WO2006037336A1

WO2006037336A1 - A medical device comprising at least one enlarged drainage passage

Info

Publication number: WO2006037336A1
Application number: PCT/DK2005/000641
Authority: WO
Inventors: Robert Snell; Signe Uhre Guldfeldt; Egon Triel; Kren Erik Nielsen; Søren Bøgvad PETERSEN
Original assignee: Coloplast A/S; Ranier Limited
Priority date: 2004-10-05
Filing date: 2005-10-05
Publication date: 2006-04-13

Abstract

The present invention relates to a medical device such as a catheter, and a method for making such a device. In particular the present invention relates to a medical device comprising a tip, a drainage section and a retention section extending between the drainage section and the tip, the retention section comprises a plurality of first drainage passages defined between cross braided filaments of the retention section and is in fluid communication with the drainage section. More specifically, the invention relates to a medical device wherein at least one of the tip and the retention section defines one or more second drainages passage, said second drainages passage being in fluid communication with the drainage section, a cross-sectional area of the second drainage passage being larger than a cross-sectional area of any one of the first drainage passages which are adjacent to the second drainage passage.

Description

A MEDICAL DEVICE COMPRISING AT LEAST ONE ENLARGED DRAINAGE PASSAGE

INTRODUCTION

The present invention relates to a medical device such as a catheter, and a method for making such a device. In particular the present invention relates to a medical device comprising a tip section, a drainage section and a retention section extending between the drainage section and the tip section, the retention section comprises a plurality of first drainage passages defined between cross braided filaments of the retention section and is in fluid communication with the drainage section. More specifically, the invention relates to a medical device wherein at least one of the tip section and the retention section defines one or more second drainages passage, said second drainages passage being in fluid communication with the drainage section, a cross-sectional area of the second drainage passage being larger than a cross-sectional area of any one of the first drainage passages which are adjacent to the second drainage passage.

BACKGROUND OF THE INVENTION

Catheters with a retention section are known in the art. One such catheter is disclosed in

US 5,041,093 wherein a catheter is made from an elongated flexi ble tubular member with a conduit. The catheter discloses in the reference comprises an axially and radially elastically extensible, woven tube. The woven tube is translatable between three configurations, i.e. a relaxed configuration, an extended configuration and an over-centre configuration. In the over-centre configuration, the woven tube forms a cup-like shape whereby the catheter can be maintained in place inside the body.

Furthermore braided catheters are known from US 6 033 413, US 4 572 186, US 4 154 242, US 2003/144636, US 3 854 483, US 4 921 484, US 6 558 350, US 5 221 261 and GB-patent applications 0314503 and 0314504.

However, when designing a braided portion the designer is faced with two contradictory problems. On one hand it is desirable to provide a retention section with as many filaments as possible, as this increases the ability of the retention section to retain the medical device inside the body. On the other hand it is desirable to reduce the number of filaments as this increases the cross-sectional area of the flow passages defined between the filaments, and thus larger objects such as coagulated blood, pieces of body tissue and debris, may pass through the drainage passages of the medical device. Especially i n connection with post- operational use of the device this is desirable as it makes it possible to have the device inserted into the body for a longer period of time, e.g. for several days or ever weeks, as the risk of occlusion is reduced or eliminated.

DESCRIPTION OF THE INVENTION

In order to overcome the aforementioned problems, it is an object of a preferred embodiment of the present invention to provide a medical device, wherein the risk of occlusion is reduced. Accordingly, a first aspect of the present invention relates to a medical device with a proximal end for insertion into a body of a living being and an axially opposite distal end, the device comprising:

- a tip section for guiding the catheter into a body canal, the tip section defining a tip which in a first configuration of the device forms the proximal end of said device;

- a drainage section forming a conduit extending in an axial direction of the device; and

- a retention section extending between the drainage section and the tip section, the retention section comprising a plurality of first drainage passages defined between cross braided filaments, the passages being in fluid communication with the drainage section;

wherein at least one of the tip section and the retention section defines at least one second drainage passage, each said second drainage passage being in fluid communication with the drainage section, a cross-sectional area of each second drainage passage being larger than a cross-sectional area of any one of the first drainage passages.

It will be appreciated that the provision of at least one second drainage passages reduces the risk of occlusion by particles such as coagulated blood, pieces of body tissue and debris which often are present after surgical operation.

