BIORETENTIVE FILTERED INFUSION CATHETER

Abstract: A bioretentive filtered infusion catheter comprises a cylindrically shaped bioretentive filter inserted into a catheter lumen to prevent passage of microbial agents during a drug infusion process. Filter material placed within the catheter fluid flow path captures fluid contaminants. Alternatively, the filter material is disposed within a filtering assembly comprising a fluid conduit adapted for use with a previously implanted infusion catheter or an infusion pump.

Description: BIQRETKNΠVK FΠ/ΓERED ΓNFIJSION CATH TRP BACKGROUND OF THE INVENTION The present invention relates generally to methods and apparatus for preventing microbial contamination of drug infusion sites; and more particularly relates to such methods and apparatus implementing the use of an implanted bioretentive filter placed within a catheter infusion path. Implantable, continuous fusion has been shown to be an effective medication delivery method because it maintains continuous therapeutic drug delivery, improves patient quality of life, reduces rates of infection, and is more cost effective than traditional methods. However, the chronic infusion of drugs through permanently implanted catheters connected to either catheter access ports or implanted infusion pumps equipped with catheter access ports still creates significant risk to the patient from microbial infections. Conventional methods and apparatus directed to minimizing microbial infection focus on external bioretentive filters placed within the hypodermic needle used to deliver the drug. Such conventional methods are deficient, however, in that there is still a substantial risk of infection from the introduction of the hypodermic needle through the patient's skin to access the catheter access port, as each access through the skin provides an opportunity for bacterial infection. Typically, the risk results in microbial infection at a rate of 5-15 % . However, the probability of infection increases with the number of accesses into the catheter to administer the infusion therapy, and further escalates where preservative-free drugs or drugs which inherently support microbial growth are used. Such drugs may include peptides, polypeptides, proteins, glycoproteins, lipoproteins, oligonucleotides, oligonucleosides, hormonal agents, and/or other biologically derived trophic agents. Further, a particularly significant application of the invention is the treatment of neurological patients involving a penetration of the blood/brain area. Such procedures usually are accompanied by an even greater rate of infection. SUMMARY OF THE INVENTION As explained in more detail below, the present invention overcomes the above- noted and other shortcomings of prior apparatus and methods for preventing microbial infection of drug infusion sites. Generally, the invention is directed to incorporating within a catheter infusion path a fluid conduit with an implanted bioretentive filter which prevents the microbial contamination of the target site to receive the infused drug. A first embodiment is configured so that a cylindrically-shaped bioretentive filter inserted into the catheter's lumen prevents passage of microbial agents during the infusion process. In a particularly preferred embodiment, the filter is fabricated in a cylindrical shape having sufficient surface area for filtration to occur without adverse interruption of flow. As an example of physical size, the outside diameter of the filter assembly would probably be on the order of 0.5 to 1.0 mm, and 2 to 5 cm in length. The filter may be fabricated from one or several filter mediums having known compatibility with the drugs prescribed for infusion delivery. One example of such a filter would be one made of polyvinylidiene fluoride and polysulfones having pore sizes in the range from about 0.10 to about 0.22 micrometers. Such a suitable material is available from Amicon and is marketed under the name microporous hollow fiber. A second embodiment of the present invention comprises the in-line insertion of a filtered fluid conduit with previously implanted infusion catheters to produce a bioretentive barrier between the point of infusion access and the target infusion site. Such a device would typically include a connector suitable for mating with either a permanently implanted catheter access port or an infusion pump at a first location, and a connector adapted for joining to an existing implanted infusion catheter at a second location downstream of the filter member. Again, the bioretentive filter is preferably cylindrical in shape, and is inserted into the lumen of the filtering device so as to create a bioretentive barrier for microbial agents. Filtering devices suitable for permanent implantation comprise known biocompatible and biostable materials, such as silicone elastomer, fluoroelastomer, fluoropolymer, titanium, and titanium alloys. The two embodiments of the present invention broadly outlined above are shown in Figs. 1-6. As is evident from the drawings, and as is more fully described below, both embodiments generally are described as having a fluid flow within a fluid conduit from one point to another along a path from the interior of a cylindrical filter toward the exterior through the filter medium. One of ordinary skill in the art with the benefit of this disclosure will undoubtedly appreciate and understand that other filtering devices are possible which have an inverted fluid flow path as compared to the one described herein. All that is necessary to do that is to reverse the orientation of the entire assembly relative to the fluid flow path. Such an embodiment may require, for example, additional structural spacers to be inserted within the filter to maintain its central passageway. The depicted embodiment is far preferable in that respect. However, under certain circumstances, it may be desirable to reverse the relative positions of the filters and seals in such a manner to allow filtered drug to flow from the lumen of the filter to allow outside catheter diameter reduction to access small target sites (such as spinal intrathecal space, intracerebroventricular access, specific brain nuclei, etc.). Thus, it should be understood that for convenience and brevity only the preferred embodiment of the present invention is described herein, and that the description of the invention provided is not intended to be limiting on the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of an exemplary bioretentive filtered infusion catheter in accordance with the present invention, depicted in a three-dimensional view. FIG. 2 is an illustration of the bioretentive filtered infusion catheter shown in FIG. 1, depicted in a cross-sectional view. FIG. 3 is an illustration of the bioretentive filtered infusion catheter shown in FIG. 1, depicted in a cross-sectional view taken along the line 3-3 shown in FIG. 2. FIG. 4 is an illustration of the bioretentive filtered infusion catheter shown in FIG. 1, depicted in a cross-sectional view taken along the line 4-4 shown in FIG. 2. FIG. 5 is an illustration of a bioretentive filtered fluid conduit in accordance with the present invention, depicted in a cross-sectional view. FIG. 6 is an illustration of the bioretentive filtered fluid conduit shown in FIG. 5, depicted in a cross-sectional view. DETAILED DESCRIPTION OF THE INVENTION FIGS. 1-4 show a bioretentive filter 10 incorporated into the body of a catheter or fluid conduit 12. Filter 10 is placed near a first catheter or fluid conduit end 14 adapted and configured to connect to either an access port (such as the Model 8501 Catheter Access Port manufactured by Medtronic, Inc., of Minneapolis, Minnesota) or an implanted infusion pump (such as the one used in the SynchroMed™ Infusion System developed and marketed by Medtronic, Inc.). Catheter 12 will be forward of a conventional biocompatible material as known to the art which is suitable for implantation with the body. In the depicted exemplary preferred embodiment, cylindrical seal ring 16 seals the annular space between an inside catheter surface 18 and the filter 10 to direct flow into the filter's central core 20 and outward through the cylindrical wall of the filter 10. The solid retention block or seal ring 16 may not be required if the filter 10 is attached completely about the inner wall 18 of the catheter. Preferably, an annular seal 22 distal to the first catheter connection end 14 is perforated to allow flow of the filtered drug through die remainder of conduit 12 to the target site. However, the perforated retention block or seal 22 may not be necessary, in which case the filter assembly would essentially represent merely a bag. The core 20 of the cylindrical filter 10 at the filter end 24 opposite the catheter connection end 14 may comprise either a solid plug 26, or additional filter material. A second embodiment of the present invention is shown in FIGS. 5-6. The assembly comprises a fluid conduit 42 generally cylindrical in shape, having on one end 14 a molded connector 15 for mating with an access port or infusion pump, and on the other end 40 a fluted male connector 45 fabricated from a rigid material (i.e., for example, titanium, titanium alloys, or fluoropolymer) for mating with the implanted catheter to be retrofitted. Other configurations of mating connectors may be incorporated for facilitating coupling to selected devices. The mating of the male connector 45 to the rest of the assembly preferably is accomplished as shown with a metal compression ring 38. Of course other suitable means for attaching the male connector 45, such as polysiloxane adhesive or overmolding processes, may be used. Although the preferred embodiment of this invention has been described hereinabove in some detail, it should be appreciated that a variety of embodiments will be readily available to persons utilizing the invention for a specific end use. Again, the description of the apparatus and method of this invention is not intended to be limiting on this invention, but is merely illustrative of the preferred embodiment of this invention. Other apparatus and methods which incorporate modifications or changes to that which has been described herein are equally included within this application. Additional objects, features and advantages of the present invention will become apparent by referring to the above description of the invention in connection with the accompanying drawings.

