Patent Publication Number: US-2020297307-A1

Title: Catheter with Seal Layer

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to medical devices used in conjunction with ultrasound imaging systems, and more particularly to devices used in medical procedures such as nerve blocks, biopsies, or any other procedure where access is provided via a catheter. 
     BACKGROUND OF THE INVENTION 
     Detection of anatomical objects using medical imaging is an essential step for many medical procedures, such as regional anesthesia nerve blocks, and is becoming the standard in clinical practice to support diagnosis, patient stratification, therapy planning, intervention, and/or follow-up. Various systems based on traditional approaches exist for anatomical detection and tracking during medical procedures, such as computed tomography (CT), magnetic resonance (MR), ultrasound, and fluoroscopic imaging systems. 
     For example, ultrasound imaging systems utilize sound waves with frequencies higher than the upper audible limit of human hearing. Further, ultrasound imaging systems are widely used in medicine to perform both diagnosis and therapeutic procedures. In such procedures, sonographers perform scans of a patient using a hand-held probe or transducer that is placed directly on and moved over the patient. 
     One problem during procedures that utilize ultrasound imaging, such as regional anesthesia nerve block procedures or biopsy procedures, is the accurate placement of a needle in order to deliver the nerve block (e.g., via the delivery of an anesthetic through the needle, via the insertion of a catheter to deliver the nerve block via RF energy, or via the combination of the delivery of an anesthetic and RF energy) to the desired nerve bundle or to biopsy the correct tissue sample. Thus, the placement of an ultrasonic transducer at the tip of the needle can be used in conjunction with an ultrasound imaging system to visualize the location of the tip of the needle to assist a medical professional in accurately positioning the tip of the needle. 
     However, often, a catheter-based infusion system is utilized to block the nerve bundles at the incision after surgery to provide a continuous, low flow rate of the anesthetic over a period of time (e.g., 2-5 days following surgery) for post-operative pain management. Often, it is desirable to use a catheter-based system that has a rounded or blunt distal end or tip instead of a needle or other introducer that has a pointed distal tip, as such a configuration may allow the catheter assembly to be placed in, or remain at, a target area while causing less damage to nerves or tissues than a sharp or pointed introducer, tunneler, or needle based infusion system. Therefore, as the needle, when used, is generally removed after placement of the catheter, it can be difficult for medical professionals to easily place, or confirm the continued placement of the catheter after removal of the needle containing the transducer. 
     Further, the ultrasonic transducer is typically connected to an external power supply via a large coaxial cable in order to minimize the signal noise associated with the electrical connection between the ultrasonic transducer and the external power supply. While minimizing the signal noise is important, the size of the typical coaxial cable required to sufficiently minimize the signal noise can be problematic when it is desired to advance the transducer assembly to a nerve bundle or tissue or to remain connected to a patient for a period of time. For instance, the increased diameter of the transducer assembly due to the presence of a large coaxial cable can make it difficult for the transducer assembly to reach a target nerve bundle or tissue located beneath several layers of skin, muscle, etc, and also becomes problematic as the large size may increase the likelihood of contact or pulling by the patient, increasing the changes of movement from the target. 
     As such, a need exists for a catheter assembly that includes an ultrasonic transducer to enable periodic monitoring of the placement of the catheter assembly. Additionally, a need exists for a means of electrically connecting an ultrasonic transducer to an external power supply where the connection has a reduced size while still effectively minimizing the signal noise through the wire. 
     SUMMARY 
     Objects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. The invention will be described in greater detail below by reference to embodiments thereof illustrated in the figures. 
     According to one embodiment of the present invention, a catheter assembly is provided. The catheter assembly includes a catheter having a catheter body defining a proximal end and a distal end, and a tip located at the distal end of the catheter, the tip being capable of being inserted into a body of a mammal; a transducer located at the distal end of the catheter proximal to the tip; one or more transducer wires extending from a proximal end of the transducer towards the proximal end of the catheter; and a length of tubing surrounding the catheter, the transducer, and the one or more transducer wires, wherein the length of tubing has a proximal portion and a distal portion, wherein the proximal portion surrounds the one or more transducer wires and the distal portion surrounds the transducer. 
     In one particular embodiment, the transducer can be disposed on an outer surface of the catheter. Further, the length of tubing can hold the transducer in place against the outer surface of the catheter. 
     In another embodiment, the length of tubing can include polytetrafluoroethylene, polyethylene, polyurethane, silicone, or a combination thereof. 
     In still another embodiment, the length of tubing can be shrinkable. For instance, the length of tubing can be heat shrinkable. 
     In another embodiment, the proximal portion of the tubing can include a conductive filler. 
     In one more embodiment, the conductive filler can include a metal, a conductive polymer, carbon, or a combination thereof. For example, in some embodiments, the conductive filler can include nickel, copper, silver, gold, platinum, or a combination thereof. In other embodiments, the conductive filler can include polypyrrole, poly(3,4-ethylenedioxythiophene), polythiophene, polyaniline, poly-p-phenylene-sulphide, polyacetylene, polyisoprene, polybutadiene, or a combination thereof. 
