axial position of the piston in the cylindrical body.

This makes it possible to control the flow as accurately as with a piston syringe, with the difference that once empty, the volume of the flexible bag is reduced to a very small fraction of the initial volume. Such a device also reduces substantially the size.

Preferably, the volume of material forming the wall of the flexible bag is less than 1% of the volume contained in said pocket.

Advantageously, the flexible pouch is PE polyethylene or PP polypropylene with a thickness of the order of 35 microns. This pocket could also be made of a laminate comprising, in known manner, a metallized layer to prevent the evaporation of liquid.

To facilitate the sliding of the side wall of the flexible bag pushed by the endless flexible lip against the side wall of the cylinder, the side wall of this cylinder is advantageously made of PE or PP. The choice of this material also makes it possible to really achieve a cylinder without any taper, which is necessary according to the materials used to allow demolding. In the case where one would like to make a non-disposable device, it could be anodized aluminum.

To prevent an air pocket from forming between the piston and the flexible bag, a vent is preferably provided in the wall of the piston. Advantageously this vent is formed by a hydrophobic porous material, to prevent the passage of liquid in case of leakage of the flexible bag. Advantageously, the piston is driven by a motor actuating a screw. Preferably, it is a telescopic screw in two, three, or even four sections to reduce the bulk of the drive mechanism and reduce the overall size of the device.

The section of the cylinder may comprise four segments of alternating circles of two different radii. This flattened section facilitates the storage of the device in a blouse pocket for example, in the case of a portable application. Preferably, the piston of the device is of polyethylene or polypropylene.

Advantageously, the lid closing the opening for receiving the flexible bag is in two parts assembled to one another and to the cylinder by latching means or a slide.

The accompanying drawings illustrate, schematically and by way of example, two embodiments and a variant of the device object of the present invention.

Figure 1 is a top view of the device; Figure 2 is an elevational sectional view along the line II-II of Figure 1, in a first position of the piston; Figure 3 is an elevational sectional view along the line III-III of Figure 1, in a second position of the piston; Figure 4 is an enlarged partial view of Figure 3; Figure 5 is a perspective view of the device, separate cover of the cylindrical body; Figure 6 is a sectional elevational view of the second embodiment, in a first extreme position of the piston; Figure 7 is a sectional elevational view of the second embodiment, rotated 90 ° clockwise with respect to Figure 6 and in the other end position of the piston; Figure 8 is an enlarged partial view of Figure 6; Fig. 9 is a plan view of a flattened flexible pouch used in the infusion device, with the indication of characteristic parameters; Figure 10 is a longitudinal sectional view of the housing of the device with the indication of characteristic parameters; Figure 11 is a diagram of the size of the folds as a function of the thickness of the wall of the flexible bag; Figure 12 is a perspective view of the upper end of the second embodiment in the open position of the housing of the device; Figure 13 is an axial torque view of a valve mounted on the liquid distribution conduit; Figure 14 is a partial perspective view of an element illustrated in Figures 12 and 15; FIG. 15 is a perspective view of the end of the flexible pouch illustrated in FIG. 12.

The first embodiment that will be described relates to an enteral or parenteral infusion device illustrated in Figures 1 and 2 which comprises a cylindrical body 1, preferably non-circular, whose section comprises four segments of alternating circles of two radii different as shown in Figure 1. This shape of the section is preferred to that of a rectangle with rounded corners in that this section has no straight segment, which is an advantage in the particular case for the reason that it will be explained later. This cylindrical body 1 encloses a piston 2 whose axial displacement is controlled by a telescopic screw 3 comprising three segments as seen more particularly in FIG. 3. This screw is driven by an electric motor 4, preferably a stepping motor. , or brushless, powered by a battery 5 and controlled by an electronic programmer 6.

The cylindrical body 1 is closed at its front end by a lid formed of two parts 7a, 7b each provided with a latching element 8a, 8b intended to snap into complementary openings 8c, respectively 8d, to maintain the two halves 7a, 7b assemblies. The edge of each half 7a, 7b adjacent to the front end of the cylindrical body has a groove 9a, respectively 9b, while a groove 10 is formed near the front end of the cylindrical body 1, at the same distance from the front edge of this cylindrical body as the distance between the grooves 9a, 9b of the rear edges of the two halves of the lid 7a, 7b. With this arrangement, the solid portions of the walls of the lid 7a, 7b and the cylindrical body 1 located between the grooves and the respective edges of the cylindrical body and the cover fit into these grooves 9a, 9b, 10 and secure the lid 7a , 7b and the cylindrical body 1. To separate the cover 7a, 7b of the cylindrical body 1, it is sufficient to disengage the latching elements 8a, 8b of the complementary openings 8c, respectively 8d and to move the two parts 7a, 7b away. one of the other.

