Abstract:
Methods and devices are disclosed for the in-vivo creation and maintenance of contiguous fluid passages in tissue through the use of tissue buttressing portions with interrupted perimeter walls. These portions can be formed from hollow fiber or extruded components. One end of the tissue-buttressing portion is connected to a hollow tube, which may be connected to a fluid source. The other end of the buttressing portion may be attached to a needle or other device suitable for the penetration of tissue and the formation of passageways in tissue. When the device is installed in tissue, the hollow tube portion of the device is passed part way through the surface of the patient and serves as the conduit for the transfer of fluid to the implanted tissue-buttressing portion of the device. The presence of the buttressing portion within the tissue causes a bridging of the local tissue thereby forming an infusion passage between the external surface of the buttressing portion and the abutting tissue. Therapeutic fluids may be passed from the hollow fiber conduit of the device and though the infusion passage created by the buttressing portion of the device and the surrounding tissue.

Description:
RELATED PATENT APPLICATIONS 
     This application is a continuation-in-part application of Ser. No. 11/142,589 filed on Jun. 1, 2005, now abandoned, which is a continuation-in-part of application Ser. No. 10/909,717, filed on Aug. 2 2004, now U.S. Pat. No. 7,875,055, which is a continuation of application Ser. No 10/727,367, filed on Dec. 4, 2003, the contents of which are incorporated herein in their entirety. 
    
    
     FIELD OF INVENTION 
     The present invention generally relates to surgical devices for the infusion of therapeutic fluids into tissue and methods of implantation for said surgical devices. 
     BACKGROUND OF INVENTION 
     Patients may benefit from the infusion of therapeutic fluids into tissues surrounding a wound in a variety of ways. Local anesthetics may be infused directly to the wound site to help manage pain post-operatively. Antibiotics may be infused to a wound site to eliminate infections. Growth factors or oxygen rich fluids may be infused to facilitate wound healing and recovery. A variety of other active agents including but not limited to chemotherapeutics, stems cells, hemostatic agents, angiogenic, and anti-angiogenic agents may also provide patient benefit when delivered locally to tissues via infusion. 
     Traditional infusion devices are fabricated with a contiguous lumen that generally extends from the fluid source and along the entire length of the device to the tissues intended to receive the fluid. The lumen is typically formed as a continuous hollow element through extrusion or other processes, and ordinarily has a solid wall that contains exits or ports for fluid egress. If the device is intended to deliver a fluid over an extended distance within tissue, multiple ports or exits are formed along the axis of the device in an attempt to distribute the fluid from the lumen along the implanted length of the device. 
     For example, U.S. Pat. No. 3,821,956 to Gordhamer discloses a device for the dilation and treatment of a bovine teat. The device is hollow and has a spiral groove on the external surface of the device. There are exit ports that extend from the inner lumen of the device to the external groove. This device appears to be relatively inflexible. 
     In U.S. Pat. No. 4,159,720, a method of treating tissue with a device comprised of a wicking material that may be implanted in a wound is disclosed. This reference describes that the wicking material may be a hollow monofilament provided with lateral perforations through which the fluid will pass into the tissue. Alternatively, the wicking material is described as being a solid filament having spiral or longitudinal grooves in its external surface. This patent further describes the concept of attaching a suture needle directly to the wicking material to facilitate implantation of the device in tissue. For example, this reference discloses that the wick may be installed into position as if it were a suture, and in one embodiment, the wick may serve as a suture for holding the severed flesh together as well as a carrier or conduit for delivering fluid to the affected area. 
     U.S. Pat. No. 5,458,582 to Nakao describes an anesthesia delivery device comprising an elongate flexible tubular member in the form of a hollow tube made of bioabsorbable material, the tubular member having a proximal end portion with a continuous cylindrical side wall and a distal end portion provided with a plurality of apertures spaced longitudinally along the distal end portion. 
     Similarly, U.S. Pat. No. 6,626,885 describes an infusion catheter exhibiting a plurality of apertures located along the implantable segment, and a method of implantation with an auxiliary tissue-penetrating device, whereby the infusion catheter is introduced via the auxiliary tissue-penetrating device through skin adjacent to an incision site. It is generally accepted by the medical community that using a catheter entry site remote from the incision site reduces the risk of infection associated with the use of a catheter that is left in place over a period of time. 
     However, there are several problems associated with the approaches described in the prior art for the delivery of fluids transcutaneously. The first problem is associated with the formation of exit ports from the device. The creation of the ports requires the machining of the tube through processes such as drilling, punching, laser cutting or other suitable methods. Many of these processes are intrinsically difficult and costly, Additionally, these processes typically become more difficult and costly to implement as the diameter of the catheter decreases, with most traditional infusion catheters exhibiting large diameters in excess of 0.020″. 