     In one particular embodiment, the conductive filler can be present in the proximal portion of the length of tubing in an amount ranging from about 0.05 wt. % to about 10 wt. % based on the total weight of the proximal portion of the length of tubing. 
     In one embodiment, a human tissue impedance matching material can be disposed between the transducer and the distal portion of the tubing. 
     In still another embodiment, the one or more transducer wires can have a diameter ranging from about 15 micrometers to about 300 micrometers. 
     In one more embodiment, the catheter assembly includes a human tissue impedance matching material disposed between the transducer and the distal portion of the tubing. 
     In one particular embodiment, the distal end of the catheter includes at least one aperture. 
     In still another embodiment, the transducer can be electrically connected to an external power supply via the one or more transducer wires. 
     In yet another embodiment, the transducer can transmit and receive signals for detection by an ultrasound imaging system, wherein the transducer enhances the visibility of the distal end of the catheter on an ultrasound image. 
     In a further embodiment, the catheter assembly may include an article configured to be received in the lumen of the catheter, which, in one embodiment, the article may be a needle, stylet, probe, or guidewire. 
     Additionally or alternatively, the catheter assembly is configured to be received in the lumen of an article, and, in one embodiment, the catheter is disposed within the lumen of an article. In a further embodiment, the article within which the catheter assembly is disposed is a needle, stylet, probe, or guidewire. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention to one skilled in the art, including the best mode thereof, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which: 
         FIG. 1  is a perspective view of one embodiment of the catheter assembly of the present invention when used in conjunction with an ultrasound imaging system; 
         FIG. 2  illustrates a block diagram one of embodiment of a controller of an ultrasound imaging system with which the catheter assembly of the present invention is used; 
         FIG. 3  illustrates one embodiment of the catheter assembly of the present invention; 
         FIG. 4  is illustrates a side view of a portion of the catheter assembly of  FIG. 3  including the catheter, transducer, one or more transducer wires, and a length of tubing which shields the one or more transducer wires connecting the transducer to a power supply from signal noise; 
         FIG. 5  illustrates one embodiment of the catheter assembly of the present invention; 
         FIG. 6  illustrates a side view of a portion of the catheter assembly of  FIG. 5  including the catheter, transducer, one or more transducer wires, and a length of tubing which shields the one or more transducer wires connecting the transducer to a power supply from signal noise; 
         FIG. 7  illustrates a schematic diagram of one embodiment of a catheter assembly according to the present disclosure; 
         FIG. 8  illustrates a cross-sectional view of one embodiment of a needle of the catheter assembly of  FIG. 7 ; 
         FIG. 9  illustrates a cross-sectional view of one embodiment of a catheter of the catheter assembly according to the present disclosure; and 
         FIG. 10  illustrates a cross-sectional view of another embodiment of a catheter assembly according to the present disclosure; 
     
    
    
     Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the figures. Each embodiment is provided by way of explanation of the invention and is not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that the present invention include these and other modifications and variations coming within the scope and spirit of the invention. 
     Generally speaking, the present invention is directed to a catheter assembly for locating an object of interest (e.g., an anatomical region such as a muscle, nerve bundle, etc.) or maintaining and/or confirming that the catheter assembly remains at an object of interest for a period of time. For instance, the catheter assembly may generally include a transducer. Thus, the catheter assembly may be initially located at an object of interest, and may also be capable of having the location confirmed, or relocated, after a period of time. The catheter assembly includes a catheter having a catheter body defining a proximal end and a distal end, where the distal end is adjacent to a tip, where the tip may be formed by a distal end of the catheter, or another article, such as a needle, stylet, probe, or guidewire, for example. Regardless of the article that forms the tip, the tip may be shaped and sized so as to be inserted into a body of a mammal. Additionally, the catheter assembly includes a transducer located at the distal end of the catheter and one or more transducer wires extending from a proximal end of the catheter towards the proximal end of the catheter, and a length of tubing surrounding the catheter, the transducer, and one or more transducer wires. The length of tubing has a proximal portion and a distal portion, where the proximal portion surrounds the one or more transducer wires and the distal portion surrounds the transducer, wherein the proximal portion includes a conductive filler. 
     Referring now to the drawings,  FIGS. 1 and 2  illustrate a medical imaging system  300  (e.g., an ultrasound imaging system) for use in conjunction with the catheter assembly  100  of the present invention for scanning, identifying, and navigating toward anatomical objects  152  of a patient  310  (e.g., a mammal). As used herein, the anatomical object  152  and surrounding tissue described herein may include any anatomical structure(s) and/or surrounding tissue(s) of a patient  310 . For example, in one embodiment, the anatomical object(s)  152  may be a nerve bundle, a muscle, or any other anatomical object that can be visualized in a medical procedure (e.g., nerve block, biopsy, medicament delivery, etc.) performed by a medical professional  312 . More specifically, as shown, the medical imaging system  300  may correspond to an ultrasound imaging system or any other suitable imaging system that can benefit from the present technology. Thus, the medical imaging system  300  may generally include a controller  316  having one or more processor(s)  318  and associated memory device(s)  320  configured to perform a variety of computer-implemented functions (e.g., performing the methods and the like and storing relevant data as disclosed herein), as well as a user display  306  configured to display an image  314  of an anatomical object  152  to an operator or medical professional  312 . In addition, the medical imaging system  300  may include a user interface  304 , such as a computer and/or keyboard, configured to assist the medical professional  312  in generating and/or manipulating the user display  306 . 
