Patent Description:
More specifically, the invention provides apparatus and methods for treating such internal defects through the application of a negative pressure at the site of the defect, for example to assist closure of an abscess cavity and/or to remove bodily fluids that may have accumulated at the defect.

Abscess cavities may include breaches in the continuity of the wall of the upper and lower gastrointestinal (GI) tract, which can create internal defects known as 'leak cavities'. Such breaches may be a result of anastomotic leak or spontaneous / iatrogenic perforation, which can often result in severe sepsis. Traditionally, open surgery and/or radiological drainage is required to treat such defects, though this approach is often associated with high rates of morbidity and mortality, and furthermore may not always be feasible. It is estimated that around <NUM>% of patients who have a leak from the upper gastrointestinal (GI) tract that requires surgical intervention do not recover.

Abscesses occurring in the peritoneal and pleural cavities usually occur due to bacterial infection within that cavity, for example following visceral perforation in the peritoneal cavity, such as perforated appendicitis or perforated diverticulitus, or following pneumonia or other insult such as penetrating trauma in the pleural cavity. It is recognised that drainage of the cavity (i.e. removing contaminants) can help to control infection at these internal defects, though drainage by way of surgery is associated with increased morbidity and mortality.

It is desirable to provide an apparatus and method for treating such internal defects that may avoid the need for open surgery.

<CIT> describes an endoluminal and intracorporeal negative pressure, wound care treatment and prophylaxic system. The system includes a fluid communication means connected to a pressure distributor which serves as a collecting means at the site of a wound or abscess. The system also includes an introducer sleeve for introducing the pressure distributor into the wound/abscess site. The introducer sleeve is removed once the pressure distributor is in position, and negative pressure is then communicated through the fluid communication means to the site of the wound/abscess.

According to an aspect of the invention there is provided a catheter for treatment of a defect internal of a human or animal body, the catheter comprising: a tube adapted for insertion into the body; an applicator disposed within and moveable relative to the tube; and a porous medium attached to the applicator; wherein the porous medium is capable of fitting inside the tube, whereby the applicator can be controlled at a proximal end of the tube to deploy the porous medium from a distal end of the tube so as to treat the defect, and wherein the tube is arranged to provide a fluid conduit for application of a negative pressure to the deployed porous medium.

The defect may be an abscess cavity, possibly caused by a breach in the wall of the lower or upper gastrointestinal (GI) tract, including in the pharynx and oesophagus, whereby the catheter may be adapted for insertion into the body to access the defect endoluminally.

Alternatively, the defect may be an abscess in the peritoneal and pleural cavity, possibly caused by bacterial infection, whereby the catheter may be adapted for insertion into the body to access the defect percutaneously, and optionally using radiological guidance. The apparatus may further be suitable for drainage, such as for drainage of an abscess cavity, whether in the abdominal or thoracic cavity, optionally wherein the catheter is arranged to be inserted percutaneously.

Thus, the catheter may be utilised to place the porous medium into the defect, optionally under endoscopic visualisation or radiological guidance, depending on the defect. By attaching the porous medium to the moveable applicator, instead of the tubing, it may be possible to deliver the end of tube to the site of a defect before deploying the porous medium, and then subsequently deploying the porous medium. The porous medium may also be retracted back into the tube using the applicator to allow it to be removed at the end of the treatment. In addition, it may be possible to use the applicator to control and adjust the extent to which the porous medium is deployed, e.g. into a defect cavity, once the catheter is in situ.

Optionally, the porous medium may be capable of being deformed such that it can fit inside the tube, and the porous medium may be arranged to return to its pre-deformed shape when deployed from the tube. Optionally, the porous medium may initially, prior to deployment, be contained within the tube, for example in a deformed (for example, compressed or 'non-expanded') state.

Optionally, the tube may be arranged to provide a fluid conduit, for flushing of liquid into the defect and/or for drainage purposes. Optionally, the applicator may be arranged to provide structural support to the tube, for example to inhibit the tube from collapsing and/or kinking.

Optionally, the applicator may be moveable in a longitudinal direction, for example wherein the amount of movement may be varied to control the amount of porous medium deployed. Optionally, the applicator may be a guidewire, for example a coiled guidewire having an internal bore. Optionally, the porous medium may be attached to the distal end of the applicator.

Optionally, the porous medium may be attached to the end of the applicator by a cord, thread, adhesive, heat-shrink wrap, or other suitable attachment means, whereby a first end of the cord may be secured to the porous medium and a second end of the cord may be secured to the applicator at a position spaced from the porous medium, such that the cord extends at least partway along the length of the applicator. Optionally, the second end of the cord may be attached to the applicator at a position that is external to the tube. Optionally, the porous medium may be attached to the end of the applicator by a suture.