     An additional problem of these tubular devices is that they are ordinarily smooth along the external surface. The smooth surface abuts the surrounding tissues and forms a lightly sealed surface surrounding the exit ports. This effect can result in an increase in the pressure differential from within the tube to overcome this sealing effect to enable fluid egress from the device. 
     In view of the drawbacks associated with the infusion devices described above, it is desirable to have an infusion device where the infusion passage is maintained in a continuous fashion from the point of fluid egress to the terminus of the device in the tissue, thereby enabling the egress of fluid from the device into the surrounding tissue along the full length of the implanted device. 
     SUMMARY OF INVENTION 
     The invention enables the transcutaneous delivery of fluids to a patient through a device comprised of a first length of hollow tube and a tissue-buttressing portion with discontinuous circumferential surfaces. Implantation of said device in tissue can be facilitated through use of a leading needle. Once positioned, the device can be anchored through the use of knots. The present invention overcomes the difficulties described above in that the tissue-buttressing portion of the device maintains an infusion passage and enables the egress of fluid from the device and into the surrounding tissue along its entire length. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment of the device in accordance with the present invention; 
         FIG. 2   a - 2   d  depict a method of manufacturing the channel in the tissue-buttressing portion of the device; 
         FIG. 3   a - 3   b  is representative of attachment means of the tissue buttressing portion and proximal portion of the present invention; 
         FIG. 4   a - 5   c  show cross-sections of the tissue-buttressing portion; and 
         FIGS. 6   a - 7   c  depict implantation techniques using the described device. 
     
    
    
     DETAILED DESCRIPTION OF INVENTION 
     For the majority of applications under consideration, the tissue will surround and make intimate contact with the infusing segment of the device. As used herein, the term “tissue-buttressing” means the act of maintaining a space within the tissue surrounding the infusion device in such a manner as to enable fluid to be transported and emitted along that segment of the device designated as the “tissue-buttressing” portion. 
     Referring to  FIG. 1 , the device  5  comprises an elongate flexible tubular member with a proximal end portion  15 , a tissue-buttressing portion  25  and an optional distal end portion  35 . The proximal end portion  15  has a continuous cylindrical sidewall  10  and the distal end portion  35  has a cylindrical sidewall  60 . The tissue-buttressing portion  25  has a channel  20 , which interrupts its sidewall. The tissue-buttressing portion may be comprised of hollow tubes with interrupted sidewalls. Alternatively, the tissue-buttressing portion  25  may be comprised of a plurality of tissue-buttressing tubes each having a channel  20  that interrupts its sidewalls, where the plurality of tubes is joined at one end to the proximal end portion  15 , and the optional distal end portion  35  or a suture needle  50  on the other end. 
     This tissue-buttressing portion  25  acts to maintain a passage in tissue, thereby enabling the transport of fluids along its length within tissue. It can be a variety of lengths to accommodate a wide range of sites to be treated depending on the surgical procedure, and can vary from 3 cm to 35 cm. The tissue-buttressing portion may optionally transition back to a distal end portion  35 , which comprises a continuous cylindrical sidewall portion  60  distal to the channel  20 . A suture needle  50  is attached to the distal end portion  35 , which facilitates the creation of infusion passages and/or provides a means of implantation in surgical incisions. Alternatively, the suture needle may be attached to the distal end of the tissue-buttressing portion  25 . 
     The suture needle may be either straight or curved, depending on the particular procedure to be performed. Curved needles offer the surgeon the ability to easily and accurately weave the device through various tissue planes. Additionally, a curved needle facilitates the formation of a knot at the distal end of the cylindrical side wall  60  or the distal end of the tissue-buttressing portion  25 . Said knot may be used to prevent the accidental dislodgment of the infusion device from a wound or implantation site. Straight needles may be used when it is desirable to form a tunnel or tissue passage over a long distance beneath the skin or other tissue plane, such as between subcutaneous tissue and fascia, or between fascia and peritoneum. When it is desirable to penetrate the skin at a substantial distance from the wound site before drawing the device into the wound, a straight needle would be advantageous. Also, when it is desirable to implant the device along a tissue plane for an extended distance without implanting any portion of said device in an incision, a straight needle may be used. As such, a straight needle may also be preferred in certain laparoscopic procedures. Additionally, a variety of needle point designs may be used to optimize surgeon control and/or minimize the size of the hole produced in the various tissues. Needle point designs may include, but are not limited to: cutting edge, taper point, taper cut, and blunt point and may be selected according to the operative procedure and technique to be practiced. 
     One or more elongate flexible tubular member may be connected to the suture needle by techniques well known in the art of needle and suture making, including, but not limited to mechanical swaging and adhesive attachment. 
