CA1184820A - Blood access systems - Google Patents

Abstract

ABSTRACT
Improvements and accessories for a septum closed T-shaped blood access device adapted for implantation into a patient. The implantable device has a stem portion extending above the skin of the patient and defining a septum closed opening into the device.
The improvements include an improved septum having a groove in the side thereof encircling the septum and an elastomeric ring carried within the side groove, an improved needle assembly which provides access to the circulatory system through the septum, and a flexible cap for sealing the stem of the implantable device from the outside atmosphere which may be fitted in place or removed without the necessity of specialized tools.
One of the accessories is a septum assembly insertion tool which simultaneously inserts the septum, a pressure plate and a retaining ring into the stem cavity of the implantable device. Another accessory is specialized forceps clamp for gripping the flanged upper edge of the stem of the implantable device. The clamp has curved finger holds which permit the stem of the implanted device to be stabilized during insertion of the septum assembly.
Yet another accessory is a back-up septum system for plugging the cavity in the stem of the implanted device above the principal septum when the principal septum begins to fail. The back-up septum system comprises a specially designed spacer member, a septum conforming generally to the shape of the stem cavity above the retaining ring for the principal septum and a specially designed clamp for holding and compressing the back-up septum within the stem cavity. The back-up system permits continued access to the circulatory system until assistance can be obtained in replacing the primary septum.
A final accessory is a hemispherical implant cap which protects the stem cavity of the implantable device during implantation of the device in the body.

This application is a division of Canadian Application No.
376,507 filed April 29, 1981.
This application relates to improvements in, and accessories for, implantable septum closed blood access devices of the type disclosed in co-pending Canadian application Serial No. 374,940, filed April 8, 1981.
Various approaches to implanted blood access devices are known, however, none of these have been entirely satisfactory.
Shunt techniques have problems of infection, clotting and erosion.
The arteriovenous fistula has some advantages over shunts, but there is a need for recurring needle puncture and there are still infection problems as well as other disadvantages.
It is also known to provide implanted blood access devices wherein access to the circulatory system is accomplished by means of a percutaneous spigot valve.
In said co-pending application Serial No. 374,940, there is disclosed an implantable generally tubular T-shaped structure in which the stem of the T is constructed and arranged to cooperate with a needle structure that penetrates a septum seal means at the junction of the stem of the T with the balance of the T
structure. By reason of the structure of the invention, the interior stemmed portion of the T can be rinsed clean and sterilized between each use without elaborate procedures, thus minimizing the likelihood of infection as a result of access to the circulatory system. The invention thus provides an implantable blood access device which may be semi-permanently installed into the circulatory system and used repeatedly. This invention also has a low profile body external portion which minimizes the possible catching of clothing and the like on the external portion.
Further features of the invention of said co-pending application Serial No. 374,940 include a specialized septum construction, a cooperating needle carrier structure and a cap which seals the flanged edge of the external.

Description

T-stem.

~rief DescriDtion of ~e Invention . . _ This application discloses improvements in the septu~ co~figuration, the needle assembly and the e~ternal 5 cap for blood access devices of the type disclosed in Canadian application Serial ~umber 374,~40. Further improvements are specialized tools designed ~o facilitate placement or replacement of the septum, a bac~-up sep~um system which can seal the device while still permitting con-10 tinue~ use thereof until assistance can be obtainedin replacing a failing septum and an implant cap which is used to protect the interior of tlle device during implantation thereof.
The new septum configuration has, in the pre-15 ferred embodiment, two slits running in opposite directionsfrom near the center to the side of the septum~ nearly dividing it in half. The side of the septum is recessed in a ~oove~ portion thereof. A ring surrounding the septum ~Id carried within the recess thereof holds the 20 septum together and maintains the slit edges together in sealed relationship by applying a radial orce on the se?tum. Recesses on the top and bottom surface of the septum surrounding the needle penetration ~oints are also provided. This configuration provides improved 25 service life of the septum, especially for silicone base elastomers.
The improved needle assembly presents a right angle ~rofile which ma~es insertion of the needle pair into the device easier. Tu`bing connections to the 30 needle carrier are suDstantially parallel rather than ap~roaching from divergent directions~ thereby decreasing likelihood of patient or assistant entanglement with the tubing. Channeling within ~he carri r ~etween the needles and the tubing connectors permits closer spacing 35 of the needles than ~at of the tubing connectors. This in turn allows a smaller T-stem for the implanted blood ' f ~