There may be provided more than one second drainage passage such as one or two or five or ten. In one embodiment the second drainage passages are evenly distributed along the periphery of the retention section.

In one embodiment the cross-sectional area of each second drainage passage is larger than a cross-sectional area of any one of the first drainage passages which are directly adjacent to said second drainage passage. In the context of the present invention the phrase 'any one of the first drainage passages which are directly adjacent to the second drainage passage' shall be understood as those first drainage passages which are immediately adjacent to the second drainage passage, i.e. the first drainage passages which adjoin the second drainage passage. Such adjoining first drainage passages may be said to be neighbouring or bordering the second drainage passage, as for any such adjoining first drainage passage a peripheral edge part is defined by a portion of a filament, which portion also defines a peripheral edge part of the second drainage passage.

In one embodiment at least one second drainage passage is encircled by said directly adjacent first drainage passages. In another embodiment at least one second drainage section is provided in-between two first drainage passages.

In one embodiment each second drainage passage is directly adjacent to and encircled by first drainage passages. In the latter embodiment no second drainage passage is directly adjacent to another second drainage passage as at least one first drainage passage is defined between any two second drainage passages. In another embodiment at least two first drainage passages are defined between any two second drainage passages, such as three, such as five or ten.

The retention section may define a centre area encircled by an encircling area. The circling area may comprise at least one second drainage passage and at least one first drainage passage. Furthermore, the encircling area may comprise at least one second drainage passage located in-between two first drainage passages. In one embodiment the term in- between shall be understood such that at least one straight line must intersect the passages of the second drainage passage and the passages of the two first drainage passages in- between which the second drainage passage is located. In one embodiment the encircling area may comprise groups of second drainage passages e.g. between groups of first drainage passages.

The centre area may exclusively comprise first drainage passages, or it may comprise a mixture of or groups of second drainage passages between groups of first drainage passages.

In one embodiment each filament extends between the drainage section and the tip section, i.e. each filament extends from a proximal end of the retention section to a distal end of the retention section. In one embodiment the filaments have identical length.

In one embodiment the cross-sectional area of each second drainage passage is larger than the cross-sectional area of any one of the first drainage passages which are directly adjacent to the second drainage passage, when the retention section is in a second configuration wherein the size of the retention section in a direction transverse to the axial direction of the device is larger than when the device is in said first configuration.

To facilitate comfortable insertion or to reduce the risk of adherence of body tissue to the surface of the device, at least a part of the device, e.g. the braided portion or the tip-section may have an outer surface, i.e. a surface towards the body tissue when the device is inserted into the body, which surface has a low surface friction characteristic compared to other parts of the device. To provide the low friction characteristic, the medical device, e.g. the braided portion thereof may have a hydrophilic surface, e.g. provided by a hydrophilic coating of the surface, e.g. a coating comprising polyvinylpyrolidone.

In one embodiment, namely when a first part of the braided portion is located inside a second part of the braided portion, the low friction surface may in particular be provided on the second part of the braided portion. During retention inside the body, the body tissue is thereby protected by the low friction character of the second part. A hydrophilic coating may further reduce irritation of the body tissue, e.g. the mucosa. If a hydrophilic coating is applied to the braided portion, the coating may incorporate an anti-infective compound or a compound which counteracts ingrowth.

In one embodiment the at least one second drainage passage is provided in the inner half of the first part of the retention section, when the medical device is in the second configuration. By inner half is meant the inner most of two ring shaped surface parts, one encircling the other, defined on the first part of the retention section. When the device is in the second configuration, the size of the first drainage passages increases in size the closer they are to rim portion defined by the first part and the second part of the retention section, i.e. in a transition zone between the two parts. Accordingly, in this configuration the size of the second drainage passages may be smaller than the size of the first drainage passages which are close to the rim portion, but which are not adjacent to the second drainage passage. However, as the first drainage passages which are close to the rim portion, are provided in an area, wherein the inner surface of the first part and the second part of the retention section are close to each other, it may not be possible for larger objects to be drained due to the narrow space between walls of the first part and the second parts.

