CA2222142A1

CA2222142A1 - Vascular access system

Info

Publication number: CA2222142A1
Application number: CA002222142A
Authority: CA
Inventors: Gerald S. Melsky
Original assignee: Individual
Current assignee: Therex LP
Priority date: 1995-03-21
Filing date: 1996-03-21
Publication date: 1996-09-26
Also published as: WO1996029112A1; JPH11514248A; EP0814865A1; AU5318296A

Abstract

A vascular access system has an implantable head which includes a pair of similar access ports, each port having an internal chamber with an open mouth, an outlet cannula extending from the port and being in fluid communication with the corresponding chamber and a domed septum closing the mouth of the corresponding chamber. A flexible dual-lumen catheter is connected to the head. The catheter has a pair of unitary closely spaced-apart parallel lumens which are separable so that the catheter proximal end can be connected to the head's outlet cannulas, with the outlet cannula of one port being received in one of the catheter lumens and the outlet cannula of the other port being received in the other catheter lumen. Locking sleeves are provided on the head for locking the outlet cannulas in their respective catheter lumens and a special access needle is provided for accessing the head to avoid coring of the head's septa.

Description

-

2 PCI'/US96/03814 VASCULAR ACCESS SYSTEM

FIELD OF THE INVENTION
This invention relates to a v~scu~ c~ess system. It relates more S particularly to a v~sP ~ ccess device and ~-ssoci ~led access needle which facilitate l,e",apl,eresis.

BACKGROUND OF THE INVENTION
For ~,dtients with certain chronic conditions, it is often necessA~ to 10 remove blood from a patient's body in order to collect blood cells, remove a specir,c cell type or for plas~a ex~ange and then to return blood to the body as quickly as possible. For exampl?, during plasr"a,c l ,eresis, blood is withdrawn from the patient's v~scn~~h~re using a needle allacl ,ed to a tube leadi"g to a centrifuge. The centrifuge sepa~ dtes the blood plasma from the 15 other blood cG""~nenls which are then mixed with fresh plasma and retumed to the patient's body via a secGnd tube and needle. In some cases, this procedure must be repealed as often as twelve times per month.
In order to obtain the requisite blood flow to and from the patient, e.g., 85 ml/min, an eA1er"al ~tl ,eter is often used as the principle hemapheresis 20 ~coess. The catl,eter consisls of a tube, generally of silicone rubber, having a round or oval crossection and two lumens. The distal end of the catheter resides in the patient's v~scul~tl ~re. A common location for that end is the superior vena cava. The proAi",al end of the catheter lies outside the patient's skin so that it is ~ccessible by ",edical personnel pe, ror",ing the 25 procedure. That end is usually fitted with Luer connectors for coupling the catheter to conduits leading to the external separating machine that processes the patient's blood.
The connectors at the proAilllal end of the catheter, while offering a Uneedle free" means of connecting the patient to the external machine, are 30 difficult to maintain in a sterile condition. Once these connectors become conla"~inated the organisms may be lrans",itted to the patient during the pro~dure. Also even though th~ se catl ,et~ rs are flushed with I ,epari"ized ~ol~ tions after each use th~ir lumens frequently becG",e occlvded with ll,ro"lbus. This is due in part to blood being drawn into the lumens in order 5 to make up for the volume of fluid lost by the process of diffusion through the wall of that seg"~ent of the ~tl ,eter which resides outside of the patient.
To avoid the problem of infection implantable dual cl,a"lber v~scu'~
~ccess devices' have been developed which provide direct Access to the vAsc~ system of a patient receiving extracor~,oreal blood t(~dtlllf nt. Such 10 devices' are disclosed in patent 5 041 098. One embodiment comprises a head consisling of a pair of ports joined at their peripl ,eries. Each port has an int~,.,al ~I,s"lber and a sclf~ 'ing septum spar,r,in~ the open face of the cl ,a,nber to establish a closed reservoir within the port. A tubular cannula e~tends from the side wall of each port to establish fluid communication 15 between the reservoir and an exte" ,al c~tl ,eter leading to the infusion site.
The ~.ro,~i",al end of each catl,eter is permanently connected to a coupling member which is releAsz~hly connected to the ~r, esponding port's outlet cannula by means of a coupler. The distal ends of the two catheters are usually cut to length so that the two lumens ter",inate about one inch apart.
20 Also in some cases there may be side openings ~5~cent the ends of the catl,ete,s.
In use that prior device is surgically implanted within the patient's body so that the catheters Access the vAsc~ tl-re through a major vessel such as the subclavian vein. The head is surgically implanted within the 25 body e.g. in a pocket in the ml~sc~ tl~re of the chest and the proximal ends of the catheters are tunneled to this pocket and connected to the head using the couplers.
That known device is ~ccessed by inserting hypodermic needles co""ecled to the extemal machine through the septa into the internal 30 cha,nbers of the two ports. Blood is withdrawn from the vasculature through

