Patent Description:
Such a catheter comprises a tube having a length to extend through a stoma of a patient, an outer member fixed or fixable on the tube to rest against the patient's skin and an inner member fixed or fixable on the tube to rest against an inner lumen wall of the patient.

Percutaneous feeding, in particular percutaneous endoscopic gastrostomy (PEG), is an endoscopic medical procedure in which a tube is inserted into a patient's lumen, particularly the stomach, through the abdominal wall. PEG may be used for feeding when oral intake is not adequate. Thus, although nutrition is not provided via the mouth, the natural digestion process is maintained.

A catheter as mentioned above is described in <CIT>. A gastrostomy tube with a stretchable section which is lengthened by a trocar prior to insertion to provide a required retention force is disclosed in <CIT>.

The tube usually provides a certain amount of flexibility to allow movements of the patient. However, when applying such catheters, generally the distance of the outer member and the inner member, i.e., the length of the tube portion therebetween, has to be adjusted relatively precisely to the anatomy of the patient, and is fixed after adjustment. If the distance is set too small, a relatively large pressure is exerted on the skin and inner lumen wall. This may lead to irritation or even damaged tissue in this area. On the other hand, if the distance is set too large, there is a risk of leakage at the stoma.

Therefore, the application of such catheters generally relies on the experience of a health care professional.

Instead of, e.g., a plate as inner member, an inflatable balloon may be used. <CIT> describes a corporeal access tube assembly and method with a balloon. In many cases, variations of the anatomy of different patients can be compensated by inflating such a balloon. However, balloon catheters generally need to be checked for leak-tightness regularly, what might again be too difficult for the patient.

It is an object of the instant invention to improve the usability of a catheter for percutaneous feeding.

This object is achieved by means of a catheter having the features of claim <NUM>.

Accordingly, the tube comprises a stretchable section that can be arranged to be (or is arranged) between the outer member and the inner member, the stretchable section being stretchable in length, wherein a retaining structure is provided limiting the length, e.g., defining a maximum length, of the stretchable section.

Thereby, the catheter tube is allowed to stretch (at the stretchable section) for a specific length (i.e., until the maximum length), defined by the retaining structure, with relatively low force and without a risk of breaking. Exceeding the length limitation activates the retaining structure thus preventing additional elongation (and a possible breakage). This does not require additional steps performed by the user. Too long elongation by the user, e.g., during placement, will be prevented by the retaining structure. As a result, the catheter offers a wide window in which the user can fix the catheter length without a negative impact on the tissue and use of the catheter. This allows an intuitive placement and adjustment of the catheter. Thus, the usability of the catheter can be strongly improved.

Furthermore, the comfort for a patient might be increased, because after being successfully placed, the catheter tube with its stretchable section, can be suitable to compensate for patients movements.

The stretchable section connects a first adjacent section with a second adjacent section of the catheter, particularly in a fluid-tight manner. That is, the stretchable section may be arranged between two other portions of the catheter. This allows a simple manufacturing of the catheter. The stretchable section may fully encompass a section of a duct defined by the tube. The stretchable section and one or both of the adjacent sections may be formed in one piece. The stretchable section is fixedly connected with both of the adjacent sections.

The retaining structure connects the first adjacent section with the second adjacent section. This allows a simple construction. The retaining structure is fixedly connected with both of the adjacent sections. The retaining structure and one or both of the adjacent sections may be formed in one piece. The retaining structure may fully encompass a section of a duct defined by the tube.

For example, the first adjacent section is a part of the tube and/or the second adjacent section is a part of the tube or the second adjacent section is a section of the inner member. The inner member may be a plate.

Optionally, the material of the stretchable section has a larger elasticity than the material of the adjacent sections. Particularly, the material of the stretchable section may have a larger elastic modulus, e.g., Young's modulus, than the material of the adjacent sections. By this, the elastic properties of the stretchable section can be precisely adjusted.