     The proximal end portion of the one or more elongate flexible tubular members may be directly connected to a fluid source (not shown), or alternately may be attached to an adapter  40  that enables connection to a fluid source, as shown in  FIG. 1 . This adapter  40  may be of any standard or non-standard design commonly used in the field of medicine including, but not limited to, male or female luer lock fittings, twist-lock connectors, or press-fit connectors. The proximal end portion  15 , the distal end portion  35 , and the tissue-buttressing portion  25  can all have a diameter equal to that of a suture thread, although smaller or larger diameters may also be used. This can practically range from about 0.005″ to about 0.030″. 
     The proximal end portion, distal end portion, and tissue-buttressing portion of the device may be produced from a variety of polymer systems, including but not limited to polyglycolic acid (PGA), polylactic acid (PLA), PGA/PLA copolymers, polycaprolactone (PCL), PCL/PGA copolymers, polydioxanone, trimethylcarbonate (TMC), polyproylene, polyamide, polytetraflouroethylene (PTFE), and polyethylene. 
     The tissue-buttressing portion  25  shown in  FIG. 1  may be fabricated in a number of ways. In one embodiment, a hollow tube is extruded using standard extrusion and optional drawing techniques known to those skilled in the art. The channel  20  is fabricated by removing a portion of the hollow tube to produce a single continuous channel  20  along a specified length of the distal end. Sharp cutting instruments such as razor blades, knives, or various shearing instruments may be used to section and remove a portion of the hollow extrusion. Alternatively laser light may be used to produce a channel or slit along a specified length of the tube. To facilitate removal of a portion of the hollow extrusion, fixtures that compress a portion of the hollow extrusion may be used as shown in  FIGS. 2   a  through  2   d . Referring now to  FIG. 2   a , mating die components  21  and  22 , with one or more of the dies exhibiting a recess or ledge  23 , may be used to compress the hollow tube  5 . A portion of the hollow tube is then forced above the top plane formed by the mating dies in a predominantly flattened form  26 , as shown in  FIG. 2   b . The portion of the tube extending above the top plane of the dies  26  may then be cut away from the tube by sliding a sharp cutting instrument along the top surfaces of the mating dies. Cutting instruments may include but are not limited to knives, razor blades, die punches. In this way the cutting action removes tube material to a depth equal to or greater than the lumen wall thickness. At this step the tube will appear as represented in  FIG. 2   c  with a continuous slit  27  spanning the full length of the constrained portion of the tube. The components of the die are opened to release the tube, as shown in  FIG. 2   d , and the tubing material recovers elastically to a cylindrical shape with a channel  20 . 
       FIGS. 3   a  and  3   b  show alternate embodiments of fabricating the tissue-buttressing portion  25 . This tissue-buttressing portion  25  may be formed as a separate part utilizing the techniques described above, then joined together to the continuous cylindrical sidewall portions  10  and/or  60  of proximal portion  15  and/or distal end portion  35 . Referring to  FIG. 3   a , the outer diameter of the proximal end portion  15  is smaller in diameter than the inside diameter of the tissue-buttressing portion  25  and therefore is positioned at least partially into the inner diameter of proximal end portion  15 . Referring now to  FIG. 3   b , the outer diameter of the tissue-buttressing portion  25  is smaller in diameter than the inside diameter of the proximal end portion  15  and therefore the tissue-buttressing portion  25  is positioned at least partially into the inner diameter of the proximal end portion  15 . In either embodiment, fluid flows through the continuous cylindrical sidewall portion  10  of proximal end portion  15  and into the channel  20  of tissue-buttressing portion  25 . Insertion of the proximal end portion  15  into the tissue-buttressing portion  25 , as shown in  FIG. 3   a , or vice versa, as shown in  FIG. 3   b , followed by application of thermal energy at the site where the two portions overlap will yield a functional device. Sources of thermal energy that may be employed may include, but are not limited to: heated dies, ultrasonic welding horns, friction welding equipment, and radio frequency sources. Alternatively, adhesives may be used to join the tissue-buttressing portion and the proximal and/or distal end portions  15  and  35 . In any case, the adhesive must be biocompatible and in some cases preferably bioabsorbable. 
     A schematic representation of the cross-section of the proximal end portion  15  shown in  FIG. 1  along A-A in its simplest form is shown in  FIG. 4   a . The cylindrical sidewall  10  and lumen  65  of the extrusion are both continuous. A schematic representation of one embodiment of the cross-section of the tissue-buttressing portion  25  and channel  20  shown in  FIG. 1  along slice B-B is shown in  FIG. 4   b . The wall of the extrusion  70  is interrupted by a channel  20  that is in fluid communication with the lumen  90  of the tissue-buttressing portion  25 . The width of the channel may vary from a fine slit  100  with a width that is microscopic in dimension, as depicted in  FIG. 4   c , to a half-circle or c-shape as schematically depicted in  FIG. 4   d.    