     Additionally, as shown in  FIG. 2 , the controller  316  may also include a communications module  322  to facilitate communications between the processor(s)  318  and the various components of the medical imaging system  300  (e.g., any of the components of  FIG. 1 ). Further, the communications module  322  may include a sensor interface  324  (e.g., one or more analog-to-digital converters) to permit signals transmitted from one or more probes (e.g., the ultrasound imaging probe  302 , the catheter assembly  100 , or both) to be converted into signals that can be understood and processed by the processor(s)  318 . It should be appreciated that the ultrasound imaging probe  302 , the catheter assembly  100 , or both may be communicatively coupled to the communications module  322  using any suitable means. For example, as shown in  FIG. 2 , the ultrasound imaging probe  302  may be coupled to the sensor interface  324  via a wired connection  308 . However, in other embodiments, the ultrasound imaging probe  302  and/or the catheter assembly  100  may be coupled to the sensor interface  324  via a wireless connection, such as by using any suitable wireless communications protocol known in the art. For example, as shown in  FIG. 2 , the catheter assembly  100  may be coupled to the sensor interface  324  wirelessly. As such, the processor(s)  318  may be configured to receive one or more signals from ultrasound imaging probe  302  and/or the catheter assembly  100 . 
     As used herein, the term “processor” refers not only to integrated circuits referred to in the art as being included in a computer, but also refers to a controller, a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, a field-programmable gate array (FPGA), and other programmable circuits. The processor(s)  318  is also configured to compute advanced control algorithms and communicate to a variety of Ethernet or serial-based protocols (Modbus, OPC, CAN, etc.). Furthermore, in certain embodiments, the processor(s)  318  may communicate with a server through the Internet for cloud computing in order to reduce the computation time and burden on the local device. Additionally, the memory device(s)  320  may generally comprise memory element(s) including, but not limited to, computer readable medium (e.g., random access memory (RAM)), computer readable non-volatile medium (e.g., a flash memory), a floppy disk, a compact disc-read only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disc (DVD) and/or other suitable memory elements. Such memory device(s)  320  may generally be configured to store suitable computer-readable instructions that, when implemented by the processor(s)  318 , configure the processor(s)  318  to perform the various functions as described herein. 
     Referring now to  FIGS. 1 and 3-6 , various embodiments of a catheter assembly  100  that may be visualized via the medical imaging system  300  are illustrated. More specifically, as shown, the catheter assembly  100  can include a catheter  118  having a body  128  having an outer diameter  124  ranging from about 1 millimeters to about 12 millimeters, such as from about 2 millimeters to about 11 millimeters, such as from about 3 millimeters to about 10 millimeters, such as from about 5 millimeters to about 9 millimeters, or any range therebetween, and defined by a distal end  120  and a proximal end  122 . A transducer  102  (e.g., an ultrasound transducer) can be disposed on an outer surface  146  of the catheter  118 . 
     Further, the distal end  120  of the catheter  118  can, in one embodiment, have a tip  126  that can be used for the delivery of energy or treatments suitable for creating a nerve block, such as for the treatment of pain, or may instead utilize openings  144  in the distal end  120  for the delivery of energy or treatments. For instance, the tip  126  and/or distal end  120  can include an opening  144  or openings  144  for delivery of a fluid and/or medicament, such as for delivery of an anesthetic nerve block, or can include a cutting tool (not shown) for taking a biopsy a tissue sample. For instance, in the embodiment shown in  FIG. 3 , the distal end may include one or more apertures  144  in the distal end  120 , for the delivery of fluid and/or medicament. Whereas, in a further embodiment, such as shown in  FIG. 4 , the aperture  144  or apertures  144  may be located in the tip  126  of the catheter  118  and/or article. While there may be more or less apertures, the catheter body may generally contain at least 1 aperture, such as at least about 2, such as at least about 3, such as at least about 4, such as at least about 5, such as at least about 7 such as at least about 10 apertures. The catheter body may also comprise less than about 20, such as less than about 18, such as less than about 15, such as less than about 13 apertures. 
     The apertures may be spaced apart radially, grouped in a similar radial plane, axially spaced apart, or both radially and axially spaced apart along the catheter body. In one embodiment, the apertures may be generally located adjacent to the distal end, such as within about 50 millimeters (mm) from the distal end, such as within about 45 mm, such as within about 40 mm, such as within about 35 mm, such as within about 30 mm, such as within about 25 mm, such as within about 20 mm, such as within about 15 mm, such as within about 10 mm of the distal end. In another embodiment, the apertures may be evenly or randomly spaced radially, axially, or a combination of radially and axially along the entirety of the length of the catheter body 
     The apertures may have a diameter such as about 1 millimeter or less, such as about 900 micrometers or less, such as about 800 micrometers or less, such as about 700 micrometers or less, such as about 600 micrometers or less, such as about 500 micrometers or less, such as about 400 micrometers or less, such as about 300 micrometers or less, such as about 100 micrometers or greater, such as about 200 micrometers or greater, such as about 300 micrometers or greater, such as about 400 micrometers or greater, such as about 500 micrometers or greater, such as about 600 micrometers or greater in diameter. In a further embodiment, some of the apertures may have a fairly large diameter and some of the apertures may have a fairly small diameter. In an embodiment with apertures that have a mixture of diameters, the ratio of the diameter types may be fairly even, or in an alternate embodiment there may be more large diameter apertures, such as twice as many large, such as three times as many large, such as five times as many large diameter apertures. Alternatively, there may be more small diameter apertures such as twice as many small, such as three times as many small, such as five times as many small diameter apertures. 