In an embodiment the tip section or at least a part thereof is made from a material which is soluble in water, such as PVA, such that once the catheter is inserted and the tip has been used to ease insertion, the tip section dissolves when it is brought into contact with a body fluid e.g. urine. In the context of the present invention the term soluble in water shall be understood as soluble by any body fluid and not only water. In some embodiments the tip is only soluble in body fluids under temperatures close to body temperature e.g. between 30 and 45 degrees, such as between 37 and 40 degrees. When the tip section has dissolved, a second drainage passage may emerge. When the medical device is removed it may be pulled in a direction opposite the tip (the distal direction) and thus a smooth tip may not be needed anymore. In one embodiment the tip is provided as a foam which may be retracted through a second drainage passage e.g. defined by a ring shaped element, so as to enable fluid passage in said second drainage passage. As an example this may be done after insertion of the medical device.

In order to further increase the degree of expansion or to form a specific shape of the braided portion in the second configuration, a first part of the braided portion may be located inside a second part of the braided portion when the device is in the second configuration. These first and second parts of the braided portion do not have to be structurally separated, but could form one uniform braided portion, and merely the fold arising by the inverting or rolling of one part of the braided portion into another part of the braided portion defines the transition between the first and second parts of the braided portion. In the first configuration, the braided portion could extend un-folded in the axial direction.

In the first configuration, i.e. in an extended state wherein the first and second parts of the braided portion are located in axial extension of each other, the braided portion has a generally cylindrical or ovoid shape facilitating insertion into the body. Depending on how the braiding angle is varied, the shape of the resulting funnel can be controlled, and in the second configuration, the braided portion may be provided to form an ovoid shape of a larger dimension transverse to the axial direction, a funnel shape, a tulip-like shape, a disc-shape, a hemispherical shell, a conical shell, a elliptic parabolic shell or any other cup like shell or any other shapes which support retaining of the device in the body. In particular, axially disposed rim portions of the braided portion may form a larger braiding angle than an intermediate centre portion.

The medical device, especially the retention section, may be designed with "shape-memory" such that it will automatically move towards a predetermined shape i.e. towards a more relaxed state. In a first embodiment the medical device is designed such that the predetermined shape is the first configuration, i.e. the medical device will have a tendency to move towards the first configuration, but may be moved into the second configuration by axial displacement of the first part of the braided portion into a second part of the braided portion. In some embodiments, the first configuration is a configuration wherein the larger dimension of a cross-section of the braided portion is equal or less than the larger dimension of a cross-section of the remaining part of the tube. In a second embodiment the medical device is designed such that the predetermined shape is the second configuration, i.e. the medical device will have a tendency to move towards the second configuration, but may be moved into the first configuration by axial displacement of the first part of the braided portion out of the second part of the braided portion. In some embodiments, the second configuration is a configuration wherein the largest dimension of a cross-section of the braided portion is larger than the largest dimension of a cross-section of the remaining part of the tube.

In a third embodiment the medical device is designed such that the predetermined shape when the braided portion is located inside the remaining part of the tube, e.g. the drainage section, coaxially therewith. When the medical device is located in the body, the second part is displaced out of the remaining part of the medical device to form a medical device in the second configuration, i.e. retained in the body. To operate the medical device between the different configurations, a deployment member could be attached to the proximal end, e.g. to a proximal tip of the medical device, and extend to the distal end to facilitate manipulation of the proximal end from outside the body. A Deployment member could e.g. extend inside the lumen. The tip section may be shaped as a Nelaton tip or as a Tiemann tip, or the tip could have the form of an open ring, e.g. with a smoothly rounded part extending in a forward direction to form a proximal end of the device and thus to facilitate comfortable insertion of the device into the body.

There may be provided one or more second drainage passages in the tip and/or in the retention section . The length of the shorter dimension of a cross-section of one drainage passage determines how large particles may pass through the drainage passage. Accordingly, it may in some embodiments be desired that the second drainage passages are as round (or square) as possible instead of being oblong, as an oblong drainage passage may provide the high flow capacity but may obstruct larger particles. Accordingly, in one embodiment the longest dimension of a cross-section of one drainage passage is below 300 % of the shortest dimension of the same cross-section, or smaller than 200 % or even 150%.

The area of one of the second drainage passage may be between 2 and 25 mm², such as between 10 and 15 mm². The area of one second drainage passage may be between 50% and 100% of the cross-sectional area of the conduit of the drainage section, such as between 60% and 90% or between 70% and 80%. Alternatively the area of half or all of the second drainage passages may be between 50% and 100% of the cross-sectional area of the conduit of the drainage section, such as between 60% and 90% or between 70% and 80%.

