Abstract:
A medical device for placement of regional anesthesia catheters. The device comprises a hollow shaft needle, a plunger attached to the posterior end of the needle, a housing dimensioned so that plunger can slide inside the housing with friction, a regional anesthesia catheter preloaded inside the needle, a protective cover sheath covering the catheter, and a catheter adaptor attached to posterior end of the sheath and the catheter. The medical device allows a practitioner to quickly and effectively place a regional anesthesia catheter inside an organism without the use of an assistant, and with minimal risk of contaminating the catheter before it enters the organism&#39;s body. At the end, the needle is withdrawn inside the housing and disposed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit, under 35 U.S.C §119(e)(1), of U.S. provisional patent application No. 61/153,277 filed on Feb. 17, 2009, titled: “Medical Device for Placement of Continuous Regional Anesthesia Catheters,” the disclosure of which is herein incorporated by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       FIELD OF INVENTION 
       [0003]    The invention relates generally to medical devices that enable the placement of catheters into body of an organism, and more specifically to medical devices designed to assist the placement of regional anesthesia catheters for continuous infusion of local anesthetics. 
       BACKGROUND 
       [0004]    Regional anesthesia catheters are hollow body flexible catheters that are designed to be placed next to a nerve or nerve plexus of the human body, and kept in place for up to a few days. Liquid medicine is injected into proximal end of the catheter. The medication then exits from distal end of the catheter and is deposited around the nerve that is intended to be anesthetized. The dispersal of medication around the nerve causes the area innervated by that nerve to become anesthetized. In current anesthesia practice, hollow shaft metal needles are used to place such catheters into position. 
         [0005]    Such needles are covered with an electrically insulating covering over the outer surface of most of their length, except the tip and proximal end. An electric impulse sent to the needle is conveyed axially down to the tip of the needle and not radially to surrounding tissues. This allows for more precise placement of the needle tip. A stimulating wire is attached to the proximal end of the needle and is used to connect the needle to an electric supply source or so-called a nerve stimulator device. The distal end of the needle is placed through the skin of the patient and is advanced toward the target nerve. The amount of electric impulse that is sent toward the needle tip is gradually decreased as the needle advances into the patient&#39;s body, which helps to localize the target nerve. A muscle contraction at a specific low current verifies the proximity of the needle tip to that nerve. Next, the catheter is placed through needle. 
         [0006]    Needles and catheters come in different gauges and lengths, and it is imperative to use catheters with matching needles. Catheters are either stimulating or non-stimulating. Non-stimulating catheters are composed of an elongated hollow body and generally are similar to epidural catheters. Stimulating catheters generally have a hollow body and means for conveying electric current from the proximal end of the catheter to its distal tip. Only a small portion of the distal and proximal ends of the catheter are electrically exposed, while the body is electrically nonconductive. This allows for precise placement of catheter tip next to a nerve. 
         [0007]    These days some practitioners use ultrasound devices to visualize the target nerve and place the needle tip, followed by the catheter tip, next to the target nerve. Practitioners may choose to perform the procedure, using ultrasound alone, or they may employ ultrasound and a nerve stimulator simultaneously. In current practice, however, the majority of practitioners prefer to use nerve stimulators. 
         [0008]    Placement of regional anesthesia catheters is done using strict sterile techniques to avoid catheter and needle contamination, and thus patient infection. For example, the skin area were the needle and catheter will be inserted into the patient is prepped and extensively draped. The long resilient catheter is always prone to contamination from surrounding objects. It is also necessary for the practitioner to wear a mask, hat and sterile gloves and even sterile gown in some instances. An assistant is needed to help open sterile packages, connect and disconnect stimulating wires of needle and catheter to nerve stimulator, and operate the nerve stimulator. The assistant will help utilize the ultrasound device as well, if one is used. 
       SUMMARY 
       [0009]    The current invention is directed to a device that:
       Reduces chance and frequency of catheter and needle contamination.   Reduces time needed to place the catheter adjacent to the target nerve.   Eliminates need for an assistant in most parts of a procedure.   Eliminates the need for anesthesia provider to wear hat, mask, sterile gloves, and gown.   Eliminates the need to drape insertion site.   Reduces risk of needle injury to medical staff because the needle is housed safely in a protective covering.       