access device of whicn the needle carrier cooperates.
~he needles of the assem~ly have a ~lurality of side holes on the lower ends thereof, one above anoth~r, the total cross-sectional area of which is greater than or equal to the internal diameter of the needles. The plurality of holes maintains flow rate through the needles while reducing li~elihood of paring of septum material as the needles pass through the se?tum.
The cap for the external T-stem protects the interior of the s.em from contamination an~ provides a means whereby an antiseptic may be included in the cavity betwee~ the septum and the cap to maintain the sterility of the unit between usage. Whereas ~he cap structure disclosed in the previous application required a retaining ring to securely hold the cap on the stem, the improved cap is held in place without the necessity of the retaining ring. This is accomplished by making the cap of a flexible material and by providing the interior side surface of the cap with a groove having a slightly smaller diameter than that of the flanged edge of the T-stem. A centrally located protrusion extending down-w~rd from the cap assists in maintaining alignment thereof on the T-stem. The cap may be fitted in place or removed without tools making servicing of the unit easier. Slits in the flared edge of the cap improve air circulation under the flared edge of the cap and reduce pressure against the skin if the cap edges come in contact there-with.
Another improvement in the blood access device vf application Serial Num~er 374,940 is a septum loading tool. In the device of the previous application, it was contemplated that the se~tum pressure plate and retaining ring would be inserted individually. Insertion of the retaining ring required use of a specially adapted forceps for crimping the ring as it was mserted. This piece-meal assembly procedure created problems because of t~e time required tb insert the septum assemhly and because significant patient blood loss occurred during the assembly operation. The blood loss also obstructed tlle view of the doctor or technician. The loading tool of the present invention is a simple device which holds ~11 5 three sealing elements. These elements are rapidly and simultaneously inserted in the T-stem by insertion of the b~ol into the stem and depression of a plunger by the thumb. The simplicity of the device permits factory preassembly and packaging of a disposable loaded tool 10 containing the retaining rin~, pressure plate and se~tum in sterile condition.
A second tool is a specially designed forceps for clamping on the lip of the r-Stem while inserting or removing the sealing elements therein. The clamp has 15 finger hooks on either side thereof which permits counter pressure to be ap~lied to the stem as the septum loading tool or forceps 2ush down on the device. The result is less danger of trauma to tissue surrounding the implanted blood access device and stabilization of ~le device, facilitating 20 placement or replacement of the septum assembly. When used in co~bination with the septum insertion tool of the present invention, this forceps clamp significantly increases the speed with which a septum may be replaced, thereby limiting blood loss from dialysis patients who 25 typically have low hemoglobin levels.
The back-up septum system of the -present invention may be used to temporarily seal the blood access device of application Serial Number374,940 while still allowing access to the circulatory system when ~le 30 primary system has begun to fail. Although tile septums of the present invention have especially good sealing characteristics after repeated punctures, lifetimes do vary and it is conceivable that on occasion a septum may begin to leak before it has been replaced. A further 35 improvement in the device of Serial ~umber 374,940, therefore, is a clamp which may be used witll a second or "back-up~ septum placed in the cavity between the septum retaining rinq and the top of the implanted T-stem. The clamp holds the back-up septum in place and deforms it in such a way as to assure that the se~tum seals around the interior surfaces of the T-stem ~ereby sealing the device 5 until the leaking primary septum can be replaced. The back-up septum may be provided with needle openings thexe-through s~ as to allow continued access to the blood stream~
The final device is a hemispherical cap which 10 is used to cover the T-stem cavity of the device of co-pending application Serial Number 374~940 during implanta-tion thereof. A tab defining a hole therethrough is located on the top of the cap. Suture material wound about the T and passed through the hole in the cap tab is 1~ used to pull the device stem up through an opening in the skin.

Brief Description of the_Drawings Figure 1 is an exploded pictorial view of ~
T-shaped device in accordance with the device of applica-20 tion Serial N~m~er 374,940 and including the improved septum cap member and needle carrier of the present disclosure.
Figure la is a pictorial view of an obturator for use with the septums of the present disclosure.
Figure 2 is a plan top view of the implantable T-shaped assembly with the improved septum mcluded therein~
Figure 3 is a side elevAtional view partly in section as taken alcng the lines 3-3 of Figure 2 with 30 an implant cap shown in phantom.
Figure 4 is a plan view of the top side of the septum of the present disclosure.
Figure 5 is a section view ~ong ~he lines 5-5 of Figure 4.
Figure 6 is a plan view of the bottom interior facing side of the sept~n o the present disclosure.

