WO2009125181A1

WO2009125181A1 - Subcutaneous port and catheter

Info

Publication number: WO2009125181A1
Application number: PCT/GB2009/000918
Authority: WO
Inventors: Amolak Bansal
Original assignee: Epsom And St Helier University Hospitals Nhs Trust
Priority date: 2008-04-08
Filing date: 2009-04-08
Publication date: 2009-10-15
Also published as: GB2459101A; GB0806378D0

Abstract

The present invention relates to a subcutaneous port and fenestrated catheter for the administration of fluids subcutaneously to be infused over a large volume of tissue.

Description

SUBCUTANEOUS PORT AND CATHETER

The present invention relates to devices for delivering medicaments to a body, preferably subcutaneously, and in particular, using subcutaneous ports attached to catheters.

Classically, medicaments that could not be taken orally, for instance because they reacted with acids in the stomach or were degraded by gut enzymes have been injected using a hypodermic needle and a syringe. The hypodermic needle could be inserted either subcutaneously if the medicament was to be placed just under the skin or in the muscle. Alternatively, a hypodermic needle could be inserted directly into a vein in the case where the medicament needed to enter the bloodstream quickly or directly.

However, certain medicaments need to be given either frequently or in large doses: Frequent piercing of the skin, particularly in the small area available over a vein, causes scarring. Scarring has at least two problems associated with it. It is unsightly and it also makes that area of skin more difficult to pierce subsequently because of hardening of the skin in the scar area. Furthermore, recurrent venous cannulations damages veins and can lead to thrombosis, which is dangerous to the patient.

When administering medicaments intravenously, it is important that a hypodermic needle punctures the wall of the blood vessel as well as the skin. Possible targets on a human patient are small and limited and increasing areas of scar tissue make these available targets even scarcer.

Medicaments that need to be given in large doses can cause problems when they are delivered intravenously because a high concentration of the medicament may be found in a small volume of blood, causing unpredictable peak dose effects and that volume of blood to have different properties from normal blood, such as being thinner or thicker or having different flow properties. This can cause serious problems if the volume of blood with the high dosage of medicament finds its way to a sensitive area of the body, such as the brain or the heart or any other organ. A solution to this latter problem has been proposed: large doses of medicament can be supplied subcutaneously (under the skin) such that the medicament would infuse slowly into the bloodstream. This is referred to as subcutaneous infusion. However, the present inventors have found that there is a problem with introducing a large amount of fluid under the skin, namely that a bubble or bulge may form under the skin or in the muscle, causing stretching and discomfort, thereby limiting the amount of medicament that can be administered at a single site.

Recently, the subcutaneous infusion of immunoglobulin (SCIG) has become widely used because of a lower incident of adverse affects when compared to intravenous infusion of this medicament. To overcome the risks associated with introducing large amounts of fluid under the skin, a process has been proposed wherein a pump is used slowly to infuse the medicament at a site under the skin using a needle. This infusion is performed slowly, which reduces accumulation of medicament within a small area of skin and prevents the bubble or bulge where the fluid builds up. However, this slow infusion of a dose of immunoglobulin may take over 90 minutes to perform and requires a pump. The latter is expensive and the procedure is time consuming, not to mention uncomfortable for the patient, even if several sites are chosen for immunoglobulin delivery and two or more pumps are used.

One aim of the present invention is to improve methods and devices for introducing fluids to patients, particularly when the fluid needs to be frequently administered, or given in large doses.

The present invention builds on the concepts of intravenous catheters and injection ports.

Catheters have been used in the past to carry medicaments into veins that are either deep below the surface of the skin (or protected by bones, such as in the skull or within the ribcage) so that they are difficult to reach using a hypodermic syringe. Catheters have also been used in such a way that they remain in place even after a dose of medicament has been given such that medicaments may be subsequently administered via the same catheter. The catheter is partly inside the patient and partly outside the patient and this has the advantage that medicament may be given at frequent intervals without having to re-pierce the patient's skin every time. Where the catheter emerges from the patient's skin, a port is known that may be attached and this can be stitched, taped or otherwise adhered the patient's skin. The port offers a sealable entry into the catheter so that medicament may be easily introduced while reducing the risk of infectious materials entering the catheter. Frequent injections via this port into the catheter can therefore be made without further damage to the patient or the development of more scar tissue than the amount that is created by just the entry hole of the catheter.