-3 -one port and intro~ ~ced or re-intro~h ~ced into the v~sclJlntllre through the other port.
V~s~ ~ c~ss devioes typified by the ones in the above patent are disadvantaged in that they allow only relatively low blood flow rates. This is 5 bec~use in order for the devices' septa to reseal they must be pe"et, ated by relatively small needle~ i.e. 19 gauge or smaller dia",eter. Larger gauge "eed'es result in coring of the septa and reduc~d puncture life. Such coring would require that the prior devices be replaced relatively often.
The prior devices of this general type are disadvantaged also because 10 their outlet cdtl.ete,s have to be customized to the patient prior to i",plantation of the device. More particularly the .listance bet~ccn the i,npla, Itdtion site for the head e.g. the subclavean pocket and the infusion site e.g. the superior vena cava may vary from patient to patient depending upon the palisnt's size. Since the p, oxi" ,al end of the catl ,eter is 15 perma"entl~ fixed to the head itself or to a coupling ",e")ber that is connected to the head the critical dislance for a given patient must be measured and the catl ,~ler cut to the proper length and per",ane, ltly connected to the coupling ",~"lber prior to implantation. The alternative is to utilize an ~ccessdevice having an unnecess~rily long ~II,eter and to accon""GJale the extra 20 catheter length as a ",eanJering or fold within the body. However this results in an unwanted increase in the fluid flow resistance of the device.
AccordMgly it would be desirable to be able to provide a vAsclll~r ~ccess system especi-~lly suited for l,e,napl ,eresis which allows a maximum amount of fluid flow to and from the infusion site and which can remain 25 implanted in the body for a prolonged period.

SUMMARY OF THE INVENTION
Accordingly it is an object of the invention to provide an improved implantabl~ v~scular ~ccess device and system for hel"dpl)eresis.

WO 96/29112 PCI'tUS96/03814

4-Another object of the invention is to provide a device of this type which has a relatively long useful life.
- A further object of the invention is to provide a v~sc~ r Access device for he",apl ,eresis which is relatively easy to in,plant.
S Yet an~ltl,er object of the invention is to provide such a device which is no more ex~,6"sive to make than prior comparable devices of this general type.
Other objects will in part, be obvious and will, in part, appear I ,erei"dfler.
The invention accordingly comprises the features of construction, combi. .at;on of ale."ents and a"an~c",ent of parts which will be exemplified in the following dePiled ~es~ ip~ion, and the scope of the invention will be indicated in the claims.
In ~aeneral, the prese, It system co,n~,rises an implantable V~SCIJl~r 15 ~ccess device and ~ssoci~ted needle for use in the extra~rporial treatment of blood or fra~AiGns ll ,ereof. The device inch~des dual access ports, each port having an i"~e",al chamber ~erined by the side and bottom walls of the port. A self-sealing, needle-penetrable septum closes the open top of each cl ,ar,lber. Each septum is quite thick, being dome shaped so it protrudes 20 from the top of the co" espor,~l;ng port. Consequently, when the device is implanted, the septa are relatively easy to locate. More i"~po, lanlly, the septa are not prone to leakage even after being pe"elraled a relatively large number of times by a relatively large diameter needle.
A separate outlet cannula extends from each port. The proximal end 25 of each cannula is in fluid communication with the chamber in the corresponding port. The opposite or distal end of each cannula is barbed so that the proximal end of a flexible resilient catheter can be engaged tightly over the barL,ed end. r, e~rably, the outlet cannula of each port carries a locl~i"g collar which can be slid over the proximal end of the catheter to hold 30 that end in place and to provide stress relief at that location.