Figure 7, sheet 1, is a sectional view of the implantable blood access device with the improved needle assembly in operative engagement with the improved septum of the present disclosure.
Figure 8, sheet 1, is a side elevational view partly in section of the implanted blood access device and improved cap structure.
Figure 9, sheet 1, is a side elevational view partly in section of the improved needle assembly of the present disclosure.
Figure 10 is a pictorial view of the septum loading tool of the present disclosure.
Figure 11 is a sectional view of the septum loading tool taken along the line 11-11 of Figure 10.
Figures 12a, 12b, 12c and 12d, sheet 3, are sectional views of the loading tool ~aken along the lines 12a-12a~ 12b-12b, 12c-12c, and 12d-12d, respectively of Figure 11.
Figure 13 is a view of the septum loader as iA Figure 11, but with the loader inserted into the stem of the blood access device and the plunger depressed.
Figure 14 is a top plan view of the forceps clamp of the present disclosure.
Figure 15 is a sectional view of the ends of the forceps clamp with portions removed showing the clamp in engagement with the upper flange of the blood access device stem.
Figuxe 16 is a side plan view of the end of the forceps clamp.
Figure 17 is a view of the clamp taken along line 17-17 of Figure 16.
Figure 18 is a pictoxial view of the clamp as it is held in use.
Figure 19 is an exploded pictorial view of the back-up septum system of the present invention with the implantable blood access device shown in phantom.
Figure 20 is a side plan view partly in section of the back-up septum, space-- and clamp in operative engagement with a T-shaped hlood access device as disclosed in applicatio~ Serial Number 374,940.
Figure 21 is a top plan view of the spacer S member for the back-up septum sys~em.
Figure 22 is a sectional elevation view of the spacer member taken along lines 22-22 of Figure 21.
Figure 23 (sheet 2) is a pictorial view of the blood access device of application Serial Number 138,579 showing the implant cap thereon and suture winding thereabout for implantation in the body.
Figure 24 is a top plan view of the implantable T-shaped assembly as in Fig. 2, but with an alternate back-up septum held in place above the principal septum by means of a retaining ring;
Figure 25 is a side elevational view partly in section as taken along lines 25-25 of Fig. 24.

Detailed Description of the Invention Referriny to the drawings, there will be seen in Figure 1 a blood access device similar to that shown in application Serial Number 374,940 which includes a T-shaped unitary tubular body generally designated 10 having a stem portion 11 and a straight tube portion 12.
Body 10 is formed of a unitary body of a biologically compatible material such as titanium. At least the exter~al surfaces of body 10 may be coated with a con-tinuous layer of pyrolytic carbon to enhance blocompati-bility. Expanded tetrafluoroethylene tubes 14 are shown joined to the ends of tube portion 12 by slipping over these ends. The expanded tetrafluoroethylene slipped over the ends of 12 may be provided as an intermediary for joining blood vessels to the assembly 10.
As can best be seen in Figures 3 and 7, body 10 is formed with an external extension 15 which subs-tantially provides a separation of the internal chamber of T shaped member 11 from the cavity of portion 12 except for the opening 16. Member 15 provides a support surface for an improved elastomeric septum member 18 throuyh which a needle or needle pair may gain access to the bloodstream. Member 18 has a broadly elliptical configuration. As can be seen in Figure 2, stem 11 has a generally round opening. However, there are provided along the ~xis of tube 12 o?positely ~sposed protrusions lg so that the stem opening has an internal shape which conforms generally t~ the ends 20 of septum 18 for indexing purposes.
Overlying septum 18 is a pressure plate 22 of ~tanium or other substantially biologically compatible material which defines openings 23 which are spaced to confor~ in position to slits 21 in the septum ~nd opening 16 in the T-stem. Pressure plate 22 is in turn locked 10 into enga~ement with septum 18 by a spring retaining ring 24.
Other parts of the tubular blood access device are more fully described in application Serial Number 374,940.
15 Im~roved Septum _ I~ is desirable that septum 18 have a configura tion that will allow a maximum number of needle penetra-tions without leakage through the needle passage. ~hereas the septum confi5uration of application Serial N~nber 374,940 which included a precut three-directional star-shaped nee~le opening and concave septum edges, provided reasonable performance with a natural rubber septum, silicone based elastomeric septums having such a configuration typically begin leaking after 10 or less 25 penetrations~ Silicone elastomers, however, have been found tG be preferred over natural rubber for septums of the present invention because natural rubber deterio rates upon exposure to betadine (iodine polyvinylpyrolidone complex) antiseptic which is used to sterilize the cavity 30 above the septum.
The improved septum configuration of the present invention provide5 a sl~stantial improvement in septum life (as measured by average number of penetrations before leakage) e5pecially when silicone based elastomers 35 are used.
The principal problem in maintenance of septum * trade mark life is caused by loss of material through coring, tearing or abrasion on the sides of the septum opening.
~eedles with rounded ends and holes in the side ~ereof, as disclosed in co?ending application Serial Number 5 374/940~ substantially minimize coring problems.
Howe~er, there remains some possibility of paring the septum material as the needle is inserted or ~emoved along the side of the needle passage. The present design substantially lessens this problem by providing additional 10 room for material displacement when the needle is inserted through the septum. By providing room for septum material displacement, the septum does not undergo as much 03m-pression when the needle is insexted and consequently there is less tendency for septum material tD push into 15 the needle opening as the needle passes through the septum.
The preferred embodiment of the septum configura-tion is shown in ~igures 4 - 6. The precut needle openings are t~o slits 21 cut through the septum and extending from near the center of the septum out to the edge thereof.
20 For a septum oi about .44 inches between ends 19, the uncut center portion 30 is only about .04 inches wide.
The edges of the septum have a groove 32 therein encircling the entire body thereof. Groove 32 carries an ~lastomeric ring 34 which preferably has an 25 elliptical or circular cross-section. Ring 34 which has a smaller inner circumference than that of the septum serves to hold the slit septum together and maintain the slit surfaces together in sealed relationship by applying an inwardly directed radial force on the septum.
30 The el~iptical or circular shape of the ring leaves gaps in the groove into which sept~m material may move as the needle is inserted.
The septum i5 also preferably provided with an elongated bottom recess 36 and a pair of generally 35 semi-spherical top recesse5 38 aligned with holes 23 in pressure plate 22 when assen~led in the blood access device stem.