 
         [0016]    In this invention, a metal hollow shaft needle is manufactured to a size that is almost twice as long as commercially-available similar needles. The needle is electrically insulated throughout most of its length, on the outer surface, except its proximal end and distal tip. The needle&#39;s proximal end may be attached to a stimulating wire which is adapted to allow it to be connected to a nerve stimulator device. The proximal portion of the needle shaft is permanently placed inside a plunger and the plunger is placed inside a housing. The plunger is situated inside the housing so that it can slide up and down the housing with friction. A removable protective cap is placed over distal end of the housing to ensure sterility. 
         [0017]    In the present invention, a stimulating regional anesthesia catheter is preloaded inside the needle. The catheter tip may be electrically in touch with electrically conductive inside surface of the needle. A protective sheath made of clear collapsible plastic covers most of the length of the catheter, which is left proximal to the needle. The sheath has a proximal hub and a distal hub and is secured and sealed at the peripheral ends of the hubs. The distal hub is attached to the proximal end of the needle, while the proximal hub is placed around the proximal end of catheter, leaving a small portion of the catheter (approx. 1-2 cm.) out. A regional anesthesia catheter adaptor is attached to the sheath&#39;s proximal hub in a releasable manner. This adaptor accepts and rigidly maintains the catheter&#39;s proximal end. It has components to electrically connect the nerve stimulator to the catheter&#39;s proximal end and provides fluid access into the interior lumen of the catheter for injection of liquid medicine using a syringe or infusion pump. 
         [0018]    After prepping the insertion site, the catheter adaptor is connected to a nerve stimulator device. The housing distal protective cap is removed and the distal end of the housing is placed over the insertion site. The needle is then advanced toward the target nerve by advancing the plunger into the housing. At this time, the catheter is manipulated, through the catheter sheath, to bring the catheter&#39;s tip into electrical contact with the inside lumen of the needle. The anesthesia provider can operate the nerve stimulator to send a decreasing amount of electric impulse to the catheter tip, and simultaneously advance the needle tip through the patient&#39;s body towards the target nerve. After the needle tip is placed in close proximity to the target nerve, the catheter is pushed through the catheter sheath by the practitioner and advanced until the desired length of the catheter&#39;s distal end exits beyond the needle tip. 
         [0019]    At this point, any satisfactory muscle contraction is a result of direct stimulation of the nerve by the catheter&#39;s tip and will confirm that the catheter tip has been correctly placed near the target nerve. Next, the proximal end of the catheter is released from the catheter adaptor to free the catheter, and then the needle is withdrawn while the catheter is maintained in place. Finally, the catheter adaptor is detached from the sheath&#39;s proximal hub and securely reattached to the catheter&#39;s proximal end. Care should be taken not to touch and contaminate the proximal end of the catheter and the distal part of the adaptor. At this time the catheter should be properly secured to the patient. 
         [0020]    In an alternative method of using this embodiment, a first impulse is sent to the needle using the needle&#39;s stimulating wire. The catheter is advanced beyond the needle&#39;s distal tip, then a second impulse is sent to the catheter to verify the catheter&#39;s correct placement. 
         [0021]    In alternative embodiments, a non-stimulating catheter is used. In non-stimulating catheter embodiments, the needle may be comprised of components that connect the needle to a supply source of electricity. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]      FIG. 1  is a side elevational view of a prior art needle. 
           [0023]      FIG. 2  is a side sectional view of a needle and plunger inside the housing according to an embodiment. 
           [0024]      FIG. 2A  is a side sectional view of a needle and plunger according to an embodiment. 
           [0025]      FIG. 2B  is a side sectional view of a housing according to an embodiment. 
           [0026]      FIG. 2C  is a side sectional view of a beveled distal end of a housing according to an embodiment. 
           [0027]      FIG. 3  is a side sectional view of a regional anesthesia catheter placed inside covering sheath according to an embodiment. 
           [0028]      FIGS. 4A and 4B  are side elevational views of a catheter adaptor according to an embodiment. 
