WO2000044424A1

WO2000044424A1 - Access system and methods having reversible cannulas

Info

Publication number: WO2000044424A1
Application number: PCT/US2000/002359
Authority: WO
Inventors: James M. Brugger; Jeffrey H. Burbank
Original assignee: Vasca, Inc.
Priority date: 1999-01-27
Filing date: 2000-01-27
Publication date: 2000-08-03
Also published as: EP1154814A1; CA2361039A1; EP1154814A4; AU2747900A; JP2002535096A

Abstract

A system for accessing a patient's vasculature or other luminal or non-luminal target site comprises a pair of implantable ports and a pair of connecting cannulas (fig. 1). Each of the connecting cannulas will have differently configured distal and proximal ends, typically having side holes or other flow diffuser elements at the distal end (10). Connecting cannulas are selectively attached to the implantable ports by cutting the cannulas at preselected points spaced inwardly from their ends (10). In particular, one of the cannulas will be cut so that the modified end is removed, and the cut end is attached to the implantable port (fig. 2A). The other of the connecting cannulas will be cut so that the non-modified end is removed, and the cut end attached to the implantable port. In this way, systems comprising identical connecting cannulas can be put together while still permitting the user to select between at least two implantable cannula tip configurations.

Description

ACCESS SYSTEM AND METHODS HAVING REVERSIBLE CANNULAS

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to the design and use of medical devices, and more particularly to a method and system for establishing access to a patient's vascular system for hemodialysis and other extracorporeal blood treatments. Access to a patient's vascular system can be established by a variety of temporary and permanently implanted devices. Most simply, temporary access can be provided by the direct percutaneous introduction of a needle through the patient's skin and into a blood vessel. While such a direct approach is relatively simple and suitable for relatively short procedures, such as intravenous feeding, intravenous drug delivery, and the like, they are not suitable for hemodialysis, hemo filtration, or other extracorporeal procedures that must be repeated periodically, often for the lifetime of the patient.

For hemodialysis and other extracorporeal treatment regimens, a variety of transcutaneous catheters and implantable ports have been proposed over the years.

Transcutaneous catheters, such as the Tesio catheter available from Med Comp and the Perm-Cath™ available from Quinton, comprise a single catheter tube having a distal end placed in a vein in an in-dwelling manner and a proximal end which extends through the skin and is which available for connection to a hemodialysis or other blood treatment system.

Implantable ports, in contrast, are entirely subcutaneous and connected to a vein or an artery by a subcutaneous "connecting" cannula. Access to the port is achieved by percutaneous placement of a needle or other connecting tube. Such ports typically comprise a needle-penetrable septum to permit percutaneous penetration of the needle. Recently, several valved-port designs have been proposed, where percutaneous introduction of a needle or other access tube into the port opens the valve to permit flow to or from the cannula which connects to the blood vessel.

Frequently, for both port-access and transcutaneously implanted cannula systems, the implanted ends of the draw and return cannulas may differ, e.g., the blood draw cannula may have a distal end with a plurality of side holes (flow diffusers) over a portion thereof in order to reduce possible blockage resulting from a "fibrin sheath" which forms over the catheter in some patients. The return catheter, however, is at less risk of such fibrin sheath blockage and may therefore have fewer or no side holes or other means for flow diffusion. The need to provide separate draw cannulas and return cannulas, however, makes maintaining an inventory of these cannulas more difficult.

For these reasons, it would be desirable to provide improved methods and systems for implanting draw and return catheters in a patient's vascular system. It would be particularly desirable if such improved systems and methods were useful with both port-access and transcutaneous access systems for hemodialysis, hemo filtration, and other extracoφoreal treatment systems. Preferably, the improved systems and methods will permit inventory reduction and/or simplification while still allowing the treating physician to choose from different cannula designs for implantation in a blood vessel or other body lumen.