Functionally, the septum configuration shown ~n Figures 4 - 6 operates in two modes. When the needles are not inserted in~o the septum, the septum operates under a compression mode hermetically sealing the blood 5 conduit by coacting with support member 15 and pressure plate 22. Elastomeric ring 34 provides radial compression to hermetically close the septum openings creat2d by slits 21. ~hen a needle or needles are inserted throug~
the septum slits, the outwardly expanding sept~n material 10 is accommodated by the space provided in groove 32 while the downwardly expanding septum material is accommodated by recess 36. The radial force exerted by the elastomeric ring 34 seals the -needle or needles between the blood stream and the cavity of stem 11. The radial force exer 15 ted by ring 34 thus causes the se~tum to operate in a shear mode. Because the present septum operates in ~oth a compression and a shear mode, substantial increases in the working life of an elastomeric material such ~s the preferred silicone based elastomexs are achieved.
The rnaterial displacement characteristics of the new septum are illustrated in Figure 7. Comparison of this Fig~lre in which the needles have been inserted through the septum with the relaxed septum shown in Figure 3 shows that the gaps in groove 32 have been 25 substantially filled and the bottom recess partially filled by displaced septum material. It should also be noted that, as the needles are inserted, septum material parts along the slit so that, when the needles have side openings aligned with the slit as shown in Figure 7, 30 there is a reduced tendency for septum material to press inwardly on ~e needle openings and become pared thereby.
Whereas the preferred embodiment of the septum of the present invention has a pair of oppositely directed slits through the sep~um extending all the way to the 35 edges thereof, other slit configurations may be employed without departing from the essence of the invention if sueh embodiments employ a circumferential side groove carrying an elastomeric compression ring therein as dis-closed in the present application. Specifically, it is contemplated that alternative embodiments may employ oppositely directed slits which do not extend all the way 5 to the edges of the septum or a single central slit which likewise does not extend all the way to the edges of the septum.
It has also been found that, after insertion of the septum i~to the stem 11 of device 10, the slits 21 10 are initially resistant to penetration by a needle. It is therefore preferable that the initial penetration of the septum within the device be made byan obturator as shown in Figure lan The obturator has a body 130 which may be inserted into the cavity in stem 11, a pair of blank 15 needles 132 which have xounded bottoms and no holes there-through extending downwardly from body 130 and having the same spacing as that of a needle carrier structure dis-closed hereafter, and a finger hold 134 to facilitate insertion of the device into the septum or removal there-20 from. After one or two penetrations by the obturator,the septum is much less resistant to penetration by a needle and therefore needles having holes in the sides ~hereof may be inserted repeatedly with a reduced likeli-hood of paring or coring the slit surfaces.
25 Improved Ca~ Structure . .
The improved cap member 40 snaps over flanged edge 42 of the blood access device s.em. The ca~ member i5 held in sealed relationship ~erewith without the need for a retaining ring. This is accomplished by 30 making the cap from a flexible material and by providing the interior side surface of the cap with a groove 44, thP diameter of which is slightly smaller than that of the outer diameter of flanged edge 42 with which the cap surf ace engages. It is necessary that the cap be made 35 of a flexible ~,aterial so that it may be snapped over ~le slightly larger flange 42. The cap also has a downwardly , r ~

