Snap-lock fitting catheter for an implantable device

0001This invention relates to an implantable device and, in particular, to a vascular access device that is implanted subcutaneously. Within the prior art, a variety of implantable access devices are known and have been brought to the point of commercial acceptance. Typical of the commercially available devices is the INFUSAID Infus-a-Port™. This device comprises, in its most basic form, an implantable port having access via a septum at a perpendicular angle to the skin via a needle. It has coupled to it a percutaneous catheter extending generally at a right angle to the direction of needle access to the port's inlet. These implantable devices use a variety of materials, typically plastic such as PVC, Teflon, polyethylene, polypropylene, polyurethane, polycarbonate, polythermalsulfane, polysulphone, polyolefin, nylon and the like. Additionally silicon and rubber may be employed, while special components can be made of stainless steel or titanium.

0002An example of a self-sealing implantable body utilizing an integral housing is described in U.S. Patent 4,543,088. As illustrated therein, fluid communication between the internal reservoir and catheter (not shown) is via a passageway. While the catheter is not illustrated, the '088 patent mentions the use of rigid connectors which can be incorporated in the fluid passageway to provide attachment of catheters and tubing to the implanted port.

0003An example of such rigid connection is found in U.S. patent 4,673,394. As illustrated and described in that patent, an implantable drug dispensing reservoir employs a twist-lock catheter coupled to a bayonet type connection. That is, the implantable port has a T-slot into which a metallic flanged fitting is fitted and rotated into a locking arrangement. The '394 patent also employs a tab which is sutured into place against the base plate of the port to prevent detachment of the twist-lock connector from the port body.

0004Examples of press couplings of catheters into implantable ports are illustrated in and described in U.S. Patents 4,645,495, 4,692,146, 4,710,167, and 4,710,174. In each, press fitting by frictional contact is used to hold the catheter in place with the port body. In the '146 patent, a metal nipple or tube may be used to prevent inadvertent puncture of the catheter itself. U.S. Patent 4,464,178 is also directed to an implantable port having an outlet catheter and employs a retainer having a pair of ears which engage matching voids in the reservoir. Such a retainer provides a positive locking and prevents the catheter from disengaging. However, problems in manufacture and replacement of the catheter are inherent in such a scheme. Another alternative of frictional yet detachable mounting of a catheter to an implantable device is found in U.S. Patent 4,581,020, which employs a tapered fluid connector which frictionally fits into an inlet to allow the catheter assembly to be detached.

0005U.S. Patent 4,704,103 employs a catheter coupling using a coaxial elastomer clamping member that is deformed as a pressure sleeve is screwed into the port. To prevent the clamping member from crushing the catheter, a rigid hollow support projects from the outlet bore and the catheter slides over it. Thus fluid communication is maintained as the catheter is clamped into position. Such a system is difficult to assemble <u style="single">in situ</u> and contains a large number of components requiring surgeon time and precision.

0006French patent application FR-A-2 586 569 discloses an implantable device in which the catheter is secured to a connection nozzle by means of a U-shaped clip which is fitted outside the port housing.

0007In U.S. patent 4,632,435 a tubing connector system is described which requires the use of a connector assembly tool to couple the ends of each tube by compressing together a connector body and each clamping ring.

0008One of the difficulties with these various prior art techniques is that the catheter is difficult to engage to the implanted port during an implantation procedure. The implantation of such a drug delivery device should be as simple as possible to minimize patient trauma and the degree of skill required by the surgeon. In general, the reservoir is implanted subcutaneously at a location in the body cavity of the patient to provide needle access for infusion of medication. The catheter is then placed having one end at the drug delivery site and having the other end attached to the port. Given limited space, devices which require twist lock fittings and the like are difficult to connect <u style="single">in vivo</u> and difficult to utilize in practice.

0009Moreover, in many of the devices which simply fit by means of pressure fitting, friction or the like, there is no indication that a complete and positive connection has been made. That is, no audible or tactile reference occurs indicating that an acceptable connection between the catheter and the port has been achieved. During the implantation procedure the surgeon must visually check or pull to determine whether the components have been coupled. Finally, devices which utilize machined parts and the like are more expensive to manufacture, have problems of material incompatibility, and present, to varying degrees, the problems of patient discomfort.

