CA2086484A1

CA2086484A1 - Implantable infusion device

Info

Publication number: CA2086484A1
Application number: CA002086484A
Authority: CA
Inventors: William Darrel Ensminger; James Carroll Andrews; James Alan Knol
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-01-10
Filing date: 1992-12-30
Publication date: 1993-07-11
Also published as: US5226879A; AU653662B2; JPH06142210A; DE69224892D1; EP0551017B1; DE69224892T2; EP0551017A1; AU3050492A; ES2113930T3

Abstract

ABSTRACT OF THE DISCLOSURE
An infusion device which permits transcutaneous access to an implanted catheter for use in introducing an external filament such as a optical fiber, external catheter, guide wire or rigid needle. In accordance with this invention the device includes a valve assembly including a first valve element defining an aperture with a sealing member which is normally to engage and sea} against the aperture. The sealing element is made from a hard material such as a metal. Upon introduction of a rigid external introducer such as a needle, the needle directly contacts the sealing member plug unsealing it from the valve element aperture which then closes against the external element.
The device enables repeated access using a sharp introduced element such as a needle without it contacting soft sealing elements which could be degraded by such repeated access.

Description

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IMPLANTABLE ACCESS DEVICE

Thi~ i~vention is xela~ed ~o a pa~ient a~ce~s dsvice and particularly ~o one which permits the ~ntroduc~ion o~ an external ~ilament such as a needle, ext~rnal ca~heter, guid~ wire, or optical ~iber transGutan~ou~
This inven~ion xelat~s to a device ~o ~nable multiple patient access proce~ures including in~using a therapeutic agent to a desired site within a patient, ~eed~ng a ~ilament to a desired internal site, or withdrawing a ~luid ~rom a patientJ and more partiaularly, to such a deYice which is implanted ~u~h that no portion i~ transcutaneous. It~ asc~ss portion is subcutaneous but designed so as to racili~at~ repeated aacess by th~
percutaneous route.
In curren~ human and ani~al medical pra~ics, there are numerous instanc~s where therapeutia agents must be delivered to a speci~ic organ or tissu~ wlthin the-~ody. An example i~ the infusion of chemotherapy into a central vein on a recurring ba~is over a lengthy treatment period ~or widespread sites of malignant ........

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~umor. Withou~ an access d~vice ~or intravenous ~rug infusion, multiple vein punctures over a lengthy period can result in progressive thrombosis, venous sclerosis, and destruction of small diameter pexipheral vessels. In other cases~ it may be desirable to infuse chemotherapy to a localized malignan~ tumor site. It may be difficult or impossible to ~eliver an agent speci~ically to such a site on a regular repeti~ive basis without surgically implanting an access system. Similarly, repeated arterial access is occasionally needed for injection of an X-ray dye or contrast agent into an artery ~or diagnos~ic purposes.
In other situations, there is a need to remove a body fluid from a remote body ~ite repeti~ively for analysis. Finally, sensing and physiological measuring devlces incorporated into small diameter cathe~ers and small diameter optical fibers are increasingly being utilized for monitoring body processes and could be more easily implemented through a properly designed access device with an adequate internal diameter.
In prior medical practice, peroutaneous catheters have been used to provide vascular or organ access ~or drug therapy or removing body fluids. Although such systems generally performed in a satis~actory manner, numerous problems were presented by such therapy approaches, including the substantial care requirements by patients, è.g. dressing changes with sterile techniques, a significant rate of infection o~ the catheter because o~ its transcutaneous position, and a high rate of venous thrombo~is, particularly if the catheter was located within an extremity vein.

Implantable infusion devices or "ports" have recently become available and are a significant advance over transcutaneous catheters. Pres~ntly available in~usion ports havs a number of common ~undamental design ~eatures. The ports themselves comprise a housing which ~orms a reservoir which can be constructed ~rom a varie~y o~ plastic or me~al materials. A
surface of the reservoir is enclosed by a high~density, salf sealing septum, typically made o~ silicone xubber. Connected to the port housi~g is an outflow catheter which communicates with a vein or other site within the patient where it is desired to infuse therapeutic agents. Implantation of such d vices generally proceeds by making a small sub~utaneous pocket in the patien~ under local anesthesia. The i~ternal out~low catheter is tunnelled to the desired infusion site and is connecteclto the infusion port. When the physician ~esires to infuse or remove material through the port, a hypodermi~ needle is used which pierces the skin over the infusion port and is placed into the port.
Although presently avàilable implantable infusion ports generally operate in a satisfactory mannex, they have a number of shortcomings. S~nce these devices rely on a compressed rubber septum for seallng, there are limitations in the diameter of needles which can be used to penetrate the septum, since large diameter needles can seriously damage the septum. These diameter limitations severely restrict the flow rate o~ fluids passing through the port. Moreover, the needles used must be of a special design which minimizes septum damage.