The piston 2 comprises in the example of Figures 2 and 3 a rear portion 2a of larger diameter slidably mounted against the side wall of the cylindrical body 1 and a front portion 2b of smaller diameter. An endless flexible lip 11 extends over the entire periphery of the piston 2 and flares out to the outside and towards the front of the piston 2. The cross section of the front end of this lip 11 in the free state is greater than that of the internal section of the cylindrical body. The free volume formed between the piston 2 and the cover 7a, 7b closing the front end of the cylindrical body 1 is intended to receive a sealed flexible bag 12 provided with a filling valve 13 and a distribution duct 14, controlled at its end by a dispensing valve 15 for maintaining a pressure inside the flexible bag 12 throughout the distribution of the liquid under the pressure exerted by the piston 2. The dispensing valve at the end of the conduit serves to maintain a pressure in the pocket 12, thus against the side wall of the pocket 12 in contact with the side wall of the cylindrical body 1 and serves to promote a folding of the accordion side wall with regular folds as small as possible. The dispensing valve also serves to prevent loss of infusion fluid upon connection to the patient and at the end of the infusion.

Advantageously, the wall of the flexible bag 12 is as thin as possible. In a preferred example, the flexible bag 12 is made of polyethylene or polypropylene with a thickness of a few tens of microns, typically 35 microns. With such a thickness, the volume of the side wall of the flexible pouch once completely folded accordion, corresponds to less than 1% of the maximum injection volume of the flexible pouch 12, even less than 0.5% of this volume. The small interstitial volumes are also limited to the same order of magnitude.

The pressure prevailing in the flexible pouch 12 and the small thickness of the wall of this pouch 12 make it possible to maintain a determined correlation between the volume of this pouch pocket and the axial position of the piston 2 in the cylindrical body 1, ensuring a flow rate equal to that of a syringe pump.

FIG. 3 shows the volume of the clearance formed between the wall of the front part 2a of the piston 2 and the wall of the cylindrical body 1, in this case that of the cover 7a, 7b, chosen to receive the side wall of the flexible bag 12 driven and folded by said flexible lip 11 at the end of the displacement of the piston 2 towards the front. So that the flexible lip 11 can drive the wall of the flexible bag 12, it must be able to slide against the wall of the cylindrical body 1. It has already been mentioned polyethylene or polypropylene to form the flexible bag. The same materials can advantageously be used to form the cylindrical body 1 and the piston 2. These materials are also useful for allowing the cylindrical body 1 to be unmolded without requiring a slight clearance, as is the case for other materials such as polycarbonate. - bonate. Now it is important that the side wall of the cylindrical body is effectively cylindrical, in particular for driving the wall of the flexible bag 12 by the flexible lip 11. Another non-ambulatory embodiment can be made of aluminum.

Preferably, the wall of the piston 2 has a vent 2c (Figure 2) formed by a porous hydrophobic material to allow the evacuation of air between the piston 2 and the flexible bag 12. Such a hydrophobic vent 2c prevents the passage of liquid, which is a guarantee that the treatment product can not escape the infusion device in case of leakage of the flexible bag 12.

A distribution duct 14 is fixed to a connector 16, itself fixed inside the pocket 2. In another embodiment, especially when it is a reusable aluminum device, the vent 2c can be replaced by a conduit which serves to evacuate any leakage of liquid to the outside of the device. In the second embodiment of FIGS. 6 to 8, the flexible lip 11 'is adjacent to the front end of the piston 2' and to an annular clearance 2 '' formed in the front face of the piston 2 'to receive the wall the soft pouch as it folds. The second embodiment of the invention serves to replace the electromechanical syringe pumps used in the operating room, recovery room, hospital and outpatient. In these applications, accuracy is important because the doses to be infused are very variable. Existing syringe shoots use 5 - 10 - 20 - 50 ml syringes. The device of this invention makes it possible to use a constant diameter of piston-cylinder, typically of 0 28 mm for 4 volumes of disposable soft bags made of very fine PE of volume 5 - 10 - 20 and 50 ml, corresponding to dimensions respective axial dimensions of flexible pouches of 8.1 - 16.2 - 32.5 - 81.2 mm. The advantages are the practical and economical aspect of a pre-filled flexible pouch (or not) as well as the precision that can be obtained if one takes into account the elements exposed below. The ecological advantage is important if we compare the discarded material of a 50 ml syringe (35 gr of PP) plus a glass vial containing the drug against 1 to 2 gr for the flexible pouch PE used in the device object of the invention. The device according to the second embodiment differs from that of the first embodiment essentially in that the cylindrical housing body intended to receive the flexible bag 12 'is of circular section. lar. The battery 5 'and the electronics 6' are housed beside the drive screw 3 'of the piston 2' and the cylindrical housing body 1 containing the flexible bag 12 '. The geared motor 4 'is used to drive the screw 3'. The desired flow rate accuracy is at least 10%, but preferably 1%. To arrive at such a precision, it is necessary to work on two sources of error, one linked to the mechanism, the other to the flexible pocket:

The embodiment shown shows the driving screw 3 'mounted in the axis of the cylindrical body. This limits the games and especially the bending of a pusher off the usual syringe pushers. The volume of a cylinder and its errors are defined by the error of the axial dimension and the error of the diametric dimension. For the axial error one reaches a mechanical precision of the order of 0.1%. For the error due to the tolerance on the diameter one reaches about ± 0.01 mm, which gives, in the example described a relative volume error of ± 0.01-2 / 28 = 0.07%. (The factor 2 is due to the effect of the square of the diameter on the volume error). This gives a total volume error due to the mechanism factors of ± 0.17%.

The second source of error is related to the air volumes trapped between the flexible pouch 12 'and the body l' with cylindrical housing. The flexible bag must be delivered without any bubbles, so perfectly pre-purged first to avoid the risk of embolism and for reasons of precision. We will see further the additional purge safety operation.

To achieve the desired accuracy, it is also necessary to minimize the wrinkles, especially to avoid the air volumes created when moving from the two-dimensional flexible pouch formed of two sheets of plastic welded to the filled three-dimensional pocket. The cartridge being made either from of low elastic sheets of PE or PP (or other), either from an extruded and then flattened tubular element, the passage to a volume of generally cylindrical shape can be advantageously done in the following manner: The piston 2 'conical head and the end of the cylindrical housing body of the same shape (same angle), as illustrated in Figure 10, have an angle between 5 and 70 °, preferably 30 °. The pocket 12 'is formed either from two welded hexagonal sheets or from an extruded tubular element flattened to form the conical ends (FIG. 9). In both cases, this hexagonal pocket comprises two isosceles triangles each formed by two opposite opposite faces respectively of the hexagon, intended to form the conical parts of the flexible bag once it is filled with liquid and thus passing from an element. two-dimensional to a three-dimensional element, while the other two opposite sides of the hexagon will form the cylindrical wall of the flexible bag once it filled with liquid. A distribution duct 14 is inserted between the two hexagonal sheets at the top of one of the isosceles triangles.

Advantageously, the flexible pouch is made of laminate having a metallized layer to prevent the evaporation of the liquid. In the second embodiment, the connector 16 'has a particular shape and function, as illustrated by FIGS. 12, 14 and 15. This connector comprises an upper part 16' a and a lower part 16 'b. The upper part is shaped to cooperate with a slide 17a of a slider 17 mounted on the end of the body in which is formed the cylindrical housing of the pocket 12 '. The lower part 16 'b is intended to be introduced into the pocket 12 'and ends with an inclined face with the same angle as the conical end of the piston 2'.

As illustrated in FIG. 15, the conical end of the flexible pouch 12 'is shaped to cover the lower part of the connector 16' and is fixed to it by a weld or glue 18.

In the case where the ladle is formed from an extruded tube, the isosceles triangles intended to form the conical ends are formed by welding and cutting along the welds. In the case of the pocket 12 ', the end which must receive the connector 16', must be shaped to allow to wrap this connector without losing its conical general shape.

Once filled with liquid, this pocket 12 'thus forms a cylinder with two conical ends. When the piston 2 'moves from the position illustrated in FIG. 6 to that illustrated in FIG. 7, the conical end of the pocket 12' adjacent to the conical piston 2 'will progressively become a reentrant cone, starting from its center towards its cylindrical side wall until it takes the form of the piston 2 '. This arrangement no longer requires excessive filling of the flexible pouch and minimizes wrinkling when the flexible pouch changes from its two-dimensional hexagonal shape to its cylindrical shape with conical ends after filling, minimizing the wrinkled areas.

By matching the height A of each isosceles triangle of the ends of the flexible bag (see FIGS. 9 and 10) to the length A of the generatrix of the conical surface of the end of the casing, the voids between the flexible bag 12 are minimized. "and the cylindrical body 1" and it limits the folds on the wall of the flexible bag.