           [0029]      FIG. 5  is a side sectional view of a fully-assembled invention according to an embodiment. 
           [0030]      FIG. 6  is a side sectional view of one embodiment of the invention having a stylet placed inside needle. 
           [0031]      FIG. 6A  is a side sectional view of a plunger and needle, with the plunger having a side slot for insertion of the stylet, according to an embodiment. 
           [0032]      FIG. 6B  is a side sectional view of a stylet according to one embodiment of the invention. 
           [0033]      FIG. 7  is a side sectional view of one embodiment of the housing with side longitudinal slot. 
           [0034]      FIG. 7A  is a side sectional view of one embodiment of the needle with curved proximal end. 
           [0035]      FIG. 7B  is a side sectional view of one embodiment of the invention with the needle placed inside the housing and with the curved proximal end of the needle placed inside side slot. 
           [0036]      FIG. 8  is a side sectional view of one embodiment of the invention fully assembled with schematic depiction of switch pad and nerve stimulator device (NS). 
           [0037]      FIG. 9A  is a side sectional view of one embodiment of the invention with distal conduit in the released position. 
           [0038]      FIG. 9B  is a side sectional view of one embodiment of the invention with distal conduit in the locked position. 
       
    
    
     DETAILED DESCRIPTION 
       [0039]    Referring to  FIG. 1 , a conventional hollow shaft metal needle  11  is shown. These needles are well known to prior art. They are made in different lengths and gauges suitable for intended use. The needle shown in  FIG. 1  has a shaft  12 , a proximal end  16  and a distal tip  15 . The tip  15  may be straight or beveled, or it may be made with an angle at the end of the straight shaft  12 . The proximal end  16  is provided with a hub  18 . The stimulator wire  14  has a first end attached to proximal end  16  and a second end adapted to connect to nerve stimulator device using connection plug  17 . Using a nerve stimulator, electric impulse is sent through connection plug  17 , which conveys the impulse to tip  15 . 
         [0040]    Needles, such as the one shown in  FIG. 1 , are usually manufactured with a shaft  12  that is covered with electrically non-conductive material on its outer surface, except along its proximal end  16  and its tip  15 , which are not coated with the non-conductive material. This allows for precise placement of the tip  15  next to a nerve. A stylet (not shown) may be placed inside the shaft  12 . In such an embodiment, the stylet is removed after the needle tip  15  penetrates the patient&#39;s body. Stylets are generally used to facilitate needle insertion into the patient&#39;s body and to prevent body tissues from plugging needle lumen. 
         [0041]    Referring to  FIG. 2 , a hollow shaft metal needle  11  is made almost twice as long as commercially-available, similar needles. The needle  11  has a shaft  12 , a proximal end  16 , and a tip  15 . Using standard industry methods that are well known in the art, the shaft  12  is coated with a thin layer of non-conductive material over the shaft&#39;s  12  outer surface; the tip  15  and the proximal end of the shaft  16  are not coated. The tip  15  may be straight or beveled or it may make an angle with the shaft  12 . The proximal section of the needle  11  is permanently and coaxially placed inside the plunger  6 . The plunger  6  has a proximal end  7 , a distal annular ring  8 , a thumb rest  28 , and an entry hub  18 . The plunger  6  divides the shaft  12  into sections  2  and  4 . Section  2  is coaxially disposed within the plunger  6 . The hub  18  is in fluid communication and provides access to the inside of the lumen of the needle shaft  12  and the needle tip  15 . 
         [0042]    The proximal end  16  may be attached to a stimulating wire  14  which is adapted to connect the needle  11  to a electric supply source. The plunger  6  is placed inside the housing  10 . The housing  10  preferably has a cylindrical body. It has a distal end  20 , a proximal end  23 , and a distal conduit  22 . The housing  10  has a length that allows the needle  11  to be withdrawn completely inside the housing  10 . The inner diameter of the conduit  22  is slightly larger than the outer diameter of the needle  11 , and the inner diameter of the conduit  22  will guide the needle  11  out of the distal end of the housing  10 . A finger flange  24  may be attached to the proximal end  23  of the housing  10 . 