For prolonged in~usion using a conventional port, the `.infusion needle is taped to the patien~'s s~in to ~old it in position. Conventional ports do not allow the needle to penetrate deeply into the port; and consequently, a small displacement o~ the needl~ can causc it to be pulled ~rom the port, allowin~ ex~ravasation. In cases where locally toxic material~ are being in~used, extravasation o~ such materials can cause local tis~ue damage which can lead to a reguirement for corrective surgery such as skin gra~ting or removal of tissue.
Presently available implantable in~usion devices mus~ also have a signi~icant size to provide an acceptable target surface area for the physician who mus~ locate the port and penetrate the sep~um properly with a needle. ~ha port housing becomes bulky as the septum size increases since s~ructure is re~lired to maintain the septum in compr~ssion ~o provide el~-sealing a~ter the needle is removed. Moreover, presently available infusion ports are di~icult ~o ~lsar if thrombosis occurs within them or in the implanted outflow catheter, since it is difficult if not impossible to feed a cleaning wira through the penetrating hypodermic needle in a manner which will clear the :Ln~usion device and the i~ternal out~low catheter. Present inPusion ports have a space which contains a retained fluid volu~e beneath the self-sealing septum which increases the volume o~ drug which must be administered to enable a desired quantity ts reach the in~usion site. This retained volume also poses problems when a physician desires to deliver di~ferent drugs to the same infusion site which are incompatible or rendered less e~fective when mixed. In addition, when it is desired to withdraw blood through ~ h~6l~8 '~

the port, the retained volume o~ the prior art in~usion ports is an area where blood clotting can occur, ~hus in~er~ering with future access to the site. And finally, ~or present infusion ports, there is a risk that the physician attempting to pierce ~he port septum will not properly enter it, leading to the po sibility o~ extravasation which can cause signi~icant undesirable cons~guences as mentioned previously.
In applicants~ related patent application and issued patents, various approaches toward permitting transcutaneous access to implanted cathe~er are described. In accordance with those devices, multiple sealing members are us d to provide an adequate fluid seal across the access device, both when an external filament i8 introduced into the dsvice and a~ter it is removed. Th~ acce s ports in accordance with this invention achieve simplicity in construction and reduce ~he number o~
components necessary to provide the ne~essary ~luid seal. In those applications where it i8 desired to access a port using a sharp needle, damage to elas~omeric sealing elements can occur over repeated entries to the port in prior port designs. In accordanc with this invention, the implanted port has an articulating valve mechanism in which the accessing needle (or other filament~ contacts a hard material such as a metal to open the valve. ~ccordingly, a durable device is provided which is not damaged through long term use.
~ he ~eatures of the present invention are primarily achieved through use o~ a valve asse~bly in which a sealing elemen~ is normally maintained in contac~ with a valve seat. When introducing an external ~ilamen~, which may be a needle, 2 ~ 8 l~

catheter, wire, optical ~iber etc., ~he filament engages ~he sealing element forcing it ~rom engagement with the valve s~at.
once fully inserted into the access device, fea~ures are providsd to assure a ~luid ~eal around the introduced ~ilament.
Additional benefit~ and advantages o~ the present invention will become apparent to those skillsd in the art to wh~ch this invention relates from the subsequent description of the preferred embodiments and the appended olaims t taken in ~onjunction with the accompanying drawings~

