Method and apparatus for percutaneously accessing an implanted port

Methods and apparatus for percutaneously accessing an implanted port use an access cannula which is periodically introduced to an aperture on the implanted port so that the cannula passes through the same tissue tract. It has been found that repeated passage of the cannula through the same tissue tract reduces patient trauma, with minimized bleeding, reduction in sensitivity. The tract may be initially formed by percutaneously placing a penetrating element through intact skin to the port and leaving the element in place for a time sufficient to created the tract.

BACKGROUND OF THE INVENTION 
1. Filed of the Invention 
The present invention relates generally to the design and use of medical 
devices. More particularly, the present invention relates to a method and 
apparatus for accessing an implanted port. 
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 applications, such as 
intravenous feeding, intravenous drug delivery, and other applications 
which continue over only a short time, they are not suitable for 
hemodialysis, peritoneal dialysis, hemofiltration, and other 
extracorporeal procedures that must be repeated periodically, often for 
the lifetime of the patient. 
For long-term vascular access suitable for hemodialysis, hemofiltration, 
and the like, the most common approach is to create a subcutaneous 
arteriovenous (A-V) fistula. The fistula is preferably created by 
anastomosing an artery, usually the radial artery, to a vein, usually the 
cephalic vein. The vein dilates and eventually arterializes, becoming 
suitable for repeated puncture using a needle for access. A-V fistulas may 
also be created using autologous or heterologous veins, by implanting 
synthetic blood vessels, typically PTFE tubes, and the like. 
The cannulas used for percutaneously accessing an A-V fistula may be large 
bore coring needles, often referred to as fistula needles. Alternatively, 
fistula access may be obtained using a blunt cannula which carries a 
removable trocar or stylet. In both cases, the cannulas are usually 15 ga. 
(having a bore diameter of 1.49 mm) or larger, and permit the high blood 
flow rates needed for hemodialysis, hemofiltration, and other 
extracorporeal procedures. Usually, the fistula needles or other access 
cannulas are introduced through a different site on the skin each time the 
fistula is accessed. By choosing successively different skin access sites, 
the tissue penetrations to the fistula are allowed to heal. 
An alternative technique for repeatedly accessing an A-V fistula is 
referred to as the "button hole" technique. Such technique relies on 
repeatedly accessing the fistula through the same tissue tract, eventually 
creating a channel through the tissue overlying the fistula. The channel 
is lined with scar tissue which forms over time. While generally 
successful, the button hole technique results in significant back bleeding 
from the A-V fistula every time the fistula needle is removed after a 
treatment is completed. The bleeding, in turn, causes significant clot 
formation over the length of the tissue tract, and the resulting clot 
"plugs" must be removed prior to subsequent needle insertion in order to 
avoid the risk of pushing clot into the fistula. The removal of the clot 
plug causes patient discomfort and bleeding and increases the risk of 
infection. More significantly, should the user fail to or incompletely 
remove the clot plug, portions of the clot can enter circulation and cause 
embolism. Usually, the access tract to the A-V fistula is at a low angle 
over a relatively long path, increasing the discomfort, bleeding, and 
risks of infection and clot embolism. 
While the button-hole technique for an A-V fistula can be successful when 
implemented by skilled personnel, and can result in decreased pain to the 
patient after the access channel is established, it is a very difficult 
procedure to learn. In particular, since the user cannot see or feel the 
entry point on the fistula, proper alignment of the needle to pass 
precisely through the established tissue tract to reach the same site on 
the fistula every time is very difficult. Because of the need to 
repeatedly pass the needle through the established tissue tract, it is 
recommended that the buttonhole technique be performed by the same 
"sticker" every time. Usually, this means that the buttonhole technique is 
only used by home users where the patient or a dedicated assistant can 
perform the needle stick each time dialysis is performed. As most dialysis 
is performed in clinics, however, such a requirement greatly limits the 
utility of the buttonhole technique. 