     The arrangement of the apertures, number of apertures, and diameter of the apertures may be selected based upon the target area, the type of drug or anesthesia to be delivered, or the desired rate of delivery, to name a few considerations. For example, a larger number of apertures or apertures with a larger diameter, or both, may be selected when a greater rate of delivery is desired. Alternatively, arrangements of apertures may be selected based upon the location and orientation of the target area. For example, if a small target area is desired, all of the apertures may be located fairly close together either radially or axially. In an additional embodiment for example, if a target area may only be located on one side of a catheter, then the apertures may mainly be located on a single side of the catheter body such that the apertures are all located on generally the same side, area, or radius. Alternatively, if a more central location is chosen for the catheter, the apertures may extend radially around the catheter body such that an aperture is located on several different radii around the catheter body. 
     In one embodiment, the rate of delivery of a drug or anesthetic using a catheter assembly according to the present disclosure may be at least about 0.01 mL/hr, such as about 0.05 milliliters(mL)/hr or greater, such as about 0.1 mL/hr or greater, such as about 0.5 mL/hr or greater, such as about 1 mL/hr or greater, such as about 3 mL/hr or greater, such as about 5 mL/hr or greater, such as about 7.5 mL/hr or greater, such as about 10 mL/hr or greater, such as about 12.5 mL/hr or greater, such as about 15 mL/hr or greater, such as about 17.5 mL/hr or greater, such as about 20 mL/hr or greater, such as about 22.5 mL/hr or greater, such as about 25 mL/hr or greater, such as about 27.5 mL/hr or greater, such as about 30 mL/hr or greater, such as about 35 mL/hr or greater, such as about 40 mL/hr or less, such as about 37.5 mL/hr or less, such as about 35 mL/hr or less, such as about 32.5 mL/hr or less, such as about 30 mL/hr or less, such as about 27.5 mL/hr or less, such as about 25 mL/hr or less, such as about 22.5 mL/hr or less, such as about 20 mL/hr or less, such as about 17.5 mL/hr or less, such as about 15 mL/hr or less, such as about 12.5 mL/hr or less, such as a rate of delivery of about 10 mL/hr or less. 
     Further, a handle  130  can be coupled to the proximal end  122  of the catheter  118  to assist the medical professional  212  in accurately positioning the catheter  118  within the patient  210 . As shown in  FIGS. 1 and 3 , the handle  130  can be connected via an electrical connection  132  to a power supply  134 . The power supply  134  can provide energy to the transducer  102  on the catheter  118 . Further, the transducer  102  can enhance the visualization of the catheter assembly  100  (e.g., the distal end  120  of the catheter  118  or the tip  126  of the catheter  118  or article) when used in conjunction with the medical imaging system  200 . The transducer  102  can be any piezoelectric element that can transmit ultrasound signals as known in the art. In one particular embodiment, the transducer can be a ceramic piezoelectric transducer. In another embodiment, the transducer can be a capacitive micromachined ultrasonic transducer. It is also to be understood that in addition to transmitting ultrasound signals, the transducer  102  can also receive ultrasound signals, such as from the medical imaging system  300 . As shown, the transducer  102  can have a distal end  138  and a proximal end  140 , where one or more transducer wires  104 , which can connect the transducer  102  to a power supply and which can be used for transmitting and receiving signals, extends from the proximal end  140  of the transducer  102  towards the proximal end  122  of the catheter  118  in order to connect the transducer  102  to the power supply  134 . The one or more transducer wires  104 , which can extend along the outer surface  146  of the catheter  118 , can be formed from any conductive material such as nickel, copper, silver, gold, platinum, or a combination thereof. Further, the one or more transducer wires  104  of the present invention can be non-coaxial in order to decrease the size of the catheter assembly  100 , which enables the use of the catheter assembly  100  of the present invention in medical procedures requiring the catheter assembly  100  to have a reduced footprint or diameter. For instance, the one or more transducer wires  104  can have a diameter  148  ranging from about 15 micrometers to about 300 micrometers, such as from about 20 micrometers to about 275 micrometers, such as from about 25 micrometers to about 250 micrometers. The ability of the catheter assembly  100  of the present invention to use one or more transducer wires  104  having such a reduced diameter compared to conventional transducer wires where a larger, more cumbersome coaxial cable is required to shield the one or more transducer wires from electrical signal noise is facilitated by the use of a length of tubing  106  surrounding the catheter  118  and the transducer  102 , as discussed in more detail below. 