The size of the cross-sectional area of at least one second drainage passage may be at least 30% larger than size of the cross-sectional area of any one of the first drainage passages which are directly adjacent to the second drainage passage, such as at least 50%, such as at least 100%, such as at least 200%, such as at least 300% or 400%.

Moreover, the size of the cross-sectional area of one or all of second drainage passages may be larger than the size of the sum of the cross-sectional areas of the first drainage passages, which are directly adjacent to the second drainage passage, such as twice as big or three times as big or four times as big.

The retention section may com prise a braided portion with crossed filaments which mutually form a braiding angle. The braiding angle may vary along the length of the retention section e.g. such that the braiding ang Ie in the middle of the retention section is different from the braiding angle in the top and bottom of the retention section.

The wording "braided portion" includes in general a device portion provided with through- going windows, i.e. openings formed from an outer peripheral surface to an inner peripheral surface and often being symmetrically arranged to form a uniform grid of windows. More specifically, the braided portion may comprise cross-braided filaments, i.e. threads which are braided over and under each other. Preferably, the braiding enables the filaments to slide relative to each other. The braided portion could also be constituted by a section of the device with openings forming a mesh-pattern. Irrespective of the type of braiding, the angle, α, which the filaments form with the axial direction, is important for determining the degree of radial expansion and the more precise shape of the retention section which arises when the first part is displaced into the second part of the braided portion. This is described in further details later.

The braided filaments may be braided over and under each other. Alternatively, the filaments are arranged in two separate layers provided over each other, wherein the filaments of one layer extend in a direction different from the direction of the filaments of the other layer. In each intersection between a filament of one of the layers and a filament of another layer, the filaments of the two layers may be joined by adhesion.

In connection with one device there may be used between 20 and 100 filaments, such as between 24 and 48 filaments.

The braiding may be provided in the retention section and/or the drainage section and/or the deployment member. Furthermore the tip of the device may be made of the same braided material as the retention section. In order to provide a homogeneous surface of the tip, the braided material may be shaped by means of a heated tool or a tool for plastically deforming the material in to e.g. a bullet-like shape. By providing a drainage section comprising a bra ided material, the strength of the drainage section is reinforced as the braided section and a n appropriate matrix material constitutes a composite. Accordingly it is possible to make the wall of the drainage section thinner. Thus for a given outer diameter of the medical device the cross-sectional flow area may be larger.

In the table below, it is indicated how the use of a braided drainage section can increase the cross section of the conduit in a catheter.

Traditional silicone catheter cross Cross sectional area with a braided

Ch size sectional area [mm²] drainage section [mm²]

8 1,3 2,3

10 3, 1 4,2

12 3,8 7,1

14 4,9 10,8

16 3,8 14,5

18 8,O 19,6

Moreover the filaments of the drainage section may form an extension of the filaments of the retention section.

At least the drainage section may be at least partially coated with polymeric material. Furthermore the retention section may be at least partially coated with polymeric material, the coating on the retention section being thinner or having the same thickness as the coating on the drainage section.

The filaments could e.g. be made from polyester, polyamide, polyalkane, polyurethane, PET, PBT, Nylon, PEEK, PE, Glass Fibre, Metal Wire or Acrylic materials or any composition of the mentioned materials. A preferred material would be PET or polyester.

The medical device may include a matrix material, e.g. any medical grade polymer that can be dissolved in a solvent or manufactured as a polymer emulsion. Examples of these are polyurethane, polyurethane dispersions, acrylic, PVC, block copolymers (SIS SBS) etc, natural rubber, silicone, neoprene, nitrile or compositions thereof. Polyurethane, acrylic, PVC, block copolymers (SIS SBS) etc, natural rubber, silicone, or EPO or compositions thereof, could be used if the medical device is made by extrusion or injection moulding.

The device may comprise reduction means for reducing the cross sections of at least a part of the first and/or second drainage passages. The reduction means could e.g. be constituted by a filler material disposed between the filaments or by a lining, i.e. e.g. a skirt shaped foil which covers at least a part of the braided portion, e.g. in contact with an inner surface of the braided portion or in contact with an outer surface of the braided portion. The filler and the lining can either substitute each other to prevent ingrowth into the braided portion or the filler may be combined with a lining.

