Abstract:
A device useful for making retrobulbar injections includes an inner syringe contained within an outer syringe. A spring retained within the outer syringe biases the inner syringe proximally, which a catch mechanism on the two syringes prevents the inner syringe from moving out of the outer syringe. A distal needle on the inner syringe is movable within a distal sheath of the outer syringe, and can be extended beyond the distal end of the sheath to permit the device to piece more resilient tissues, and can be withdrawn by action of the spring within the sheath to protect more delicate tissues from the needle.

Description:
[0001]    This application claims priority under 35 U.S.C. §119 to U.S. provisional application No. 61/504,858, filed 6 Jul. 2011, the entirety of which is incorporated by reference herein. 
     
    
     BACKGROUND 
       [0002]    1. Field of Endeavor 
         [0003]    The present invention relates to devices, systems, and processes useful as injection syringes, and more specifically to syringes useful for making retrobulbar injections. 
         [0004]    2. Brief Description of the Related Art 
         [0005]    Many ophthalmology procedures are performed with a local anesthetic and intravenous sedation. Retrobulbar or peribulbar (behind the eye or adjacent to the eye) injections of local anesthetic are often used for intraocular surgeries, such as cataract extraction, retinal, vitreous, corneal, and pterygium surgeries. Retrobulbar injections are typically performed by placing a 1½ or 1¼ inch needle through the lateral lower lid adjacent to the inferior orbital rim and pushing deep into the orbit. In some cases the needle may be directed superomedially when it is deep in the orbit. This movement is to permit better flow of local anesthetic into the orbital apex. The local anesthetic is injected after the needle is in place. The needle is then withdrawn. The purpose of the local anesthetic is to provide anesthesia and akinesia (prevent movements of the eye which is critical during delicate intraocular surgery). 
         [0006]    Peribulbar injections of local anesthetic involve placing the needle through the lateral lower lid adjacent to inferior orbital rim. However, the needle is not pushed as deep into the orbit as with a retrobulbar injection. 
         [0007]    During these procedures, the surgeon cannot visualize the needle or orbital structures with this technique; that is, the needle is placed blindly. Therefore, vital structures such as the optic nerve, blood vessels, and the eye cannot be avoided. 
         [0008]    Many complications can occur during retrobulbar, and to a lesser extent peribulbar, injections of local anesthetic. A retrobulbar hemorrhage can occur if the needle encounters a blood vessel. A severe retrobulbar hemorrhage can place pressure on the optic nerve and cause blindness. The needle can also puncture the eye which may result in severe visual loss. The needle can also penetrate the optic nerve sheath. The injection of a commonly used anesthetic, bupivicaine, causes respiratory arrest in these cases. 
         [0009]    An effort to avoid these complications has been the use of anesthetic eyedrops alone for cataract extractions. This technique is not possible in patients who are not cooperative and are too anxious. The use of anesthetic eyedrops alone is not possible for long surgeries such as retinal or vitreous surgeries. Retrobulbar anesthesia is still needed for patients who are anxious, unable to cooperate, or for retinal or vitreous surgeries, or corneal transplants. 
         [0010]    An effort to reduce the complications of retrobulbar anesthetic injections is shown with the metal Atkinson retrobulbar needle. This needle is somewhat more rounded at the tip than typical needles used for local anesthetic injections. However, the needle is still sharp and metallic and can cause all of the complications listed above. 
         [0011]    Another problem is that the injection is out the distal end of the needle only. The surgeon must angle the needle toward the optic nerve to make the anesthetic flow toward the orbital apex. This maneuver increases the rate of complications described above. 
         [0012]    Needles are also used during other types of surgery for the injection of local anesthetic. In many procedures, the same syringe and needle are used repeatedly. That is because the local anesthetic effect may dissipate during the procedure, or the surgery may extend to more areas that were not anesthetized by the original injections. In other cases, areas of bleeding require additional injections to allow the epinephrine in the local anesthetic to constrict the blood vessels and stop the bleeding. 