As an alternative to the use of an A-V fistula, a variety of implantable 
ports have been proposed over the years for use in hemodialysis, 
hemofiltration, and other extracorporeal treatments. Typically, the port 
includes a chamber having an access region, such as a septum, where the 
chamber is attached to an implanted cannula which in turn is secured to a 
blood vessel. In the case of veins, the cannula is typically indwelling, 
and in the case of arteries, the cannula may be attached by conventional 
surgical technique. 
Percutaneous access to a port through a septum, however, is generally 
limited to small diameter, non-coring needles. Large diameter needles will 
core the septum, i.e. form permanent channels therethrough, which will 
destroy the septum after repeated uses. Small diameter, non-coring needles 
will remove little or no material from the septum, allowing it to close 
after the needle is removed. While small needles will thus preserve the 
septum, they are generally incompatible with the high flow rates which are 
used with hemodialysis and other extracorporeal treatments. 
Implantable ports having an access aperture and internal valve mechanism 
for isolating the implanted cannula have also been proposed. One type of 
implantable valved port is described in a series of issued of U.S. patents 
which name William Ensminger as inventor. The Ensminger access ports have 
internal lumens for receiving a percutaneously introduced needle and an 
internal valve structure for isolating the port from an associated 
implanted cannula. Generally, the Ensminger ports have a needle-receiving 
aperture which is oriented at an inclined angle relative to the patient's 
skin. The Ensminger ports employ relatively large funnel-like entry ports 
so that needles can be introduced through many different sites in 
accordance with conventional procedures. The Ensminger patents do not 
describe port access using large diameter, coring needles, such as fistula 
needles. Moreover, as many of the specific Ensminger designs employ 
elastomeric valve elements, it is likely that the valve mechanisms would 
be damaged if the ports were accessed by a fistula needle or other large 
bore coring needle. Representative Ensminger patents are listed in the 
Description of the Background Art below. 
Thus far, implantable ports have not found wide spread acceptance in the 
performance hemodialysis, peritoneal dialysis, or other procedures where 
large volumes of blood, dialysate, or other fluids are to be exchanged. To 
the extent implantable ports have been used, it is generally been 
recommended to move the access site through the skin and/or move the skin 
relative to the port in order to change the location of the tissue tract 
between successive access procedures. 
For these reasons, it would be desirable to provide improved methods and 
apparatus for percutaneously accessing a patient's vasculature. Such 
methods should reduce patient trauma, provide for reliable access to the 
vasculature, minimize the risk of infection to the patient, and preferably 
require only minor modifications to present procedures. In particular, it 
would be desirable to-provide methods and apparatus which combine the 
advantages of the "buttonhole" access technique, such as low pain needle 
insert and formation of a denervated tissue tract, with the advantages of 
subcutaneous port access, e.g. reliable performance and low failure rates, 
high blood and fluid flows through the port with minimum degradation of 
the blood or other fluid, compatibility with peritoneal dialysis and other 
non-blood procedures and the ability to utilize an internal valve to 
provide improved isolation of the blood vessel or other accessed body 
lumen. Moreover, it would be desirable to overcome certain disadvantages 
associated with the buttonhole technique when used to access an A-V 
fistula. For example, it would be desirable if the tissue tract could be 
formed and accessed by different users so that the procedure could be 
employed in clinics and other locations where different personnel will 
treat different patients. Additionally, it would be desirable to reduce 
the formation of clot from back bleeding into the buttonhole tissue tract 
and thus lessen the need to remove the clot and reduce the risk of clot 
emboli. At least some of these objectives will be met by the invention 
described hereinafter. 
2. Description of the Background Art 
The "button hole" technique was first described by Dr. Zbylut Twardowski as 
the "constant site" access method in Twardowski et al. (1977) Pol. Arch. 