Optionally, the porous medium may comprise a foam material such as an open-cell foam, which may comprise polyurethane. For example, a suitable open-cell foam may be a 'vacuum assisted closure' foam, VAC (REGISTERED TRADEMARK).

Optionally, the porous medium may comprise bio-active material, for example a bio-active collagen. The porous medium may be carried on the applicator and held in place either by friction, or by an additional binding such as an adhesive, or by wrapping it around the applicator or by mechanical fixing means, for example. Optionally, the porous medium may comprise a material designed to treat a cavity and/or restore continuity of a wall.

Optionally, the porous medium may be a tangled mesh of wire capable of being unravelled, stretched or drawn out into one or more single strands, the wire being arranged to have resilience causing it to reform the mesh when not restrained and/or under tension. Optionally, the porous medium may comprise a nickel titanium alloy, for example nitinol.

Optionally, the distal end of the tube may be arranged to provide a flared opening, for example a conical-shaped opening. Optionally, the tube may comprise fluorinated ethylene propylene (FEP). Optionally, the tube may be configured for nasogastric intubation.

Optionally, the catheter may further comprise an adaptor arranged to fit the applicator and provide a detachable fluid connection between the tube and a fluid flow generator capable of applying a negative pressure to the tube, for example a vacuum apparatus or a pumping apparatus. Optionally, the adaptor is arranged to provide a luer-lock connection with the fluid flow generator. The adaptor may also be used to couple a fluid source to the lumen of the catheter, for example to supply a fluid such as saline to the working (distal) end of the catheter to flush the defect and/or for example to deliver antibiotics.

Optionally, for insertion endoluminally, the catheter (or tube) may have an outer diameter arranged to fit within the working channel of an endoscope. For example, an endoscope having a working channel of <NUM> diameter would, preferably, require a catheter to have an outer diameter of less than <NUM>. For example, an endoscope having a working channel of <NUM> would, preferably, require a catheter having a working channel of less than <NUM>. Preferably, a clearance gap is required to allow movement of the catheter within the working channel of an endoscope - which typically has an internal diameter of about <NUM> or <NUM> - otherwise even so-called 'low friction' plastics (such as PVC, for example) may present a problem due to the length of channel and catheter. Optionally, for endoluminal insertion, the catheter (or tube) exterior may comprise a very smooth, preferably 'ultra-smooth', and/or a low-friction material, such as PVC (e.g. a material having a low friction coefficient), at least on its exterior surface.

Optionally, the length of the catheter may be at least <NUM>% longer, and preferably at least <NUM>% longer, than the length of the endoscope. Preferably, the catheter is flexible, and optionally it is sufficiently flexible to undergo a <NUM> diameter <NUM> degrees bend.

Optionally, for percutaneous insertion, the catheter may be arranged to be deployed along a guidewire arranged to guide the catheter into position within the body. The guidewire may be introduced to the body using a needle (or cannula). Preferably, the outer diameter of catheter is not specifically restricted for percutaneous use, such as may be necessary if the catheter is for endoluminal insertion, for example. Optionally, however, if the catheter is to be placed into a deep cavity between other structures, the catheter (or tube) may have an outer diameter similar to the outer diameter of the catheter for endoluminal insertion, and, for example, less than about <NUM>. The catheter for percutaneous insertion may have a similar rigidity to the endoscopic catheter. Optionally, the catheter may have a length of between about <NUM> and about <NUM>. Optionally, the catheter may comprise a low-friction material similar to the material of the catheter for endoluminal insertion.

Optionally, the catheter may be radio-opaque to aid x-ray guided visualisation of its insertion. Optionally, at least part of the applicator may be radio-opaque, for example if it comprises a metal or another suitably radio-opaque material.

According to another aspect not belonging to the invention there is provided a method for treating a defect, such as a leak cavity caused by a breach in a wall, of the lower or upper gastrointestinal (GI) tract internal of a human or animal body, the method comprising: introducing a catheter containing a deployable porous medium into the body, for example via endoluminal insertion; positioning the catheter at the defect (for example in an opening of a leak cavity, or adjacent the opening and preferably close enough to allow the porous medium to be deployed into a leak cavity); deploying the porous medium from the catheter; placing the porous medium into the defect; and applying a continuous negative pressure via the catheter to treat the defect.