2. Description of the Background Art

U.S. Patent No. 5,718,692 describes a double catheter assembly where each catheter has side holes at its distal end. U.S. Patent Nos. 5,562,617 and 5,041,098 are exemplary of implantable systems employing cannulas extending between a port and a blood vessel for providing extracoφoreal circulation. U.S. Patent Nos. 5,417,656 and 5,281 , 199 show implantable ports which are connected to vascular cannulas via a transition region (Fig. 1 A) and to a multiple branch cannula (Fig. 21). U.S. Patent No. 4,892,518 shows an implanted port with a transition region extending to a cannula. U.S. Patent Nos. 5,234,406 and 5,215,530 show two-piece catheters having a distal portion which can be placed percutaneously. The '406 patent discloses a large diameter proximal portion to enhance the flow rate of anesthetics to the subarachnoid region of the spine. U.S. Patent Nos. 5,203,771 and 4,181,132 show implantable connectors which provide for percutaneous access to implanted shunts. Related co-pending applications, assigned to the assignee of the present application, include serial numbers 08/745,903; 08/724,948; 08/634,634; 08/539,105; 08/856,641; and 60/036,124.

The full disclosures of each of the U.S. Patents and co-pending applications listed above are hereby incoφorated herein by reference.

SUMMARY OF THE INVENTION The present invention provides improved systems, methods, and kits for connecting an implantable port to a connecting cannula to establish access to a patient's body lumen or other target location. While the present invention is particularly suited for establishing access to a patient's vasculature for performing extracoφoreal treatment on circulating blood, it might also find use in other procedures, such as drug delivery, peritoneal dialysis, cerebral shunting, bladder cannulation, and the like. Exemplary extracoφoreal treatment procedures include hemodialysis, hemofiltration, plasmapheresis, apheresis, and the like.

The present invention is most advantageous with access systems comprising a pair of connecting cannulas having tubular bodies, where one of the cannulas will have a modified end and the other of the cannulas will be intended for use with an unmodified or differently modified end. In the exemplary embodiments, one of the connecting cannulas will be intended as a "draw" cannula for removing blood from the patient's vasculature while the other of the cannulas will be intended as a "return" cannula for returning treated blood to the patient. Thus, in the exemplary embodiments, the "modified end" will be modified to have flow diffusers formed integrally as side holes or otherwise formed in or attached to the cannula at or near the end. The present invention will cover any other functional and/or structural modifications of one end of the cannula where a user has the option of implanting either end of the cannula depending on selection criteria. In the exemplary embodiments, the draw catheter will be provided with flow diffusers, typically with side holes, over a portion of one end, while the return catheter will have a plain (unmodified) tubular end intended for placement in the vasculature. Heretofore, access systems employing such connecting cannulas have usually included one plain tubular cannula free from side holes or other modifications and a second cannula having the desired side holes at one end thereof. The need to maintain systems having two different types of catheters is inconvenient. It would be advantageous to provide for access systems which utilize only a single common catheter for both the draw and return functions.

The present invention provides such simplified systems and methods for their use, where each cannula in the pair of cannulas may be identical to the other and includes flow diffusers at one end while the other end is plain and unmodified. In use, a first of the two connecting cannulas may be introduced into the vasculature with the modified end in place, typically an end with side holes or other flow diffusers intended for blood draw. The plain or unmodified end of the other of the connecting cannulas is then placed in the vasculature for blood return. The proximal end of the second catheter will be cut to a desired length, with at least the modified portion (containing the flow diffusers, side holes, or other modifications) being removed. Usually, the first catheter will also be cut to length. The implanted cannulas may then be connected to implantable ports, be placed transcutaneously, be connected to other cannulas (which may optionally have different sizes, characteristics, etc.), or be otherwise used to establish flow and return access to the vasculature.