Med. Wewn. 57:205-214 and has been subsequently described in Scribner 
(1982) Proc. Europ. Dial. Transplant Assoc. 19:95-98 and Scribner (1984) 
Dial. Transplant 13:652. U.S. Pat. No. 5,562,617 and WO 95/19200, assigned 
to the assignee of the present application, describe implantable vascular 
access systems comprising an access port having an internal slit or duck 
bill valve for preventing back flow into the port. Vascular access ports 
having various articulating valves for isolating the port from the 
vascular system in the absence of external percutaneous connection to the 
port are described in the following U.S. Patents which name William 
Ensminger as an inventor: U.S. Pat. Nos. 5,527,278; 5,527,277; 5,520,643; 
5,503,630; 5,476,451; 5,417,656; 5,350,360; 5,281,199; 5,263,930; 
5,226,879; 5,180,365; 5,057,084; and 5,053,013. Other patents and 
published applications which show implantable ports having valve 
structures opened by insertion of a needle include U.S. Pat. Nos. 
5,741,228; 5,702,363; 4,569,675; 4,534,759; 4,181,132; WO 97/47338; and WO 
96/31246. Other patents and published applications relating to peritoneal 
dialysis include 5,770,417; 5,770,193; 5,752,939; and WO 98/17333. 
Implantable ports and subcutaneous catheters for connecting the ports for 
hemodialysis, peritoneal dialysis, and other procedures which are useful 
in the present invention are described in co-pending application Ser. Nos. 
08/539,105; 08/724,948; 09/009,758; 08/942,990; 08/857,386; 08/896,791; 
08/856,641; and 09/003,772, the full disclosures of which are incorporated 
herein by reference. 
SUMMARY OF THE INVENTION 
The present invention provides improved methods, apparatus, and kits for 
creating and establishing access to subcutaneously implanted ports for a 
variety of purposes, including hemodialysis, hemofiltration, 
hemodiafiltration, apheresis, peritoneal dialysis, drug delivery, and the 
like. The methods rely at least partly on the surprising discovery that 
repeated percutaneous penetrations with an access cannula, including but 
not limited to large bore diameter needles, to a subcutaneously implanted, 
self-closing access port result in a tissue tract which has minimum back 
bleeding after the cannula is removed, which rapidly heals even when 
accessed multiple times in a single day, and which minimizes patient 
trauma as the tissue tract loses its nerve sensitivity over time. The 
tissue tracts which result from accessing such implanted ports appear to 
differ from those which result from accessing an A-V fistula using the 
so-called "button hole" technique, even when using identical fistula 
needles. 
The tissue tracts created and utilized by the present invention do not 
result in the same type of tunnel which is developed over time with the 
"button hole" fistula access technique described above. In particular, the 
tissue tract formed by the present method will usually have reduced or no 
clot formation, often eliminating the need to remove a clot plug and 
significantly reducing the risk of emboli release. It is presently 
believed that such reduction in clot results at least partly from the 
ability of a valved or other self-closing port to inhibit bleeding back 
into the tissue tract when the needle is withdrawn. Inhibition of back 
bleeding lessens or eliminates clotting and scab formation over the 
penetration point and through the access tract. The ability to eliminate 
or lessen scab removal is thus a significant benefit to the patient. In 
addition, by utilizing the preferred access ports of the present 
invention, the tissue tract may be formed vertically, thus lessening its 
length and further reducing bleeding and patient trauma. The access port 
is also particularly easy to locate beneath the skin, and when combined 
with the ability to vertically introduce the needle, targeting of the port 
is greatly simplified. The ability to accurately and simply target the 
port lessens the chance that the cannula will be misdirected, still 
further reducing patient trauma and enhancing the unique tissue tract 
formation which underlies the present invention. 
According to a first aspect of the present invention, a method for 
percutaneously accessing an implanted port in a patient comprises locating 
a preformed access tract which extends from an entry point on the 
patient's skin surface to the port. A cannula is percutaneously introduced 
through the preformed access tract to establish a flow path through the 
cannula to the port. As described above, over time, repeated percutaneous 
introductions of the cannula will create a unique tissue tract which 
becomes lined with scar tissue and has lessened nerve sensitivity, 
reducing patient trauma as the same tissue tract continues to be used for 
access. The port will usually have an aperture for receiving the cannula, 
and the locating step will comprise manually aligning the cannula with a 
line from the skin entry point (which remains visible on the patient's 
skin surface) to the aperture on the port, where the aperture can be 
manually located by feeling the port through the patient's skin and 
determining the location of the aperture. Usually, the aperture will have 
dimensions which correspond to those of the cannula, e.g. they will have 
similar diameters, although in other cases the aperture could comprise a 
funnel having dimensions substantially larger than the cannula diameter. 