Optionally, the catheter may be positioned using endoscopic visualisation. Optionally, the porous medium may be applied to the wall of the gastro-intestinal tract outside of the defect. Negative pressure can then be applied to the wall of the gastro-intestinal tract around the defect whereby to close the defect and/or inhibit the entry of bowel contents and other contaminants into the defect so as to assist healing.

According to another aspect not belonging to the invention there is provided a method for treating a defect, such as an abscess in a peritoneal or pleural cavity internal of a human or animal body, the method comprising: inserting a guidewire into the body, the guidewire being positioned at the site of a defect (for example at an abscess or infection having collection of fluid); inserting a catheter containing a deployable porous medium into the body percutaneously, wherein the catheter is deployed along the guidewire arranged to position the catheter at the defect; deploying the porous medium from the catheter; placing the porous medium into the defect; and applying a continuous negative pressure via the catheter to treat the defect.

Optionally, imaging guidance, for example ultrasound, may be used to position the guidewire at the defect. Optionally, the positioning of the guidewire may be checked using imaging, for example radiology.

Optionally, the porous medium may be initially contained within the catheter in a deformed state, whereby deployment of the porous medium causes it to return to its pre-deformed state.

Optionally, the catheter may comprise an applicator controllable to deploy the porous medium, the method further comprising controlling the applicator at a proximal end of the catheter to deploy the porous medium at a distal end of the catheter.

Optionally, the negative pressure applied may be less than <NUM> Hg, for example less than <NUM> Hg, for example less than <NUM> Hg.

According to another aspect not belonging to the invention there is provided a method of treating a defect, comprising using a catheter as described above with a method as described above.

According to another aspect of the invention there is provided a system for treating a defect internal of a human or animal body, the system comprising: a catheter as described above; and a fluid flow generator adapted to provide a fluid connection with the catheter, such that, when fluidly connected, a negative pressure can be applied by the fluid flow generator, via the catheter, to treat the defect.

According to another aspect of the invention there is provided a system for treating a defect internal of a human or animal body, the system comprising: a catheter, an elongate element disposed within and moveable relative to the catheter, and a porous substrate attached to an end of the elongate element, such that the porous substrate can be deployed from the catheter by controlling a proximal end of the elongate element, wherein the catheter is arranged to provide a fluid conduit for application of a negative pressure to the deployed porous substrate; and a vacuum apparatus adapted to be fluidly connected to the catheter, such that, when fluidly connected together, a negative pressure can be applied by the vacuum apparatus, via the catheter, to treat the defect.

Optionally, the system further comprises an endoscope capable of positioning the catheter at the defect under endoscopic visualisation.

Optionally, the system further comprises visualisation means for positioning the catheter at the defect.

Optionally, the system may be arranged such that the catheter is deployed alongside the endoscope, for example wherein the catheter may be attachable to the endoscope, such that it can be positioned at a defect with the endoscope. Alternatively, the catheter may be arranged to fit within the lumen of the endoscope, such that it can be positioned at a defect with the endoscope.

Optionally, the system further comprises a guidewire and insertion needle (or cannula) arranged to insert the guidewire into the body.

Optionally, the system may be arranged such that the catheter is deployed along a guidewire introduced into the body percutaneously so as to position the catheter at a defect.

Optionally, the guidewire may pass through the catheter or it may run alongside the catheter.

A fluid source may be connectable to the lumen of the catheter, for example to supply a fluid such as saline to the working (distal) end of the catheter to flush the defect and/or for example to deliver antibiotics.

Miniaturisation may allow the catheter to be used in other areas of the body.

According to another aspect of the invention there is provided a kit of parts for a catheter, comprising an applicator and a porous medium attached to an end of the applicator.

Optionally, in the kit, the applicator may be a guidewire, for example a coiled guidewire having an internal bore. Optionally, in the kit, the porous medium may be attached to the end of the applicator by a suture. Optionally, in the kit, a first end of the suture thread (or cord) may be secured to the porous medium and a second end of the suture thread (or cord) may be secured to the applicator at a position spaced from the porous medium, such that the suture thread (or cord) may extend at least partway along the length of the applicator.

Optionally, the kit may further comprise a tube arranged to fit over the applicator so as to provide a fluid conduit. Optionally, the kit may further comprise an adaptor for coupling the tube to a vacuum apparatus, the adaptor arranged to allow the applicator to pass therethrough.

Optionally, the kit may further comprise a guidewire and a needle or cannula for inserting the guidewire into a body, preferably wherein the guidewire is arranged so as to pass through the applicator whereby to enable percutaneous insertion of the catheter into the body via the guidewire.