- 1~

projecting central portion 47 which fits into the cav~ty of stem 11 for alignment purposes.
The outer projecting surface 46 is flared down-wardly in a cone shaped manner, the lower flared edge 49 5 being spaced when in use slightly above the skin layer S0 of the user. Pressure ~ontact between edge 4~ and the skin is undesirable as necrosis may occur. The flared contour of cap 40 is desirable, however, because it provides a profile for the exposed external portion of 10 member 10 that is less likely to catch an object such as clothins. To reduce pressure applied by the cap if it occasionally comes in contact with the sXin, the flared exterior surface 46 of cap 40 is provided with a plurality of slits 52 which increase the flexibility of the exterior 15 surface 46. The slits 52 also provide increased air clrculation under the cap ther~by aiding in preventing infectious growth on the skin around the protruding stem of member 10.

Improved Needle Ass_mbly The improved needle assembly is illustrated in Figures 1, 7 and 9. The needle carrier 52 includes parallel right angle tubing oonnectors 54 which provide the structure with an improved profile, allowing easy insertion of the needles into the device by thumb pressure 25 and eliminating the awkwardness of tubing 55 coming in from different directions as was the case with the needle carrier structure oE application Serial Number 374,940. Maintaining the tubing pair in closely spaced parallel relationship and at right angles uo the needle 30 carrier lessens the dangers of entanglement and o~nse-qu~ntial damage to the implant or disconnection of the blood flow.
It is desirable, however, to have the needles more closely spaced to~ether than is typically possihle to space the tubing. The further the needles are spaced apart, the larger implanted member 10 must be. The ~ 13 -improved needle carrier therefore c~ntains internal channeling which allows for closer spacing of the needles than of the connected tubing.
Member 52 is most conveniently manufactured as 5 a multi-park structure. The basic element of the needle carrier is body member 58 which has lower apertures 60 into which needles 62 may be adhesively or otherwise secured. A circular flange 64 provides an attachment surrace for a clip not shown ,o fasten the needle assembly 10 to the flange 42 on stem llo Male fittings 68 extend above flange 64. Female openings o~ hollow right angle tubing c~nnectors 54 ~ngage members 68. The centers of needles 62 are spaced closer together than those of tubing connectors S4 and male ~ers 68 by providing 1~ members 68 with a tapered non-concentric bore 70 as is best shown in Figure 7. This bore channels the blood flow between the needles and the further spaced apart tubing connectors 54.
To assure proper orientation of the needles with 20 the slits in septum 18, the tubing connector body 58 may be provided with protrusions not shown which conform to the internal shape of the opening in stem 11 as shown in Figure 2.
The need~es of the improved assembly preferably 25 have ~wo or more small side holes 78, one above the other, rather than a single large hole. This structure maintains flow while minimi7ing needle hole contact with the septum slit surfaces.
Unless the needles are made of a self-lubricating 30 material, the needles ~ust be provided with a surface lubricant such as a silic:one fluid or oil to reduce abrasion as the needles pass thr~ugh the septum.