0010An overriding consideration is that the connection, in addition to providing the above requirements, establishes a fluid-tight coupling between the catheter and the implantable reservoir.

0011Given the deficiencies of the prior-art, it is an object of this invention to provide an improved catheter to implantable port coupling which provides an indication of a complete and operative connection between elements.

0012Yet another object of this invention is to provide an improved coupling between the catheter and an implantable port which is leak-tight and may be connected in a quick, simple manner.

0013These and other objects are accomplished by the present invention. According to the present invention, there is provided an access device for implantation comprising a housing with a reservoir therein, a self-sealing septum to provide subcutaneous access to said reservoir, an outlet in fluid communication with said reservoir and having a nipple section therein, and a catheter having one end slidably mounted over said nipple section, characterised in that there is provided a locking sleeve having a through-hole for slidably mounting onto said catheter, said locking sleeve having a series of radially expansible fingers which slide over said nipple section and engage said housing in an outlet cavity while compressing said catheter thereby locking said catheter and said sleeve to said housing and provide, upon engagement, an audible or tactile indication that locking has been achieved. This connection technique may be used for both single and double lumen catheters.

0014Preferably the said outlet cavity comprises an opening of first cross-sectional area for receiving a first section of said outlet and an opening of second cross-sectional area greater than said first cross-sectional area for receiving a second (nipple) section of said outlet, said second cross-sectional area positioned inward from exit of said outlet cavity into said housing. The first section of said outlet may comprise an anchoring portion to adhere said outlet to said housing, said nipple section having a flange abutting said housing at the opening of said second area to prevent further insertion of said outlet into said housing.

0015In another aspect of the invention, the said housing further preferably comprises a shoulder section of reduced area to engage outer portions of said fingers when said locking sleeve slides over said nipple section. The said outer portions of said fingers may comprise a first inner section engaging an inner portion of said housing shoulder section and an adjacent second outer section of reduced area engaging an outer portion of said shoulder section, whereby said fingers are compressed inward by said second outer portion of said shoulder section when said locking sleeve slides over said nipple section and then expand radially outward to engage said inner portion. The said expansible fingers are preferably disposed circumferentially around said locking sleeve.

0016The locking sleeve may comprise a generally cylindrical outer section, a generally tapered conical outer section, or a saddle shaped outer section having an annular recess to permit gripping.

0017In an alternative embodiment, the catheter comprises a pair or lumens separated by an internal wall, the housing comprises first and second reservoirs, first and second self-sealing septums and fluid communication means coupling a respective lumen to a respective reservoir. The nipple section may comprise an elongated barbed member having conduits coupling respective lumens to said fluid communication means and an elongation slot engaging said internal wall of said catheter.

0018In a further aspect of the present invention, the outlet comprises a conical wall section, said radially expansible fingers being compressed as said locking sleeve slides over said nipple. The said conical wall section may have a circumferential groove, and the locking sleeve an annular shoulder engaging said groove to lock said sleeve to said housing and provide an audible or tactile indication that locking has occurred.

0019This invention will be described in greater detail by referring to the attached drawings and a description of the preferred embodiments that follow. <ul id="ul0001" list-style="none"><li>Fig. 1 is a schematic perspective view illustrating the basic components of a first embodiment of this invention prior to attachment;</li><li>Fig. 2 is a schematic perspective view of the components of a first embodiment of this invention during an intermediate stage of attachment;</li><li>Fig. 3 is a schematic elevation view illustrating the components of a first embodiment of this invention in an engagement or locked position; and</li><li>Figs. 4A, 4B, 4C illustrate in a schematic view, three configurations of the snap-lock fitting in accordance with this invention;</li><li>Fig. 5 illustrates a second embodiment of this invention for use with a double lumen catheter; and</li><li>Fig. 6 is a schematic view of the details of the engagement structure of the second embodiment of this invention.</li></ul>

0020Referring now to Figs. 1-3, the construction and assembly of this invention pursuant to a first embodiment of the invention is depicted. The implantable device may be similar to a commercial Infus-a-Port™ comprising a generally round shaped housing (10) having a recess forming a reservoir (12) for retaining medication. A septum (14) is formed utilizing a self-sealing polymer such as silicon rubber or latex and is adapted to permit access utilizing a hypodermic needle to the reservoir (12). The housing (10) may also be formed of a compatible polymeric material. As illustrated in Figs. 1 and 3, the septum (14) is press fitted into the housing (10), the housing having a generally rounded shoulder portion (16) to provide a tactile reference for locating the septum (14). That is, during charging of the reservoir (12), the technician physically locates the housing (10) by tactilely sensing the location of the septum (14) as a function of determining the position of the annular shoulder portion (16).