Usually, however, provision of such a funnel for directing the cannula 
into the aperture is undesirable since it allows the user to penetrate the 
cannula through different access tracts. 
The cannula may comprise a needle having a sharpened or chamfered distal 
tip to permit self-penetration of the cannula through the patient's skin. 
Alternatively, the cannula could comprise a blunt tubular body, optionally 
including a trocar, stylet, blade, or other sharpened element to assist 
with self-introduction of the cannula. In some cases, after the access 
tract is established, it will not be necessary to provide a sharpened 
element with the cannula in order to assist in percutaneous introduction. 
That is, a blunt cannula will be able to be passed inwardly through the 
established tissue tract. Usually, the cannula will have a diameter which 
is larger than that of the tissue tract which will have collapsed after 
the cannula was removed in the previous treatment protocol. Thus, as the 
cannula is introduced through the established tissue tract, the tissue 
tract will be dilated. Such repeated introduction and dilation of the 
tissue tract is believed to be part of the treatment method which results 
in the scar tissue formation and desensitized tissue tract. 
In the exemplary embodiments, the cannula will be a large bore cannula, 
typically having a bore size of at least 1.16 mm (16 gauge), preferably 
being at least 1.33 mm (15 gauge) and more preferably being at least 1.55 
mm (14 gauge) and in some cases being at least 1.73 mm (13 gauge), and in 
still other cases being at least 2.80 mm (12 gauge). In particular, the 
cannula may be a large bore fistula or other needle having these 
dimensions. The needle can be sharp or dull, with the use of sharp needles 
being presently preferred. 
In a second aspect of the present invention, a method for forming a 
percutaneous access tract to an implanted port comprises percutaneously 
introducing a cannula to initially define the access tract. The access 
tract will have a skin entry point and extend to a port, typically to an 
aperture on the port as generally described above. The access tract is 
established by repeatedly accessing the port with a cannula (usually 
different cannulas which may have the same or different geometries, 
dimensions, and the like) through the same access tract at intervals and 
over a time period sufficient to cause scar tissue formation over the 
access tract. Usually, the access intervals and time periods will depend 
at least in part on the procedures to be performed on the patient. For 
example, patients undergoing hemodialysis will typically have the cannula 
introducing step repeated at intervals of at least twice a week, more 
usually three times a week, for a period of at least three months, usually 
for indefinite periods. For patients undergoing peritoneal dialysis, the 
access interval will be much more frequent, usually being at least twice a 
day, often being at least four times a day, for periods of at least three 
months, and typically for indefinite periods. 
Usually, although not necessarily, the cannula will be introduced in a 
consistent direction, e.g. generally normal or perpendicular to the skin 
surface through which it is being introduced, with the repeated access 
steps eventually creating the nerve depleted tissue tract described above. 
In a third aspect of the present invention, a method for creating an access 
tract at the time a port is initially implanted comprises implanting the 
port in a subcutaneous tissue pocket where an access cannula-receiving 
aperture of the port is disposed beneath an intact region of the skin. 
This is usually accomplished by creating an initial surgical incision 
which is laterally offset from the main portion of the tissue pocket so 
that the port may be disposed under skin which has not been surgically 
penetrated. After the port is in place, a penetrating element may be 
introduced through the intact region of skin and into the port aperture. 
The penetrating element, which may be a rod, tube, or preferably access 
cannula of the type used for subsequent access to the port, will be left 
in place and remain anchored in the aperture for a time sufficient to 
create the access tract, usually for at least about one week, more usually 
for a least about two weeks, and until sufficient healing has occurred 
around the penetrating element to leave an access tract for subsequent 
cannula introduction. A particular advantage of this method for creating 
the access tract is that the tract will be formed simultaneously with 
healing of the surgical introduction of the port and associated 
subcutaneous cannula. A further advantage, when an access cannula is used 
as the penetrating element, is that fluids may be introduced and removed 
from the port during the healing period. 