Alternatively, or in addition, the material of the stretchable section may have a larger elasticity than the material of the retaining structure. Particularly, the material of the stretchable section may have a larger elastic modulus, e.g., Young's modulus, than the material of the retaining structure. By this, the properties of the stretchable section and the retaining section can be precisely adjusted.

Alternatively, or in addition, the stretchable section may have a smaller thickness than the adjacent sections and/or than the retaining structure. This allows a particularly simple solution. Particularly, but not exclusively, in that case the stretchable section and one or both of the adjacent sections may be made of the same type of material, e.g., a polyurethane (PU), particularly a thermoplastic polyurethane (TPU), or a silicone, or of the same material, e.g., the same PU, TPU or silicone. In that way the manufacturing can be simplified.

Alternatively, or in addition, the retaining structure may be made of the same type of material, e.g., a polyurethane (PU), particularly a thermoplastic polyurethane (TPU), or a silicone, or of the same material, e.g., the same PU, TPU or silicone and/or have a larger thickness than the stretchable section and/or the adjacent sections. By this the manufacturing can be further simplified.

Optionally, the retaining structure is bent, alternating or wavy or has a spiral form when no external force is applied on the stretchable section and/or straightened when the stretchable section is stretched. This allows to use thin materials with high tensile stiffness for the retaining structure which do not interfere with the inner duct of the tube or with outer tissue.

The retaining structure may be arranged inside an inner volume of the tube, so that it does not contact tissue outside of the tube. Alternatively, it is arranged at an outside of the tube (and/or of the stretchable section).

Optionally, the retaining structure is surrounded by the stretchable section at least along a part of its length. For example, the retaining structure connects both adjacent sections in a fluid-tight manner. This allows to ensure the function of the catheter even if the stretchable section is damaged.

The retaining structure may be embedded in material of the stretchable section. For example, the retaining structure may be surrounded by and/or in contact with material of the stretchable section over the majority or all of its (inner and outer) surface. This allows to avoid contact of the retaining structure with tissue and contents of the inner volume of the tube.

As a further example, the stretchable section can have an inner wall surrounded by an outer wall of the stretchable section, together defining a chamber therebetween. Optionally, the retaining structure is arranged in the chamber. This also allows to avoid contact of the retaining structure with tissue and contents of the inner volume of the tube. The chamber may be annular.

The inner member (e.g., plate) may be fixed on the tube and/or the outer member may comprise a plate with a guide for the tube and a lock movably mounted on the plate for selectively locking the tube with respect to the plate. By this, a simple adjustment is possible.

Optionally, the stretchable section and the retaining structure together form a polymer nanocomposite having switchable mechanical properties and comprising the stretchable section in the form of a matrix polymer and the retaining structure in the form of a nanoparticle network, wherein the nanoparticle network is formed by a formation of a substantially three-dimensional network of nanoparticles which are incorporated in the matrix polymer and interact with each other and/or with the matrix polymer, wherein the polymer nanocomposite in a first switching state comprises a first stiffness characterized by a first tensile storage modulus, e.g., greater than <NUM> GPa, in a second switching state comprises a second stiffness characterized by a second tensile storage modulus, e.g., of less than <NUM> GPa, and is switchable between the first switching state and the second switching state by exposing the polymer nanocomposite to a stimulus that influences interactions among the nanoparticles and/or between the nanoparticles and the matrix polymer. The stimulus may be for example a body fluid, at the temperature of the stimulus, for example <NUM>. The polymer nanocomposite may have the properties as described in <CIT> and/or in <CIT>.

The idea underlying the invention shall subsequently be described in more detail with reference to the embodiments shown in the figures.

<FIG> shows a general scenario of a patient P being subjected to a gastro-intestinal feeding. A PEG catheter <NUM> is placed on the patient P, entering into the patient P through a stoma S. A container <NUM> encloses food and/or medicine for administration to the patient P and is in fluid connection with a tube <NUM> of the catheter <NUM>.