Septum Assembly Loading Tc~l The preferred form of the septum assembly 35 loading tool is shown in Figures 10 - 13. The basic elements of the tool are ~le hollow outer body member 80 ~ h~ 3 and a plunger member 81 within and extending upwardly out of body member 80. Twin pins 82 attached b3 the lower surface of plunger member 81 extend downwardly through the lower opening in body member 80. For ease 5 of manufacturi.ng, body mem~er 80 is made of two s parate portions a3 and 84. Likewise, plunger m~r~er 81 is made of two parts, lower mem~er 85 and upper member 86.
Member 84 has a stem insertion portion 87, the diameter of which, as can be best s~en in Figure 13, is 10 slightly less tha~ the blood access device stem opening above rinq retaining ridge 8~, but greater than that of the retaining ridge. Therefore, when the loading tool is inserted into the stem, the lower surface 89 of member 80 rests against ring retaining ridge 88.
At least the lower portion 90 of th~ bottom opening into body member 80 has a diameter slightly less than that of retaining ridge 88. When loaded, a crimped retaining ring 24 is held within body member 80 b~ inner opening surfaces 90. In the preferred embodiment, a 20 shoulder 91 on the inner portion of member 80, against which the outex portion of the upper side of retaining ring 24 may rest, is provided.
The cross-section of the lower surface 92 of plunger rnembe~ 81 is of sufficient width so that surface 25 92 engages at least a portion of the upper side surface of retaining ring 24 when the plunger is depressed.
This engagement is shown in Figure 13.
Pins 82 carry the pressure plate 22 and the septum 18, holding them in proper align~ent for insertion 30 As shown in Figure 13, when the plunger is depressed, ',he septum, pressure plate an~ retaining ring are pushed downward until the retaining ring snaps into the retaining ring groove 96 under ridge 8B. This requires some compression of the septum 18, as shown in Figure 13.
The plunger is held in the withdrawn position by r~ans of rod 98 which ~asses throush hole 99 in ~le plunger ab~ve the upper surface of body m~mber 80. Rod 98 engages the upper surface of body men~er 80 and serves as a stop means for the plunger. Withdrawal of rod 98 permits the plunger to be depressed.

Stem Clam~ing Forceps Figures 14 - 18 depict a stem clarnping fo~ceps 100 which is designed to be used with im?lanted blood access device 10. The body of the clamp is a standard forceps clamp having opposing arms 101 and 102. The ends of the clamp, however, are specially adapted to 10 engage upper stem flange 42 of device lQ. This is accomplished by providing the ends of arms 101 and 102 with semi-circular interior opening surfaces 103 and 104, respectively, which are sized to fit about the cuter diameter of stem 11. Central grooves 105 and 106 15 securely engage flange 42 of stem 11 as shown in Figure 15.
The ends of the clamp are also provided with oppositely disposed finger holds 108 which project upwardly and curve outwardly from the ends of the clamp.
20 As shown in Pigure 18, these ear-like finger holds are used to hold stem 11 against downward pressure which may be exerted on device 10, as for instance, when ~e thumb is used to depress ~le plunger of the septum loading tool as disclosed herein. The stem clamping forceps may 25 also be useful for holding the blood access device in place during surgical implantation thereof.
In the preferred form of ~he forceps clamp of this invention, arms 101 and 102 have a flattened S-sha~ed curve thereon as is shown in Figures 16 and 18.
30 This shape allows the clamp to be more easily manipulated since the ends of the clamp are held closely against the skin of the implant recipient.

Back-up Septum System -The back-up septum clamp is a device by which 35 a spacer member and a circular septum may be held within ~he opening in stem 11 of device 10 above the retaining ring 24 in such a manner ~at the circular septum seals against tne interior surfaces of stem 11, thereby stopping leakage of blood occurring because the principal septum has begun bO leak.
The back-up septum clamp has three pri~cipal ~rts. Semu-~ircular members 110 and 111 having interior grooves 112 and 113, respectivelyl sized to engage flange 42 of stem 11, are held together by means of screws 114.
Within the cavity of stem 11, there is placed a spacer member 138 which has an outer ring 140 and a de-pressed c~n~ral portion 142. Spacer rnember 138 defines two holes 144 through which a needle pair may pass. ~lember 15 138 sits above retaining ring 24, outer ring 140 providing an unbroken circumferential surface against which the lower edge of a back-up septum 118 may be compressed.
Generally, circular elzstomeric septum member 118 is placed within the opening in stem 11 above the 20 spacer ring 138. The septum is held in place by clamp cap member 120. Cap member 120 has a central aperture 121 and a circular downwardly projecting portion 122 which fits into ~he opening in stem 11. Cap member 120 is held in place by means of screws 123 which 25 p25S through holes 125 in the cap member and engage holes 126 and 127 in members 111 and 110, respectively. As screws 123 re tightened downward, oentral por-tion 121 pushes against septum 118 causing it to bulge outwardly. The outward bulging of septum 118 seals 30 the septum against the inner surfaces of ~le cavity in stem 11 and asainst spacer 138, effecting closure of the stem until assistance in replacing the leaking principal septum can be obtained.
If septum 118 is provided with precut holes or 35 slits aligned with slits 21 in the primary se~tu~ and holes 23 and 144 in the pressure plate 22 and spacer member 138, respectively, continued access may be provided to the circulatory system while the back-up septum i5 in place. In such case, the depressed portion 142 of spacer member 138 allows se~tum 118 to function in the form of a floating diaphragm. This permits the septum to flex 5 as the needles are inserted or re~oved, thereby facilita-ting insertion and removal of a needle or needles into ,he blood access device and reducing frictîon or abrasion of the back~up septum caused by passage of the needle there through. The configuration of spacer member 138, including 10 a central portion 142, is preferred over a si~ple ring having the configuration of outer ring 140 because central portion 142, while providing some space for septum 118 to flex downwardly, substantially fills the dead space between pressure plate 22 and back-up septum 118, thereby 15 reducins the volume in which blood leaking through t~e principal septum 18 may collect.

