Abstract:
The present invention relates to syringes. The syringe of the present invention is provided with a plastics material body moulded around a needle. The syringe provides particular advantage being used for the injection of local analgesia for dentistry or surgical procedures. The syringe of the present invention is intended to be a single use, disposable syringe to help combat the problems of needle stick injury.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to syringes.  
       BACKGROUND OF THE INVENTION  
       [0002]     “Needle Stick Injury” is a problem associated with the use of syringes for medical purposes. It occurs when the person administering treatment to a patient with such a syringe is inadvertently “stuck” by the needle after it has been used on the patient.  
         [0003]     Such injuries can transmit infections from patient to user; including HIV, Hepatitis A, Hepatitis B, Hepatitis C and new variant CJD.  
         [0004]     Some state of the art syringes are reusable, and include a removable needle which fixes to the syringe, usually either by a screw thread or a bayonet fixing. This is particularly common with “dental” syringes which are of slim shape and use narrow glass or plastic vials of active material. Although the syringes themselves are reused, the needles are not and are thrown away after use into a specialised disposal unit, referred to as a “sharps” container or bin, for careful disposal.  
         [0000]     Needle Stick Injury is often likely to occur when the needle is being removed from the syringe for disposal in such a sharps box.  
         [0005]     Other known syringes are disposable but are not adapted for use with pre-filled vials. Disposbale syringes in common are supplied without needles, which must be attached by the user and are normally detached after use for disposal in a sharps container.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the present invention there is provided a syringe comprising a body and a needle, the body being moulded around the needle.  
         [0007]     Preferably the body is formed from a plastics material. The plastics material may be ABS (Acrylonitrile-Butadiene-Styrene) or other such material suitable for the moulding process.  
         [0008]     Preferably the syringe further includes a chamber within the body adapted to receive a vial of anaesthetic, drug or other substance for injecting into a patient.  
         [0009]     Preferably a portion of the needle projects into the chamber. The portion of the needle within the chamber punctures the seal of a vial when placed within said chamber, to allow the contents of the vial to be injected through the needle and into a patient.  
         [0010]     Preferably there is also provided a plunger co-operable with the body and chamber, and in use is co-operable with a vial stopper of a vial.  
         [0011]     Preferably the plunger is provided with a finger grip at one end and at the distal end there is provided a plunger tip, the plunger tip being adapted to engage with a vial stopper. In this way the plunger may be used to aspirate with the syringe in addition to injecting. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     An embodiment of the present invention will now be described, by way of example only, with reference to the following drawings, in which:  
         [0013]      FIG. 1  is a perspective view of a syringe according to the present invention;  
         [0014]      FIG. 2  is a perspective view of an aspirating plunger of the syringe of  FIG. 1 ;  
         [0015]      FIG. 3  is a detail view of the tip of the plunger of  FIG. 2 ;  
         [0016]      FIG. 4  is a perspective view of a non-aspirating plunger compatible with the syringe of  FIG. 1 ;  
         [0017]      FIG. 5  is a perspective view of the needle of the syringe of  FIG. 1 ;  
         [0018]      FIG. 6  is a perspective view of a breech plug of the syringe of  FIG. 1 ;  
         [0019]      FIG. 7  is a detail view of a vial of anaesthetic for use in the syringe of  FIG. 1 ; and  
         [0020]      FIG. 8  is a perspective view in section of a stopper of the vial of  FIG. 7 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]     Referring to the drawings and initially to  FIG. 1  there is shown a syringe according to the present invention referred to by the reference number  10 .  
         [0022]     The syringe  10  comprises a body  12 , a breech plug  14  and a plunger  16 . Integral to the body  12  and extending from one end of it is a hollow needle  18 .  
         [0023]     The body  12  is formed from ABS (Acrylonitrile-Butadiene-Styrene) resin, which is moulded to form the shape. The needle  18  is moulded within the body  12  extending between a central vial-holding chamber  12   a  through the nose  12   b  of the body  12  to the exterior of the body  12 .  
         [0024]     The vial-holding chamber  12   a  extends within the body  12  for the majority of the body&#39;s length and is divided into two sections. The first section, nearest the needle  18 , is partially open so that in use the user can easily monitor the level of a substance within a vial placed in the chamber  12   a . For that purpose, the two legs  12   d  which define the first section of the chamber  12   a  may include a graduated scale.  
         [0025]     The second section is located at the opposite side of the first section to the needle  18 , and is a simple bore through the body  12 .  
         [0026]     Two finger grips  20  are provided on the body  12 , adjacent the second section of the chamber  12   a . The finger grips  20  are formed as loop-shaped lugs on either side of the body  12 . As the finger grips  20  are formed as loops, this aids the user in keeping a firm grip on the syringe  10 .  
         [0027]     A breech plug  14  is also provided which fits into an initial portion of the second section of the chamber  12   a . Detail of the breech plug  14  is shown in  FIG. 6 .  
         [0028]     The breech plug  14  is also formed from ABS and includes a central bore  14   a  running through it. The breech plug  14  has a circular cross-section portion  14   b  that fits into the initial portion of the second section of the chamber  12   a . The breech plug  14  also has a square cross-section portion  14   c . The central bore  14   a  runs through both of these sections. In this embodiment, the body  12  and breech plug  14  have co-operating locking means to lock the breech plug  14  securely to the body  12  when the syringe  10  is in use, but permit the breech plug  14  to be removed from the body  12  when necessary. The locking means is provided by a simple projection  12   c  and L-shaped slot  14   d , the projection  12   c  being provided on the body  12  with the L-shaped slot  14   d  being provided on the square cross section portion  14   c . It will be understood that the locking means may be omitted without departing from the scope of the present invention.  