-5-ln accorclance with the invention, the two ~tl ,eters ~ssoci~ted with the two ports of the pr~sen~ AC.Ce5S device are normally joined to~et~,er along their l~n~ths so that they form a unitary dual-lumen c~the~er. However, the two catt,ete,~ sections, or at least their pr~,(i",al end sey,),ents, are separable S much like the two insul-ted conductors of a standard lamp cord, so that the two catl ,eter se~ions can be separ~ed by pulling them apart.
When the device is i."planted, the head is positione~ in a sub-cutaneous pocket made by blunt dissection of tissue just below the clavicle.
The distal snd of the ~atl ,eter is posilioned at the junction of the superior 10 vena cava and the ventricular atrium by Accessing the subclavean or jugular vein. The proAi. . .al end of the ~tl .eter is then tunneled to the pocket conlaining the head and l,i"""ed so that it just reaches the head. Next, the pr~i",al ends of the ~tl.e~er sections are pulled apart and engaged over the outlet cannulas of the two ports cG",prisi"g the head and locked in place with 15 the locking collars. Thus, at the time the device is implanted in a patient, its dual-lumen outlet catl .~ler can be cut to exactly the right length to span the distance between the head and the infusion site for that particular patient.
Thus, the catl ,eter presents a minimum flow resistance to fluid flow for that particular pa~ienl without having to be custollli~ed ahead of time to that 20 patient.
As we shall see, the system also includes an especi~'ly large needle, i.e., 16 gauge or less, to be desuibed in more detail later for ~ccessing the device. The needle has a hub and a stylet which occludes the lumen of the needle cannula during insertion of the needle through a septum of the access 2S device. With the stylet in place, the needle can penetrate the septum withoutcoring the septum material. Once the needle is in place, the stylet may be removed and the hub of the needle cannula connected to a line leading to an exte",al blood separation machine.

WO 96129112 PCI'/US96/03814 BRIEF DESCRIPTION OF THE DRAWING
For a fuller l.ndersla"ding of the nature and objects of the invention, r ~fer~, .ce should be had to the following detailed desu i~Jtion taken in co"ne~ti~j" with the accon,pan~ing drawing, in which:
FIG. 1 is an ison,et, ic view with parts broken away showing a v~su ~IAr ~c~ss device for h~l"apheresis incGl ~Gralin9 the invention, and FIGS. 2A to 2C are diagran,l"atic views illu~l~aling the operalion of the overall v~-scl~~v Acc~ss system.

10 DESCRlPTlON OF THE PKt~tKRED EMBODIMENT
Ref~jl, i"~ to FIG. 1 of the dr~ ing, our VASCI ~'nr ~ccess system co"",,ises a head 10 con,)e~ted to a call,e~er 11. The head includes a pair of s~ ~bst~utially identical ports 1 Oa and 1 Ob joined at their peripl)eries. Eachport has a bottom wall 12 and a generally cylindrical side wall 14 extending 15 up from the bottom wall so as to form an inle, nal c ha"lber 16 having an open mouth 18. A conical groove 22 is inscribed in the interior surface of wall 14 ~5~ce"l to mouth 18 for sea~ing a needle-penel~ablc self-sealing septum 24.
Septum 24 is Ushoe-homed~ into the mouth 18 so that its inner edge seats on the inner wall 22a of groove 22 and so that the outer edge of 22b of that 20 groove ov~-, I ,dngs the septum, thereby retaining the septum 24 in place so that the septum spans mouth 18.
Septum 24 has a rounded, raised central portion or dome 24a which protrudes from mouth 18. Thus, when the head 10 is implanted in the body, the raised portions 24a of septa 24 can be felt under the skin so that needles 25 can be aimed properly at the septa. Also, the extra thickness of the domed septa makes them less prone to leakage.
F'l eferably, each port 1 Oa, 1 Ob is provided with a bottom flange 26 having suture holes 28 spaced around the flange so that when the head 10 is implanted in the body, it can be sutured to Adj~cent tissue.