BRIEF DESCRIPTION OF THE DRA~WINGS
Figure 1 is a cross-sectional view through an access port in accordance wi~h a first embodiment of this invention shown in a normal condition in which an external ~ilament is not present within the device.
: Figure 2 is a somewhat enlarged cros~-sectional view of the access port of Figure 1 shown ~Yith an accessing needle penetrating the device.
Figure 3 is an exploded pictorial view o~ the valve assembly of the port shown in Figures 1 and 2.
Figure 4 is a cross-sectional view through an access port according to a second embodiment o~ this invention showing a valve assembly comprising metal seal elements affixed to a multi-lea~ elastomeric valve disk.
Figure 5 is a ~rontal view of the valve assembly of the port shown in Figure 4.
Figure 6 is an exploded pictorial view of a valve assembly in accordance with a third embodiment o~ this invention fil incorporating a unl~ary seal member for sealing against the valve seat formed by a sealing disk.
Figure 7 is a cross-sectional view of an access port incorporating ~he valve assembly shown in Figure 6 and Purther showing an acce~sing needle penetrating the devi~e.
Figure 8 is a cross-sectional view taken through an access port in accordance with a ~ourth embodi~ent o~ this invention shown with an accessing needle partially penetrating the deYice.
Figure 9 is a cross-sec~ional view o~ the access port shown in Figure 8 but showing the accessing needle penetrating the valve asse~bly to pe~mit access to an implanted catheter.
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An access device in accordance with this invention is shown in Figures 1 and 2, and is ~enerally designated by referen~e number 10. As shown, access port 10 is similar to that described in applicant~s issued patent nu~bers: 5,053,013 and 5,057,084, to which the present applica~ion is rela~ed. Access port 10 is designed to allow a sharp needle to access ~he device for purposes including infusing drugs or other ~luids in the patient or withdrawing ~luid~ from the patient. Access por~ 10 generally has housing 12 which defines a generally funnel shaped entrance orifice 14. Entrance orifice 14 has a decreasing cross-sectional area which ends at housing passageway 16~ The shape of entrance orifice 14 serves to guide a needle lnto passageway 16. To that end, the sur~a-e o~ housing 12 ~orming orifice 14 is a hardened material such as titanium which has been found to be acc~ptable for this application.

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Housing 12 together with outlet plug 18 define valve chamber ~ located between passageways ~6 and 22. As shown, the protruding catheter connector tube 24 of outlet plug 18 is bent to provide a positive means ~or preven*ing an introduced needle from passing e~tirely through the device and potentlally damaging a soft elastomeric impla~ted cathe~er 26. Connec~or tube 24 does, however, permi~ ~ore ~lexible ~ilaments such as a catheter, guide wire or optical ~iber to pass into implanted catheter 26.
~ounting pad 28 enables the device to he conveniently m~unted to subcutaneous support tissue pre~erably using sutures, staples, or other fasteners.
Valve asse~bly 34 is disposed within valve chamber 20 and is best described with reference to Figure 3. Valve disk 36 is made ~rom an elastomeric material such as silicone rubber and is positioned in valve chamber 20 alosest ~o entrance orifice 14.
Disk 36 has a central aperture 38 de~ining a valve seat which is intended to seal against the introduced needle ox ~ilament upon insertion into access po~t lO, as wlll be described in more detail as ~ollow~. Stacked directly against disk 36 is sealing member 40 which is pre~erably made, at least partially, of a hard material such as a metal. Sealing member 40 as shown in Figures l, Z and 3 is a circular metal disk having three cuts intersecting at the center o~ the disk and extending radially to the outer perimeter but stopping short of the perimeter, thus defining three 6eparate cantilever supported }eaves 42. Each of leaves 42 is locally deflected ~rom the plane of ~he disk at the disk center to define a segment 43 which combine to define conical sealing plug 44. Plug 44 has an external generally :