0021Fig. 1 illustrates an attachment hole (18) which is used to suture the housing (10) into position within a body cavity. While one such suture hole (18) is illustrated, it will be understood that a plurality of such holes may be used to adequately anchor the device (10) in place.

0022An outlet (20) from the reservoir (12) is formed by placing a barbed fitting or nipple component in the outlet cavity (22) of the housing (10). As illustrated in Fig. 3, the outlet (20) may typically have a self-tapping threaded first section (24), or another such technique, for anchoring a distal end of the fitting in fluid contact with the reservoir (12). The outlet cavity (22) is shaped to have a generally cylindrical section (26) with an inside diameter slightly larger than that of the anchoring portion of (24). A gradually tapered section (28) is used to receive the fingers, to be described herein, forming a portion of the snap-lock fitting. A wall (30) defines a positive stop by which a shoulder portion or flange (32) of the barbed fitting seats to prevent impingement into the reservoir.

0023The second section (34) of the outlet (20) has a nipple which, as illustrated in Fig. 3, protrudes slightly beyond the outer wall of the housing (10). Further, as illustrated in Fig. 3, the housing (10) has a generally annular shoulder section (36) against which the fitting mounted on the catheter seats. It can be appreciated that the housing (10) having the various cavities can be formed by molding plastic with the septum (14) inserted during manufacture.

0024Referring again to Fig. 1, the catheter and the snap-lock fitting are illustrated. The catheter (40) is made from an insert material such as a silicone and is initially supplied in a suitable length so that one end, not illustrated, can be located at the drug delivery site. A snap-lock fitting or locking sleeve (42) comprises a barrel section and an integral series of circumferentially disposed, radially expansible locking fingers (44). Each of the locking fingers (44) has an outwardly extending circumferential thickened portion and an inwardly positioned recessed portion. While the docking sleeve (42) is illustrated in Figs. 1-3 as generally cylindrical, other configurations may be used.

0025Referring to Figs. 4A, 4B and 4C, three alternatives are illustrated. Fig. 4A illustrates the generally cylindrical or barrel shaped locking sleeve while Fig. 4B illustrates a tapered locking sleeve. Those devices are used in a situation where the snap-lock connector will not be removed once it is coupled to the port housing (10). If removal or replacement is perceived, the fitting of Fig. 4C may be employed. As illustrated in that figure, the fitting has a generally extending circumferential recess or saddle shaped outer section (43) to allow finger grip on the locking sleeve (42). That is, the surgeon may physically grip in the region (43) and have a positive holding zone defined by the rearwardly extending shoulder portion (46). With one hand on the locking sleeve (42) and a second hand on the housing (10), the locking sleeve may be physically separated from the housing.

0026For installation of this device, the housing (10) is first implanted into the body cavity at a convenient site to allow for access via a hypodermic needle. The distal end of the catheter (40) is positioned at the infusion site and the catheter is trimmed to its desired length at the proximal end (50). The locking sleeve (42) is then slid onto the proximal end (50) of the catheter (40) so that the proximal end of the catheter extends about 1.3-2.5 cm (0.5-1.0 inches) beyond the fitting. The catheter (40) is then urged over the nipple tip of (34) of the outlet (20). The catheter then, as illustrated in Fig. 2, is pushed on the fitting (whereby its outside wall deforms) and abuts against the flange (32). Thus, fluid communication is established from the reservoir (12) through the outlet (20) and into the catheter (40). Next, the locking sleeve (42) is slid up to the port body and snaps into the outlet cavity (22) of the port housing. As the fitting slides over the nipple, the fingers (44) spread and then snap into locking engagement on the rear shoulder of the nipple portion of the fitting. The audible and tactile action of the spring fingers assures a good contact and at the same time provides an indication that an affirmative connection has been made. This placement of the locking sleeve also provides for stress relief of the catheter in case of bending on the nipple section. The action of sliding the locking sleeve over the nipple causes local compression and elongation of the catheter material. This material bunches up between the flange (32) and the fingers (44) providing a degree of reserve in case the catheter is accidentally pulled.