In yet another aspect of the method of the present invention, access 
cannulas may be aligned with a preformed tissue tract by visually 
observing the patient's skin to locate an access site. The access site 
will be at the proximal end of the preformed tissue tract and will be 
visually apparent, usually as a small hole or other mark on the skin. 
Prior to introducing the access cannula, the cannula will be both aligned 
with the access site and positioned so that it will be in coaxial 
alignment with the known direction of the tissue tract. In the case of the 
exemplary subcutaneous ports described hereinafter, the direction will be 
generally vertical or normal to the patient's skin in the region of the 
access site. Thus, before the access cannula is actually introduced, it 
will be at the proper orientation so that it will pass through the 
preformed access tract with minimum discomfort and trauma. 
The present invention still further provides kits comprising a cannula, 
often a large bore cannula having a bore size of at least about 1.16 mm 
(16 G), such as a fistula needle or blunt cannula with a trocar or stylet. 
The kit further comprises instructions for use setting forth any of the 
methods described above. The needle and the instructions for use are 
packaged together, where the instructions may be on a separate instruction 
sheet and/or may be provided on a portion of the packaging. Usually, the 
cannula will be part of a catheter, where the needle is connected or 
connectable to the catheter to provide a flow path through the needle and 
into a lumen of the catheter. Kits according the present invention may 
also comprise an implantable port together with instructions for use 
setting forth any of the methods described above for implanting the port 
and creating a cannula access tract to the port. The port and the 
instructions for use will typically be packaged together, using any of the 
packages described hereinafter, and other kit components, such as a 
penetrating element, access cannula, or the like, may also be provided.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
The methods and apparatus of the present invention for creating and using a 
percutaneous access tract are useful with virtually any type of 
implantable access port having an aperture capable of receiving a cannula, 
including but not limited to large bore cannulas, such as fistula needles. 
The methods of the present invention may be performed with implantable 
ports having one, two, three, or more, discrete access ports which may be 
vertically or otherwise repeatedly aligned with the access tract to be 
percutaneously formed through overlying tissue. Such access tracts will be 
useful for repeated access to the aperture, where the aperture defines a 
specific target site through the overlying tissue. 
The preferred access ports will have at least one aperture which removably 
receives the access cannula, optionally in a vertical orientation in order 
to minimize distance of the tissue tract. The access port will preferably 
be capable of immobilizing the access needle while the blood is being 
transferred through the port. Exemplary access ports are described in 
co-pending application Ser. No. 08/942,990, filed on Oct. 2, 1997, which 
was a continuation in part of application Ser. No. 60/036,124, which has 
previously been incorporated herein by reference. Typically, the port will 
be implanted beneath the skin by a distance in the range from about 3 mm 
to 20 mm, usually from 5 mm to 15 mm. 
The access cannulas utilized in the methods, apparatus, and kits of the 
present invention may comprise any of a variety of hollow bore needles, 
tubes, or the like, which are capable of being percutaneously introduced 
to the previously implanted port. Usually, the cannulas will comprise a 
sharpened distal tip, (in which case they are often referred to as 
needles) or a separate element which may be removably placed in the 
cannula to provide such a sharpened distal end. Such elements may comprise 
stylets, trocars, blades, or the like. In some instances, the tips of the 
separate elements may have diameters which are larger than the diameter of 
the cannula itself. For example, blades having a width larger than the 
cannula diameter may be placed through the cannula using a rod in order to 
cut a path as the assembly of the cannula and blade is advanced through 
the tissue tract. In such instances, the blade will usually be 
sufficiently flexible so that it may later be collapsed and withdrawn 
proximally through the cannula in order to provide clear access through 
the cannula lumen to the port. Cannulas having sharpened distal tips or 
separate elements having sharpened distal ends will usually be used at 
least for the initial percutaneous access steps which the tissue tract is 
being formed. After the tissue tract is established, i.e. sufficient scar 
tissue is formed along the tissue tract to maintain the tract between 
successive access steps with the cannulas, is not always necessary to 
provide a sharpened tip on the cannula or separate element. In those 
instances, a blunt cannula or tube can be introduced through the tissue 
tract. Often, however, it will still be preferred to use a cannula having 
a sharpened tip or separate element to facilitate such introduction. 