     The manner in which these various tissue-buttressing elements may function in tissue is schematically depicted in  FIGS. 5   a ,  5   b  and  5   c . A cross-sectional schematic representation of a tissue-buttressing element  70  comprised of a hollow extrusion with a continuous channel through the wall of the extrusion is shown in  FIG. 5   a . The surrounding tissue  95  is prevented from collapsing and closing the passage by this rigid form. Moreover, the lumen of the hollow extrusion and the channel through the wall of the hollow extrusion combine to provide a passage for the transport of fluid along the entire length of the tissue buttressing segment  70 . 
     A cross-sectional schematic representation of a tissue-buttressing element comprised of a plurality of solid fibers is shown in  FIG. 5   b . As the surrounding tissue closes around the plurality of filaments, said filaments contact one another, leaving open space or interstice between the contact points of the individual filaments. Fluids may pass through these interstices and contact the surrounding tissue at the periphery of the fiber bundle along the entire length of said fiber bundle. 
     A cross-sectional schematic representation of a tissue-buttressing element comprised of a cross-shaped buttress is shown in  FIG. 5   c . As tissue closes around this buttress it is prevented from conforming to the interior surfaces of the buttress by the exterior portions of the buttress. The interior regions consequently remain open and act as a passage for the transport of fluid. 
     The device may be implanted in a number of ways, including but not limited to, within a surgical site along an incision plane, into tissue adjacent to the surgical incision, or through exterior tissues and into a body cavity. A method for the implantation of the device in a surgical incision is depicted in  FIGS. 6   a, b , and  c.  After an incision has been made and a surgical procedure has been performed, but before subcutaneous and dermal closure, the skin of a patient and subcutaneous tissue adjacent to the proximal end of the incision is penetrated with the suture needle that is attached to the distal end of the infusion device. The needle and distal portion of the device is then driven through the tissue and into the surgical incision until the tissue-buttressing portion  25  containing channel  20  is positioned entirely within the incision and is visible to the surgeon; and leaving at least a section of the proximal end portion  15  external to the entry point in the skin. The device may be secured in the wound by tying at least one knot  140  in the fluid-buttressing portion  25  or the optional distal end potion  35 . Any excess of the tissue-buttressing portion  25  and optional distal end portion  35 , including the suture needle, is then removed from the patient by cutting it away with scissors or other appropriate surgical instrument. The wound is then closed using any of the various devices and techniques used in the practice of medicine for wound closure. A therapeutic fluid may then be delivered from an external source such as an infusion pump or syringe through the optional adapter  40 , through the proximal end portion  15  containing the continuous cylindrical sidewall  10 , into the tissue-buttressing portion  20  and into the wound site. It is important to note that with this method, the infusion device does not enter the wound through the incision in the skin, but rather enters through by first passing through the skin and subcutaneous tissue away from the incision. With this approach, the risk of infection due to transport of bacteria along the periphery of the catheter is considered by the medical community to be less severe. Fixation of the device in the wound may be facilitated at two locations. A series of knots may be tied in the in the fluid-buttressing portion  25  or the optional distal end potion  35  of the implanted device. An additional degree of fixation occurs in the tissue between the entry point of the device at the skin surface and the subcutaneous tissue leading up to the incision. If the device is subject to an accidental tugging force as may occur if the patient snags the proximal end portion  15  of the infusion device on any number of objects, the device will be pulled out through the entry site resulting in limited trauma to the tissue surrounding the incision. 
     Referring now to  FIGS. 7   a - 7   c , the device may be implanted into the tissue adjacent to a wound, but not actually within the surgical incision  120 . After an incision has been made and a surgical procedure has been performed, the skin of a patient and subcutaneous tissue adjacent to the proximal end of the incision is penetrated with the suture needle attached to the distal end of the device. The needle is then driven through the skin and into the tissue where the device is to be implanted  150 . The needle is then threaded out through the tissue and skin at a position other than the entry point, but preferably adjacent to the distal end of the surgical incision. This pulls the proximal end of the tissue-buttressing portion  25  of the device into the tissue and slightly past the location within the tissue where infusion of the therapeutic fluid is desired. Once positioned, the portion of the distal end of the device that extends outside the body of the patient is then trimmed so that it is flush with the skin surface. Optionally, the proximal end of the device may then be pulled to cause the distal end of the device to go beneath the surface of the skin and position the tissue buttressing portion at its intended location. This same method may be applied in tissue that is not adjacent to a wound. The needle may be used to guide the device through and between the various tissue layers including, peritoneum-fascial planes, fascia-subcutaneous tissues, or subcutaneous-skin tissue. 
     Alternatively, the device may have perforations in portion  25 , and/or may be utilized to drain bodily fluids from a wound or tissue site after the device has been installed with some or all of portion  25  located at a wound or tissue site, via the proximal end portion  15  that is external to the skin and connected directly or indirectly to a suction device.