0027Referring now to Figs. 5 and 6, a second embodiment of this invention is depicted. In Fig. 5 dual reservoir port housing (100) comprises an implantable port having a pair of self-sealing septums (102) and (104). As in the case of the embodiment of Fig. 1, each of the septums (102) and (104) is a self-sealing polymer such as silicon rubber or latex and adapted to permit access utilizing a hypodermic needle to the reservoirs, not illustrated. Housing (100) may also be formed of a compatible polymeric material. The septums are press-fitted into the housing with the housing having a pair of rounded shoulder portions (106) and (108). The shoulder portions are used to provide a tactile reference for locating the respective septum. While illustrated in Fig. 5 as having a generally similar shape, the shoulder portions (106) and (108) may have different contours such as radius or squared-off or a point to provide the surgeon with a point of reference for determining which septum is being accessed.

0028A series of suture holes (110) is provided on the periphery of the body for affixing the implantable device within a body cavity.

0029The embodiment of Fig. 5 therefore utilizes two distinct reservoirs which are coupled to discrete infusion sites by means of a double lumen catheter (116). This double lumen catheter has two parallel lumens, (118) and (120), separated by means of a divider or internal wall (122).

0030To accommodate the double lumen catheter (116), the nipple section of Fig. 1 must provide parallel flow channels. As illustrated in Fig. 5, this nipple section (124) has a barbed member and a pair of conduits (126) and (128) to provide fluid communication with the lumens (118) and (120) of the catheter (116). Additionally, a centrally disposed recess or elongation slot (130) is provided so that the internal wall (122) will engage the nipple section (124) so that alignment is established between the conduits (126) and (128) and the lumens (118) and (120) of the catheter.

0031The nipple section (124) is anchored into the housing (100) so that fluid communication is maintained between conduits (132) and (134) which provide separate flow paths between each lumen of the catheter through (124) into a respective reservoir in the implantable device. The nipple is secured within the housing, and the pair of O-rings (136) and (138) are provided to isolate the flow path (126) to conduit (132) and the flow path (128) to conduit (134). As in the case of the first embodiment, the nipple section is anchored by means of a shoulder or flange (140) which rests against an internal wall of the housing (100).

0032The snap-lock fitting (142) is different from that of the locking sleeve illustrated in the first embodiment. While it is an elongated cylindrical member which slides over the catheter (116), the fingers (144) are forced to move inward toward the catheter around the fitting, gripping to provide a leak-tight connection. To achieve this inward movement, the internal wall (148) is radiused inward so that its circumference progressively decreases. The sleeve or snap-lock fitting (142) has an inside diameter groove (152) which allows the fingers (144) to flex inward. At its outer periphery, as illustrated in Fig. 6, a small annular locking tooth (154) is provided to engage the annular detent or notch (150). The tooth (154) is physically compressed by plastic deformation to snap into the annular groove (150).

0033In operation, the assembly is provided in a manner generally similar to that of the first embodiment. A double lumen catheter is slid into engagement with the barbed member of the nipple section (124) with the internal wall (122) engaging the elongation slot (130) for purposes of alignment. The proximal end of the catheter (116) abuts against the shoulder (140). Thus fluid communication from both lumens of the catheter is initially established through the nipple section and conduits (132) and (134) into each reservoir of the implantable device (100).

0034The snap-lock fitting (142) is then slid over the catheter (116). The fingers are urged inward by the wall (148) as the snap-lock fitting is inserted into the opening in the housing. Inward flexing of the fingers will close the groove (152). As the fingers (144) deform inwardly, they tend to compress the outer circumferential wall of the catheter against the barbs.

0035When the locking tooth (154) engages the notch (150), the audible and tactile clicking effect occurs locking the fitting (142) in place. Thus, snap-locking occurs. It is apparent that this snap-lock fitting opening arrangement used in Fig. 5 may also be employed relative to the single lumen catheter of Fig. 1.

0036While this invention has been described relative to preferred embodiments and modifications of the snap-lock fitting, it is apparent that modifications of this invention may be practiced without departing from the essential scope thereof.