- - -WO 96/29112 PCI'/US96/03814 An outlet cannula 32 e)~tends from the side wall 14 of each port 10a.
10b. Each cannula 32 is in fluid commu"i~tion with the inter"al ~;I,a,nber 16 of the ~n esponding port and the outer end of each cannula is bal ~d at 32a.
A!so each cannula 32 carries a locki"g sleeve 34 which is slidable along that S cannula between an exte, l~ed posilion shown in FIG. 1 wherein the sleeve is positione.l over the barb 32a and a retra~ted position wherein the sleeve is sp~d somewhat from that barb. The cylindrical body of each sleeve 34 is slitted to form a circular array of flexible resilient tines 34a. The free ends of the tines have inwardly extending ribs 36 which are a" anged to el ,gage in a 10 circular groove 38 insc, il,ed in the COI ,esponding cannula 32 to rele~s~hly maintain sleeve 34 in its e~lended pOsitiol, shown in FIG. 1.
Outlet catl ,eter 11 is compos~J of two se-;tiGns 11 a and 11 b which are joined together along their lel l!Jtl ,s but which are separable by pulling the two sectiol ,s apart. To ~". .ect catheter 11 to the head 1 0 the pro~i",al end of 15 the cati ,eter is squared off and the two sectiol ,s 11 a and 1 1 b are pulled apart a suf~lcient amount to enabl~ the proxi",al end of catl ,eter section 11 a to bee,)gaged over the outlet cannula 32 of port 1 Oa and to enable the similar end of caU ,eter section 1 1 b to be slid onto the outlet cannula 32 of port 1 Ob.
Then the two locking sleevcs 34 are moved to their exle, Ided positions to 20 secure the proxi",al ends of the catl,eter sections to their respe.1i~e ports and to provide stress relief for the ~theter.
Preferably the distal end of the catheter 11 is designed so that the exit points of the two catheter seclions are spaced apart from one another by about 1 inch. This helps to reduce unwanted re-circulation of blood returning 25 to the patient s v~sclJ~ture via one catheter section being drawn back immediately into the other catheter section. The distal ends of the two catheter sections 11 a and 11_ may also be provided with one or more side ports 38 to maximize blood flow through the device.
The other co",ponent of our system is a speci~' ~ccess needle shown 30 yel ,erally at 42 in FIGS. 2A to 2C. Needle 42 includes a relatively large WO 96t29112 PCI'IUS96/03814 dia",eter cannula 44 e.g. 12 to 16 gauge having a stylet or obturator 46 which ocrl~ ~des the lumen of the cannula when the needle is inserted through septum 24 into port 1 Oa or 1 Ob. With the stylet in place the needle cannula may pen~tra~e septum 24 through the skin S as shown in FIG. 3A without 5 coring the septum.
r~aferably the stylet 46 is provided with a hub 52 at its proximal end which rel~-~e~hly engages to a connector or hub 54 at the ~,roxi",al end of the cannula 44. Once needle 42 is inserted into the port 1 Oa or 1 Ob the hub 52 may be de~!~ple~ from con"ec~or 54 and the stylet 46 withdrawn from the 10 cannula as ilh,slrated in FIG. 2B. Then connector 54 may be coupled to a mating cor" ,~;tor 56 attached to the end of a tube 58 connected to the exl~",al machine as shown in FIG. 2C.
Surgical place",enl of the illusllale.l device is similar to that of other conventiol ,al Access devices. More particularly the catheter 11 is implanted 15 under the skin S so that its distal end lies at the junction of the superior vena cava with the ventricular atrium. This may be acco",plished by ~ccessing the sub-clavean or jugular vein either by the Seldinger technique or by a direct cut-down. A kit containing a peel away introducer/dilator along with a guide wire and Seldinger needle may be provided to facilitate the Seldinger 20 ~rocedure. The head 10 may be implanted in a suhcut~neous pocket made by blunt dissection of the tissue below the clavicle. Then the proximal end of the catheter is tunneled to this pocket trimmed and connected to the port head. As noted above the catheter 11 is designed so that the end of the catheter pro~i",al to the head may be cut to the correct length and bifurcated 25 by hand so that the two branches may be securely attached to the head s two outlet cannulas 32. In other words the catheter 11 may be trimmed at the time of i"",la"l so that is has the shortest possible length consistent withproper head placement in the patient thus minimizing flow resistance. Thus it is no longer necessA-y to pre-fit the outlet catheter to the particular patient.

WO 96/29112 PCI~/US96/03814 _9_ After the head 10 is i",planted it may be ~ccessed as ~lesa ibed above using needle 42 which bec~ ~se of its relatively large diameter also mini,.,i,es fluid flow resista~.ce in the system. At the same time bec~se the needle cannula 44 contains the stylet 46 during the needle insertion process S there is minimum coring of the head s septa 24. That and the thickness of septa 24 enable eacn port to be ~ccessed many times without leaking.
Therefore the device should be able to remain implanted for a long period of time.
It will thus be seen that the objects set forth above among those made 10 apparent from the preceding Jesa iption are efficiently allained and since certain ~,a"ges may be made in the above construction without depal (ing from the scope of the invention it is i"lende.l that all matter co, ItDi. ,ed in the above desaiption or shown in the acco",pa"~ing drawing shall be inter~,,eted as illustrative and not in a limiting sense. It is also to be u"d~rslood that the 15 following claims are inter,ded to cover all of the generic and specific features of the invention ~lesc, ibed herein.

