Abstract:
A device for covering and protecting the hollow needle of a prefilled injection syringe, after the syringe has been used to inject a fluid medicament into a patient, includes a guard and a guard body. Prior to an injection, the device is installed on the prefilled injection syringe with the guard body affixed to the finger flange of the syringe. During the injection, the guard of the device retracts over the needle and into the guard body to allow the needle to be inserted into the patient. Upon withdrawal of the needle from the patient, the device passively re-covers the needle, locking the guard over the tip of the needle to prevent accidental needlesticks or inadvertent re-use of the syringe.

Description:
[0001]    This application is a continuation-in-part of application Ser. No. 09/336,405 filed Jun. 18, 1999, which is currently pending. The contents of application Ser. No. 09/336,405 are incorporated herein by reference. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    The present invention pertains generally to syringes for medical use. More particularly, the present invention pertains to protective devices for prefilled injection syringes. The present invention is particularly, but not exclusively, useful for passively covering and protecting the needle of a prefilled injection syringe after the syringe has been used for an injection.  
         BACKGROUND OF THE INVENTION  
         [0003]    Recent research from the Centers for Disease Control and Prevention (CDC) shows that approximately 384,000 needle sticks or similar injuries occur among health care workers in U.S. hospitals each year. Unfortunately, each accidental needle stick has the potential to expose a health care worker to a life-threatening virus such as hepatitis or HIV. In addition to the needle sticks that occur in hospitals, accidental needle sticks can also occur in other health care settings. For example, needle stick injuries can occur at clinics or during home health-care. In fact, some studies have estimated that over 600,000 needle sticks occur in the U.S. each year, and approximately 1,000 of these accidental needle sticks result in a life-threatening infection.  
           [0004]    For each accidental needle stick, health care providers are obligated to test and counsel the exposed worker. Further, follow-up testing for HIV must be conducted approximately six months after the exposure. It is to be appreciated that the costs associated with the testing, lab work, the workers lost time, and the associated tracking and administrative costs, can be considerable.  
           [0005]    Accidental needle sticks can occur in several ways. For example, sudden movement by the patient can cause a health care worker to lose control of a syringe, resulting in injury. Attempts to manually recap a needle after filling the syringe with a medicament or attempts to recap a syringe following an injection can also result in injury. Moreover, injuries often result when contaminated unprotected needles are left unattended or disposed of improperly. In addition to accidental needle sticks, unnecessary exposure to bloodborne pathogens can result when a health care worker mistakenly re-uses a contaminated needle on a patient.  
           [0006]    Prefilled injection syringes (i.e. syringes that are delivered to the health care worker containing a single dose of medicament) are commonly used for vaccines, low molecular weight heparins and many of the new biotechnology drugs. By using a prefilled injection syringe several needle handling steps are eliminated for the health care worker, and the risk of inadvertent re-use is lowered. Even with these advantages, the risk of exposure to a used needle is still presented by prefilled injection syringes.  
           [0007]    In light of the above, it is an object of the present invention to provide a protective device that is installable on a prefilled injection syringe to passively cover and protect the needle of the syringe after the syringe has been used to inject a medicament into a patient. It is another object of the present invention to provide a protective device for a prefilled injection syringe which allows a needle to be installed on the syringe while the needle remains capped to prevent injury during installation. Still another object of the present invention is to provide a protective device for the capped needle of a prefilled injection syringe that allows for accurately located injections by causing a small portion of the needle to be exposed after the protective device is installed and the cap has been removed. It is yet another object of the present invention to provide a protective device that is installable on a prefilled injection syringe to prevent re-use of a contaminated syringe by locking a guard in place over the contaminated needle. Yet another object of the present invention is to provide a protective device for a prefilled injection syringe that is easy to use, relatively simple to implement, and comparatively cost effective.  
         SUMMARY OF THE PREFERRED EMBODIMENTS  
         [0008]    A device for covering and protecting the hollow needle of a prefilled injection syringe, after the syringe has been used to inject a fluid medicament into a patient, includes a guard, a guard body and a coil spring. Prior to an injection, the device is installed on the prefilled injection syringe and affixed to the finger flange of the syringe. During the injection, the guard of the device retracts over the needle allowing the needle to be inserted into the patient. Upon withdrawal of the needle from the patient, the device passively re-covers the needle, locking the guard over the tip of the needle to prevent accidental needlesticks or inadvertent re-use of the syringe.  
           [0009]    For the present invention, the guard body is formed as a hollow cylinder that is large enough to slide over the hollow needle and syringe barrel of the prefilled syringe. A flat is formed at the proximal end of the guard body to seat the guard body against the finger flange of the prefilled syringe. Clips extend from the guard body to hold and lock the guard body against the finger flange of the prefilled syringe. Once the syringe and guard body are locked together, the finger flange of the prefilled syringe becomes covered by the guard body and no longer functions as a finger flange. Consequently, the guard body is formed with a replacement finger flange at the proximal end of the guard body.  
           [0010]    In detail, like the guard body, the guard is formed as a hollow cylinder defining a longitudinal axis. As such, a cylindrical aperture extends through the guard. This allows a needle that is covered by a standard needle cap to be passed through the aperture of the guard. Importantly, the cylindrical guard is sized to allow it to be inserted into the distal end of the guard body. With this combination of structure, the guard body is disposed over the guard allowing reciprocal movement between the guard and guard body. Additionally, a biasing mechanism, such as a spring, is mounted between the guard and the guard body to urge the guard in a distal direction, relative to the guard body.  