         [0043]    Minimal friction exists between the distal annular ring  8  and the housing  10 . The proximal end  23  of the housing  10  may be provided with anterior and posterior inner annular stop rings  26 . These rings  26  will maintain the needle  11  completely inside the housing  10  in such a way that the needle tip  15  will rest inside the conduit  22  at a position slightly proximal to the distal end of the conduit  22 . Slight force should be needed to move the annular ring  8  passed the annular stop rings  26  in either direction. The distal end  20  of the housing  10  may be beveled almost 30-45 degrees, this conforms to the angle with which the needle  11  will penetrate the patient&#39;s body. Except for the needle  12 , which is preferably made of metal, the other component parts of the embodiment of the invention depicted in  FIG. 2  can be made of any solid material, preferably plastic. The annular ring  8  may alternatively be made of a soft elastic material like plastic or rubber. 
         [0044]    Marks may be placed along the plunger  6 , the needle  11 , or the housing  10  to help the user determine the depth of penetration of the needle  11 . This could be accomplished by applying alternating colors of specific length to the outer surface of the plunger  6 , the needle  11 , or the housing  10 , or alternatively marking lines of different thickness along the outer surface of the plunger  6 , the needle  11 , or the housing  10 . In an alternative embodiment, the needle  11  can be attached to the distal end of the plunger  6  instead of being coaxially placed within the plunger  6 . In this embodiment an axial central conduit should exist within the plunger  6  to provide fluid communication between the hub  18  and the needle  11  and to allow catheter placement into the needle  11 . 
         [0045]    In one embodiment of the present invention shown in  FIG. 9 , a catheter assembly is shown with a locking mechanism. The locking mechanism is accomplished by constructing the conduit  22  out of a soft but resilient material. The anesthesia provider can lock the needle  11  in position by simply pinching the conduit  22  between his/her fingers. Upon the release of the pressure created by the provider&#39;s fingers, the conduit  22  will resume its straight shape and free the needle  11  from its locked position. This locking mechanism may be used during the advancement of the catheter through the needle  11 , so the needle  11  can be maintained in its position. 
         [0046]    Referring to  FIG. 3 , a conventional stimulating regional anesthesia catheter is shown placed inside of a protective sheath. As described earlier, only the distal tip and the proximal end of the stimulating catheter are electrically exposed. The catheter has a proximal end  63 , a distal tip  65 , and a body  61 . The catheter has means to convey electric impulse from the proximal end  63  to the distal tip  65 . Any electric current sent through the proximal end  63  will only travel axially through the body  61  and exit from the distal end  65 . This allows for precise placement of the catheter tip next to a target nerve. The catheter cover sheath  68  is made of thin clear plastic and is attached to the distal hub  67  and the proximal hub  62  as shown in  FIG. 3 . The sheath  68  is attached to periphery of hubs  67  and  62  in a sealed and secured way to maintain the sterility of the catheter  61 . 
         [0047]    Referring to  FIG. 3 , the sheath  68  is manufactured of adequate length as to when fully expanded, to cover the catheter  61  over its length beginning adjacent to the needle  12  and continuing until just before the proximal end  63  of the catheter  61  which is placed inside a catheter adaptor. The distal hub  67  is attached to an entry hub  18  of the plunger  6 . This attachment may be permanent or, preferably releasable but secured, like a Luer fitting, or a male-female connection, or any other way known to prior art. It is important that this connection does not come apart accidentally during the catheter placement procedure, which may render the catheter  61  exposed and subject to outside contamination. 
         [0048]    Alternatively, as explained earlier, the catheter  61  can be a non-stimulating catheter. In embodiments assembled using a non-stimulating catheter, the proximal end  63  of the catheter  61  may be maintained by a catheter adaptor attached to a proximal hub  62 , or, alternatively, it may be left free inside the catheter sheath  68 . This is because electrical stimulation of the catheter, during catheter placement, is not needed when a non-stimulating catheter is used. The catheter adaptor can be attached/reattached to the catheter&#39;s  61  proximal end  63  after the catheter  61  is placed correctly and the needle is removed from the patient&#39;s body. 