According to another aspect not belonging to the invention there is provided a substrate for delivering bio-active material into an internal wound in a human or animal body, the substrate (for example, an extensible substrate) carrying a bio-active material, wherein the substrate is configured at least partially to shed the bio-active material into a wound.

Optionally, the substrate may be flexible. Preferably, the substrate is more flexible than the bio-active material such that flexure of the substrate causes shedding of the bio-active material.

Optionally, the substrate is elongate and configured to form a mesh when not restrained and/or under tension. Optionally, the elongate substrate may be arranged to form a resilient mesh when not restrained and/or under tension. Optionally, the substrate may comprise a wire or tape. Optionally, the substrate may comprise a memory metal, such as nitinol. Optionally, the bio-active material may comprise collagen.

Optionally, the bio-active material may be water soluble. Optionally, the bio-active material may be adhered to the substrate by a water-soluble adhesive.

According to another aspect not belonging to the invention there is provided a method of delivering bio-active material into an internal wound in a human or animal body, comprising: positioning a catheter at the wound; and deploying an extensible substrate from the catheter into the wound; wherein said substrate carries the bio-active material and is configured to at least partially shed the bio-active material into the wound.

Optionally, the substrate may be deployed from a distal end of the catheter positioned at the wound. Optionally, deployment of the substrate may be controlled from a proximal end of the catheter. Optionally, the substrate may shed bio-active material while extended from the catheter, for example during deployment or during retraction. Optionally, the distal end of the catheter may be configured to cause at least some of the bio-active material to shed from the substrate into the wound as the wire is retracted back into the catheter, for example wherein the distal end has serrations. Optionally, the substrate is elongate and configured to form a mesh when not restrained by the catheter and/or under tension.

Optionally, the elongate substrate may be arranged to form a resilient mesh when not restrained by the catheter and/or under tension. Optionally, the substrate may comprise a wire or tape. Optionally, the substrate may comprise a memory metal, such as nitinol. Optionally, the bio-active material may comprise collagen.

As used herein, the term "abscess" preferably connotes a drainable, infected fluid collection.

As used herein, the terms "vacuum apparatus" and "fluid flow generator" preferably include apparatus arranged to generate a vacuum, or at least a negative pressure (i.e. suction) via a tube or catheter.

As used herein, the term "proximal" preferably connotes situated nearer to a point of attachment, to an apparatus for example. In contrast, the term "distal" preferably connotes situated away (or remote) from a point of attachment, to an apparatus for example.

As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

Any apparatus feature as described herein may also be provided as a method feature, and vice versa. Furthermore, any feature in a particular aspect of the invention may be provided independently and/or applied to other aspects of the invention, in any appropriate combination.

An exemplary embodiment of the invention will now be described with reference to the accompanying figures, in which:.

Endoscopic vacuum therapy (EVT) is a relatively new technique for treating defects, such as oesophageal perforation and certain other post-operative leakages. EVT is a minimally invasive, alternative method of treatment to traditional surgery, utilising vacuum-assisted closure (VAC) techniques.

EVT involves placing a polyurethane sponge into a defect cavity under endoscopic visualization and then applying a continuous negative pressure, causing the cavity to collapse around the sponge. The sponge is typically changed every <NUM>-<NUM> hours until the cavity shrinks and stable granulation tissue forms a barrier.

Devices used for EVT are typically 'homemade' and therefore quite crude in their construction, and could be improved. For example, one treatment method involves a nasogastric tube first being inserted through the nose under general anaesthesia, and then the distal end pulled out through the mouth, and attached to a polyurethane sponge which has been cut to size. The polyurethane sponge may be secured to the nasogastric tube by suture. The sponge is then delivered (attached to the tube) to a defect by a tripod-equipped endoscope, under direct endoscopic visualisation.

Referring to <FIG>, a schematic diagram of an oesophagus <NUM> is used to show an example of three different stages (i) - (iii) of endoscopic vacuum therapy (EVT) being used to treat a gastrointestinal defect. In this example, EVT is being used to treat a defect <NUM> in the oesophagus <NUM>, as illustrated in (i). To treat the defect <NUM>, a tube <NUM> may be inserted through the nose and then directed to the defect <NUM> under direct endoscopic visualisation, as illustrated in (ii). A sponge <NUM> attached to the tube <NUM> may be placed in the defect cavity. A negative pressure, such as -<NUM> Hg for example, may then be applied, causing the defect <NUM> cavity to collapse around the sponge <NUM> to aid healing, as illustrated in (iii). This treatment may also be referred to as endoscopic 'transluminal' or 'intraluminal' vacuum therapy.