While most useful with two cannula systems, the present invention will also find use with single cannula systems where, under different circumstances, it may be desirable to allow the treating physician to select between implanting one end of a cannula which is modified in some manner or an opposite end which is unmodified or modified in a second manner. The proximal end of the cannula (i.e., the end which is not implanted) can optionally be cut off with the cut end then being connected to a port, other cannula (via a remote connector as described in copending U.S. Patent Application No. 08/856,641, (Attorney Docket No. 17742-001700), the full disclosure of which is incoφorated herein by reference), or being placed transcutaneously. A preferred system according to the present invention for establishing vascular access comprises a pair of subcutaneously implantable ports, where each port includes an inlet aperture adapted to receive an access tube and an outlet connector. The outlet connector on each port will be sized to receive the end of a common connecting cannula, i.e., the connector will mate with the cut or uncut end of either pair of connecting cannulas. Each of the connecting cannulas will have a tubular body with one modified end portion, typically having flow diffusers, side holes, or the like. The tubular body will be adapted to be cut at a point spaced inwardly from either end in order to produce the cut end which is able to mate with the connector on either of the implantable ports. In this way, the modified end of a first of the connecting cannulas can be implanted in a blood vessel, the unmodified end of a second of the cannulas can be implanted in the same or different blood vessel. The proximal ends of each of the cannulas may then be cut to length and connected to the implantable ports, either before or after implantation. Usually, the outlet connectors on each of the ports will comprise male fittings so that the cut ends of the tubular bodies may simply be placed over the fittings. Usually, the tubular bodies of the connecting cannulas will comprise elastomeric materials, such as latex, silicone rubber, polyurethane, or the like. In order to assure compatibility with the male fittings, the cannulas will usually (but not necessarily) have a uniform inside diameter along their entire length, typically being the range from 1 mm to 15 mm, usually being in the range from 2 mm to 5 mm. The lengths of the connecting cannulas will usually, but not necessarily, be identical, typically being the in range from 15 cm to 100 cm, preferably being in the range from 20 cm to 40 cm. While it is preferred that the two connecting cannulas be identical in all respects, in order to simplify manufacturing and maintenance, in some instances the connecting cannulas may differ in certain respects, e.g., length. As the connecting cannulas would normally cut to length, the system and methods of the present invention will work equally well even if one of the cannulas has a different initial length than the other (so long as each of the cannulas is sufficiently long for the intended use). Either or both of the cannulas may then be trimmed to length during implantation.

Both ends of each connecting cannula should also be adapted in all respects for implantation within the blood vessel or other target body lumen or location. For example, it is strongly preferred that the ends of each of the connecting cannulas be chamfered or beveled in order to reduce the risk of trauma when implanted within a blood vessel. In this way, both ends of each cannula are ready for implantation within a blood vessel without modification or other preparations.

In a first aspect, the method according to the present invention comprises providing an implantable port as described above and a connecting cannula, also as described above. The connecting cannula will have one modified end, typically including flow diffusers such as side holes, and another unmodified or differently modified end. The connecting catheter is cut to length at one end to remove at least one of the modifications, e.g., side holes. The cut end is then connected to an outlet connector on the port. The method may further comprise implanting the port into the cannula subcutaneously in the patient. The implantation step may occur either before or after the connecting cannula is attached to the port. Usually, the modified end of the connecting cannula will be implanted within a blood vessel, more usually within a vein where the modified end comprises side holes or other flow diffusers and the port is intended for drawing blood. While this method will normally be employed with a pair of connecting cannulas and implanted the ports, it may also find use in circumstances where only a single connecting cannula and port will be desired.

In a further aspect of the present invention, an improved method for connecting a cannula having a tubular body with one end portion having side holes to a port having a connector comprises first determining if the end of the cannula to be implanted should have side holes or should be free from side holes. If it is determined that the distal end of the cannula should be free from side holes, the end of the cannula having side holes is then cut so that the cannula will have a preselected length, and the cut end of the cannula then connected to the connector on the implantable port.

In a still further aspect of the present invention, the method for establishing access to a patient's vasculature for establishing extracoφoreal circulation comprises providing two identical connecting cannulas and two implantable ports, generally as described above. A first of the two identical cannulas is then implanted with its flow diffuser and within a blood vessel, typically a vein. A second of the identical cannulas is then implanted with its plain or unmodified end within the same or a different blood vessel. The proximal ends of the two connecting cannulas may then be connected to ports, other cannulas, or be left transcutaneously in order to establish the desired extracoφoreal access. The connecting cannulas may be cut to length before or after implantation.