     Referring particularly to  FIGS. 3-4 , the catheter assembly  100  including the catheter  118 , the transducer  102 , and the one or more transducer wires  104  can also include a length of tubing  106  that surrounds the catheter  118 , the transducer  102 , and the one or more transducer wires  104 , which can be non-coaxial as discussed above. Specifically, the length of tubing  106  can include a distal portion  110  and a proximal portion  112 . The distal portion  110  can extend along the body  128  towards the tip  126  of the catheter  118  such that the tip  126  or some or all of the distal portion  110  of the catheter  118  is exposed and free of the length of tubing  106 . 
     As shown, the length of tubing  106  can hold the transducer  102  and one or more transducer wires  104  in place against an outer surface  146  of the catheter  118 . As such, the length of tubing  106  can have an inner diameter  114  ranging from about 1 millimeters to about 12 millimeters, such as from about 2 millimeters to about 11 millimeters, such as from about 3 millimeters to about 10 millimeters, such as from about 5 millimeters to about 9 millimeters, or any range therebetween; and an outer diameter  116  ranging from about 1.01 millimeters to about 12.1 millimeters, such as from about 2.01 millimeters to about 11.1 millimeters, such as from about 3.01 millimeters to about 10.1 millimeters, such as from about 5.01 millimeters to about 9.1 millimeters, or any range therebetween. 
     Thus, the length of tubing  106  can have a wall thickness  150  ranging from about 10 micrometers to about 101 micrometers, such as from about 15 micrometers to about 91 micrometers, such as from about 20 micrometers to about 81 micrometers. The proximal portion  112  of the length of tubing  106  can surround the one or more transducer wires  104  and the distal portion  110  of the length of tubing  106  can surround the transducer  102 . Further, the proximal portion  112  of the length of tubing  106  can include a conductive filler  108  (e.g., conductive particles, powder, flakes, etc.) that helps shield the one or more transducer wires  104  from electrical signal noise that may hinder the effectiveness of the transducer  102  in enhancing the visibility of the distal end  120  of the catheter  118 . Meanwhile, the distal portion  110  of the length of tubing  106  which surrounds the transducer  102  is free of the conductive filler  108  so as to not distort the signals that may be transmitted and received by the transducer  102 , such as when used the medical imaging system  100  to visualize the distal end  120  of the catheter  118 . 
     The length of tubing  106  can include any suitable material that is utilized in medical tubing, such as polytetrafluoroethylene, polyethylene, polyurethane, silicone, or a combination thereof. Further, the length of tubing  106  can be shrinkable, where the length of tubing can secure the transducer  102  and the one or more transducer wires  104  against the outer surface  146  of the catheter  118  when the length of tubing  106  is shrunk around the body  128  of the catheter  118 . In one particular embodiment, the length of tubing  106  can be heat shrinkable. 
     In addition, any suitable conductive filler  108  can be used, such as a metal, a conductive polymer, carbon, or a combination thereof. For instance, the conductive filler  108  can include nickel, copper, silver, gold, platinum, or a combination thereof. In other embodiments, the conductive filler  108  can include polypyrrole, poly(3,4-ethylenedioxythiophene), polythiophene, polyaniline, poly-p-phenylene-sulphide, polyacetylene, polyisoprene, polybutadiene, or a combination thereof. Moreover, regardless of the particular conductive filler  108  utilized, the conductive filler  108  can be present in the proximal portion  112  of the length of tubing  106  in an amount ranging from about 0.05 wt. % to about 10 wt. %, such as from about 0.1 wt. % to about 7.5 wt. %, such as from about 0.5 wt. % to about 5 wt. % based on the total weight of the proximal portion  112  of the length of tubing  106 . 
     Referring now to  FIG. 3 , the catheter assembly  100  as described above can also include an injection port  136  coupled to the handle  130  whereby fluid or medicament can be injected into a proximal end  122  of the catheter  118 . In addition, the catheter assembly  100  can also include an article insertion port  142  located at the handle  130  whereby an article (not shown), such as needle, stylet, probe, or guidewire, for example, can be inserted into the catheter  118  as needed depending on the medical procedure being visualized. In such an embodiment, an article configured to be contained in the lumen  128  of the catheter  118  may be contained in the lumen  128  such that a tip of the article extends through the distal end  120  of the catheter  118 , and forms the tip  126 . Of course, as discussed in greater detail below, the catheter assembly  100  may also be configured to be contained in the lumen of an article instead of as an over-the-needle catheter. 
     In another embodiment, and referring specifically to  FIGS. 5-6 , the catheter assembly  100  including the catheter  118 , the transducer  102 , and the one or more transducer wires  104  can include a length of tubing  106  that surrounds the catheter  118 , the transducer  102 , and the one or more transducer wires  104 , which can be non-coaxial as discussed above. Specifically, the length of tubing  106  can include a distal portion  110  and a proximal portion  112 . The distal portion  110  can extend along the body  128  towards the tip  126  of the catheter  118  such that the tip  126  of the catheter  118  is exposed and free of the length of tubing  106 . As shown, the length of tubing  106  can hold the transducer  102  and one or more transducer wires  104  in place against an outer surface  146  of the catheter  118 . 