         [0049]    Referring to  FIGS. 4A and 4B , a generic catheter adaptor  71  is shown. These adaptors generally have a first part  72  and a second part  74 . The first part  72  has a front end  76  and rear end  78 . The front end  76  has space in it to accept and firmly grasp the proximal end  63  of the catheter  61 . This provides for an electrical connection between the catheter  61  and the catheter adaptor  71 , and provides for fluid communication with the catheter  61 .  FIG. 4A  shows the catheter adaptor  71  in the released position. In  FIG. 4B , part  74  has moved in relation to part  72 , which puts the catheter adaptor  71  in the locked position, which locks the proximal end  63  of the catheter in place. The rear end  78  of the catheter adaptor  71  is shaped to accept syringes of local anesthetics or infusion pumps for purposes of injecting liquid medicine through the catheter adaptor  71  into catheter lumen. 
         [0050]    The rear end  78  of the catheter adaptor  71  is covered by a removable protective cap to maintain sterility. The catheter adaptor  71  depicted in  FIGS. 4A and 4B  has a stimulating wire  73  and a connecting plug  75 . The connecting plug  75  is used to connect the catheter adaptor  71  to an electric supply source. The front end  76  of the adaptor  71  is connected securely, but releasably, to the proximal hub  62  of the sheath  68 . This can be done, for example, with Luer fitting connections or any similar manner known to prior art. Accidental disconnection of the adaptor  71  from the proximal hub  62  during catheter placement can render the catheter  61  contaminated. 
         [0051]    Referring to  FIG. 5 , an embodiment of the catheter system is shown fully assembled. A protective cap (not shown) should cover the distal end  20 . The protective cap needs to be removed just prior to needle insertion. A second cap (not shown) should cover the rear end  78  of the catheter adaptor  71 . This should be removed in order to introduce local anesthetics into the catheter adaptor  71  and into the catheter lumen. As shown in  FIG. 5 , no areas of either the catheter or the needle are exposed. 
         [0052]    By preloading the catheter and placing the parts of the catheter system in protective sheaths, the anesthesia provider can touch and operate the entire catheter system unit without the need to wear sterile gloves or use extensive protective draping; a simple preparation of the insertion site will suffice. A pair of clean gloves will be needed to cover the anesthesia provider&#39;s hands. The provider will join the connection plug  75  to a nerve stimulator (not shown here), then he/she will place the distal end  20  of the housing  10  against the insertion site. 
         [0053]    Referring to  FIG. 5 , the needle  11  is advanced toward the targeted nerve by advancing the plunger  6  through the housing  10 . Advancing the plunger  6  fully inside the housing  10  will cause the needle  11  to protrude out of the distal end  20  of the housing  10  the same length as similar commercially available needles. The anesthesia provider can operate the nerve stimulator simultaneously with the catheter system. The catheter is manipulated until its tip  15  comes in contact with the electrically conducting interior lumen of the needle  11 . This will electrically couple the nerve stimulator to the needle tip  15 . When the needle tip  15  is verified to be adequately close to the target nerve, the catheter  61  is grasped through the catheter sheath  68  and advanced inside the needle  11 . 
         [0054]    Marks on the catheter  61  will show the practitioner when the catheter tip  65  exits out of the needle tip  15  and loses electric contact with it. A satisfactory muscle twitch observed after this point in time is the result of direct stimulation of the target nerve by the catheter tip  65 , which means correct placement of the catheter tip  65  within the nerve sheath. When an adequate length of the catheter  61  is placed adjacent to the nerve, the proximal end  63  of the catheter  61  is released from the adaptor  71 . This allows the catheter end to move freely inside the sheath  68 . The catheter  61  is then further fed through the plunger hub  18 , while the needle  11  is simultaneously removed from the patient. 
         [0055]    Care must be taken not to withdraw the catheter  61  while the needle  11  is being removed. When the needle tip  15  is out of the patient, the catheter  61  is held by the hand at a point distal to the needle tip  15 . The proximal portion of catheter  61  is then pulled out of the sheath  68  and the needle  11 . Care should be taken not to touch and contaminate the proximal end  63  of the catheter  61 , and the front end  76  of the catheter adaptor  71 . These two portions need to be reconnected in a sterile manner. 