         [0013]    The same needle and syringe are used repeatedly because of the added time (and cost) to obtain a new needle for each of many injections. The cap must be placed on the needle between uses. The needle and syringe must be picked up, placed on a tray, handed from the surgical technician to the surgeon and vice versa, and otherwise handled. All of these maneuvers place the operating personnel at a risk for an accidental needle stick and the transmission of disease such as HIV and hepatitis C. 
         [0014]    There are various safety needles for injections and the placement of intravenous lines available. However, all of these needles and intravenous needles/lines are for a single use only. 
         [0015]    U.S. patent application Ser. No. 12/496,431, filed 1 Jul. 2009, and published as U.S. Patent Application No. 2010/0010468 A1, by Bruce Becker (“&#39;431 application”), the inventor herein, describes several useful and innovative needles and syringes, which is incorporated by reference herein. 
       SUMMARY 
       [0016]    According to a first aspect of the invention, a retrobulbar syringe comprises an inner syringe having a hollow barrel with a proximal end, a distal end, an outer barrel surface, a plunger in the barrel, and a needle attached to the barrel distal end, an outer syringe having a hollow barrel with a proximal end, a distal end, an barrel inner surface, and a sheath attached to the outer syringe barrel distal end, wherein the inner syringe is at least partially contained in the outer syringe barrel, and wherein the needle is at least partially contained and movable in the sheath, a spring inside the outer syringe barrel bearing against the inner syringe and biasing the inner syringe toward the outer syringe proximal end; and a first locking member on the inner syringe barrel outer surface, and a second locking member on the outer syringe barrel inner surface, the first and second locking members being configured and arranged to inhibit the inner syringe from being moved proximally out of the outer syringe barrel. 
         [0017]    According to another aspect of the present invention, a method for inserting a needle into a patient&#39;s orbit, wherein said needle is contained in a sheath and is moveable in and out of said sheath, comprises squeezing two syringes together, including causing a distal tip of the needle to extend out of a distal end of the sheath, pushing said syringes, the needle, and the sheath through the patient&#39;s skin with at least the distal tip of the needle extending out of the distal end of the sheath, stopping said squeezing and allowing the needle tip to retract inside the sheath, pushing said syringes with the needle further into the orbit with the needle retracted inside the sheath, contacting delicate structures of the orbit with a softer distal end of the sheath, and pushing a plunger on an inner syringe of the two syringes and injecting an anesthetic into the orbit. 
         [0018]    According to yet another aspect of the present invention, a method of retracting a needle into a sheath, wherein the needle tip is contained in a proximal higher durometer segment of the sheath, comprises protecting delicate orbital structures from damage by the needle with the proximal portions of the sheath after inserting the needle into a patient&#39;s orbit. 
         [0019]    According to another aspect of the present invention, a method of preventing an inner syringe from detaching from an outer syringe, comprises providing the syringes with rings on the outer surface of the inner syringe on the inner surface of the outer syringe. 
         [0020]    According to another aspect of the present invention, a method of placing an inner syringe into an outer syringe, comprises providing the syringes with rings on the outer surface of the inner syringe and on the inner surface of the outer syringe, the rings each having a triangular cross-section, and placing the inner syringe inside the outer syringe, including pushing oppositely oriented faces of the rings of the inner and outer syringes against each other. 
         [0021]    Still other aspects, features, and attendant advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of embodiments constructed in accordance therewith, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    The invention of the present application will now be described in more detail with reference to exemplary embodiments of the apparatus and method, given only by way of example, and with reference to the accompanying drawings, in which: 
           [0023]      FIG. 1  illustrates a perspective view of an exemplary device with a needle thereof withdrawn proximally of the distal tip of a sheath thereof; and 
           [0024]      FIG. 2  illustrates a perspective view of an exemplary device with a needle thereof extended distally of the distal tip of the sheath thereof. 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0025]    Referring to the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures. 