An exemplary embodiment of the present invention utilizes large bore coring 
needle, such as conventional fistula needle. By "coring needles," it is 
meant that the distal tip of the needle will be sharpened and will be open 
in a forwardly direction so that the needle is capable of cutting tissue 
(and coring septums) as it is advanced therethrough in a forwardly 
direction. It is also possible to use in the present invention are needles 
having a non-coring design, such as Huber needles which have a side-facing 
distal opening as well as stylets, etc. The preferred needles and other 
cannulas will have a bore size of at least 1.16 mm (16 G), usually at 
least 1.33 mm (15 G), more usually at least 1.55 mm (14 G), still more 
usually at least 1.73 mm (13 G), and sometimes as large as 2.08 mm (12 G), 
or larger. The needles may be composed of any conventional needle 
material, typically being a stainless steel, but could also be hard 
plastic. 
In preferred embodiments, the access needle will be incorporated into a 
catheter, as described in co-pending application Ser. No. 08/896,790, or 
into a peritoneal dialysis tubing set, as described in co-pending 
application Ser. No. 08/896,791, the full disclosures of which have been 
previously incorporated herein by reference. Such catheters incorporating 
the access needle will now be described in detail together with methods 
for their use according to the present invention. 
Referring now to FIGS. 1 and 2, an access catheter 10 incorporating a large 
bore coring needle 20 in accordance with the principles of the present 
invention will be described. The catheter 10 comprises a catheter body 12 
having a proximal end 14 and a distal end 16. The catheter body 12 will 
typically comprise a flexible polymer tube, composed of a medically 
compatible organic polymer, such as polyvinylchloride, and having a length 
in the range from 10 cm to 30 cm, preferably from 12 cm to 18 cm, and a 
lumenal diameter in the range from 1 mm to 5 mm, usually from 3.4 mm to 
4.6 mm. Such polymeric tubes may be formed by extrusion and will typically 
include a single lumen extending the entire length from the proximal end 
14 to the distal end 16. 
Fitting 18 is secured to the distal end of catheter body 12, typically by 
an adhesive, heat welding, solvent bonding, penetrating fasteners (not 
shown), or other conventional means. The fitting is shown as a generally 
flat disk but could have a variety of alternative geometries. The access 
tube 20 is secured to the distally forward face of the disk, and the lumen 
of the needle is fluidly coupled to and aligned with the lumen of catheter 
body 12. An orifice 25 is disposed in the disk 18 and generally aligned 
between the lumen 21 of the needle, thus opening into lumen 27 in the 
catheter body. Usually, a connector 26, such as a luer connector, is 
provided at the proximal end 14 of the catheter body 12. Such a connector, 
however, is not necessary and it is possible to directly connect the 
catheter body to a desired treatment device, fluid source, or other 
external apparatus. 
As described in detail in co-pending application Ser. No. 08/896,790, a 
compressible element 30 is attached at the distal end 16 of the catheter 
body 12. Preferably, the compressible element is coaxially disposed about 
the proximal end of needle 20. The compressible element 30 may be 
impregnated with an antiseptic, antibiotic, or other active agent, which 
can be delivered to the skin's surface as the needle 20 is penetrated 
therethrough. Such a compressible element, although generally preferred 
for use in combination with the needles of the present invention, does not 
form part of the present invention. 
Referring now to FIG. 3, an alternative configuration 16' of the distal end 
of the catheter 10 orients the access needle 20 at an approximately right 
angle (90.degree.) relative to the distal end of the catheter body 12. The 
fitting 18 includes cap 32 which defines the 90.degree. bend with an inlet 
34 receiving the distal end of the catheter body 12 and an outlet 36 
connected to the fitting 18. The catheter body 12 can extend through the 
internal passage of cap 32 or, alternatively, may be secured at the inlet 
end. In either case, the substantially continuous lumen 27 is created 
through the catheter body to the orifice 25 and fitting 18 and thus to the 
lumen 21 of access needle 20. 