.i,~, conical surface 4~ with its oen~er de~ining~-~b~o~e sur~ace 48.
~ Sealing member 40 can be made ~rom a ~lat sheet metal stock which .~ is locally deflected at the center area to define plug 44.
Alternatively, the disk can be machined or cast such that the -, plug 44 is defined by a locally thickened region of the disk.
Valve asse~bly 34 also incorporates an additional lea~let ~ valve element 52 formed ~rom a ~lat sheet o~ elastomeric j material. Valve el~ment 52 defines radial cuts which join at the geometric center o~ the disk, defining separate valve leaves 54.
As shown 1n Figures 1 and 2, the three elements comprising valve assembly 3~ namely, valve disk 36, sealing member 40 and lea~let valve 52 are stacked directly against one another and are trapped in position between access port housing 12 and outlet ., plug 18. As shown in the Figure~, housing 12 defines a rela~ively smAll diameter passageway on the side of valve assembly 34 closest to entrance passageway 16~ In this manner, seal element 36 is constrained against de~lecting toward entrance orifice 14 except at near its central area de~ining aperture 38.
On the opposite side of valve assembly 34, outlet plug 18 defines a large diameter area ~or the deflection o~ the leaves of valve elements 40 and 52.
The operation and cooperation of ~he elements defining access port l0 will now be described with particular ref~rence to Figures 1 and 2. Figure 1 shows ~he con~iguration of valve assembly 34 when access port 10 is in its normal condition, implanted within the patient and not being used for access. In that condition, the segments o~ sealing member 40 making up sealing plug 44 project into and seal against disX aperture 38 _g_ which acts as a valve seat. Plug 44, having a conical outside sur~ace 46, presses against disk aperture 38, causing it to be stretched and enlarged. ~u~ to the contact between disk 36 and sealing me~ber 40, a seal against fluid leakage is provided.
` Leaflet valve element 52 ie provided to en~ance the level -. o~ sealing by preventing fluid leakag~ between sealing member leaves 42. In the normal condition o~ the device as shown in Figure l, the valve leave~ 54 meet to provide a ~luid seal. As ; ' shown in Figure 3, as a means of providing enhanced fluid ' sealing, the orientation of the cu~s defining leaflet valve i leaves ~4 and the cuts de~ining ~he ~ndividual sealing member leaves 42 are off~set or indexed so that they are not in : . registry.
Figure 2 shows the orientation of the elements o~ access port 10 upon insertion of accessing ext~rnal needle 58. Housing orifice 14 and passageway 16 serve to direct and orient needle 58 such that the sharp point o~ the needle strikes concave surface 48 o~ plug 44. Due to the enlargement o~ valve disk aperture 38 through i~s interaction with plug 44, the sharp point of the needle does not strike valve disk 36. As needle 58 is forced through the device, sealing member leave~ 42 are forced to deflect in th~ direction of the outlet plug pa~sageway 22.
This movement o~ leaves 42 causes ~he segments defining plug 44 to move from engagement with disk aperture 38 which is allowed to contract in diameter. The undeformed diameter of aperture 38 is selected so that it wi}l ~orm a fluid seal against needle 58 (or another introduced filament such as a catheter around the Y, needle whi~h can be left in the dev1ce after the needle is .i ~ -10-'~ ' "~i s removed~. Continued de~lec~ion of leaves 42 allows free passage o~ the needle 58. Such de~lsctions also causes valve leaves S4 .' to separate, allowing passage of needle 58 but without beinq damaged by contact with the needle point.
', ~s is eviden~ from ~he above descrip~ion of the operation 3 of access port 10, repe~ted access using needl~ 58 will not t damage the device ~ince th~ needle r~peatedly strikes the hard material forming plug 44~ ~ccess port 10 al~s permits the introduction of other external ~ilaments~ such as an external catheter, optical ~iber or gu~de wire, provided that it has t sufficient xigidity to deflect the valve elements in the manner previously described~ Acaess port 10 s~ould also enable external filaments to be introduced via needle 58 ei~her as fed through 2 its center passageway, or introduced around the need~.e like a ¦ typical angiography catheter.
,', Figure 4 i}lustra~es an access port 60 inoorporating a valve s a~sembly 6~ in accordance with the second embodiment o~ this invention. This embodiment, al~ng With ~hose described elsewhere in this specification have alements and features identical to . those of the ~irst embodiment, and are identified with like reference numbers. Figure 5 illustrates valve assembly 62 which includes a valve disk 36 identical to that previously described.
The distinction of this embodiment over valve assembly 34 is that the sealing member 64 which de~ines plug 70 is a composite structure. Sealing element 64 is formed ~rom an elastomeric or i flexible base disk 66 having a number of radially projecting cuts :! defining individual leaves 68 as in the case o~ sealing member ~ 40 described previously. Attached to leaves 68 near the center .,~ .
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of base disk 66 ara plug segments 70 which together define a sealing plug 72 as in the prior embodiment which are made of a , hard material such as a metal. Plug elements 70 are bonded or ~ otherwise structurally a~fixed to disk 66.
'. In use, valve assembly 62 operates in a manner consistent with the description of valve assembly 34. A principle advantage ~t of the con~iguration o~ val~e assemb}y 6~ is ~hat 6ealing element ' disk 66 performs the combined ~unctions o~ se~ling as with the lea~let valve element 52 of the first embodiment, and *urther supports plug segments 70.
Figures 6 and 7 illustrate an acoes~ port 78 in accordanc~
with a third embodiment of this invention, Access port 78 has valve assembly 80 with a valve disk 36 identical to tha~ present in the first and second embodiments. In this en~odiment, : howeve.r, sealing member 8~ is a uni~ary s~ructure whia~l includes plug element ~4 attached to a mounting ring 86 via a cantilever arm 88. As with the prior embodiments, plug 84 de~ines an external conical surfac~ 90 and a central concave surface 92.
In this design, however, the plug 84 is a unitary element.
In operation, valve assembly ~0 opera~es as like those of ;3 the prior embodiments in that in a normal condition without an . external filame~t inserted within the access device, plug 84 is in sealing engagement with disk aperture 38. Upon the introduction of an extsrnal filament such as needle 58, engagement between the needle and sealing plug 84 urges it out of engagement with disk aperture 38, and deflects i~ suf~iciently to allow passage of the needle, as shown in Figure 7. This process also resu~ts in the contraction o~ the diameter of - ~, , f ~