Implant Cap Implantation of the blood access device o~ co-pending application Serial ~umDer 374,940 is preferably 20 accomplished by cutting a first opening through the skin into the body, connecting the device to the circulatory system, tunneling under the skin to a second openi~g through the skin and pulling the device througl the tunnel by means o~ suture material wound about the Dody of ~ e device so 25 that stem 11 is pulled up through the second skin opening.
To accomplish this without filling the cavity in stem 11 with tissue or blood, device 13 is preferably ~rovided with a hemispherical cap 150 shown in Figure 23 and in phantom in Figure 3 which is used to cover stem 11 during i~planta-30 tion.
Cap 150 is a generally hemispherical mem~erhaving a lower protrusion 152 which fits into the cavity of ste~ umber 150 also has a tab 154 on the top thereof defining an opening 156 through which suture material 158 35 wrapped a~out device 10 may be passed. The winding of the suture material as shown in Figure 23 permits a surgeon to pull the device 10 into place in the second skin opening as described in the pre~ious p~ra~raph Alternate Back-up Septum System Fig~re 24 is a top plan view of the implantable T-shaped assembly as in Pigure 2, but with the back-up sept~ held in place above the principal septum by means of a retaining ring as disclosed hereinafter.
Figure 25 is a side elevational view partly in section as taken along lines 25-25 of Figure 24.
As an alternate to the back-up septum clamp as descri~ed hereinbefore, a back-up septum 160 may be held within the stem cavity of device 10 by means of a com-pression ring 162 and a retaining ring 166. To do so, the upper portion of the cavity in stem 11 is provided 15 with a groove 169 in which a retaining ring similar to but sliqhtly larger than ring 24 may be held. The back-up septum system of this alternative embodiment a~so employs the spacer 138 which is shown in Figures 21 and 22.
The compr~ssion ring 162 conforms generally to the shape of the T-stem cavity and has a thickness such that, when retaining ring 166 is in place, the compression ring exerts su:Eficient pressure on septum 160 to cause the septum to seal the cavity opening.
By providing septum 160 with openings there-through such as slits 170, continued access to the circu-latory system can be achieved.
Septum 160 may, but need not, have a side grooye carrying an elastomeric ring similar to the con-30 struction of improved septum 18.

Claims (15)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A needle assembly for a septum closed blood access device, the assembly comprising a body member having a pair of substantially parallel hollow needles extending downwardly from said body member and a pair of substantially parallel tubing connector members extending outwardly from said body member, said body member further having a pair of channels therethrough, each said channel extending between one of said needles and one of said tubing connectors and providing fluid communication therebetween, said channels diverging outwardly between said needles and said tubing connectors such that the needle centers are closer together than the tubing connector centers.

2. A needle assembly as in claim 1, wherein said tubing connectors extend from said body member at substantially right angles from said needles.

3. A needle assembly as in claim 1, wherein said channels diverge outwardly by means of a nonconcentric tapered bore.

4. A needle assembly as in claim 1, wherein said needles are provided with a surface lubricant.

5. A needle assembly as in claim 1, wherein the needles each have a rounded sealed lower end and plurality holes through the lower sides thereof, one above the other, and wherein the needles are aligned within said assembly such that said holes enter said septum along the axis of precut slits in the septum.

6. A needle assembly as in claim 5, wherein said tubing connectors extend from said body member at substantially right angles from said needles, said needles are provided with a surface lubricant and said body member channels diverge outwardly by means of a nonconcentric tapered bore.