Referring now to FIG. 3A, a second alternative configuration 116 of the 
distal end of the catheter 10 orients an access cannula 120 having a blunt 
distal end 122 at an approximately right angle (90.degree.) relative to 
the distal end of the catheter 10. A fitting 118 receives the catheter 10 
in a nipple 124 which aligned at a right angle relative to a vertical 
passage 126. A penetrable seal 128 is positioned at the upper end of the 
passage 118 and permits removable entry of a stylet 130 having a sharpened 
distal end 132 which extends through the blunt end 122 of cannula 120. The 
stylet includes a handle 134 at its proximal end to permit removal the 
stylet after the cannula 120 has been introduced through a tissue tract to 
an implanted port. The sharpened tip 132 of the stylet may take any of the 
forms discussed above, including a conical taper, a chamfered taper, a 
widened blade, or any other configuration which facilitates penetration of 
the assembly of the cannula 120 and stylet 130 through skin as the cannula 
is advanced toward the implanted port. The dimensions of the cannula 120 
will usually but not necessarily be within the ranges set forth above. 
Referring now to FIGS. 4A-4D, use of the catheter 10 having the distal end 
16' (FIG. 3) and access needle 20 for creating an access tract and 
accessing an implanted port P through the access tract will be described. 
The port P will have an aperture A which is preferably oriented to receive 
a vertically aligned needle. That is, the access needle 20 will preferably 
be percutaneously introduced through the skin surface S in a direction 
which is normal to or perpendicular to the plane of the skin at the point 
where the needle is being introduced. While vertical access is preferred 
and may be accomplished using the exemplary ports of the present 
invention, percutaneous access according to the present invention may also 
be achieved used non-vertical access direction, i.e. where access is 
accomplished by penetrating a needle or other device at a relatively low 
angle relative to the skin, often between 15.degree. and 45.degree. 
relative to the skin surface. After entering the port P, the access needle 
20 will actuate an internal valve (not shown) to open a flow path with a 
lumen and cannula C, where the cannula may be connected to a blood vessel 
or other body lumen or cavity, as described in detail in co-pending 
application Ser. No. 08/856,641, filed on May 15, 1997. The present 
invention is useful with a variety of other valved and non-valved access 
ports. For example, it will be useful with valved access ports of the type 
described in the Ensminger patents listed above, as well as ports 
described in issued U.S. Pat. Nos. 5,741,228; 5,702,363; 4,569,675; 
4,534,795; 4,181,132; and published PCT applications WO 97/47338 and WO 
96/31246, the full disclosures of which are incorporated herein by 
reference. While the use of valved ports which provide for positive 
shutoff and isolation of the attached body lumen, and in particular 
provide for complete cessation of back bleeding when an access cannula is 
removed from ports attached to blood vessels, the present invention may 
also find use with other self-sealing ports, such as septum ports, a 
number of which are described in the patents listed in the Background 
section of the application. The access needle 20 may be aligned over the 
aperture A by manually feeling the top of the port P. The port P is 
generally symmetric with the aperture positioned in the center of the 
port. The user can feel the periphery of the port P and visually determine 
its center. The needle 20 is then vertically penetrated through the skin 
and into the aperture, as shown in FIG. 4B. The thickness of tissue T 
overlying the aperture is generally from 3 mm to 15 mm, as described 
above. 