         [0056]    In some embodiments of the present invention, marks may be placed along the catheter  61  at a distance that is almost one inch away from the proximal end  63  to warn the practitioner of the eminent exit of the proximal end  63  out of the needle  11 , so accidental contamination of the catheter end  63  can be avoided. The adaptor  71  at this point is released from the proximal hub  62  and reconnected to the proximal end  63 . Next, the needle  11  is pulled completely into the housing  10  and is disposed of safely. Lastly, the catheter  61  is secured to the patient properly. 
         [0057]    In an alternative embodiment, a first electric impulse is sent from a source of electricity to the needle tip  15  using the needle&#39;s stimulating wire  14 . The needle tip  15  is positioned next to the nerve and the catheter  61  is then advanced, through the catheter sheath  68  and through the needle  11 , to a point beyond the needle  11  tip. When the catheter  61  has been advanced to a point beyond the needle  11  tip, a second electric impulse is sent to the catheter tip  65  using the stimulating wire  73  of the catheter adaptor  71  to verify correct catheter placement. Then, the catheter proximal end  63  is freed from catheter adaptor, the needle  11  is removed, and the catheter&#39;s  61  proximal end is reattached to catheter adaptor. 
         [0058]    In one embodiment, the invention is made the same way as described above, but instead of a stimulating catheter  61 , a non-stimulating one is preloaded inside the needle  11  lumen and covered by a protective cover sheath  68 . The proximal end of the catheter  61  may be grasped by a catheter adaptor, or it may be left free inside catheter sheath  68 . In this embodiment, an electric impulse is sent to the needle  11  tip using the needle&#39;s  11  stimulating wire  14 , the needle  11  tip is then positioned near the target nerve, and the catheter  61  is then advanced through the catheter sheath  68  and through the needle  11 , to a point beyond the needle&#39;s  11  tip. The needle  11  is removed and catheter adaptor is attached/reattached to the catheter&#39;s  61  proximal end. Correct positioning of the catheter tip can be verified by visualizing the catheter tip, using an ultrasound device, or by injecting doses of local anesthetics into the catheter lumen and around the nerve and confirming the occurrence of a nerve block. 
         [0059]    In another embodiment, the needle  11  is manufactured as a hollow shaft metal needle without insulating covering over the outside surface and without a stimulating wire  14 . A non-stimulating catheter  61  is preloaded inside the needle  11  and covered with a protective sheath  68 , in the same way as in other embodiments. The catheter&#39;s  61  proximal end  63  may be grasped by a catheter adaptor or it may be left free inside the catheter sheath  68 . 
         [0060]    In various embodiments, an ultrasound device may be used to visualize the target nerve and the needle  11  as the needle  11  travels through the patient&#39;s skin and into the body, and to place needle tip  15  in a position that is close to that target nerve. In embodiment described above, using ultrasound device, the needle tip  15  is placed next to a nerve, then the catheter  61  is advanced through the catheter sheath  68  and through the needle  11 , and extrudes through and beyond the needle tip  15 . The needle  11  is removed from the patient&#39;s body and the catheter adaptor  71  is attached/reattached to the catheter&#39;s proximal end  63 . Correct positioning of the catheter tip  65  can be verified by visualizing the catheter  61  through the use of an ultrasound device, or by injecting doses of local anesthetics into the catheter lumen and around the target nerve and confirming the occurrence of a nerve block. 
         [0061]    In an embodiment of the invention assembled using a non-stimulating catheter  61 , a non-stimulating catheter adaptor  71  may be used. While a stimulating catheter adaptor  71  is comprised of components that allow a nerve stimulator device to be connected to the catheter&#39;s proximal end  63  to send electrical impulses to the catheter  61 , a non-stimulating catheter adaptor  71  is devoid of such components. However, similar to a stimulating catheter  61 , a non-stimulating catheter  61  will tightly grasp the catheter&#39;s proximal end  63  and provide for fluid access into the catheter lumen. 