The filler could comprise a matrix material disposed between the filaments or partly covering the filaments. The material could be any medical grade polymer that can be dissolved in a solvent or manufactured as a polymer emulsion. Examples of theses are polyurethane, polyurethane dispersions, acrylic, PVC, block copolymers (SIS SBS) etc, natural rubber, silicone, neoprene, nitrile or compositions thereof. Polyurethane, acrylic, PVC, block copolymers (SIS SBS) etc, natural rubber, silicone, or EPO or compositions thereof, could be used if the medical device is made by extrusion or injection moulding.

The lining could form a skirt or mantle on the surface of the braiding. The lining could be a pre-formed funnel shaped piece of a thin elastically flexible polymeric film, e.g. made from any medical grade polymer that can be dissolved in a solvent or manufactured as a polymer emulsion, e.g polyurethane, polyurethane dispersions, acrylic, PVC, block copolymers (SIS SBS) etc, natural rubber, silicone, neoprene. The lining could also be made from PU, Evoprene or nitrile and possibly with a surface layer of a hydroge l. The thickness of the film could be in the range of 3-1000 μm. such as 20-200 μm., such as 40-80 μm. In one embodiment, a foam material, e.g. a hydrogel, PEG-PL), or Kraton™ can be used with in a thickness of up to 5 mm.

At least two filaments may form a peripheral edge of the second drainage passage, such as three or four filaments. The second drainage passage may be provided by enlarging a first drainage passage e.g. by attaching one or more filaments to each other. The filaments may be attached by gluing the filaments together or by welding a part of two filaments together. Alternatively, the filaments may be tied together. In order to defi ne a large second drainage passage, different points along the periphery of a said second drainage passage may be tied to another filament and thus a rim-portion of said drainage passage is pulled in different directions.

A first drainage passage may be enlarged my insertion of a dilatating element e.g. a ring shaped element, into said first drainage passage, whereby a second drainage passage is defined. The element may be fastened to the rim portion of the drainage passage, e.g. by means of gluing or welding. Alternatively, the surfaces of the element which engage the rim portion may define a groove, adapted to engage the rim portion, such that the dilatating element is retained in the drainage passage.

Moreover, at least a part of one filament may be removed such that two first drainage passages are merged and a second drainage passage is defined. The free ends of the cut filaments may be attached to another filament or the cut surface may be rounded , such that it will not irritate the body lumen into which the medical device is inserted. Furthermore, the filaments may be heat shaped before, under or after the process of braiding of the retention section. The filaments may be heat shaped after braiding, this may be done by forcing a heated element into a first drainage passage, whereby the heat and the force is u sed to enlarge the drainage passage such that a second drainage passage is defined. The latter may be combined with a dilatating element.

The tip section of the medical device may define a side wall terminating in the proximal end, e.g. the tip, and may be bullet-shaped or cone-shaped. In one embodiment the proximal end of the tip section is as smooth as possible so as to ease insertion of the medical d evice and ease the comfort for the patient.

The inlet of the second drainage passage may be provided on the side wall of the tip section or in the proximal end of the tip section.

A lining may be provided over the braided retention section. The second drainage passages may be defined in the lining. In one embodiment predetermined areas of the linin g is water- soluble such that the areas open when having been brought into contact with a body fluid after a predetermined period of time, whereby the second drainage passages are opened. In one embodiment of the device, a part of the retention section or the entire retention section is covered by a lining comprising a hydrophilic surface, and the tip of the device is open so as to define a second drainage passage. In another embodiment the lining is provided such that the first drainage passages are reduced. One advantage of the latter two embodiments is that it is possible to provide a larger hydrophilic surface. This improves the comfort of insertion for the patient.

The device could be used for transporting fluids or substances into or out of a body, e.g. for gastro content aspiration. The device could be applied subcutaneously or through, insertion of the catheter into a natural or artificial opening in the body, or the medical device could be applied for stent delivery, e.g. for placing a stent within the prostatic urethra, or in general for draining fluids from a natural or artificial body lumen, for anal insertion or for insertion into the gastrointestinal region, e.g. with the purpose of fixating a camera or surgical instruments inside the body or in general to establish a passage into the body. Alternatively, the device may be used for urinary drainage, i.e. wherein the catheter is inserted! into a natural or artificial urinary canal e.g. urethra, and into a bladder for draining urin e.