If we refer to Figures 7 and 8, we see that: cos (/ 0 = ^ _* («) = _£ where tg {a) =

τcos (/ 7) for example, for β = 30 °, α = 36 °

To further reduce the risk of air volume between the flexible bag 12 'and the cylindrical body, a radius r between 0.5 and 15 mm, preferably between 3 mm and 7 mm, preferably 5 mm is provided at the link between the sides of the hexagon forming the flexible pouch.

To minimize the residual volume at the end of infusion, the piston head 2 'must have the same angle as the end of the cylindrical body 1'.

In order to minimize the volume of air between the cylindrical body 1 'and the flexible bag 12', the diameter of the flexible bag must correspond to at least 80% of the diameter of the cylindrical body 1 ', but advantageously correspond to 99% of this diameter. .

To minimize wrinkles and to obtain regular folds, it is necessary that the diameter of the flexible pouch corresponds to a maximum of 110% of the diameter of the cylinder, but advantageously to 101%.

Therefore observing the two conditions above, it appears that the diameter of the flexible bag must be at most 99% to let the air and at least 98% of the diameter of the cylindrical body, so as not to deform too much the pocket and risk a break.

The thickness of the wall of the flexible pouch also plays an important role in the size and regularity of the pleats. Figure 11 shows the variation in radius of the cylin ^¬ drique portion of the flexible bag folded according to the thickness of its wall. It can be seen that the variation of radius corresponding to the width of the folds does not exceed 1 mm up to a thickness of 40 μm. Beyond, the width of the folds increases rapidly.

The last important factor in obtaining good accuracy is to dispense the liquid from the flexible bag while maintaining a minimum internal pressure.

Without a particular device, the pressure in the chamber can fluctuate between 0, or the venous pressure of 5.10 ³ Pa less 5.10 ³ Pa due to a 0.5 m tubing with the patient located 0.5 m below the device, and 1, 2.10 ⁵ Pa maximum if the user injects for example contrast liquid through very fine capillaries. It should not become negative at the risk of emptying the cartridge into the patient, which can have catastrophic consequences.

Maintaining at a minimum pressure can be done using a silicone-type dome valve 15 for example, advantageously housed in the connector (for example a Luer connector) located at the end of the distribution duct 14 (see FIG. Figures 12 and 13). This valve 15 will have the other advantage of eliminating the risk of drug leakage in case of disconnection and acts as a security, in case the distribution conduit 14 would be depressed by other devices connected to the system. This valve allows the filling of the cartridge and opens in the emptying direction at a pressure of 10 kPa to 300 kPa, preferably 110 kPa ± 10 kPa to eliminate any risk of inadvertent emptying by possible suction generated by other instruments connected to the patient - pump - syringe circuit. For independent systems, for example, ambulatory without suction device, can work at 20 kPa, which reduces the energy consumption.

A vigorous purge generating a piston end-of-stroke shock when it meets the flexible bag removes residual air trapped between the flexible pouch and the body. tubular in which it is housed. Vents 2c about 0.5 mm in diameter (Figure 2), located in the piston 2 and the end of the cylindrical body allow the evacuation of air. An "orange peel" surface or fine ridges on the wall of the cylindrical body also make it possible to eliminate the air trapped during the introduction of the flexible pouch.

The purge pressure is the maximum pressure generated by the motorization dimensioned to reach 10 ⁵

Pa at 2.10 ⁵ Pa which corresponds to the maximum user need, plus the shock effect as the piston 2 'comes against the flexible bag 12' at the maximum speed of the piston.

Another quality required for an injection device is to retain only a very small residual volume. Indeed, some drugs injected are very expensive or very toxic.

For this purpose the front portion 2b of smaller diameter of the piston head 2 household between the piston and the cylindrical body 1 a volume close to the volume occupied by the side wall of the flexible pouch 12 folded accordion. Here too, a cartridge thickness of the order of 30 .mu.m makes it possible to limit the residual volume to approximately 1% of the initial volume of the flexible pouch 12, which is of the order of magnitude of the volume of liquid lost in the hose. 'injection.