aperture 38, causing it to constrict around the introduced filament. A signi~icant benefi~ of valve assemb~y 80 results s from the fact that plug ~4 i8 a unitary structure and, therefore, does not provide a fluid leakage path. In the normal condition with plug 84 against disk aperture 38, a ~luid seal is provided, and therefore, additional sealin~ elements such as a leaflet valve 52 shown in the ~irst embodiment are unnecessary.
Figures 8 and g provide an illustration of acaess port 102 in accordance with a fourth embodiment o~ this invention. T~is embodiment features a modi~ied housing 104 and outlet plug 106.
Housing 104 ~orms a small diameter counterbore 108 extending toward entrance orifice 14. Piston element 110 is positioned 1, within housing cavity 112 and includes a central filament passageway 114. Piston 110 butts against elasto~eric bushing 116 having passageway 117, which is trapped within counterbore 10~.
1 The head of piston 110 forms a dished concave surface 118 which supports valve ball 120. Piston sur~ace 118 is ~ormed to position ball 120 such that it is displaced ~rom alignment with ~, piston passageway 114. Outlet plug ~06 ~orms a generally flat J surface 122 within housing cavity 112 which provides for movement of ball 120, ac is described in more detail below.
Operation o~ access port 102 will be described with reference to Figures 8 and 9. Figure 8 represents the orientation of the elements comprising the device while inserting access needle 58. As is shown in F1gure 8, access needle 58 engages ball 120 o~-centsr. Con~inued insertion o~ needle 58 causes ball 120 to be displaced upward to the position shown in Figure 9. During such displacement, piston 110 is caused to move toward entrance orifice 14 as ball 120 ~rides out" of concave surface 118. This displacement o~ piston llO compresses bushing 116. Since bushing 116 is trapped within counterbore 108 its axial compression causes bushing passageway 117 to cons~rict, thus causing it to seal against the introduced needle or other ~ilament. As show~ in Figure 9, once ball 120 is fully displaced, free passage to the exit passageway 1~4 is provided.
When needle 58 is completely removed from the device, ball lZ0 reseats in position within concave surface 118 which provides a ~luid seal. It would be possible to enhance the fluid seal provided by ball 120 in i~8 normal position by providing an 0-ring or other elastomeric valve seat (not shown) installed either on outle~ plug 106 or a piston l~0 and engaging the ball.
While the abo~e descrip~ion constitutes ~he preferred embodiments o~ the present inv~ntivn, it will be appreciated that the invention is susceptible o~ modification, variation and change without ~epart1ng from the proper scope and fair meaning of the accompanying claims.