     As such, the length of tubing  106  can have an inner diameter  114  ranging from about 1 millimeters to about 12 millimeters, such as from about 2 millimeters to about 11 millimeters, such as from about 3 millimeters to about 10 millimeters, such as from about 5 millimeters to about 9 millimeters, or any range therebetween; and an outer diameter  116  ranging from about 1.01 millimeters to about 12.1 millimeters, such as from about 2.01 millimeters to about 11.1 millimeters, such as from about 3.01 millimeters to about 10.1 millimeters, such as from about 5.01 millimeters to about 9.1 millimeters, or any range therebetween. 
     Thus, the length of tubing  106  can have a wall thickness  150  ranging from about 10 micrometers to about 101 micrometers, such as from about 15 micrometers to about 91 micrometers, such as from about 20 micrometers to about 81 micrometers. The proximal portion  112  of the length of tubing  106  can surround the one or more transducer wires  104  and the distal portion  110  of the length of tubing  106  can surround the transducer  102 . Further, as shown in  FIGS. 5-6 , it is to be understood that like the distal portion  110 , the proximal portion  112  of the length of tubing  106  can be free of the conductive filler  108  described above with respect to  FIGS. 3-4  so as to not distort the signals that may be transmitted and received by the transducer  102 , such as when used the medical imaging system  100  to visualize the distal end  120  of the catheter  118 . 
     The length of tubing  106  can include any suitable material that is utilized in medical tubing, such as polytetrafluoroethylene, polyethylene, polyurethane, silicone, or a combination thereof. Further, the length of tubing  106  can be shrinkable, where the length of tubing can secure the transducer  102  and the one or more transducer wires  104  against the outer surface  146  of the catheter  118  when the length of tubing  106  is shrunk around the body  128  of the catheter  118 . In one particular embodiment, the length of tubing  106  can be heat shrinkable. 
     Referring now to  FIG. 5 , the catheter assembly  100  as described above can also include an injection port  136  to the handle  130  whereby fluid or medicament can be injected into a proximal end  122  of the catheter  118 . In addition, the catheter assembly  100  can also include an article insertion port  142  located at the handle  130  whereby an article (not shown), such as needle, stylet, probe, or guidewire, for example, can be inserted into the catheter  118  as needed depending on the medical procedure being visualized. In such an embodiment, an article configured to be contained in the lumen  128  of the catheter  118  may be contained in the lumen  128  such that a tip of the article extends through the distal end  120  of the catheter  118 , and forms the tip  126 . Of course, as discussed in greater detail below, the catheter assembly  100  may also be configured to be contained in the lumen of an article instead of as an over-the-needle catheter. 
     Turning to  FIGS. 3-6 , although not required, in some embodiments, the catheter assembly  100  can include an impedance matching material  154  disposed between the transducer  102  and the distal portion  110  of the tubing  106 . The impedance matching material  154  can eliminate any air between the transducer  102  and the distal portion  110  of the tubing  106 , where air could attenuate or otherwise negatively impact the signals being transmitted and received by the transducer  102  via the one or more transducer wires  104 . In addition, the impedance matching material  154  can have an acoustic impedance that is similar to the impedance of human tissue (e.g., skin), such as an acoustic impedance that is +/−20%, such as +/−15%, such as +/−10%, such as +/−5% of the impedance of human tissue. By having a similar acoustic impedance as human tissue, the impedance matching layer  154  can reduce the possibility of any reflection of the signals being transmitted and received by the transducer  102  via the one or more transducer wires  104 . For instance, in one embodiment, the impedance matching layer can be silicone, polyimide, or any other polymer having an acoustic impedance similar to that of human tissue. In addition, the impedance matching material  154  can be applied to the catheter assembly  100  by disposing, such as by coating, dabbing, painting, brushing, etc., a thin layer of the impedance matching material  154  on a surface of the transducer  102  and the distal end  120  of the catheter  118  around which the tubing  106  will be disposed. Further, the impedance matching material  154  and the tubing  106  can be applied around the catheter  118  in a vacuum chamber to ensure that any air is eliminated between the catheter  118  and the tubing  106 . 
     In  FIGS. 2-6 , the embodiments of the catheter assembly have been described as either a catheter alone, or as an “over the needle” (“OTN”) catheter, where it is noted that the “needle” may be a needle, stylet, probe, or guidewire, for example. For instance, referring back to  FIG. 2 , a needle  234  may be, and/or may be configured to be located in the lumen (shown more clearly in  FIGS. 3-6 ) of a catheter  118 . In such an embodiment, the needle  234  may have a tip  236  that extends through an opening or aperture  144  at a distal end  120  of the catheter  118 . As shown, the catheter  118  has a transducer  102  located adjacent to the distal end  120 , although, while not shown, it should also be understood that the needle  234  may also contain a transducer, in an embodiment where a needle is used. However, as discussed above, the needle  234  is optional, and in one embodiment, no needle or other article is located in the lumen of the catheter  218 , or further yet, the needle may be replaced with a guidewire, stylet, or other article. 