The needle 20 will be left in place in port P while the desired procedure, 
such as hemodialysis, hemofiltration, peritoneal dialysis, or other 
procedure, is performed and completed. After completion of the procedure, 
the needle 20 will be withdrawn, as illustrated in FIG. 4C. Withdrawal of 
the needle will leave a tissue tract TT through the tissue T overlying the 
port P. Because the internal valve of port P will have closed, bleeding 
from the body lumen, typically a blood vessel, will be inhibited. Both the 
vertical orientation of needle entry and the inhibition of back bleeding 
into the tissue tract which is left after withdrawal of the needle 
contribute to the lessening or elimination of scab formation and reduction 
in patient trauma and rapid healing. Surprisingly, such benefits may be 
achieved even when using the preferred large bore access needles described 
above. The rapid healing and minimum trauma have been found even when the 
port is accessed as many as four times per day. Such a result could not 
have been predicted prior to the present invention and provides 
substantial advantages over the use of the non-coring needles typically 
used with implanted ports, where the user is instructed not to puncture 
the needle in the same location twice in succession. 
The tissue tract remaining after withdrawal of the catheter, as shown in 
FIG. 4C, is ready to receive a second catheter as shown in FIG. 4D 
virtually immediately after the first catheter is withdrawn. Typically, 
additional access needles 20 and associated catheters will be introduced 
over periods of from two hours to four days, usually from four hours to 
two days. Such cycle times are suitable for performing a wide variety of 
chronic procedures, such as hemodialysis, hemofiltration, peritoneal 
dialysis, and the like. 
As just described, the tissue tract of the present invention may be 
established at any time after a port has been subcutaneously implanted. In 
many instances, it will be desirable to begin creating the tissue tract at 
the time the port is initially implanted. Referring to FIGS. 4E-4G, a port 
P, which may be any of the valved or non-valved ports described above, is 
implanted by creating a tissue pocket PT by making an incision in the skin 
S and forming the pocket laterally from the incision. The port P may then 
be placed in the pocket PT and connected to a cannula in any manner. After 
the tissue pocket PT is closed, as shown in FIG. 4F, an intact region of 
skin IR will overlay the access cannula target aperture A. A tissue 
penetrating element, which may be a needle, rod, stylet, tube, or 
virtually any other penetrating element, may then be introduced through 
the intact region of skin IR, as shown in FIG. 4G. In FIG. 4G, an access 
cannula 16' is used as the penetrating element, but it will be appreciated 
that this is not necessary for initial tissue tract formation. It is 
preferable, however, since use of an access cannula permits blood or other 
fluids to be exchanged through the implanted port from a time very shortly 
after implantation of the port. The penetrating element will be left in 
place transcutaneously through the skin for a time sufficient to at least 
begin forming the tissue tract, usually for at least one week, preferably 
for at least two weeks. After that initial time, the tissue penetrating 
element may be removed and the resulting tissue tract accessed using 
access cannulas according to the method of the present invention described 
above. Continued accessing of the port P through the preformed tissue 
tract will continue to cause scarring and denervation of the tissue tract, 
further establishing and defining the tissue tract over time. 
Referring now to FIG. 5, a needle 50, typically but not necessarily a large 
bore coring needle, according to the present invention, may be packaged 
together with instructions for use (IFU) in a kit, as shown in FIG. 5. A 
conventional package which may be a pouch 52 or any other suitable 
package, such as a tray, box, tube, or the like, may be used to contain 
the needle 50 and the IFU, where the IFU may be printed on a separate 
sheet and/or may be printed on the packaging itself. Optionally, but not 
necessarily, the needle may be sterilized within the package, e.g. by 
radiation, steam, or ethyleneoxide. The instructions may set forth any of 
the aspects of the method of the present invention described above. 
Referring now to FIG. 6, a port P may be packaged together with 
instructions for use (IFU) in a kit. A conventional package 100, which may 
be in the form of a pouch, tray, box, tube, or the like, may be used to 
contain both the port and the instructions for use. Additional kit 
components, such as a penetrating element, access cannula, or the like, 
may also be included in the kit. Optionally, but not necessarily, all kits 
components may be sterilized within the package, and the instructions for 
use may be set forth on a separate sheet of paper and/or on the packaging 
itself. The instructions may set forth any of the aspects of the method of 
the present invention for implanting the port or subsequently accessing 
the port using an access cannula as described above. 
While the above is a complete description of the preferred embodiments of 
the invention, various alternatives, modifications, and equivalents may be 
used. Therefore, the above description should not be taken as limiting the 
scope of the invention which is defined by the appended claims.