Recently, a port has been developed that can be inserted and remain under the skin. This "injection port" is a small reservoir implanted under the skin that has a self- sealing membrane allowing the repeated insertion of hypodermic needles for the administration of drugs or fluids. The membrane can be injected hundreds of times before replacement of the port is required. This also removes the disadvantage of repeated cannulations when fluids are to be given frequently.

However, these subcutaneous injection ports do not solve the problem of accumulation of drugs or fluids causing uncomfortable bulging of the skin.

According to an aspect of the present invention there is provided a device for enabling the administration of fluids or drugs, the device comprising: a fenestrated catheter; and a subcutaneously implantable port arranged to receive fluid and to supply said fluid to the fenestrated catheter. The fenestrated catheter of embodiments of the present invention preferably comprises at least one aperture in the side of the catheter, rather than at the end (as in a conventional catheter). Of course, the catheter may or may not additionally comprise a hole at the end.

The fact that all of the parts of the device are subcutaneously implantable means that there are no parts that are emerging from the patient's skin, thus reducing the risk of infection or of catching the port on something if the patient moves. The device enables the infusion of a fluid over a larger area (or volume) than any of: a port on its own, a normal open-ended catheter used with a port, or a hypodermic needle on its own. This larger volume over which the fluid is administered means that bubbles or bulges are less likely to form and larger doses may be administered at a time. The fenestrations can extend over the whole length of the catheter and may be evenly spaced along the length.

According to one embodiment, the port comprises a plurality of holes for supplying fluid to at least one fenestrated catheter. A single catheter may have both ends attached to holes in the port, or there may be a plurality of catheters, each attached to a hole and each extending in the same or different directions, to increase the infusion volume and therefore the infusion rate even more than a single catheter, hi the case of a plurality of catheters extending in different directions, the plurality of holes in the port are spaced around a perimeter of the port, preferably evenly spaced. The fenestrated catheter may be attached to the port using at least one of: a luer lock; corresponding threads on the catheter and a port hole; an adhesive; friction; or indeed any method imagined by the skilled person. Alternatively, the fenestrated catheter and the port may be made as a single integral unit. In order to prevent the fluid from flowing out of the second end of the catheter (that is not attached to the port) and bypassing the fenestration(s), the second end of the fenestrated catheter may be sealed, hi a further embodiment, the fenestrated catheter may comprise more than two ends and at least two ends may be either attached to the port or be free, with a minimum of one end being attached to the port.

There may be one fenestration in the catheter length (e.g. a slit running along its length), or there may be a plurality of fenestrations and these may be evenly spaced along the length of the catheter. The fenestrations may be all on the same side of the catheter, facing into the skin or into a specific tissue, or the plurality of fenestrations may be spaced in a spiral around a circumference of the catheter to maximise the infusion volume of an administered fluid. For even administration of drug or fluid along the length of the catheter, the fenestrations may be of uniform diameter. The catheter may be flexible or pliable, or it may be rigid; e.g. made of rubber, metal, any recognised catheter material or any material suitable for the intended purpose. For subcutaneous administration of normal fluid medicaments, the combined length of the port and a catheter may be 10 to 30cm. Preferably, the combined length may be 15 to 25cm. More preferably the combined length is approximately 20cm. A hypodermic needle can conveniently by used to supply fluid to the port. A one-way valve can be used to allow fluid flow in only one direction along the catheter. Such valve may be positioned between the port and the catheter. There may be further valves positioned along the catheter.

According to a further aspect of the invention, there is provided a device for enabling the subcutaneous administration of fluids, the device comprising: a subcutaneously implantable port arranged to receive fluid and to distribute fluid to a volume surrounding the port through a plurality of holes arranged around a periphery of the port. At least one catheter may be provided, wherein at least one of the holes arranged around the periphery of the port is arranged to attach to an end of a respective at least one catheter. Rather than having a fenestrated catheter, the port may simply have a plurality of holes about its periphery, thus creating a large enough infusion volume for the fluid to infuse into the tissue surrounding the port in an acceptable amount of time.

According to a further aspect of the invention, there is provided a method of manufacturing a device for enabling the subcutaneous administration of fluids, comprising: providing a subcutaneously implantable port; and attaching a fenestrated catheter to the port.

A free end of the fenestrated catheter may be sealed.