<FIG> shows the catheter <NUM> in more detail. The catheter <NUM> comprises a tube <NUM> having an opening <NUM> to be arranged in the stomach of the patient P. At the other end, a lid allows to close the tube.

At the end opening <NUM> an inner member <NUM> in the shape of an inner plate is fixedly connected with the tube <NUM>. The inner member <NUM> is circular in this example. The inner member <NUM> is adapted to rest against an inner gastric wall of the patient P to protect the catheter <NUM> against accidental removal. Further, the catheter <NUM> comprises an outer member <NUM>. The outer member <NUM> comprises a plate <NUM> with a guide <NUM> for the tube <NUM>. Further, the outer member <NUM> comprises a lock <NUM>. In an unlocked state of the lock <NUM> the tube <NUM> can be displaced with respect to the plate <NUM>, guided by the guide <NUM>. When the lock <NUM> is in a locked state, the tube <NUM> is fixed relative to the plate <NUM>. By this, the correct position of the outer member <NUM> on the tube <NUM> may be adjusted. This procedure will now be described with reference to <FIG>.

As shown in <FIG>, the tube <NUM> has been arranged to extend through a stoma S into the stomach M of the patient P. The outer member <NUM> is placed on the skin A of the outer abdominal wall. The tube <NUM> is received in the guide <NUM> of the outer member <NUM>. The lock <NUM> is open, so the user can adjust the distance d between the outer member <NUM> and the inner member <NUM>.

<FIG> illustrates the adjusted state of the catheter <NUM>. The lock <NUM> is in the locked state and fixes the position of the outer member <NUM> on the tube <NUM>. The catheter <NUM> is secured to the patient P in order to avoid, for example, an accidental removal or displacement of the catheter <NUM>. The inner member <NUM> rests against the inner gastric wall G in the stomach M. A small force is applied on the gastric wall G and skin A to ensure a secure fit and to prevent liquids from entering the Stoma S outside the tube <NUM>. This force is, however, small enough to avoid an irritation or even damage of the abdominal wall.

To simplify find the optimal position of the outer member <NUM> on the tube <NUM>, the tube <NUM> comprises a stretchable section 100A-100D which is arrangeable (and arranged when the catheter <NUM> is applied on the patient P) between the outer member <NUM> and the inner member <NUM>, wherein a retaining structure 13A-13D is provided limiting the length (more specifically, defining a maximum length) of the stretchable section 100A-100D, as will be described with reference to <FIG> below.

<FIG> shows the end part of the tube <NUM> with the opening <NUM>. At or close to the end opening <NUM> the inner member <NUM> is fixed to the tube <NUM>.

According to <FIG>, the tube <NUM> comprises a stretchable section 100A. The stretchable section 100A defines a part of the duct extending through the tube <NUM>. The stretchable section 100A has an annular shape. The stretchable section 100A encompasses an inner volume, which is a part of the inner volume V of the tube <NUM>.

The stretchable section 100A is located between a first adjacent section <NUM> and a second adjacent section <NUM> of the tube <NUM>. The first adjacent section <NUM> corresponds to the part of the tube <NUM> from the stretchable section 100A until the outer end of the tube <NUM>. The second adjacent section <NUM> corresponds to the part of the tube <NUM> from the stretchable section 100A until the inner end (with the opening <NUM> and the inner member <NUM>) of the tube <NUM>. The length of the second adjacent section <NUM> is such that the stretchable section 100A is arranged in the stoma S in an applied state of the catheter <NUM>. The second adjacent section <NUM> may be very short. The inner member <NUM> may optionally serve as the second adjacent section or part.