         [0026]    The &#39;431 application described a retrobulbar needle that protects the delicate structures of the orbit and eye from injury and reduces complications during retrobulbar or peribulbar anesthetic injections. Retrobulbar needles and syringes as described herein accomplish this with a design that is less costly to manufacture. 
         [0027]    As illustrated generally in the  FIGS. 1 and 2 , a first exemplary embodiment of a syringe  10  adhering to principles of the present invention is illustrated. The syringe  10  includes an outer syringe  12  and an inner syringe  14 . The outer syringe  12  is usually a 12 or 10 cc syringe, and the inner syringe  14  is usually a 5 or 6 cc syringe; however, other sizes may be used. A key characteristic is that the inner syringe  14  fits inside the outer syringe  12 . 
         [0028]    The outer syringe  12  has a hollow barrel  18 , typical of syringes, with an open proximal end  16  and a closed distal end  20 . A cannula  22 , having a lumen therein, is attached to the end  20  via a hollow hub  24  in a known manner, and fluidly communicates the interior of the barrel with the exterior of the syringe  10 . The outer syringe  12  also includes a holder or stop  26  formed on the inner surface of the barrel  18 , and extends radially inwards from the barrel. The stop  26  is, in the embodiment of  FIGS. 1 and 2 , formed as a continuous ring; however, in other embodiments, the stop can be a series of one or more discontinuous projections from the inner surface of the barrel. 
         [0029]    The inner syringe  14  is constructed in the manner of a typical, commercially available syringe, except as noted herein, and includes a hollow barrel  28 , a plunger  40  movable in the barrel  28 , a closed distal end  30 , a needle hub  32 , and a hollow, sharpened needle  34  extending distally from the hub and fluidly communicating the interior of the barrel  28  with the exterior of the syringe. The inner syringe includes a catch or stop  36  on the exterior of the barrel  28 , which cooperates with the stop  26  to prevent the inner syringe  14  from moving too far proximally relative to the outer syringe  12 , for the reasons discussed below. As with the stop  26 , the stop  36  is, in the embodiment of  FIGS. 1 and 2 , formed as a continuous ring; however, in other embodiments, the stop  36  can be a series of one or more discontinuous projections from the outer surface of the barrel. A resilient member  38 , in the illustrations embodied as a coil spring, is positioned on the outer surface of the distal end  30  of the inner syringe, and also is positioned against the inner surface of the distal end  20  of the outer syringe  12 . The resilient member  38  is sized and configured so that the inner syringe  14  cannot slide past the member  38 ; when the member  38  is a coil spring, for example, the spring is sized to fit around the hub  32 , but radially smaller than the barrel  28 . 
         [0030]    As described above, the outer syringe  12  has a holder or stop attached to the inside of the barrel. The holder is positioned between the distal and proximal ends of the syringe barrel. In other embodiments, however, it could be positioned at the proximal end of the barrel. The ring usually extends 360 degrees around the inside of the barrel, as is illustrated, but may be less than 360 degrees or have multiple segments. The inner syringe  14  has a catch that is formed on the outside of the barrel. The catch may extend 360 degrees around the barrel or less than 360 degrees, and the catch may have one or more than one segments. According to one exemplary embodiment, the catch is triangular shape when viewed in cross section. The side of the triangle facing the proximal end of the syringe is perpendicular to the syringe barrel. The second side of the triangle is the syringe barrel. The third side of the triangle faces the distal end of the syringe and forms an acute angle with the syringe barrel. The outer diameter of the catch  36  on the inner syringe  14  is slightly greater than the inner diameter of the holder  26  on the outer syringe  12 . During the manufacturing process (after the placement of the spring  38  and needle  34 ), the inner syringe  14  is pushed inside the outer syringe  12  until the inner syringe catch is pushed distal to the outer ring holder. This is possible because the syringes  12 ,  14  are made of material that is slightly flexible. The inner syringe catch is thus permanently kept inside the outer syringe holder because of the shape of the two stops, which keeps the inner syringe from falling out of the outer syringe during usage. 