Referring to <FIG>, a basic apparatus <NUM> for use in endoscopic vacuum therapy may include a sponge <NUM> attached to an end of a tube <NUM> using a suture <NUM>. The tube <NUM> may be <NUM>-16F nasogastric (feeding) tube. The sponge <NUM> may be polyurethane. The suture <NUM> may be made using '<NUM> silk'. Due to the sponge <NUM> being in an expanded state, it cannot be passed down the working (or 'tool') channel of an endoscope but rather has to be secured to the outside of the endoscope for placement into a defect cavity, meaning placement of the sponge <NUM> can be difficult.

Referring now to <FIG>, a catheter <NUM> may include a porous medium <NUM> secured to a distal end <NUM> (shown in <FIG>) of an applicator <NUM>. The applicator <NUM> may be disposed at least partially within a tube <NUM>. The tube <NUM> may have a distal end <NUM> and a proximal end <NUM> (as shown in <FIG>). The distal end <NUM> of the tube <NUM> and the distal end <NUM> of the applicator <NUM> may be substantially coincident.

The proximal end <NUM> of the tube <NUM> may be secured to an adaptor <NUM>. The applicator <NUM> may be arranged to pass through the adaptor <NUM> into the tube <NUM>. A distal end <NUM> of the applicator <NUM> may be arranged to extend out from the other side of the adaptor <NUM>. The adaptor <NUM> may be arranged to provide a fluid connection with a vacuum apparatus (not shown). When the adaptor <NUM> is connected to a vacuum apparatus, a negative pressure may be applied to the porous medium <NUM> via the tube <NUM>.

<FIG> show the catheter <NUM> in side profile. <FIG> is a cross-sectional view of the catheter taken along line A-A as indicated in <FIG>.

The applicator <NUM> may be elongate. The applicator <NUM> may be sufficiently elongate (and of suitable diameter) that it can be inserted through a patient's nose. The applicator <NUM> may be arranged to provide flexibility without creating sharp kinks. The applicator <NUM> may be flexible while substantially maintaining an inner bore that can act as a fluid conduit. The applicator <NUM> may be metal, for example a stainless steel such as <NUM> or <NUM> stainless steel. The applicator <NUM> may have a diameter of less than <NUM> or <NUM>, so that it can fit inside a standard endoscope having an internal diameter of <NUM> or <NUM>. The applicator <NUM> may have a perforate or foraminous wall. The applicator <NUM> may be a guidewire. The guidewire may be a guide coil.

The applicator <NUM> may be moveable relative to the tube <NUM> in a longitudinal direction. The applicator <NUM> may also be moveable relative to the tube <NUM> in a rotational sense. The porous medium <NUM> may be deployed from a distal end <NUM> of the tube <NUM> by moving the applicator <NUM> in a longitudinal direction relative to the tube <NUM>. The applicator <NUM> may be moved relative to the tube <NUM> by controlling the applicator <NUM> at a region of the applicator <NUM> that is not disposed within the tube <NUM> or adaptor <NUM>. The applicator <NUM> may be controlled at a proximal end <NUM> of the applicator <NUM>. The extent to which the porous medium <NUM> is deployed from the tube can be controlled by the applicator <NUM>. The applicator <NUM> may have a measurement guide disposed on at least its proximal end <NUM> to aid deployment of the porous medium <NUM>.

The tube <NUM> may fit closely over the applicator <NUM>. The tube <NUM> may provide a fluid conduit between the adaptor <NUM> and the porous medium <NUM>. The tube <NUM> may provide a fluid tight seal between the adaptor <NUM> and the porous medium <NUM>. The tube <NUM> may be supported structurally by the applicator <NUM> to maintain a fluid conduit through the tube <NUM>.

The distal end <NUM> of the tube <NUM> may be flared open (not shown) to aid retraction of the porous medium <NUM> back into the tube <NUM>. The tube may have an external diameter that allows it to fit (and have relative movement) inside the working channel of a standard endoscope, preferably either less than <NUM> or less than <NUM>, depending on the endoscope.

The tube <NUM> may be a thin-walled polymer. The tube <NUM> may be a low-friction polymer, compared to silicon and/or PTFE. The tube <NUM> may have greater elasticity than PTFE. The tube <NUM> may be arranged to be resistant to kinking. The tube <NUM> may be capable of twisting or bending with a curvature of about <NUM> radius. The tube may be capable of bending greater than <NUM> degrees without rupturing or kinking. The applicator <NUM> may provide structural support that helps the tube <NUM> from kinking. The tube <NUM> may be formed from fluorinated ethylene propylene (FEP).