         [0062]    In other embodiments, one or more orifices may be provided along the section  2  of the needle  11 . Space should exist between this portion of the needle  11  and the interior lumen of the plunger  6 . The plunger  6  should be made of clear plastic. In this embodiment, if accidental intravascular entry happens, blood will enter into the open space inside the plunger  6  and can be seen by the anesthesia provider. Exit holes may be placed, preferably on the proximal end of the plunger  6 , to allow air to exit as blood flows in. In this embodiment, it is necessary that the catheter tip  65  be placed proximal to the orifices so as not to block the flow of blood if intravascular entry happens. 
         [0063]    In the embodiment depicted in  FIG. 6 , the invention may include a stylet  50 . A stylet  50  is comprised of an elongated body made of metal or preferably plastic. The stylet  50  may be removably placed inside a hollow needle. Stylets are designed to facilitate insertion of a needle into a patient&#39;s body and also prevent skin or other tissue materials from plugging the needle&#39;s relatively large bore. In  FIG. 6 , the plunger  6  is comprised of a proximal portion  6   a , a middle portion  6   b , and a distal portion  6   c . The section  2  of the needle  11  also has a proximal portion  2   a  and a distal portion  2   b.    
         [0064]    Needle portions  2   a  and  2   b  are connected by a metal plate  6   b (p), which runs through the middle portion  6   b  of the plunger  6 . The middle portion  6   b  of the plunger  6  is an enlarged space that is in fluid communication with needle portions  2   a  and  2   b . The middle portion  6   b  of the plunger  6  not only allows for the insertion or withdrawal of the stylet  50 , it will also allow blood to freely flow into the plunger  6  in case the needle  11  accidentally pierces a vein or artery when the stylet  50  is removed. The internal diameters of portions  2   a  and  2   b  are the same as the internal diameter of the entire needle  11 . The needle  11  again is electrically insulated on its outer surface, except its tip  15  and proximal end  16 . The proximal end  16  may be connected to a stimulating wire  14 . 
         [0065]    Any electric current coming through needle portion  2   a , either through the wire  14  or by way of contact with the catheter tip  65 , will exit only from the tip  15 . The middle portion  6   b  of the plunger  6  also has a slot  6   b (s). This slot  6   b (s) is designed to allow insertion of the stylet  50 .  FIG. 6B  depicts a stylet  50  designed to fit the embodiment shown in  FIG. 6 . It has a body  52 , a tip  58  and a knob  54  and a plug  56 . The stylet  50  can be inserted and withdrawn through slot  6   b (s) of the middle portion  6   b . The plug  56  is sized to fit snugly into slot  6   b (s) and the knob  54  can be grabbed by the practitioner so the stylet  50  can be inserted or withdrawn. When fully advanced, the stylet tip  58  will reach the needle tip  15  and will be flush with the needle tip  15 . 
         [0066]    In one embodiment shown in  FIGS. 7 through 7B , the housing  10  is provided with a longitudinal side slot  21 . The side slot  21  runs on the side of the housing  10 , from the proximal end  23  to just above the conduit  22 . It is sized to fit the needle  11 . In this embodiment, the proximal end  23  of the needle  11  is curved and faces outward as is shown in  FIG. 7A . This curve allows the needle hub  18  to maintain its position just next to and out of the housing  10 . This positioning allows the practitioner to grab the hub  18  in order to advance the needle  11  through the housing  10  by way of sliding the needle alongside the slot  21 . An annular ring  8  is placed around needle  11  at a place between the curved and straight portions of the needle  11 . As in the other embodiment of the invention shown in  FIG. 5 , the catheter  61  is preloaded inside needle  11  and is covered with the sheath  68 . The distal hub  67  is attached to the hub  18  as it is in other embodiments of the invention. As can be seen in  FIG. 7B , by providing a slot  21 , the needle  11  and the catheter system can be made much shorter than other embodiments without sacrificing the actual needle length available to penetrate the patient&#39;s body. 