The present invention still further comprises kits having different configurations. In a first configuration, the kit comprises the system of at least one (usually two) implantable ports and at least one (usually two) cannulas as generally described above. The system components will then be packaged in a conventional and usually sterile package, such as a pouch, tray, tube, box, or the like. In a second configuration, the kit comprises at least one implantable port and one connecting cannula, generally as described above, in combination with instructions for use according to any of the methods described above. Optionally, the port, connecting cannula, and instructions may be packaged in the conventional medical device package.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an isometric view of an access system constructed in accords with the principles of the present invention which comprises a pair of implantable ports and a pair of identical connecting cannulas.

Figs. 2A-2C illustrate an exemplary connecting catheter having flow diffusers in the form of side holes constructed in accordance with the principles of the present invention.

Fig. 3 illustrates a connecting cannula attached to an implantable port, where the modified end having flow diffusing side holes has been cut off prior to attachment.

Fig. 4 illustrates an implantable port attached to a connecting cannula, where the portion of the unmodified end of the connecting cannula has been cut prior to attachment to the implantable port.

Fig. 5 illustrates patient vasculature to which the implantable access systems of the present invention can be attached.

Fig. 6 illustrates an initial step in implantation of the pair of connecting cannulas in accordance with the principles of the present invention.

Fig. 7 illustrates connection of the connecting cannulas of Fig. 6 to implantable ports according to the methods of the present inventions.

Fig. 8 illustrates the optional connection of the cannulas of Fig. 6 to ports via the use of intermediate connectors according to the methods of the present invention. Fig. 8 A illustrates the optional connection of the cannulas of Fig. 6 to transcutaneous (Tesio) catheters.

Fig. 9 illustrates a kit according to the present invention comprising a pair of implantable ports, a pair of connecting cannulas, instructions for use, and a package for holding all kit components.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS The present invention provides methods and apparatus for facilitating percutaneous and transcutaneous access to a body lumen or other target site of a patient. 8 Exemplary body lumens, include blood vessels, the peritoneal cavity, and the like. The methods are particularly useful for accessing blood vessels, and most particularly for accessing venous blood vessels. While the remaining description is directed particularly at accessing veins, it will be appreciated that the invention applies to all body lumens and cavities where selective percutaneous access might be desired.