         [0031]    Prior to placement of the inner syringe  14 , the needle  34  with hub  32  is mounted, e.g., screwed, into the distal end of the inner syringe. The needle  34  usually has a 22 degree beveled end  40  that is less traumatic to tissues than typical needles; however, the needle end may be of any shape. 
         [0032]    Prior to placement of the inner syringe  14  inside the outer syringe  12 , the resilient member  38 , e.g., spring, is placed. The spring has a diameter smaller than the inside diameter of the outer syringe. The spring has a diameter that is large enough to fit over the threaded segment on the distal end of the inner syringe. The inner diameter of the spring is smaller than the outside diameter of the inner syringe barrel. 
         [0033]    The cannula or sheath  22 , with the hub  24  on its proximal end, is mounted, e.g., screwed, into the distal end of the outer syringe  12 . The sheath has a higher Durometer (hardness) proximal end and a lower Durometer distal end. The usual length of the sheath is 1¼ inch but may be shorter or longer. The distal ¼ inch of the sheath is softer that the proximal portions of the sheath, but the length of the distal softer end may be shorter or longer. 
         [0034]    The manufacturing process involves the placement of the needle  34  on the distal end of the inner syringe  14 . The sheath  22  is placed on the distal end of the outer syringe  12  (alternatively, the sheath may be placed on the distal end of the outer syringe as the last step in the manufacturing process). The spring  38  is then placed inside the outer syringe  12 . The inner syringe  14  with the plunger  40  and needle  34  is placed inside the outer syringe  12  and pushed in until the catch  36  on the inner syringe is distal to the holder  26  on the outer syringe. The needle  34  is slid inside the sheath during the placement of the inner syringe into the outer syringe. 
         [0035]    Example of use of the retrobulbar needle and syringe 
         [0036]    With continued reference to  FIGS. 1 and 2  together, the health care professional removes the plunger from the inner syringe. Local anesthetic is squirted or otherwise placed inside the inner syringe. The plunger is placed back into the inner syringe. The syringe is turned with the needle facing up and any air is pushed out the needle by pushing on the plunger. 
         [0037]    The physician grasps the retrobulbar syringe. He pushes on the handle of the inner syringe while placing counter traction on the handle of the outer syringe. This pushes the inner syringe toward the distal end of the outer syringe while compressing the spring. This simultaneously pushes the needle  34  out of the sheath  22 , and more specifically pushes the sharpened distal end of the needle distal of the distal end of the sheath  22 , exposing the distal end of the needle. 
         [0038]    The physician then pushes the syringe and exposed distal end of the needle through the patient&#39;s lower lid, usually temporally adjacent the inferior orbital rim through the lid skin and orbital septum. Alternatively, the needle can be pushed through any part of any lid into the orbit. The sheath around the needle also goes through the lid skin and orbital septum into the orbital fat. The needle is required to penetrate the more resistant skin and orbital septum. The sheath is now in the soft orbital fat. The physician releases the pressure with his fingers on the handles of the syringes. This allows the spring to push the inner syringe proximally relative to the outer syringe. This movement causes the needle to retract into the higher Durometer segment of the sheath. The needle thus cannot harm any orbital or ocular structures when it is completely inside the sheath. 
         [0039]    The syringe and sheath are now pushed deeper into the orbit. Only the soft distal end of the sheath contacts structures inside the orbit (e.g., nerves, blood vessels, muscles) or eye. This prevents harm to these delicate structures. The physician now pushes on the plunger, thus causing the contents of the inner syringe barrel (e.g., local anesthetic) to be injected into the orbit. The syringe and sheath are now removed. 
         [0040]    While the invention has been described in detail with reference to exemplary embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention. The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.