     Additionally or alternatively, as shown in  FIGS. 7-10 , the catheter assembly  200  may be used alone, or placed within an article, such as a needle  234 . In such an embodiment, the catheter assembly  200  may be configured to be placed within the lumen of an article, such as a needle, stylet, probe, or guidewire. 
     For instance, as shown in  FIGS. 7-10 , the catheter  218  is designed to be received within the lumen  240  of the needle  234 . More specifically, as shown, the catheter  218  also has a proximal end  222  and a distal end  220 . Further, as in the embodiments of  FIGS. 3-6  above, the ultrasound transducer  202  may be mounted on the catheter  218 , e.g. at the distal end  220  thereof. As such, during use, the distal end  220  of the catheter  218  can be inserted into the lumen  240  of the needle  234  that can then together be inserted into a patient. Similar to the embodiments discussed above, and as shown more clearly in  FIG. 9 , the catheter  218  may have a body  228  having an outer diameter ranging from about 1 millimeters to about 12 millimeters, such as from about 2 millimeters to about 11 millimeters, such as from about 3 millimeters to about 10 millimeters, such as from about 5 millimeters to about 9 millimeters, or any range therebetween, and defined by a distal end  220  and a proximal end  222 . Of course, a catheter  218  such as shown in  FIGS. 7-10  may also have a smaller or larger outer diameter than as discussed above, and may instead have a outer diameter selected based upon the diameter  244  of the lumen  240  of the needle  234  (see,  FIG. 8 ). A transducer  202  (e.g., an ultrasound transducer) can be disposed on an outer surface  246  of the catheter  218 . 
     Further, as discussed above, the distal end  220  of the catheter  218  can, in one embodiment, have a tip  226  that can be used for the delivery of energy or treatments suitable for creating a nerve block, such as for the treatment of pain, or may instead utilize openings  244  in the distal end  220  for the delivery of energy or treatments. For instance, the tip  226  and/or distal end  220  can include an opening  244  or openings  244  (such as, in  FIG. 9 , an open end located at tip  226 ) for delivery of a fluid and/or medicament, such as for delivery of an anesthetic nerve block. 
     In one embodiment that includes a catheter assembly  200  contained within an article such as a needle  234 , the needle  234  further may include at least one window  256  or opening in an outer wall thereof. Thus, as shown, the transducer  202  of the catheter  218  can be aligned with the window(s)  256  when the catheter  218  is inserted into the lumen  240  of the needle  234 . In such embodiments, the ultrasound transducer  202  is configured to transmit or divert signals  258  through the window(s)  256 . Additionally or alternatively, in such an embodiment, the needle  234  may include a transducer (not shown) in addition to the transducer  202  located on the catheter  218 . When used, the transducer on the needle  234  may be generally located at or near the location of the window(s)  256  of  FIGS. 7 and 10 , or may be located in an alternative position. In such an embodiment, the transducer  260  on the needle  234  may be used for the initial position of the catheter assembly  200 , and the transducer  202  located on the catheter  218  may be used to check, or relocate, the catheter assembly  200  after placement of the catheter assembly  200  and removal of the needle  234  from around the catheter  218 . 
     Nonetheless, in an embodiment that includes a catheter assembly configured to be contained within an article such as a needle  234 , during use, the distal end of the catheter  218  can be inserted into the lumen  240  of the needle  234  that can then together be inserted into a patient. Additionally or alternatively, the needle  234  may be inserted into the patient, and the catheter  218  may be introduced through the needle  234  after placement of the needle. 
     As discussed in reference to  FIGS. 3-6 , the embodiment shown in  FIGS. 7-10  may also include a handle  130  that can be coupled to the proximal end  222  of the needle  234  or catheter  218  to assist the medical professional  312  in accurately positioning the catheter  218  within the patient  210 . The handle  130  can be connected via an electrical connection  132  to a power supply  134 . The power supply  134  can provide energy to the transducer  202  on the catheter  218 , and the transducer may be any transducer as discussed above. 
     Still referring to  FIG. 7 , the needle  234  may also include a needle hub  268  at its proximal end  235 . Thus, in certain embodiments, the handle  130  may be sized to fit within the needle hub  235 . In addition, as shown, handle  130 , and the needle hub  268  may each be configured with one or more locking features  272 ,  274  configured to secure the handle  130  to the needle hub  268 . More specifically, the locking features  272 ,  274  may correspond to one or more of ribs, protrusions, fasteners, or similar or combinations thereof. For example, as shown, the protrusion  272  of the handle  230  may be configured to snap fit with the recess  274  of the needle hub  268   
     As shown, the transducer  202  can have a distal end  238  and a proximal end  240 , where one or more transducer wires  204 , which can connect the transducer  202  to a power supply and which can be used for transmitting and receiving signals, extends from the proximal end  240  of the transducer  202  towards the proximal end  222  of the catheter  218  in order to connect the transducer  202  to the power supply  234 . The one or more transducer wires  204 , which can extend along the outer surface  246  of the catheter  218 , can be formed from any conductive material and have a size and diameter as discussed above. As discussed above, the ability of the catheter assembly  200  of the present invention to use one or more transducer wires  204  having such a reduced diameter compared to conventional transducer wires where a larger, more cumbersome coaxial cable is required to shield the one or more transducer wires from electrical signal noise is facilitated by the use of a length of tubing  206  surrounding the catheter  218  and the transducer  202 , as discussed in more detail below. 