According to a further aspect of the invention, there may be provided a method of administering a fluid to a body comprising: making an incision in the skin of the body; inserting a fenestrated catheter below the surface of the skin of the body; inserting a subcutaneously implantable port attached to the fenestrated catheter just below the surface of the skin of the body; reclosing the incision; using a hypodermic needle, piercing a surface of the subcutaneously implantable port through the skin of the body; and using a syringe or pump attached to the hypodermic needle, introducing a fluid via the hypodermic needle into the fenestrated catheter via the subcutaneously implantable port, thus enabling the fluid to infuse through fenestrations in the fenestrated catheter into tissue surrounding the catheter.

Embodiments of the description will now be described, purely by way of example, and with reference to the Figures, in which:- Figure 1 depicts an external injection port and catheter according to the state of the art;

Figure 2 depicts an injection port and catheter according to a first embodiment of the present invention; Figure 3 shows a plan view of the injection port and catheter according to the first embodiment of the present invention;

Figure 4 depicts the port and catheter of the first embodiment in use;

Figures 5 and 6 depict a port according to variations on a second embodiment of the present invention; Figure 7 depicts a plan view of a port according to the second embodiment of the present invention;

Figures 8 and 9 depict plan views of a port and catheter according to variations on a third embodiment of the present invention;

Figure 10 depicts a port and a plurality of catheters according to a fourth embodiment of the present invention;

Figure 11 depicts a port and a catheter according to a fifth embodiment of the present invention; and

Figure 12 depicts a port according to a sixth embodiment of the present invention.

Figure 1 shows an external port 101 attached to a catheter 401 according to the prior art. Flange 301 of the port 101 is sewn, taped or otherwise attached to the outside surface of a patient's skin. The catheter 401 is inserted into the skin in such a way that the open end 501 is positioned within a blood vessel. When a fluid is to be introduced to the blood vessel, a hypodermic needle is inserted into the open end 201 of the port 101 and the fluid travels down the catheter 401, out of the open end 501 and into the blood vessel. This system is useful where a patient is in hospital for the duration of the regime of their medication administration. However, this is not useful where the patient is not staying in a hospital, or wishes to be active (such as the case of a child). This is because the patient must be careful not to knock or infect the port that is on the outside of their body and attached to a catheter that is inside it. Furthermore, this is suitable for a regime where small doses of medication need to be given frequently. If large doses need to be given, this is possible, but the application of the fluid must be done slowly to avoid the problems mentioned above and so administering large doses is cost- and time- consuming. If a patient wishes to be active between doses of their medicament, or they are children, for example, who would like to play between doses and may be prone to activities that raise the risk of infection, the external port and catheter of the prior art would not be suitable. This is also true for people (such as children) who are not willing or able to stay still for long periods of time (e.g. over 90 minutes) while a large dose of medicament is administered.

One solution to these problems is described below.

Figures 2 and 3 show a side view and a plan view of a port 10 with a chamber 30 inside the port 10 and a septum 20 covering an open end of the chamber 30. The septum may be made of silicone or another material that may be pierced by a hypodermic needle for the administration of fluid into the chamber 30, but that will reseal itself such that it may be used many times. This port 10 may be implanted subcutaneously such that the septum 20 is facing outwards from within the patient's skin. There are therefore no external parts, thus reducing the risk of knocking the port and reducing the risk of infection. The chamber 30 also has an exit hole within a nipple 32, which enables attachment of the port 10 to a catheter 40. There maybe no nipple 32, but only a hole 34 in the side of the port 10 (see Figure 6).

The port 10 may comprise a chamber 30 including a first hole open to the chamber and covered by a septum 20 through which fluid is. receivable into the chamber, and a second hole 34 open to the chamber through which fluid is suppliable from the chamber to the catheter 40, e.g. via a nipple or projecting tube 32. The catheter will contain a lumen running at least part of the length of the inside of the catheter, which is in fluidic communication with the chamber in order that fluid is transmitted from the port 10 to the catheter 40. A preferred method of attaching the catheter to the port is with a luer lock. However, many types of attachment may be envisaged, including threaded respective portions, adhesive, friction, snap-fit, etc. The port 10 may have the shape of a cylindrical body with a first hole on a flat side of the cylindrical body for receiving fluid (e.g. via a hypodermic needle and syringe) and a second hole 34 in the curved side of the cylindrical body for supplying fluid to the catheter. Rather than transmitting the fluid from the chamber 30 to the end of the catheter

40, the catheter is made with one or more fenestrations 50 such that fluid that is injected into the port 10 is infused from at least one place within the length of the catheter into a patient's body cavity or under the patient's skin. By "fenestration", it is understood that there are perforations or holes in the wall of the catheter that may have been punched, drilled or otherwise made somewhere along the length of the catheter. The holes may alternatively have been made at the time of manufacture of the catheter. There may be a single hole on one side, which may be substantially round as shown in the Figures, or which may be a slit.