         [0029]     An aspirating plunger  16  is also provided, detail of which is shown in  FIG. 2 . The aspirating plunger  16  comprises a central stem  16   a  with a finger grip  16   b  provided at one end of the stem  16   a . The finger grip  16   b  is also formed as a loop.  
         [0030]     At the other end of the stem  16   a  from the finger grip  16   b  there is provided a vial-engaging tip  16   c , shown in greater detail in  FIG. 3 .  
         [0031]     The vial-engaging tip  16   c  is formed from three sections. The first section  16   d  is frusto-conical in shape, and tapers from the diameter of the stem  16   a  to a lesser diameter. The second section  16   e  follows on from the first section  16   d  and is a short cylindrical section which leads to the third section  16   f , a flange of greater diameter than the second section  16   e  but of lesser diameter than the stem  16   a.    
         [0032]     A non-aspirating plunger  116  is shown in  FIG. 4 , compatible with the syringe  10 . This non-aspirating plunger  116  differs from the plunger  16  in that there is no vial-engaging tip  16   c.    
         [0033]     Referring to  FIG. 5  there is shown detail of the hollow needle  18 . The hollow needle  18  includes a long needle section  18   a , a short needle section  18   b  and a cube section  18   c.    
         [0034]     When the needle  18  is moulded within the body  12 , the long needle section  18   a  projects out from the body  12  for insertion into a patient. The short needle section  18   b  projects into the vial-holding chamber  12   a . The cube section  18   c  is located within the nose  12   b  of the body  12 . The shape of the cube section  18   c  assists the fixing of the needle  18  in place within the body  12  and impedes movement of the needle  18  within the moulded body  12 .  
         [0035]     In use, the user removes the breech plug  14  by twisting it so that the projection  12   c  is disengaged from the L-shaped slot  14   d . The breech plug  14  can then be removed from the body  12  along with the plunger  16 .  
         [0036]     A vial  28  is inserted into the vial-holding chamber  12   a . The sealed lid end (not shown) of the vial  28  is inserted first and is pushed through into the chamber  12   a . The breech plug  14  is reattached to the body  12  and locked into place. The dimensions of the breech plug  14  and the action of reattaching forces the short needle section  18   b  to penetrate the sealed lid of the vial  28 .  
         [0037]     A plunger  16  or  116  can be fed through the breech plug  14  to engage a vial stopper  30  (see  FIGS. 7 and 8 ). The vial stopper  30  depicted in  FIGS. 7 and 8  has a conical bore  32  within it. Detail of the conical bore  32  can be seen in  FIG. 8 .  
         [0038]     With the aspirating plunger  16 , the plunger tip  16   c  is inserted into the conical bore  32 . The flange  16   f  is slightly wider than the initial section of the conical bore  32 , but since the vial stopper  30  is formed from a resilient material, the user can force the flange  16   f  into the conical bore  32 . Once the plunger tip  16   c  is engaged with the vial plunger  30 , the user is then able to inject by forcing the vial plunger  30  toward the nose  12   b  of the body  12  or can aspirate by pulling the vial plunger  30  away from the nose  12   b . The ability to aspirate as well as inject allows the user to ensure that the long needle section  18   a  is correctly placed within the patient. If, for example, the syringe  10  is being used to inject a local anaesthetic into a patient it can be dangerous to inject a local anaesthetic into a blood vessel as this can cause bradycardia, slowing of the heart rate.  
         [0039]     For situations where the ability to aspirate is not needed, a non-aspirating plunger  116  can be used instead of a plunger  16 . The non-aspirating plunger  116  does not engage the vial stopper  30 , but simply pushes against it, forcing it toward the needle  18  in use. Drawing the non-aspirating plunger  116  out of the vial chamber  12   a  does not aspirate, since the non-aspirating plunger  116  does not draw the vial stopper  30  back along the vial  28  from the needle  18 .  
         [0040]     Since the syringe  10  is made from a relatively inexpensive material, the present invention finds particular advantage as a single use or single patient (i.e. used several times but only with the one patient) device. After use, the entire syringe  10  can be disposed of without the user having to remove the needle  18  from the body  12 .  
         [0041]     The embodiment of present invention described herein also provides particular advantage when used for the injection of local analgesia for dentistry or cervical procedures, such as LLETZ (Large Loop Excision of the Transformation Zone), cold coagulation, etc, particularly due to its relatively slim profile (the body is approximately 10 mm in diameter).  
         [0042]     In prior art metal syringes where the syringe body is reprocessed after use, there is a tendency for the syringe to wear and slightly deform. In syringes that have been used many times, this can lead to a vial breaking within the vial chamber because of misalignment between plunger and body. The relatively short lifetime of the present invention mitigates this tendency.  
         [0043]     Modifications are envisaged to the present invention which do not depart from its scope. In addition to the graduated scale on the legs  12   d , a collar made of rubber, foam or other suitable material may be provided in the vial chamber  12   a  to help locate the vial within the vial chamber.  
         [0044]     It is to be understood that the present invention is not limited to the embodiment described herein, but may be further modified in both construction and detail.