The adaptor <NUM> may have a first connector <NUM> (not shown) for connecting to the tube <NUM>. The first connector <NUM> may be a "Christmas tree" connector. The first connector <NUM> may have one or more barbs <NUM>. The tube <NUM> may be capable of being stretched to fit over the barbs <NUM> and sufficiently elastic that upon retraction it crimps over the barbs <NUM> to secure the tube <NUM> to the adaptor <NUM>. The adaptor <NUM> may have a second connector <NUM> for connecting to a vacuum apparatus (not shown). The second adaptor <NUM> may be a 'luer lock' type connector. The adaptor may be substantially straight so that the first connector <NUM> and second connector <NUM> are substantially in-line. The adaptor <NUM> may be made from nylon or polycarbonate.

The porous medium <NUM> may be 'bullet-shaped'. Alternatively, the porous medium <NUM> may be "teardrop-shaped". Indeed, the porous medium <NUM> could take the form of many different 3D shapes, such as a cuboid, pentagonal prism and cylinder for example. The porous medium <NUM> may be resiliently deformable from a first state to a second state. The porous medium <NUM> may be deformable to the second state, and may further be maintained in that second state, under a compression force, provided by squeezing the porous medium by hand, for example. The porous medium <NUM> may return to the first state when the compression force is removed.

The porous medium <NUM> may be polyurethane foam. Alternatively, the porous medium <NUM> may be an expandable mesh, preferably a wire mesh. The mesh may be capable of being unravelled, stretched out, or drawn out into a single thread of wire and to return to its mesh form when released. The mesh may be formed of a shape-memory material. The mesh may be formed from a nickel titanium alloy. The mesh may be formed from nitinol.

Alternatively, the porous medium <NUM> may be formed from a bio-active material, such as bio-active collagen. The bio-active material may be arranged to degrade itself after a predetermined period of time. The bio-active material may be capable of being wrapped around the applicator <NUM> (or otherwise attached) to create a porous, sponge- or foam-like medium.

Prior to deployment, the porous medium <NUM> may be compressed within the tube <NUM>. Upon deployment, a portion of the porous medium <NUM> that is no longer contained within the tube may expand or undeform back to its pre-deformed state.

Referring to <FIG>, the porous medium <NUM> may be secured to the distal end <NUM> of the applicator <NUM> by way of a suture <NUM>. The suture <NUM> may be secured to the applicator <NUM> at a point that is spaced-apart from the porous medium <NUM>. The suture <NUM> may be secured to the applicator <NUM> at a point along the length of the applicator <NUM> that is not disposed within the tube <NUM> or adaptor <NUM>, with the suture <NUM> passing either alongside or through the applicator <NUM>. Alternatively, the porous medium <NUM> may be glued or otherwise secured to the applicator <NUM>.

The catheter <NUM> as shown in <FIG> is not shown to scale. The tube <NUM> may be of sufficient length to extend from outside of a patient's body to the defect <NUM> inside the patient's body. The tube <NUM> may have a length of between about <NUM> and <NUM>. The applicator <NUM> may be at least as long as the tube <NUM>. In use, the adaptor <NUM> may be located outside of the patient's body. The portion of the applicator <NUM> that extends out of the adaptor <NUM> may be of sufficient length to be controlled to allow relative longitudinal movement within the tube <NUM> to allow deployment of the porous medium <NUM> from the distal end <NUM> of the tube <NUM>. The applicator <NUM> may be allowed to move relative to the tube <NUM> a longitudinal distance of between <NUM>-<NUM>, for example. The size of the defect <NUM> will to a great extent dictate the amount of porous medium <NUM> to be deployed. Accordingly, the applicator <NUM> may be required to move longitudinally within the tube <NUM> by up to <NUM>, perhaps further.

For small defects <NUM>, the porous medium <NUM> may be deployed within the lumen of a delivery endoscope, which may then be placed adjacent the defect <NUM> and a negative pressure applied to cause the wall tissue at the defect to be sucked into the lumen for treatment of the defect <NUM>.

A skilled person will appreciate that the apparatus <NUM> shown in <FIG> differs from the catheter <NUM> shown in <FIG> at least because the apparatus <NUM> has a sponge <NUM> secured to the outside of the tube <NUM>, which is therefore not a porous medium capable of fitting inside the tube <NUM>, and further because there is no applicator disposed within the tube <NUM>.