Claims: WHAT IS CLAIMED IS: 1. An implantable bioretentive filter assembly to filter fluid passing from an implanted fluid source to a delivery location in a patient's body, comprising: a fluid conduit having a first end configured to be placed in fluid 5 communication with said implanted fluid source and a second end configured to be placed in fluid communication with said delivery location within said patient's body, said fluid conduit formed of a material implantable within the patient's body; and a filter retained within said fluid conduit to filter all fluid passing between said 10 first end and said second end. 2. A fluid delivery system for delivering fluid from a fluid source implanted in a patient's body at a first location to a delivery point at a second location in said patient's body comprising: a fluid source; !5 a fluid conduit having a first end in fluid communication with said fluid source and a second end in fluid communication with said delivery location; a filter retained within said fluid conduit and arranged to filter all fluid passing between said first end and said second end. 3. The fluid delivery system of claim 2, wherein said fluid conduit comprises a 0 portion of a catheter, said catheter extending to said delivery location. 4. The fluid delivery system of claim 2, wherein said fluid source comprises an implanted access port. 5. The fluid delivery system of claim 2, wherein said fluid source comprises an infusion pump. 5 6. The fluid delivery system of claim 2, wherein said filter comprises a generally elongated and generally tubular filter element having an exterior surface sealingly coupled to said conduit at a first end and having an interior surface closed to fluid flow proximate a second end. 7. The fluid delivery system of claim 2, wherein said filter comprises a generally 0 tubular elongated filter element having a relatively exterior portion sealingly coupled to said conduit. 8. The implantable bioretentive filter assembly of claim 1 , wherein said filter comprises a tubular filter element. 9. The implantable bioretentive filter assembly of claim 1 , wherein said filter comprises a bag-like filter element coupled to said conduit.

Inventors: ELSBERRY DENNIS D, ELSBERRY, DENNIS, D.
Applicants: MEDTRONIC INC, MEDTRONIC, INC.
Application year: 1996
Main classification: A61M5
IPC codes: A61M5, A61M25, A61M39