Claims

1. An implantable patient access port to permit the introduction of a needle for the removal or infusion of a fluid through an implanted catheter or permitting the introduction of a filament such as an external catheter, guide wire or optical fiber, comprising:
a housing defining a generally funnel shaped entrance orifice for guiding said needle into a housing entrance passageway, said housing further having an exit passageway with a valve chamber within said housing between said entrance and exit passageways, said housing further having means for connecting said exit passageway to said implanted catheter, an elastomeric valve element positioned within said valve chamber and having an aperture positioned in alignment with said housing entrance passageway, a plug which is normally biased into sealing engagement with said valve element aperture, at least a portion of said plug being formed of a hard material for repeated engagement with said needle, said plug positioned within said valve chamber such that upon insertion of said needle and engagement with said plug said plug is forced to deflect out of sealing engagement with said aperture, and mounting means formed by said housing enabling fastening of said housing subcutaneously.

2. An implantable access port according to Claim 1 wherein said aperture is circular.

3. An implantable access port according to Claim 1 wherein said plug is shaped to extend partially through and expand said valve element aperture when said needle or external filament is not within said housing and wherein said valve element aperture constricts into sealing engagement with said external filament upon said plug being forced from sealing engagement with said aperture.

4. An implantable access port according to Claim 1 wherein said plug defines a convex outer surface which engages with said valve element apertures and aids in expanding said valve element aperture.

5. An implantable access port according to Claim 1 wherein said housing passageway is oriented with respect to said plug whereby upon introduction of said needle or external filament, said needle or filament contacts said plug and is prevented from contacting said sealing element.

6. An implantable access port according to Claim 1 wherein said plug defines a concave central area which is engaged by said needle or external filament.

7. An implantable access port according to Claim 1 wherein said plug is at least partially formed of a metal material defining a hard surface which is contacted by said needle or external filament upon introduction of said needle or external filament and said hard surface resisting being damaged or gouged by said needle.

8. An implantable patient access port according to Claim 1 wherein said sealing member comprises a disk having plural leaves which join at near the center of said disk to define said plug.

9. An implantable access port according to Claim 8 wherein said plug is defined by a plug segment disposed at the center region of each of said leaves.

10. An implantable access port according to Claim 8 wherein said sealing means disk is made of metal and wherein said plug segments are formed integrally by said disk.

11. An implantable access port according to Claim 8 wherein said plug segments are formed by separate metal elements bonded to a substrate.

12. An implantable access port according to Claim 1 wherein said plug is supported by an arm urging said plug into engagement with said valve element aperture.

13. An implantable access device according to Claim 1 wherein said plug defines a convex shaped outer surface which engages said valve element aperture with a concave central region for engaging said needle or filament.

14. An implantable access device according to Claim 1 further comprising a second elastomeric valve element disposed in engagement with said elastomeric valve element and positioned adjacent said exit passageway.

15. An implantable access device according to Claim 14 wherein said second elastomeric valve element comprises a leaflet valve having plural leaves which join near the center of said valve.

16. An implantable access port according to Claim 1 wherein said plug is in the form of a sealing ball element disposed within said valve chamber, and wherein said valve element is disposed in said housing valve chamber defining a ball seat wherein when said ball element rests on said ball seat, fluid flow between said entrance and exit passageways is inhibited, said ball seat positioning said ball such that said needle or filament engages said ball and displaces said ball from sealing contact with said ball seat thereby allowing said needle or filament to enter said exit passageway, said ball being resiliently biased into engagement with said seat when said needle or filament is removed.

17. An implantable access device according to Claim 16 wherein said ball seat positions said ball off-center with respect to the longitudinal axes of said entrance and exit passageways.

18. An implantable access device according to Claim 16 wherein said ball seat is defined by a piston member which is resiliently biased by an elastomeric biasing member.

19. An implantable access device according to Claim 18 wherein said piston member is caused to be displaced toward said entrance orifice upon said ball being displaced allowing passage of said external filament.

20. An implantable access device according to Claim 19 wherein said elastomeric biasing member comprises a bushing having a central passageway through which said needle or external filament passes upon introduction of said needle or filament and wherein compression of said bushing caused by displacement of said ball element causes said central passageway to constrict into sealing engagement with said needle or filament.

21. An implantable access device according to Claim 16 wherein said sealing ball element is formed of a hard material which is not gouged or damaged by engagement by said needle.