For percutaneous access, ports are implanted subcutaneously so that a passage therein lies a short distance beneath the surface of the patient's skin, typically being within 3 mm to 20 mm of the skin's surface. An access tube may then be percutaneously inserted into the passage in the access port in order to provide a connection to the blood vessel via the access port. For transcutaneous access, a cannula according to the present invention is implanted through the patient's skin with a distal end in the target blood vessel and a proximal end of the catheter adapted for connection to an external catheter. In both cases, access can be provided for a variety of puφoses, usually involving withdrawal of blood, the extracoφoreal treatment of the withdrawn blood, and/or the return of the treated blood to the patient. Such extracoφoreal blood treatment will most often be for hemodialysis, but can also be for hemo filtration, hemodiafiltration, apheresis, and the like. In addition to extracoφoreal treatment, the access port of the present invention can be used for perfusing drugs, fluids, and other materials directly into a patient's circulation for a variety of puφoses. Referring now to Figs. 1 and 2, systems 10 according to the present invention will usually comprise one or more implantable ports 12 and one or more, usually at least two, connecting cannulas 14. The ports 12 are subcutaneously implantable and provide for percutaneous access by means of a needle or other access tube which is introduced through the patient's skin into an inlet aperture 16 on the top of the port. The port will also include an outlet connector 18 typically a male fitting, which is intended to attachably receive a cut end of the connecting cannula 14, as described in more detail below. While the illustrated ports 12 include internal valves which open and close in response to insertion of the access tube through the aperture 16, as described in detail in co-pending Application Serial No. 08/942,990, the full disclosure of which is incoφorated herein by reference, the present invention may also utilize a wide variety of ports having other valve structures, membrane-access structures, and other means for permitting an access tube to connect to a flow path defined by the outlet connector. The connecting cannulas will comprise tubular bodies, typically fabricated by extruding biocompatible polymeric materials, such as silicone rubber, latex, polyurethane, PTFE, and the like. The cannulas will have lengths, lumen diameters, and other dimensions as generally set forth above, and will have at least one end modified to include features other than a plain tubular body. The exemplary embodiments, the modification comprises flow diffusers, more particularly comprising side holes 20 which extend over one end portion of the tubular body of the cannula as best observed in Figs. 2A-2C. In the exemplary embodiment, side holes 20 extend in a spiral pattern over a length of the catheter in the range from 1 cm to 60 cm, usually from 2 cm to 40 cm. Figs. 2A-2C illustrate the same catheter, with the catheter being rotated 90° about its axis in each of the three views. Preferably, each of the two or more cannulas 14 will be identical in construction and dimensions. More preferably, each of the cannulas 14 will comprise tubular bodies having a uniform luminal diameter, more preferably a uniform luminal and outside diameter over the entire length so that connection may be made to the male fitting 18 regardless of where the catheter is cut along its length. Also preferably, both ends of the catheter will be chamfered, rounded, or radiused so that either end may be placed into a blood vessel with reduced risk of trauma. The chamfer is typically at 45° relative to the axial direction, but could vary between 10° and 80°, usually 25° and 75°. An "unmodified" end 21 of each cannula 14 may be plain or have a simple chamfer or radiused end, as shown in Fig. 1. Alternatively, the other end may be differently modified, e.g., having an angled end optionally including one or more side holes 22, as shown in Figs. 2A-2C. This second type of end is presently preferred as the return cannula.

Referring now to Fig. 3, when intended for returning blood to a blood vessel, the cannula 14 may be cut to a preselected length, with the end including side holes 20 being removed. The cut end may then be attached to the male fitting 18 (Fig. 1) as shown in Fig. 3. The distal end 26 of the cut cannula 14' which is intended for implantation will thus be free from side holes 20 or other modifications.

Referring now to Fig. 4, when intended for blood return, the cannula 14 may be cut on the modified end, and the cut end attached to implantable port 12. The distal end 28 of the cut cannula 14" which is intended for implantation will thus have the side holes 20 intended for flow diffusion for the draw cannula. The access systems described above are particularly suitable for establishing percutaneous and transcutaneous access to single or multiple locations in the patient's vasculature, including both the arterial and venous vasculature. As illustrated in Fig. 5, the arterial and venous vasculature of patient P in the region immediately surrounding the heart H includes the jugular vein JN, the subclavian vein SN, the subclavian artery SA, and the aorta A.

Referring now and in particular to Fig. 6, the implantation of a pair of connecting cannulas 14 of the system 10 of Fig. 1 into the jugular vein JN will be described. The connecting cannulas 14 may be implanted by either a cut-down procedure or by the Seldinger technique. For simplicity, only the cut-down procedure will be described. After appropriately preparing and anesthetizing the patient, a small venotomy is performed at the desired site in the jugular vein JN, typically from 5 cm to 10 cm above the junction of the superior vena cava SVC and the right atrium of the heart H. The distal tip of a first connecting cannula 14 is then inserted through the incision in the vascular wall with the end having side holes 20 therein positioned within the venous lumen. A second connecting cannula 14, which is usually identical to the first, is then inserted into the venous lumen through the same incision so that it's non-modified tip (i.e., free from side holes 20) is located approximately 4 cm above the distal tip of the first cannula. The positioning of the distal tips of the access cannulas 14 may be verified by X-ray. At this point, the cannulas 14 may be prepared for transcutaneous use, i.e., where the proximal ends remain outside the patient's body available for connection to the desired extracoφoreal recirculation system. The proximal end of the cannula 14 having the exposed side holes 20 will be cut off to desired length, with at least the portion having the side holes being removed. The other cannula will also be cut to a desired length. Both cannulas may then be connected to suitable external connectors for interconnection to the extracoφoreal recirculation system.