7. In combination, a needle assembly as in claim 1 and an implantable access device for providing access to the circulatory system, the access device comprising a body of biologically compatible material, said body having a generally T-shaped tubular configuration with the stem of the T joined to and in fluid communication with the arms of the T, a support member depending from and projecting inwardly into the cavity of said stem adjacent the inner tube surfaces of the arms, an elastomeric septum member having first and second sides, said support member in supporting engagement with a first side of said elastomeric septum member when it is positioned within the cavity of said stem, a pressure plate defining at least one opening therethrough on the opposite side of said septum member and in contacting relationship therewith, and removable retaining ring means for locking said plate in contact with said septum.

8. A needle assembly and implantable blood access device as claimed in claim 7, further comprising an improved cap for use with the blood access device having a flanged upper stem surface extending above the skin surface, the cap comprising a unitary body of flexible material, the body comprising:
a flat cap surface;
an interior side projection extending downwardly from the edge of said cap surface and encircling said stem member, said interior side projection having a groove on the inner surface thereof for engaging said stem flange in sealed relationship therewith, said groove having a slightly smaller diameter than that of said flange; and a flared exterior side projection extending a distance conically downwardly and outwardly from said cap surface edge so as to be adjacent but not in contact with the skin when said cap is mounted on said stem, said exterior side projection having a plurality of slits therethrough extending from the outer end thereof toward said cap surface edge.

9. The article of claim 8, wherein said cap has a central projection extending downwardly within said interior side projection, said central projection having a diameter less than that of a cavity within said device upper stem, whereby the cap may be aligned on said device stem.

10. A needle assembly as claimed in claim 1, further comprising a back-up septum clamp for the blood access device having a flanged stem extending above the skin surface and defining an opening into said device, the septum clamp comprising a pair of opposing flange clamp members, members each having a concave interior face, said interior faces in combination conforming substantially to the outer circumference of said device stem, each said flange clamp member also having a central groove in the interior face thereof, the radius and width of which are substantially equal to that of said stem flange, means for securing said flange clamp members together around and in engagement with said flange, a cap member having a generally circular projection extending down-wardly from the lower surface thereof, said projection having a diameter less than that of the interior opening into said stem, and means for securing said cap member to said flange clamp members when said flange clamp members are secured to said stem, said cap member projection extending downwardly into said stem opening when said cap is secured to said flange clamp members a sufficient distance to engage and compress a septum member held in said flanged stem and thereby to effect closure of said stem.

11. A clamp as in claim 10, wherein said cap member projection defines a central opening through said cap member.

12. A clamp as in claim 11 in combination with a septum member having at least one opening therethrough and conforming generally to the shape of said stem opening, and a generally circular spacer member for placement within said stem opening below said septum, said spacer member comprising an outer circumferential ring and a depressed central portion, said central portion defining at least one hole through said spacer member.

13. The article of claim 12 in further combination with said implantable device, said implantable device comprising a body of biologically compatible material, said body having a generally T-shaped tubular configuration with the stem of the T joined to and in fluid communication with the arms of the T, a support member depending from and projecting inwardly into the cavity of said stem adjacent the inner tube surfaces of the arms, a second elastomeric septum member having first and second sides, said support member in supporting engage-ment with a first side of said second elastomeric septum member when it is positioned within the cavity of said stem, a pressure plate defining at least one opening therethrough on the opposite side of said second septum in contacting relationship therewith, removable retaining ring means for locking said plate in contact with said second septum, said first septum conforming generally to the shape of the stem cavity above said retaining ring means.

14. A needle assembly as claimed in claim 1, wherein the blood access device comprises a body of biologically compat-ible material, said body having a generally T-shaped tubular configuration with the stem of the T joined to and in fluid communication with the arms of the T, a support member depending from and projecting inwardly into the cavity of said stem adjacent the inner tube surfaces of the arms, an elastomeric septum member having first and second sides, said support member in supporting engagement with a first side of said elastomeric septum member when it is positioned within the cavity of the stem, a pressure plate defining at least one opening therethrough on the opposite side of said septum in contacting relationship therewith, removable retaining ring means for locking said plate in contact with said septum and means for securing a second septum within the cavity of the stem above the first said septum in sealed relationship with the inner surfaces of said stem cavity.

15. A device as in claim 14, wherein said means for securing said second septum comprises a generally circular spacer member for placement within said stem below said second septum, said spacer member comprising an outer circumferential ring and a depressed central portion, said central portion defining at least one hole therethrough, a pressure ring, the outer diameter of which conforms generally to the interior shape of said stem cavity above said second septum, and removable retaining ring means for locking said compression ring in contact with said second septum.