The purpose of the fenestrations in the sides of the catheter is to enable the administration of fluid from at least one place other than the end of the catheter, thus increasing the volume in which the fluid may be infused into the surrounding tissue or blood (if the catheter is inserted intravenously).

The larger volume of administration prevents fluid from building up in one location and allows all of the fluid to be injected relatively quickly. Various lengths of catheter may be considered, depending on the dose of fluid that is to be administered and the desired length of time taken to administer this fluid, as well as to the volume in which the fluid may be administered safely. The fenestrations may be a single window near the top or bottom of the side of the catheter or a single slit along the entire length of (or a portion thereof) the catheter that administers fluid relatively evenly over the length of the slit.

Alternatively, the fenestrations may be evenly spaced holes along one or more sides of the catheter, or may even be positioned in a spiral around the whole perimeter of the catheter as well as along its length. The fenestrations maybe of uniform size or they may be increasing or decreasing in size along the length of the catheter. They may be round or any other shape that is possible to incorporate in a catheter wall. Yet alternatively, the fenestrations may be very small such that they are the size of pores, causing the catheter to be porous. This may allow fluid that has been injected into the catheter via the port to diffuse through the pores into the surrounding tissue. The pores may be made into a very flexible catheter material such that the catheter may expand to contain the fluid and then contract, thus forcing the fluid out through the pores.

The fenestrations may be achieved by micro-machining or laser machining, punching, melting or any other method which is suitable for making small holes in what is usually a soft, flexible material such as rubber. As mentioned above, the fenestrations may be made as part of the manufacturing process (e.g. moulding or extruding) of the catheter.

The number and diameter (or area) of the fenestrations may be chosen to allow infusion rates (i.e. the rate at which the fluid is taken up by the tissue) to be in an acceptable range for reasonable injection pressures compatible with hand injection from a standard syringe at the port end. This is because the fluid is generally introduced into the port 10 using a hand-held syringe and hypodermic needle 60 as shown in Figure 4.

The catheter 4Q and port 10 are preferably implanted as follows. A small incision is made in the skin 70. Sometimes the catheter 40 can be directly inserted beneath the skin 70 via the incision (particularly if the catheter is reasonably rigid). However, if the catheter is very soft, a rigid needle (e.g. made of stainless steel) is inserted first, to create a bore into which the catheter 40 may be subsequently inserted. Yet alternatively, a flexible catheter may be inserted by being threaded over a rigid needle, the rigid needle being removed from the inside of the catheter once the catheter is in place. The port may be attached to the catheter either before the catheter is inserted, or afterwards. The port may be manufactured as one device with the catheter. The port may be then tucked into the opening made by the incision, following the catheter under the skin. If required, the incision is then sutured or closed by some other means. The port and catheter thereby may remain under the skin until the septum 20 wears out and needs to be replaced, the course of medicaments is finished or other incidents occur (such as infection) that require the removal of the port 10 and catheter 40. To administer the medicament, a hypodermic needle 61 is injected into the chamber 30 of the port 10 via the septum 20 and hand pressure on a syringe 60 or a pump is used to introduce fluid into the chamber 30 of the port 10. The fluid enters the catheter 40 via the hole 34 (e.g. through the nipple 32). The fluid is then infused from the catheter 40 via the fenestrations 50 into the surrounding tissue 72. The larger the number and spread of fenestrations 50, the larger the volume in the tissue 72 into which the fluid will infuse, generally.

Once the fenestrated catheter 40 is positioned correctly, the fluid can continue to be infused optimally into a tissue 72 merely by injecting the fluid into a single location at the implanted injection point. The implanted injection point (i.e. the septum 20 of the port 10) also offers a stationary target that does not scar as quickly as the surface of a vein, and so it is much easier for the person administering the fluid to be more accurate with the administration of the fluid. Furthermore, this makes self-administration of drugs or fluids much easier for a patient, as they do not need to look for veins or find new areas to inject, and the target provided by the port is easy to find and to use hygienically.