More usually, the connectors 14, as shown in Fig. 6, will then be cut for attachment to implantable ports 12, as shown in Fig. 7. Placement of each of the ports 12 may be selected based on a number of criteria. The infraclavicular fossa is generally satisfactory, but the actual site may vary depending on the patient characteristics. The implantable ports 12 should be located in an anatomic area that provides for good stability, does not interfere with patient mobility, create pressure points, or interfere with clothing. Placement should allow for a proper amount of overlying cutaneous tissue, with an optimum tissue thickness in the range from 5 mm to 15 mm. Sufficient space should be available for placement of two implantable catheters when blood circulation through a single venous location is to be effected.

After the port implantation site is selected, a subcutaneous pocket is formed by a cut-down procedure using blunt dissection. The pocket should be sufficiently large to accommodate the ports 12 and allow positioning of the ports away from the incision. After the pocket is created, a tunnel is created between the pocket and the venous entry site using a tunneling tool. The distal ends of the connecting cannulas 14 are then cut to length so that the so that they terminate at the venous entry site with sufficient slack for body movement and subcutaneous connection. The cut distal ends of each connector cannula is then placed over the connector 18, and secured with a suture or other biocompatible filament.

While attachment of the connecting cannulas 14 to their respective ports 12 as shown to occur after implantation of the cannulas in Fig. 7, it will be appreciated that the ports 12 could be pre-connected to the cannulas externally to the patient prior to implantation. In such cases, will be desirable to pre-measure the desired lengths of the cannulas so that they may be precut to a selected length prior to attachment of the cut ends to the ports.

Referring now to Fig. 8, the implanted cannulas 14, as shown in Fig. 6, may be attached using intermediate connectors 30 to additional connecting tubes 30 and 34. The connecting tubes 32 and 34 may themselves be identical, e.g., be of the same diameter as the cannulas 14, but will often be different in dimensions and other characteristics than the connecting cannulas 14. The connecting tubes 32 may be positioned transcutaneously, but will more usually be connected to implantable ports, as illustrated. The use of internal connectors is described in detail in co-pending Application Serial No. 08/856,641, the full disclosure which is incoφorated herein by reference.

A third general approach for connecting the cannulas 14 of Fig. 6 is illustrated in Fig. 8A. Transcutaneous catheters, such as Tesio catheters available from Med Comp, Harleysville, Pennsylvania, may be connected to the remote ends, i.e., the ends not placed in the jugular vein, in a conventional manner. The transcutaneous catheters are then implanted, also in a conventional manner. The present invention provides, as in all previously described instances, the ability to maintain a single or reduced number of cannula types where both ends of each cannula have different characteristics allowing the physician to choose which end should be implanted in a particular patient or in a particular circumstance.

Referring now to Fig. 9, kits according to the present invention will include at least one port 12 and cannula 14, as generally described above, usually including at least a pair of ports 12 and a pair of cannulas 14. Kits will also comprise instructions for use 40 setting forth any of the methods described above for connection and/or implantation of the cannulas 14 and ports 12. The instructions for use 40 will usually be printed on a separate sheet of paper (package insert), but may also be printed in whole or in part on other kit packaging. The kit components will usually be packaged in a conventional medical device package, such as a pouch 50, tray, tube, box, or the like. Kits may comprise different combination of kit components. In a first example, the kits will comprise at least two ports 12, two cannulas 14, and a package, such as a pouch 50. In a second embodiment, the kits will comprise at least one port 12, one cannula 14, and instructions for use 40. Often, the kits may comprise all of the components illustrated in Fig. 9.