         [0067]    In an alternative embodiment shown in  FIG. 8 , the invention comprises a switch pad  30 . While the switch pad  30  can be any size and shape, the switch pad  30  is preferably similar in size, shape and structure to a regular ECG pad. An electric impulse is sent to the needle  11  by way of contact with catheter tip  65 . Alternatively, the needle  11  can be connected to the nerve stimulator directly using a needle wire  14  and then the catheter is connected to the nerve stimulator by disconnecting the nerve stimulator from the needle and attaching it to catheter  61  through the catheter adaptor  71 . 
         [0068]    The switch pad  30  allows the task of electrically stimulating the needle  11  and/or the catheter  61  quickly and/or single-handedly. The switch pad  30  is made of soft plastic or a similar non-conductive material. The switch pad  30  has a top surface  30   a  and a bottom surface  30   b . The bottom surface  30   b  is covered with a layer of adhesive material which enables the switch pad  30  to be temporarily attached to the patient&#39;s body. A knob  31  is affixed into the switch pad  30 . The knob  31  is constructed of a conductive material. The knob  31  has a cylindrical top portion  31   a  and a disc-shaped bottom portion  31   b . The knob  31  is positioned into the switch pad  30  in such a way that the cylindrical top portion  31   a  sits perpendicularly on the top surface  30   a  while the disc-shaped bottom portion  31   b  is attached to and is substantially flush with the bottom surface  30   b  of the switch pad  30 . The  31   b  portion is covered with a layer of conductive gel to facilitate its electric connection to the patient&#39;s body. 
         [0069]    Attaching the switch pad  30  to a patient&#39;s body will provide an electrical connection between the patient&#39;s skin and the knob  31 . The knob  31  will function as a ground connection between the patient body and a nerve stimulator device. The switch pad  30  is further comprised of knobs  33  and  35 . These knobs  33 ,  35  are made of conductive material, but they are electrically isolated in such way that no connection exits between the two knobs  33 ,  35 , or between the two knobs  33 ,  35  and the bottom surface  30   b.    
         [0070]    The stimulating wire  14  of the needle  11  and the wire  73  of the catheter adaptor  71  can be attached to the knobs  33 ,  35  using standard alligator clips. As is shown in  FIG. 8 , a metal pivot  37  is provided on the top surface  30   a . A metal bar  39  is attached to the pivot  37  in such a way that it can move between the two knobs  33 ,  35 . The metal bar  39  maintains a constant electrical connection to the pivot  37 . A dent or slot may be provided on the side of knobs  33 ,  35  to hold the metal bar  39  snugly in position in order to provide a reliable electrical connection. As is shown in  FIG. 8 , wires from the nerve stimulator can be connected to the knob  31  and the pivot  37  using alligator clips. 
         [0071]    Referring to  FIG. 8 , at the beginning of the catheter placement procedure, wires  14  and  73  are connected to knobs  33  and  35 . The needle  11  is electrically stimulated. Thereafter, when the catheter  61  is advanced through the needle  11  and placed into position near the target nerve, the anesthesia provider can then switch to catheter stimulation by moving the metal bar  39  from its position against knob  33  to a position against knob  35 . Alternatively, the switch pad  30  may only have knob  37  and knob  31 . Knob  31  provides a grounding connection. The second wire of the nerve stimulator is attached to the knob  37  using an alligator clip. Then the anesthesia provider can switch from needle stimulation to catheter stimulation and vise versa by attaching wires  14  and  73  to the knob  37  in an alternating fashion. 
         [0072]    Other embodiments of the invention comprise a sealing diaphragm around catheter  61 . The sealing diaphragm may be needed if the anesthesia provider wishes to inject liquids like normal saline into the catheter  61 , before the catheter  61  is advanced through the needle  11 , to facilitate catheter  61  advancement within the nerve sheath. In this embodiment, a sealing diaphragm may be provided around the catheter  61  at the level of the hub  67  or the hub  18 . The function of the sealing diaphragm is to prevent liquid from flowing back inside the sheath  68 . The catheter tip is advanced to the position of the needle tip  15 , then liquid is injected into catheter  61  through catheter adaptor to exit from catheter tip and be deposited in the nerve sheath.