The stretchable section 100A of <FIG> has (at least substantially) the same cross section as the adjacent sections <NUM>, <NUM>. Thus, the stretchable section 100A has the (at least substantially) same inner diameter, outer diameter and wall thickness as the adjacent sections <NUM>, <NUM>. However, the stretchable section 100A has a smaller modulus of elasticity in tension than the adjacent sections <NUM>, <NUM>, e.g., the modulus of elasticity of the stretchable section 100A may amount to <NUM>% or less, <NUM>% or less, or <NUM>% or less, of the modulus of elasticity of the adjacent portions <NUM>, <NUM>. In this regard, the stretchable section 100A of this example is made of a different, softer, material than the adjacent sections. Alternatively, the material of the stretchable section 100A may be structurally weakened. Thus, the same tensile force leads to a substantially larger prolongation (with respect to the same initial lengths) of the stretchable section 100A compared to the adjacent portions <NUM>, <NUM>, e.g., by a factor of <NUM>, by a factor of <NUM>, by a factor of <NUM> or even more.

As a result, the stretchable section 100A can be stretched in length with little forces. The stretchable section 100A may create a nearly constant minimal force between the outer member <NUM> and the inner member <NUM>. This allows the user a wide range of possible adequate positions of the outer member <NUM> along the tube <NUM>.

Further, the tube <NUM> is provided with a retaining structure 13A. In this example, the retaining structure 13A is arranged inside the tube <NUM>. It has a smaller outer diameter than the stretchable section 100A and the adjacent sections <NUM>, <NUM>. The retaining structure 13A describes a duct. The retaining structure 13A has a larger wall thickness than the stretchable section 100A, but alternatively it can also have the same or even a smaller wall thickness. For example, the retaining structure 13A has the same wall thickness as the first and/or second adjacent sections <NUM>, <NUM>. Along the length of its duct, the retaining structure 13A is centrally bent inwards. For example, the stretchable section 100A is made of the same material as the adjacent sections <NUM>, <NUM>. The retaining structure 13A is fixed to the first adjacent section <NUM> with one end and fixed to the second adjacent section <NUM> with the opposing end, e.g., with an adhesive bond. Optionally, the first and second adjacent sections <NUM>, <NUM> and the retaining structure 13A are made in one piece.

Thus, when a tensile force stretches the stretchable section 100A, the retaining structure 13A is straightened. As soon as it is straight, it effectively blocks a further stretching. Thereby, the retaining structure 13A defines a maximum length of the stretchable section 100A. Thus, a damage of the stretchable section 100A by too wide deflections is prevented.

Turning now to <FIG>, another example of a stretchable section 100B and a retaining structure 13B is described. Here, the retaining structure 13B is embedded into the material of the stretchable section 100B. The stretchable section 100B is made of a material with a smaller modulus of elasticity in tension than the adjacent sections <NUM>, <NUM> and/or weakened. It has the same material thickness as the adjacent sections <NUM>, <NUM>.

The retaining structure 13B has the shape of a hose and has a high strength against tensile forces. For example, the retaining structure 13B comprises a metal, such as iron or titan. For example, the retaining structure 13B may be made of a foil and/or of steel. As another example, the retaining structure 13B may comprise wires. In a state without external forces acting on the catheter <NUM>, the retaining structure 13B has a wavy form. Thus, stretching the stretchable section 100B straightens the retaining structure 13B. As soon as the retaining structure 13B is straight, it blocks against a further stretching of the stretchable section 100B.

According to <FIG>, the stretchable section 100C comprises an inner wall <NUM> which is surrounded by an outer wall <NUM>. Between the inner wall <NUM> and the outer wall <NUM>, a chamber C is formed. The chamber C has an annual shape. The chamber C may be filled with a fluid, e.g., with air. Inside the chamber C the retaining structure 13C is arranged. The retaining structure 13C is configured as the retaining structure 13B of <FIG> with the difference that it is not embedded in the material of the stretchable section 100C. Here, each of the inner and outer walls <NUM>, <NUM> of the stretchable section 100C has a (much) smaller wall thickness compared to the adjacent sections <NUM>, <NUM>. Therefore, the stretchable section 100C may even be made of the same material as the adjacent sections <NUM>, <NUM>.