In a second aspect the present invention relates to a method for providing an enlarged drainage passage in a medical device comprising: a tip section for guiding the catheter into a body canal, the tip section defining a tip which in a first configuration of the device forms the proximal end of said device; a drainage section forming a conduit extending in an axial direction of the device; and a retention section extending between the drainage section and the tip section, the retention section comprising a plurality of first drainage passages defined between cross braided filaments, the passages being in fluid communication with the drainage section; the method comprising defining a second drainage passage with a cross- section area being larger than the than the cross-sectional area of any one of the first drainage passages which are adjacent to the second drainage passage, by enlarging a first drainage passage by one of the steps of

- removing at least a part of one filament so as to merge two first drainage passages whereby a second drainage passage is defined,

- elevating the temperature of at least a part of a peripheral edge of a first drainage passage and forming the side walls of said first drainage passage so as to enlarge the cross-sectional area of the passage, and

- attaching a part of a first filament and a second filament to each other.

A cutting tool e.g. a laser, may be used to cut at least a part of the filament. Alternatively, a part of the filament may by melted or burned away so as to merge to first drainage passages.

The temperature of the filament may be elevated by means of a heated element which is forced into a first drainage passage.

The filaments may be attached to each other by means of glue, welding or binding.

It will be appreciated that any feature or element of the first aspect of the invention may be combined with any feature of the second aspect of the invention.

DETAILED DESCRIPTION

In the following, the invention will be described in further detail with reference to the drawings in which:

Figs. la-3b illustrate a medical device with drainage passage(s) in the tip,

Figs. 4a-4c illustrate a medical device with drainage passages in the braided retention section, Fig. 5 illustrates a medical device with cross-braid filaments and a tip section with a drainage passage,

Fig. 6 illustrates the medical device in the first configuration wherein the tip of the tip section forms a proximal end of the device, Figs. 7 and 8 illustrate the braided filaments, and Figs. 9 and 10 illustrate a dilatating element.

Figs. Ia and Ib illustrate a medical device 102 with a proximal end 104 for insertion into a body of a living being and an axially opposite distal end 106. The device comprises a tip section 108, a drainage section 110 defining a conduit 112, and a retention section 114 extending between the drainage section and the tip section. The tip section 108 defines a tip 109. The retention section 114 comprises a plurality of first drainage passages (see Fig. 5) which are defined between cross braided filaments of the retention section and the first drainage passages are in fluid communication with the drainage section. Thus in use fluid from the surroundings of the medical device may pass through the first drainage passages through the retention section and further through the drainage section. However in order to increase the drainage capacity of the device, the tip section defines a second drainage passage 116 provided on a sidewall 118 of the tip section. The second drainage passage 116 is also in fluid communication with the drainage section. The cross-sectional area of the second drainage passage 116 is larger than a cross-sectional area of any one of the first drainage passages. The position of the tip determines the configuration of the device. The tip section may be moved by means of deployment member 120. In the drawing the medical device is in the second configuration wherein its size in a direction transverse to an axial direction 122 of the device is larger than when the device is in said first configuration (see fig. 6). In the first configuration the tip 109 forms a proximal end of the device and may thus be used to guide the catheter into a body canal.

In Figs. 2a-4c is illustrated alternative locations of the second drainage passage 116. In Figs. 2a and 2b the ring shaped tip section 108 defines the second drainage passage 116. In some embodiments additional second drainage passages may be provided on the sidewall of the tip section (not illustrated). The tip section 108 is made from a thermo-plastic material and is welded to the filaments of the braided material. In Figs. 3a and 3b the tip section comprises a ring-shaped element 124 and a proximal element 126 (which defines the tip 109) interconnected by three interconnecting members 128. Three second drainage passages 116 are defined by the ring-shaped element 124, the proximal element 126 and the interconnecting members 128. In Figs. 4a-4c the second drainage passages 116 are provided in the braided retention section 114. The second drainage passage can be made in any way as describe previously e.g. by cutting a part of some of the filaments, attaching some filaments to each other, heat shaping a first drainage passage etc. In Fig. 4b one dimension of each of the second drainage passages extends substantially from the tip 108 to the rim portion 130 which separate the first part 129 and the second part 131.

The round shape of the second drainage sections (Fig. 4b) are provided by heat shaping i.e. application of a heated element which is used to soften the filaments and application of force to the heated element so as to redefine the shape of the filaments of the first drainage passage. In Fig. 4c the second drainage passages are provided by attaching some filaments to each other, see also Fig. 8.

The cross braided filaments 132 of the retention section 114 are illustrated in Fig. 5. The first drainage passages 134 are defined by the filaments. In Fig. 6 the medical device is illustrated in the first configuration in which it may be inserted into a body canal of a body of a living being. In the figure the braiding angle varies along the length of the device. However, in some embodiments this is not the case.