Claims

1. Infusion device comprising a cylindrical body (1), one end of which is closed and the other is open to receive a piston (2) slidably mounted, this cylindrical body (1) comprising means for introducing a flexible bag (12). ) intended to contain the liquid to be infused and having a dispensing passage for this liquid, through said closed end, characterized in that the dispensing passage is controlled by a valve whose opening is chosen to respond to a specific overpressure at the interior of said pocket generated by said piston, the wall of said flexible pouch having a thickness of less than 150 microns, all so that the wall of said pocket in contact with the side wall of said cylindrical body folds accordion in a annular zone adjacent said side wall, under the pressure exerted by said piston, so that the volume of the flexible bag has a correlate determined with the axial position of the piston in the cylindrical body.

2. Device according to claim 1 wherein a vent is arranged to prevent air retention between the flexible bag and the cylindrical body.

3. Device according to one of the preceding claims wherein said closed end of the cylindrical body and the front end of said piston have converging faces of the same inclinations.

4. Device according to claim 3, wherein said flexible bag results from the sealed assembly of two sheets or two layers of a flattened extruded tubular element forming in plan a hexagon comprising two isosceles triangles each formed by two adjacent faces respectively. - opposite veins of the hexagon, whose angles α with their third side corresponds to the relation:

in which β is the corresponding angle between the converging faces of the closed end of said cylinder, respectively of the front end of said piston.

5. Device according to one of the preceding claims, wherein the cross section of said pocket after filling with the liquid to be infused is equivalent to that of the housing within said cylindrical body.

6. Device according to claim 4, wherein the connection between the sides of the hexagon is formed by arcs of circles tangential to the respective sides whose radius is between 0.5 mm and 15 mm, preferably between 3 mm and 7 mm.

7. Device according to one of the preceding claims, wherein the side face of the piston (2, 2 ') comprises an endless flexible lip (11) extending over its entire periphery and flaring outwards and towards the front of the piston, the cross section of the front end of this lip (11) in the free state being greater than that of the internal section of the cylindrical body (1), this lip (11) being adjacent to a clearance (2b, 2'd) formed in the wall of the piston (2) and whose volume defined by the wall of the cylindrical body (1) is chosen to receive the side wall of said pocket (12) driven and folded by said flexible lip (11) as the piston (2) moves forward.

8. Device according to one of the preceding claims, wherein the piston (2) has a rear portion

(2a) of larger diameter and a front portion (2b) of smaller diameter, the flexible lip (11) being disposed between these two front (2b) and rear (2a) parts, the diameter reduction of the front part (2b) being chosen to form between it and the wall of the cylindrical body (1) the volume to receive the side wall of said flexible bag ( 12) driven by said flexible lip (11) as the piston (2) is moved forward.

9. Device according to one of the preceding claims, wherein the cylindrical body (1), the piston (2) and the flexible bag are made of polyethylene or polypropylene.

10. Device according to one of the preceding claims, wherein the piston is driven by a telescopic worm (3) engaged with a motor (5).

11. Device according to one of the preceding claims, wherein the section of said cylindrical body comprises four segments of alternating circles of two different radii.

12. Device according to one of the preceding claims, wherein the means for introducing a flexible bag into said cylindrical body comprises an opening closed by a lid in two parts (7a, 7b) assembled to one another by means detent (8a, 8b) and to the cylindrical body (1) by complementary grooves (9a, 9b, 10).

13. Device according to one of the preceding claims, wherein the radius or radii of the cylindrical portion of said flexible bag is or are between 80% and 110%, preferably between 98% and 99%, of the corresponding rays of said cylindrical body.

14. Flexible pouch for infusion device with cylindrical housing (1) with closed conical end and sliding piston (2), characterized in that it comprises two layers of a sheet material forming a plane hexagon comprising two isosceles triangles formed each of two respectively opposite opposite faces of the hexagon, a distribution duct 14 "being inserted between the two hexagonal sheets at the top of one of the isosceles triangles whose angles α with the third side of the respective isosceles triangles corresponds to the relation:

tg {cc) = ² ~ - π • cos (p) in which β is the corresponding angle between the converging faces of the closed end of the cylindrical housing to which said flexible pouch is intended, so that, once filled with liquid, the flexible pouch substantially conforms to the volume of this cylindrical housing and its conical closed end.

The flexible pouch of claim 14, wherein the two layers of sheet material comprise two sheets of plastics tightly joined to each other.

The flexible pouch of claim 14, wherein the two layers of sheet material are two halves of a flattened tubular member.

17. Soft bag according to one of claims 14 to 16, wherein the connection between the sides of the hexagon is formed by arcs of circles tangent to the respective sides whose radius is between 0.5 mm and 15 mm, preferably between 3 mm and 7 mm.

18. Flexible pouch according to one of claims 14 to 17, made of laminate having a metallized layer to prevent 1 evaporation of the liquid.