The catheter <NUM> may be inserted by attaching it to the outside of an endoscope. Alternatively, the catheter <NUM> may be deployed from within the working channel of an endoscope.

Once the catheter <NUM> has been inserted into a patient and correctly positioned, the porous medium <NUM> may be deployed from the distal end <NUM> of the tube <NUM> into a defect cavity <NUM> by advancing the applicator <NUM>. A vacuum apparatus may then be connected to the adaptor <NUM> and a continuous negative pressure (i.e. suction) applied to the porous medium <NUM> via the tube <NUM>. The negative pressure causes the defect cavity to collapse around the porous medium <NUM> to aid healing of the defect <NUM>, as discussed above. Importantly, the porous medium <NUM> need only be deployed from the tube <NUM> once the catheter <NUM> has been correctly placed at a defect <NUM> after inserted into the patient's body.

The catheter <NUM> also allows the defect cavity <NUM> to be flushed out with fluid, if required and/or suction applied to remove bodily (or other) fluids, i.e. for drainage purposes, for example to remove contaminants from the defect cavity.

The endoscope may be removed while leaving the catheter <NUM> in-situ for a predetermined period of time. The applicator <NUM> may then be used again to retract the porous medium <NUM> back into the tube <NUM> before the catheter <NUM> is withdrawn from the patient's body. The catheter <NUM> can then be replaced, as required.

Thus, the applicator <NUM> may function as both a reinforcement mechanism to the tube <NUM> and a deployment mechanism providing controlled deployment of the porous means <NUM>.

When the endoscope is withdrawn, the catheter <NUM> may be left extending out of a patient's mouth. In order to retract the catheter <NUM>, a plastic tube may be inserted through the nose and reattached to the catheter <NUM>, which can then be fed back up through and out from nose.

The porous medium <NUM> may not fill the defect cavity <NUM> entirely. Only a small amount of porous medium <NUM> may be required to initiate collapse of the defect cavity <NUM> and hence aid healing.

Standard endoscopes are generally available in two sizes: <NUM> and <NUM> diameter. The <NUM> diameter version is the more common type of endoscope, but this reduces the amount of porous medium <NUM> that can be deployed, hence using collagen for the porous medium <NUM>, as described above, is of particular interest.

The catheter <NUM> is not limited for intraluminal treatment of the upper gastro-intestine (GI). The catheter <NUM> may also be used in treatment of the lower gastro-intestine (GI), such as for colonoscopy, for example, and for other parts of the body.

Alternatively, the catheter <NUM> may be introduced to a patient's body via percutaneous insertion, i.e. through the skin, similar to the method of inserting an intercostal chest drain, for example by performing a direct cut down, or using the 'Seldinger' technique. Thus the catheter <NUM> may be used to perform percutaneous drainage, for example to treat an abscess in the peritoneal or pleural cavity, and the abdominal or thoracic cavity, in addition to being used to treat internal defects, such as leak cavities, as discussed above.

The applicator <NUM> and/or porous medium <NUM> and/or tube <NUM> may be provided together in kit form for assembly when required.

<FIG> shows a system <NUM> for treating a defect according to an embodiment of the invention. The system <NUM> includes a catheter <NUM> and a vacuum apparatus <NUM> arranged to be fluidly connected together such that a negative pressure can be applied by the vacuum apparatus <NUM> via the catheter <NUM>.

The catheter <NUM> includes an adaptor <NUM> provided with a luer lock connector <NUM> for coupling with the vacuum apparatus <NUM>. The adaptor <NUM> is provided with a further connector <NUM>, which is substantially in-line with the luer lock connector <NUM>, for coupling with a flexible tube <NUM>, formed from FEP. The further connector <NUM> is provided with barbs, which the flexible tube <NUM> is stretched over so as to provide a secure fluid-tight coupling.

Disposed within the tube, but not visible in this figure (refer to <FIG>) is an applicator <NUM> that passes through the adaptor <NUM> and extends towards a distal end <NUM> of the tube <NUM>. A porous medium <NUM>, which is just about visible in <FIG>, is secured, via suture, to the end of the applicator <NUM>.

In this exemplary embodiment, the applicator <NUM> is a coiled guidewire, and the porous medium <NUM> is a teardrop-shaped polyurethane foam, which is sufficiently compressible to allow it to be compressed to fit within the tube <NUM> and sufficiently resilient that it can resume its uncompressed shape when deployed from (and hence no longer constrained within) the tube <NUM>.