     As in the embodiments discussed above, the embodiments shown in  FIGS. 7-10  may also include a length of tubing  206  that surrounds the catheter  218 , the transducer  202 , and the one or more transducer wires  204 , which can be non-coaxial as discussed above. Specifically, the length of tubing  206  can include a distal portion  210  and a proximal portion  212 . The distal portion  210  can extend along the body  228  towards the tip  226  of the catheter  218  such that the tip  226  or some or all of the distal portion  210  of the catheter  218  is exposed and free of the length of tubing  206 . However, in this embodiment, such as shown in  FIG. 10 , the tubing  206  is located between the exterior wall  246  of the catheter, and the interior wall  262  of the needle  234 . Therefore, while the tubing  206  may have the same thickness as discussed above, the tubing  206  may also have a thickness selected that enables the catheter  218  to be placed in the lumen  240  of the needle  236 . Notwithstanding the thickness of the tubing  206 , the tubing  206  may generally have the same properties and be formed as discussed above. 
     Further, the proximal portion  212  of the length of tubing  206  can include a conductive filler  208  (e.g., conductive particles, powder, flakes, etc.) that helps shield the one or more transducer wires  204  from electrical signal noise that may hinder the effectiveness of the transducer  202  in enhancing the visibility of the distal end  220  of the catheter  218 . Meanwhile, the distal portion  210  of the length of tubing  206  which surrounds the transducer  202  is free of the conductive filler  208  so as to not distort the signals that may be transmitted and received by the transducer  202 , such as when used the medical imaging system  100  to visualize the distal end  220  of the catheter  218 . 
     As discussed above, the length of tubing  206  can include any suitable material that is utilized in medical tubing, such as polytetrafluoroethylene, polyethylene, polyurethane, silicone, or a combination thereof. Further, the length of tubing  206  can be shrinkable, where the length of tubing can secure the transducer  202  and the one or more transducer wires  204  against the outer surface  246  of the catheter  218  when the length of tubing  206  is shrunk around the body  228  of the catheter  218 . In one particular embodiment, the length of tubing  206  can be heat shrinkable. 
     In addition, any suitable conductive filler  208  can be used, such as a metal, a conductive polymer, carbon, or a combination thereof. For instance, the conductive filler  208  can include nickel, copper, silver, gold, platinum, or a combination thereof. In other embodiments, the conductive filler  208  can include polypyrrole, poly(3,4-ethylenedioxythiophene), polythiophene, polyaniline, poly-p-phenylene-sulphide, polyacetylene, polyisoprene, polybutadiene, or a combination thereof. Moreover, regardless of the particular conductive filler  208  utilized, the conductive filler  208  can be present in the proximal portion  212  of the length of tubing  206  in an amount ranging from about 0.05 wt. % to about 10 wt. %, such as from about 0.1 wt. % to about 7.5 wt. %, such as from about 0.5 wt. % to about 5 wt. % based on the total weight of the proximal portion  212  of the length of tubing  206 . 
     Referring now to  FIG. 7 , the catheter assembly  200  as described above can also include an injection port  236  coupled to the catheter side handle  230  whereby fluid or medicament can be injected into a proximal end  222  of the catheter  118 . In addition, the catheter assembly  200  can also include an article insertion port  242  located at the needle side handle  231  whereby the catheter  218  can be inserted into the needle  234 . 
     As discussed above, although not required, in some embodiments, the catheter assembly  200  can include an impedance matching material  254  disposed between the transducer  202  and the distal portion  210  of the tubing  206 . The impedance matching material  254  can eliminate any air between the transducer  202  and the distal portion  210  of the tubing  206 , where air could attenuate or otherwise negatively impact the signals being transmitted and received by the transducer  202  via the one or more transducer wires  204 . In addition, the impedance matching material  254  can have an acoustic impedance that is similar to the impedance of human tissue (e.g., skin), such as an acoustic impedance that is +/−20%, such as +/−15%, such as +/−10%, such as +/−5% of the impedance of human tissue. By having a similar acoustic impedance as human tissue, the impedance matching layer  254  can reduce the possibility of any reflection of the signals being transmitted and received by the transducer  202  via the one or more transducer wires  204 . For instance, in one embodiment, the impedance matching layer can be silicone, polyimide, or any other polymer having an acoustic impedance similar to that of human tissue. In addition, the impedance matching material  254  can be applied to the catheter assembly  200  by disposing, such as by coating, dabbing, painting, brushing, etc., a thin layer of the impedance matching material  254  on a surface of the transducer  202  and the distal end  220  of the catheter  218  around which the tubing  206  will be disposed. Further, the impedance matching material  254  and the tubing  206  can be applied around the catheter  218  in a vacuum chamber to ensure that any air is eliminated between the catheter  218  and the tubing  206 . 
     The present invention has been described both in general and in detail by way of examples. These and other modifications and variations of the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit the invention so further described in such appended claims.