In the example of <FIG>, the stretchable section 100D also has a thinner wall thickness than the adjacent sections <NUM>, <NUM>. It is made of a softer material than the adjacent sections <NUM>, <NUM>. Optionally, the materials of the stretchable section 100D and of the adjacent sections may be different, but belonging to the same group of materials, e.g., PU, TPU or silicone. This allows to easily fix these sections to one another. The same holds for the retaining structure 13D (and this may also be provided for the other examples described above). According to <FIG>, the retaining structure is configured as in <FIG>, with the difference that it is not arranged inside a chamber between two walls but forms an inner surface of the duct of the tube <NUM>.

With respect to <FIG> and <FIG> it is worth noting that while arrangements are shown where the respective stretchable section 100A, 100D surrounds the restraining structure 13A, 13D, a configuration where the restraining structure 13A is arranged outside of and surrounds the stretchable section 100A, 100D is also conceivable.

As shown in <FIG>, a polymer nanocomposite <NUM> comprises a matrix polymer <NUM>. The matrix polymer <NUM>, in a preferred embodiment, comprises a - preferably highly - polar polymer capable of forming non-covalent interactions, in particular hydrogen bonds, with the nanoparticles. For example, the matrix polymer may comprise vinyl polymers such as polyvinyl alcohol (PVOH), poly(acrylic acid), poly(acryl amide)s, poly(vinyl pyridine), copolymers of these respective monomers and other monomers, polycondensates such as polyamides and polyesters, polysaccharides such as cellulose, starch, alginates, pectins, hyaluronane, chitin, chitosan and their derivatives, proteins, and other polar polymers.

In the particular embodiment described herein, the matrix polymer <NUM> is PVOH. The polymer nanocomposite <NUM> further comprises a nanoparticle, particularly a nanofiber network formed by a substantially three-dimensional network of nanofibers <NUM>, in the particular embodiment described herein tunicate nanowhiskers (TNWs) or cotton nanowhiskers (CNWs).

The matrix polymer comprises crystalline regions <NUM> and amorphous regions <NUM>. As shown in <FIG>, the matrix polymer <NUM>, in this case PVOH, is capable of forming hydrogen bonds with the nanofibers <NUM> (cellulose nanowhiskers NWs, in this case tunicate nanowhiskers TNWs or cotton nanowhiskers CNWs). Such hydrogen bonding (H-bonding) interactions between the NWs and the matrix polymer <NUM> are believed to have a reinforcing effect of the polymer nanocomposite <NUM> at least in the dry state of the polymer nanocomposite <NUM> (first switching state). Upon subjection to a stimulus, for example upon exposure to a water-containing composition, such hydrogen bonds at least partially are released, yielding a reduction in stiffness in the soft state (second switching state) of the polymer nanocomposite <NUM>.

Claim 1:
Catheter (<NUM>) for percutaneous feeding, comprising:
- a tube (<NUM>) for extending through a stoma (S) of a patient (P);
- an outer member (<NUM>) fixed or fixable on the tube (<NUM>) to rest against the patient's (P) skin (A); and
- an inner member (<NUM>) fixed or fixable on the tube (<NUM>) to rest against an internal patient's (P) lumen wall (G),
characterized in that
the tube (<NUM>) comprises a stretchable section (100A-100D) arrangeable between the outer member (<NUM>) and the inner member (<NUM>) being stretchable in length, wherein a retaining structure (13A-13D) is provided limiting the length of the stretchable section (100A-100D), wherein the stretchable section (100A-100D) connects a first adjacent section (<NUM>) with a second adjacent section (<NUM>) and the retaining structure (13A-13D) connects the first adjacent section (<NUM>) with the second adjacent section (<NUM>).