The applicator <NUM> is moveable in a longitudinal direction relative to the tube <NUM>. The applicator <NUM> can therefore be controlled to advance the porous medium <NUM> towards the distal end <NUM> of the tube <NUM> and hence deploy it. As the porous medium <NUM> is deployed from the tube <NUM>, it expands.

Thus, once the catheter <NUM> has been positioned at a defect cavity, and prior to connecting the catheter <NUM> to the vacuum apparatus <NUM>, the applicator <NUM> can be controlled to deploy the porous medium <NUM>. The vacuum apparatus <NUM> is arranged to connect to the luer lock connector <NUM> on the catheter <NUM> to provide a fluid connection to the porous medium <NUM> at the distal end of the catheter <NUM>.

In use, once the catheter <NUM> has been inserted into a patient's body, via the nasal canal for example, and positioned by the defect, and the porous medium <NUM> deployed, the vacuum apparatus <NUM> may be attached to the catheter <NUM>, via the adaptor <NUM>, and a negative pressure (or 'suction') applied to the porous medium <NUM> via the tube <NUM>, which is structurally supported by the coiled guidewire acting as the applicator <NUM>.

<FIG> shows various different stages of a porous medium <NUM> being formed of an expandable mesh (in an exemplary embodiment), which is capable of being unravelled, stretched out or drawn out into a single thread of wire <NUM> and of returning to its original mesh form <NUM> when released, being deployed from the distal end <NUM> of a tube <NUM> of a catheter.

As shown in the first (i) view, the wire <NUM> has been unravelled and is being held under tension in the tube <NUM> by the applicator <NUM>. In the second view (ii) an amount of wire <NUM> has been released by advancement of the applicator <NUM> and allowed to deploy from the distal end <NUM> of the tube <NUM>, where it is beginning to form a mesh <NUM>. In the third (iii) view, a substantial amount of wire <NUM> has been released by further advancement of the applicator <NUM> and a mesh <NUM> has formed at the distal end <NUM> of the tube <NUM>, suitable to provide a porous medium <NUM>.

Where the porous medium <NUM> is provided by such a wire <NUM>, the distance that the applicator <NUM> may be required to move within the tube <NUM> will of course be much further than if the porous medium <NUM> were a foam sponge, for example. Indeed, the applicator <NUM> may be required to travel substantially the entire length of the tube <NUM>. The wire <NUM> may alternatively be a tape, or similar elongate element.

In another embodiment (not shown), a catheter (or other suitable apparatus) may contain an extensible substrate coated in a bio-active material, such as collagen. The bio-active material may be arranged to shed from the substrate, such that at least a portion of it can be deposited into an internal wound when the substrate positioned there by the catheter. The bio-active material may be particularly suitable for treating wounds or otherwise helping them to heal.

Similar to the arrangement described above, the substrate may comprise a wire, tape or similar elongate element that is formed into a mesh configuration. Furthermore, the substrate may be sufficiently resilient that if drawn or stretched out (such that the mesh is deformed) it will return to a resilient mesh configuration, or otherwise undergo flexure of some description, when no longer under tension and/or restrained within the catheter. The substrate may comprise a memory metal, such as nitinol. The substrate is, preferably, more flexible than the bio-active material coated onto it, such that flexure of the substrate causes the bio-active material to be shed. The bio-active material may be coated onto the substrate using a water-soluble adhesive. The bio-active material may itself be water-soluble.

A distal end through which the substrate can be deployed into a wound may be configured to cause the substrate to flex as it is either deployed or retracted. The distal end may be configured for example to cause the substrate to flex, or it may have features that cause the bio-active coating to shed, such as serrations. As described above, deployment of the substrate may be controlled from a proximal end of the catheter. The bio-active coating may shed either during deployment of the substrate into the wound or retraction of the substrate into the catheter. Indeed, the bio-active coating may shed during both procedures.

Claim 1:
A catheter (<NUM>) for treatment of a defect internal of a human or animal body, the catheter (<NUM>) comprising:
a tube (<NUM>) adapted for insertion into the body;
an applicator (<NUM>) disposed within and moveable relative to the tube; and
a porous medium (<NUM>) attached to the applicator (<NUM>);
wherein the porous medium (<NUM>) is capable of fitting inside the tube (<NUM>),
whereby the applicator (<NUM>) can be controlled at a proximal end of the tube (<NUM>) to deploy the porous medium (<NUM>) from a distal end of the tube (<NUM>) so as to treat the defect; and wherein the tube (<NUM>) is arranged to provide a fluid conduit for application of a negative pressure to the deployed porous medium (<NUM>).