Fig. 7 discloses the braided filaments 132 of the retention section, which define first drainage passages 134. In Fig. 8 the some of the filaments 132' are tied together by means of an attachment ring 136, whereby second drainage passages 116 are defined. In order to enlarge a first drainage passage 134a plurality of attachment rings may be used e.g. four attachment rings may be used such that said first drainage passage is widened in four different directions, thereby forming a second drainage passage.

Fig. 9 and 10 illustrate a dilatating element 138. The element is ring shaped and the outer surface 140 comprises a groove 142 which is adapted to engage a filament 132 such that the dilatating element is retained in the second drainage passage.

Fig. 11 shows the medical device inserted in a bladder 150 and under normal conditions. Fig. 12 shows the medical device in a situation wherein the tip portion by accident has been pulled in the distal direction under insertion. Fig. 13 shows a balloon catheter inserted in a bladder and which by accident has been pulled in the distal direction under insertion. It is evident from Fig. 13, that the balloon part 178 of the balloon catheter blocks the drainage passage 180 such that the catheter cannot drain. An advantage of the present invention is shown in Fig. 12 wherein it may be seen that even when the tip portion is pulled in the distal direction, the drainage passage 182 provided in said tip portion, is not blocked and may still be used.

Claims

1. A medical device with a proximal end for insertion into a body of a living being and an axially opposite distal end, the device comprising:

2. A medical device according to claim 1, wherein the cross-sectional area of each second drainage passage is larger than a cross-sectional area of any one of the first drainage passages which are directly adjacent to said second drainage passage.

3. A medical device according to claim 1 or 2, wherein the retention section defines a centre area encircled by an encircling area, the encircling area comprising at least one second drainage passage and at least one first drainage passage.

4. A medical device according to claim 3, wherein the encircling area comprises at least one second drainage passage located in-between two first drainage passages.

5. A medical device according to claim 3 or 4, wherein the centre area exclusively comprises first drainage passages.

6. A medical device according to any of the preceding claims, wherein a portion of one single filament defines a peripheral edge part of a first and a second drainage passage.

7. A medical device according to any of the preceding claims, wherein each filament extends between the drainage section and the tip section.

8. A medical device according to any of the preceding claims, wherein the cross-sectional area of each second drainage passage is larger than the cross-sectional area of any one of the first drainage passages which are adjacent to the second drainage passage, when the medical device is in a second configuration wherein the size of the retention section in a direction transverse to an axial direction of the device is larger than when the device is in said first configuration.

9. A medical device according to any of the preceding claims, wherein at least two filaments form a peripheral edge of the second drainage passage.

10. A medical device according to any of the preceding claims, wherein at least a part of two filaments are attached to each other.

11. A medical device according to any of the preceding claims, wherein at least a part of the peripheral edge is made from a heat shaped element.

12. A medical device according to any of the preceding claims, wherein the tip defines a side wall terminating in the proximal end and wherein an inlet of the second drainage passage is provided on one of the side wall and the proximal end.

13. A medical device according to any of the preceding claims, wherein at least a part of the tip is soluble in water or a body fluid.

14. A medical device according to any of the preceding claims, wherein the size of the cross- sectional area of the second drainage passage is at least 30% larger than size of the cross- sectional area of any one of the first drainage passages which are adjacent to the second drainage passage.

15. A medical device according to any of the preceding claims, wherein the size of the cross- sectional area of the second drainage passage is larger than the size of the sum of the cross- sectional areas of the first drainage passages, which are immediately adjacent to the second drainage passage.

16. A method for providing an enlarged drainage passage in a medical device comprising

a tip section for guiding the catheter into a body canal, the tip section defining a tip which in a first configuration of the device forms the proximal end of said device; a drainage section forming a conduit extending in an axial direction of the device; and a retention section extending between the drainage section and the tip section, the retention section comprising a plurality of first drainage passages defined between cross braided filaments, the passages being in fluid communication with the drainage section;

the method comprising defining a second drainage passage with a cross-section area being larger than the than the cross-sectional area of any one of the first drainage passages which are directly adjacent to the second drainage passage, by enlarging a first drainage passage by one of the steps of

removing at least a part of one filament so as to merge two first drainage passages whereby a second drainage passage is defined,

attaching a part of a first filament and a second filament to each other.