Claims

WHAT IS CLAIMED IS:

L A system comprising: a pair of subcutaneously implantable ports, each port having an inlet aperture adapted to receive an access tube and an outlet connector, wherein the outlet connectors on each port are sized to received a common connecting cannula; and a pair of connecting cannulas having tubular bodies, each tubular body having a modified end portion, wherein the tubular body is adapted to be cut at a point spaced inwardly from either end to produce a cut end and wherein the cut end on either cannula can be connected to the connector on either port.

2. A system as in claim 1, wherein the outlet connectors on each port comprise male fittings and wherein the tubular bodies of the connecting cannulas have lumen diameters at each end selected to attach over the male fittings.

3. A system as in claim 2, wherein the connecting cannulas comprise elastomeric tubular bodies having substantially uniform inside diameters over their lengths.

4. A system as in claim 3, wherein both ends of each connecting cannulas are chamfered.

5. A system as in claim 4, wherein the cannulas have inside diameters in the range from 1 mm to 15 mm and lengths in the range from 2 cm to 5 cm.

6. A system as in claim 1, wherein the two connecting cannulas are identical.

7. A system as in claim 1, wherein the modified end comprises side holes in the tubular body.

8. A method for connecting a port to a cannula, said method comprising: providing an implantable port having an inlet aperture adapted to receive an access tube and an outlet connector; providing a connecting cannula having a tubular body having a modified end portion; cutting the connecting cannula to a preselected length, wherein at least the modified end portion is removed; and connecting the cut end of the cannula to the outlet connector on the port.

9. A method as in claim 8, wherein the modified end comprises side holes in the tubular body.

10. A method as in claim 8, further comprising implanting the port and implanting the cannula subcutaneously in a patient.

11. A method as in claim 10, wherein the other end of the port is free from flow diffusers and is implanted within a blood vessel.

12. A method as in claim 11, wherein the cut end of the cannula is connected to the port after at least one of the cannula and port are implanted.

13. A method as in claim 11 , wherein the cut end of the cannula is connected to the port before either the port or the cannula is implanted.

14. A method as in claim 8, further comprising: providing a second implantable port identical to the first and a second connecting cannula identical to the first; cutting the second connecting cannula to length, wherein an end which is free from flow diffusers is cut leaving the end with flow diffusers intact; and connecting the cut end of the second cannula to the outlet connector on the second port.

15. An improved method for connecting a cannula having a tubular body having side holes over an end portion thereof to a port having a connector, wherein the improvement comprises: determining if a distal end of the cannula should be free from side holes; and cutting the cannula to a preselected length, wherein at least the end portion having the side holes will be removed, if it is determined that the distal end of the cannula should be free from side holes.

16. A method for establishing access to a patient's vasculature for establishing extracoφoreal circulation, said method: providing two identical connecting cannulas, each connecting cannula comprising a tubular body having a modified end portion and a second end plain or modified in a different way; implanting a first of the two identical cannulas with the end having the modified end in a blood vessel; and implanting a second of the identical cannulas with the second end in a blood vessel.

17. A method as in claim 16, wherein the modified end comprises side holes in the tubular bodies.

18. A method as in claim 16, further comprising connecting the ends of the cannulas which are not in the blood vessels to implantable ports, wherein at least the second cannula is cut to a preselected length with at least the end portion having the first modified end removed before connecting to the port.

19. A method as in claim 18, wherein both cannulas are cut to preselected lengths prior to connecting the cut ends to implantable ports.

20. A method as in claim 19, wherein the cannulas are connected to the ports after the ports have been implanted.

21. A method as in claim 19, wherein the cannulas are connected to the ports before the ports are implanted.

22. A kit comprising: a system as in claim 1 ; and a package which holds the ports and the connecting cannulas.

23. A kit comprising: an implantable port having an mlet aperture adapted to receive an access tube and an outlet connector; a connecting cannula to a preselected length, wherein at least the end portion having the flow diffusers is removed; and instructions for cutting the connecting cannula and connecting the cut end of the connecting cannula to the port in accordance with claim 8.