The catheter may be made of any suitable material. Generally, catheters are made of flexible tubing which will not cause an immune response by the patient and which will allow a certain amount of movement as the patient moves. However, metal, plastic or other inert materials may also be considered if the situation so requires. For example, removing fluid from under a patient's skin may require a different material as compared with the administration of fluid. Different materials maybe used for the catheter depending on where in the patient the catheter is intended to go; a stiffer catheter might be required to hard-to-access areas that are not immediately below the skin, or are protected by bone or other structures.

In order to determine the diameter of the catheter 40 and the number, size and position of the fenestrations 50, the properties of the fluid that is to be administered are considered. The most important property of a liquid that determines its behaviour when flowing under pressure through small tubes is its viscosity. Most liquids exhibit a thickening at lower temperatures and so the viscosity at room and body temperature must both be considered. Whether or not the fluid is a Newtonian fluid is also important in predicting how its viscosity will change over different temperatures and pressures. For example, long-chain molecules or bulky molecules may well not be Newtonian fluids, and may undergo surprising transformations when compressed. A second property that affects fluid behaviour in capillaries and orifices is surface tension. Specifically, the size and behaviour of droplets of fluid as they emerge from the fenestrations 50 of the catheter 40 will depend on the surface tension of the fluid injected.

Typical infusion pressures when injecting fluids by hand or by infusion pumps . are in the range of 100-350 mrnHg, or 100-500 CmH₂O. A desired injection rate would be to inject, for instance, a 3 ml dose in about 1 minute, at a typical infusion pressure. Assuming a constant pressure, it can be determined that (for instance) human normal immunoglobulin solution ("subgam"), with an average viscosity of 6.2 cP (centipoise) and an average viscosity of 66 mN/m will have a flow rate of about 3 ml/min with a needle diameter of 0.241 mm (needle gauge 26) with a modest injection pressure of 150 mm Hg. The catheter will therefore need to be able to take this sort of pressure and flow rate. During experiments, it was found that an amorphous biomedical PEEK tube with an inner diameter of approximately 1.2mm was suitable for the purpose, with at. least 15 holes each of at least 0.10mm diameter evenly spaced along its length.

The pressure applied at the port end is preferably enough to flush the fluid out through the fenestrations in the catheter so that the fluid does not simply pool in the catheter (or return into the port). One way to apply high pressure is by the pressure applied using the syringe. A second possibility is shown in Figure 12. The port 10 may comprise a diaphragm 70 within its chamber that expands and is displaced by an amount 72 when a fluid is introduced into the chamber via the septum 20. The diaphragm 70 may then, by its restoring force, apply pressure to the fluid in the port 10, thus pushing the fluid out of the port 10 through the holes 34. The holes may lead to a fenestrated catheter. The stiffness of the diaphragm 70 (and therefore its restoring force) maybe set according to required delivery rates of the fluid, hi order to prevent a hypodermic needle from piercing the diaphragm 70 when it is injecting the septum 20, a solid yet permeable mesh 60 may be included between the septum 20 and the diaphragm 70. Alternatively, the septum 20 itself may expand when the fluid is administered and have a restoring force that imparts pressure onto the injected fluid as the septum 20 returns to its original shape. It may thereby be the septum that exerts the pressure to force the fluid out of the holes 34 at the desired rate. An advantage of having a diaphragm or similar is that the port size may be decreased and less drug may pool in the device. Alternatively, the size of the port may be large enough to contain a full dose which is slowly administered by the restoring force of the diaphragm 70.

Yet alternatively, the fenestrated catheter may be flexible enough to expand when a drug is introduced into it. The restoring force of the catheter may then be what gives rise to the pressure that causes the fluid or drug to be squeezed out of the fenestrations.

It can also be important that the fluid does not return to the port under the pressure from the catheter (or surrounding tissue), nor return into the catheter from the port if the device is being used to remove fluid from a patient. One way to ensure a positive flow is to include a one-way valve, for example at the point of the join between the port and the catheter. The valve may be a simple flap that is flexible or openable in one direction but not the other. More than one valve can be used, with valves positioned at different places along the catheter. Alternatively, the pressure exerted by the port may be maintained using methods described above such that it is always higher than any negative pressure by the catheter. In order to encourage the fluid to exit the fenestrations and not just flow out of the end of the catheter, the end of the catheter can be plugged, for example with a hot- melt adhesive. Of course, any other method of sealing the end of the catheter may be used or the catheter may be manufactured with one closed end.