Claims

1. A Vascular access system, comprising:
an implantable head, said head including a pair of similar, integrally connected access ports, each port having an internal chamber with an open mouth, an outlet cannula extending from said port and fluidly communicating with said corresponding chamber, and a relatively thick septum spanning and closing off said mouth of said corresponding chamber; and a flexible multi-lumen outlet catheter having a proximal end and distal end, and a pair of closely spaced lumens extending between said proximal and said distal ends, said lumens being separable at least at said proximal end of said catheter to enable said catheter to be cut to the proper length and bifurcated during implantation of said head, thereby enabling said proximal end of said catheter to be connected to said head after being cut to length and bifurcated with said respective catheter lumens receiving said respective outlet cannulas from each of said ports.

2. The vascular access system recited in Claim 1, wherein said septum of each port is dome shaped so that it protrudes appreciably from said mouth of said chamber of the associated port.

3. The vascular access system recited in Claim 2, further including a perforate flange extending around the perimeter of said head.

4. The vascular access system recited in

Claim 1, wherein said catheter distal end is stepped so that one of said catheter lumens is longer than the other of said catheter lumens.

6. The vascular access system recited in Claim 1, further including a catheter locking sleeve movably engaged on said outlet cannula of each port for retaining said cannula in the corresponding catheter lumen.

7. The vascular access system recited in Claim 1, further including an access needle for accessing each port by penetrating said septum associated with said port, said needle including:
a relatively large diameter access cannula having a first end and a second end;
a stylet slidably received in said access cannula, said stylet having a first end and a second end, and being co-extensive with said access cannula; and coacting first and second coupling means associated with said respective first ends of said access cannula and said stylet for releasably and mechanically coupling said stylet to said cannula so that said respective second ends of said access cannula and said stylet are maintained in a generally adjacent relationship when said needle penetrates said associated septum.

8. The vascular access system recited in Claim 7, wherein said access cannula of each needle is 16 gauge or less.

9 A vascular access system, comprising:
an implantable head, said head including a pair of similar, integrally connected access ports, each port having an internal chamber with an open mouth, an outlet cannula extending from said port and fluidly communicating with said corresponding chamber, and a relatively thick septum spanning and closing off said mouth of said corresponding chamber;
a flexible multi-lumen catheter having a proximal end and a distal end, and a pair of closely spaced lumens extending between said proximal and distal ends, said lumens being separable at least at said proximal end of said catheter to enable said catheter to be defined and cut to length during implantation of said head and connected to said head with said respective catheter lumens receiving said respective outlet cannulas from said ports;
means associated with said outlet cannula of each port for releasably securing said cannula in said corresponding catheter lumen; and an access needle for accessing one of said ports by penetrating said associated septum, said needle including a relatively large access cannula having a first end and a second end, a stylet slidably received in said access cannula, said stylet having a first end and a second end, and being co-extensive with said access cannula, and coacting first and second coupling means associated with said respective first ends of said access cannula and said stylet for releasably and mechanically coupling said stylet to said cannula so that said respective second ends of said access cannula and said stylet are maintained in a generally adjacent relationship when said needle penetrates said associated septum.

10. A vascular access system, comprising:
an implantable head, said head including a pair of similar, integrally connected access ports, each port having an internal chamber with an open mouth, an outlet cannula extending from said port and fluidly communicating with said corresponding chamber, and a relatively thick septum spanning and closing off said mouth of said corresponding chamber; and a flexible multi-lumen outlet catheter having a proximal end and a distal end, and pair of closely spaced lumens extending between said proximal and said distal ends, said lumens being separable at least at said proximal end of said catheter to enable said catheter to be cut to the proper length and bifurcated during implantation of said head, thereby enabling said proximal end of said catheter to be connected to said head after being cut to length and bifurcated with said respective catheter lumens receiving said respective outlet cannulas from each of said ports, said catheter further including at least one side opening defined therein adjacent to said distal end of said catheter.