Figure 5 shows a second embodiment of the present invention. The port 10 also has a septum 20 covering a chamber 30. However, rather than there being just one hole through a nipple 32, there are at least two holes through nipples 32a and 32b extending from the chamber 30 of the port 10. In the embodiment shown in Figure 5, there is no catheter attached to the holes 32a or 32b. Although Figure 5 does show small nipples 32 leading out from the chamber 30 through the wall of the port 10 (to which catheters maybe attached), these may simply be openings 34 in the wall of the port 10, as shown in Figure 6. This is true for any of the embodiments described herein, though some means of attaching a catheter needs to be considered, as described above.

Figure 7 shows a plan view of a similar port 10, but showing four holes through nipples 32a, 32b, 32c and 32d that extend around the periphery of the port 10. In the embodiment shown in Figure 7, there are no catheters attached to the port holes 32a, 32b, 32c and 32d. This embodiment will not administer the fluid as far away from the port as the embodiment with the catheter, however the spread of the positions of the holes means that fluid will be dispersed in multiple directions and this addresses the problems listed above.

Figure 8 depicts a third embodiment of the present invention. A plan view of the port 10 with the septum 20 on the top surface is shown. Again, there are multiple holes through nipples 32a, 32b, 32c and 32d in the walls of the port. This time, however, a catheter 40 is included. However, rather than having one free end, the catheter is joined to two of the nipples 32b and 32c of the port 10. In this way, the free end of the catheter does not need to be sealed and fluid injected through the septum 20 may still be dispersed via the fenestrations 50 of the catheter 40.

A similar or different catheter may be attached to the other nipples 32a and 32d of the port 10. Figure 9 depicts a variation on the catheter 40 being attached at both ends. In this variation, the catheter may be effectively folded in half or be made up of two catheters 40a, 40b with a joining piece 41 at their free ends. A catheter form like this may be easier to insert, as both parts 40a, 40b of the catheter maybe inserted into the same bore-hole under the skin, or the catheter parts may be substantially rigid and be insertable as they are under the skin. The infusion volume is larger than if a single length of catheter is used, thus potentially decreasing the time taken to administer a dose of medicament and reducing the likelihood of bulging or blistering.

Figure 10 depicts a fourth embodiment of the present invention. A plan view of the port 10 with the septum 20 on the top is shown with four nipples 32a, 32b, 32c and 32d. In this embodiment, each of the holes of the port may have a separate catheter 40a, 40b, 40c and 4Od respectively, each containing a number of fenestrations 50.

It will be readily understood that any number of holes 34 or nipples 32 may be incorporated into a port 10 and any number of catheters 40 maybe attached to the holes 42. For instance, the device may resemble a starfish. The number of holes and catheters will be a balance between the extent of the infusion of the administered fluid and the difficulty in implanting all of the catheters subcutaneously in a patient.

Figure 11 depicts a fifth embodiment in which the port 10 with the septum 20 is shown to have a single nipple 32. This of course applies to any number of holes 32 in the port 10. A catheter 40 is used, but rather than having only one free end, the catheter 40 may have a split 42, giving it two free ends, thus allowing faster infusion over an even larger volume via the fenestrations 50 that are in the two separate "legs" 44 of the catheter 40. Equally, separate legs 44 of the catheter 40 may be attached to different nipples 32 of the port 10 and merge to form a single free end, thus potentially making implanting of the catheters slightly easier.

There may be provided, therefore, a fenestrated catheter comprising a main body 40 and a plurality of legs 44, the legs also being catheter-shaped (and preferably fenestrated) and being split off (42) from the main body 40. There may be legs 44 at both ends of the catheter. Indeed, the catheter 40 may take any. shape that is implantable and increases the infusion volume of administered fluids. Several catheters may even come off the same port 10 and travel to different blood vessels, the catheters being shaped according to the respective positions and directions of the blood vessels.

Generally, the number of catheter splits 42 used will be a balance between the extent of the infusion of the administered fluid and the difficulty in implanting all of the catheters subcutaneously in a patient.

The skilled person will understand-that the subcutaneous port and fenestrated catheter combination of the present invention is suitable not only for administering fluids, but also for removing fluids from a patient's body. For example, air or fluid trapped in a large area under the skin or at several positions under the skin may be removed more quickly than with a standard open-ended catheter. This is particularly true where the air or fluid build-up is chronic and must be removed at several instances over a long period of time.

Claims

1. A device for enabling the administration and/or removal of fluids, the device comprising: - a fenestrated catheter; and

- a subcutaneously implantable port arranged in fluidic communication with the catheter.

2. A device according to claim 1, wherein said catheter is fenestrated along its whole length.

3. A device according to any claim 1 or claim 2, wherein a plurality of fenestrations are evenly spaced along the length of the fenestrated catheter.

4. A device according to any one of the preceding claims, wherein a plurality of fenestrations are spaced in a spiral around a circumference of the catheter.

5. A device according to any one of the preceding claims, wherein fenestrations on the fenestrated catheter are of uniform diameter.

6. A device according to any one of claims 1 to 5, wherein fenestrations on the fenestrated catheter are of variable diameter such that fluid to be administered is evenly distributed along the length of the fenestrated catheter.

7. A device according to any one of the preceding claims, wherein fenestrations on the fenestrated catheter comprise pores such that a fluid administered into the fenestrated catheter in use diffuses through the pores.

8. A device according to claim 7, wherein the fenestrated catheter is flexible and adapted to expand to accommodate an administered fluid, and then to contract to cause diffusion of the administered fluid through the pores.

9. A device according to any one of the preceding claims, wherein the combined length of the port and a catheter is between 10 and 30cm.

10. A device according to any one of the preceding claims, wherein the port comprises a plurality of holes for supplying fluid to said fenestrated catheter.

11. A device according to claim 10, wherein the plurality of holes are spaced around a perimeter of the port.

12. A device according to claim 10 or 11, wherein the fenestrated catheter has a first end attached to a first hole in the port and a second end attached to a second hole in the port.

13. A device according to any one of the preceding claims, wherein the fenestrated . catheter is attached to the port using at least one of: a luer lock, corresponding threads on the catheter and a port hole; an adhesive; and friction.

14. A device according to any one of the preceding claims, wherein the fenestrated catheter and the port are made as a single unit.

15. A device according to any one of the preceding claims, further comprising a oneway valve that allows fluid to flow only in one direction along the catheter.

16. A device according to any one of the preceding claims, wherein a first end of the fenestrated catheter is attached to the port and a second end of the fenestrated catheter is free.

17. A device according to claim 16, wherein the second end of the fenestrated catheter is sealed.

18. A device according to any one of the preceding claims, wherein the fenestrated catheter comprises more than two ends and at least two ends are either attached to the port or are free, with a minimum of one end being attached to the port.

19. A device according to any one of the preceding claims, wherein the fenestrated catheter comprises a flexible or pliable tube.

20. A device according to any one of claims 1 to 18, wherein the fenestrated catheter comprises a rigid tube.

21. A device according to any one of the preceding claims, adapted to receive fluid from^' a hypodermic needle.

22. A device for enabling the subcutaneous administration of fluids, the device comprising: a subcutaneously implantable port arranged to receive fluid and to distribute fluid to a volume surrounding the port through a plurality of holes arranged around a periphery of the port.

23. A device according to claim 22, further comprising at least one catheter, wherein at least one of the holes arranged around the periphery of the port is arranged to be attached to an end of said at least one catheter.

24. A device according to any one of the preceding claims, further comprising a diaphragm inside the port adapted to expand when a fluid is introduced into the port, and then to contract, thus exerting pressure on the fluid and causing it to exit the port via at least one hole in a port wall.

25. A method of manufacturing a device for enabling the subcutaneous administration and/or removal of fluids, comprising: - providing a subcutaneously implantable port; and

- attaching a fenestrated catheter to the port.

26. A method according to claim 25, further comprising the step of sealing a free end of the fenestrated catheter.

27. A method implanting a device enabling administration of fluid to a body, said method comprising:

- making an incision in the skin of the body;

- inserting a fenestrated catheter below the surface of the skin of the body; and

- inserting a subcutaneously implantable port attached to the fenestrated catheter just below the surface of the skin of the body.

28. A method of administering a fluid to a body, said method comprising:

- using a hypodermic needle, piercing a surface of a subcutaneously implanted port through the skin of the body; and - introducing a fluid via the hypodermic needle into an implanted fenestrated catheter via the subcutaneously implanted port, thus enabling the fluid to infuse through fenestrations in the fenestrated catheter into tissue surrounding the catheter.