           [0011]    An important aspect of the present invention involves the cooperative interaction between the guard and the guard body. To effect this interaction, a plug extends from the guard and into a linear slot that is formed on the guard body. In detail, this linear slot is aligned substantially parallel to the longitudinal axis of the guard body and is formed with a proximal end and a distal end. A latching cut out is formed between the two ends and a locking cut out is formed at the distal end.  
           [0012]    In operation, the device is initially configured with the plug of the guard located in the slot of the guard body at the latching cut out position between the ends of the slot. Next, the capped needle of the prefilled syringe is inserted into the proximal end of the guard body and passed through the aperture of the guard. The insertion of the syringe into the protective device is continued until the finger flange of the syringe contacts the flat formed in the guard body. At this point, the clips formed on the guard body lock the syringe to the guard body. Also, after the syringe has been inserted into the protective device as described above, a relatively short portion of the needle extends distally from the guard. This small extension allows the needle tip to be accurately located on the patient for the injection. The syringe is now ready for injecting the fluid medicament into the patient.  
           [0013]    To perform an injection, the needle is pushed into the body of the patient until the guard contacts the patient. During contact between the guard and the patient, movement of the guard is stopped. Meanwhile, the syringe and guard body can be further translated towards the patient, inserting the needle to the proper penetration depth. Thus, the guard body moves relative to the guard during insertion of the needle. During this movement, the plug is directed from the latching cutout, into the linear track and towards the proximal end of the linear track. Fluid medicament can then be injected into the patient by the syringe.  
           [0014]    After injection of the medicament, the needle is withdrawn from the patient. During the withdrawal of the needle, the syringe and guard body are pulled away from the patient while the guard remains in contact with the body of the patient. Specifically, the spring expands to hold the guard against the patient. Also, during the withdrawal of the needle, the spring expands to translate the plug along the linear slot towards the distal end of the linear slot.  
           [0015]    After the needle is completely withdrawn from the patient, the syringe including the needle are pulled away from the body of the patient. During this movement, the spring continues to expand causing the guard and plug to move distally until the plug reaches the distal end of the slot. When the distal end of the slot is reached, the locking cutout (detent) formed at the distal end of the slot prevents further axial movement of the plug relative to the slot. Stated differently, the locking cutout effectively locks the guard to the guard body and over the hollow needle. Importantly, in this configuration, the guard completely covers the hollow needle to protect against accidental needle sticks or inadvertent re-use. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The novel features of this invention, as well as the invention itself, both as to its structure and its operation, will be best understood from the accompanying drawings, taken in conjunction with the accompanying description, in which similar reference characters refer to similar parts, and in which:  
         [0017]    [0017]FIG. 1 is a perspective view of a protective device in accordance with the present invention installed on a prefilled injection syringe;  
         [0018]    [0018]FIG. 2 is an exploded sectional view of a protective device in accordance with the present invention together with a prefilled injection syringe as seen along line  2 - 2  in FIG. 1;  
         [0019]    [0019]FIG. 3 is a sectional view (enlarged for clarity) of the proximal end of a guard as seen along line  3 - 3  in FIG. 2 showing a pair of tabs that extend radially to limit rotation of the guard relative to the guard body after the completion of an injection;  
         [0020]    [0020]FIG. 4 is a sectional view (enlarged for clarity) of the distal end of a guard body as seen along line  4 - 4  in FIG. 2 showing a pair of grooves formed in the inner wall of the guard body that interact with the tabs of the guard to limit rotation of the guard relative to the guard body after the completion of an injection;  
         [0021]    [0021]FIG. 5A is a plan view of a protective device in accordance with the present invention after installation onto a prefilled injection syringe having a capped needle;  
         [0022]    [0022]FIG. 5B is a plan view of a protective device as shown in FIG. 5A after removal of the needle cap;  
         [0023]    [0023]FIG. 5C is a plan view of a protective device as shown in FIG. 5B after the needle of the prefilled syringe has been inserted into the body of a patient to the proper depth for an injection; and  
         [0024]    [0024]FIG. 5D is a plan view of a protective device as shown in FIG. 5C after the needle of the prefilled syringe has been withdrawn from the body of a patient. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0025]    Referring initially to FIG. 1, a protective device  10  in accordance with the present invention is shown installed on a prefilled injection syringe  12 . As shown, the device  10  includes a guard  14 , a guard body  16  and a coil spring  18 . With cross reference to FIGS. 1 and 2, it can be seen that the device  10  can be installed onto the prefilled injection syringe  12  while the cap  20  of the syringe  12  remains in place.  
         [0026]    Referring now to FIG. 2, an exemplary prefilled injection syringe  12  for use with the present invention is shown. As shown, the prefilled syringe  12  includes a hollow needle  22  mounted on a syringe barrel  24 . A finger flange  26  is formed at the proximal end of the syringe  12  to aid in depressing the plunger  28  of the syringe  12 . Further, it is to be appreciated that the prefilled syringe  12  includes a single dose of medicament that is generally placed in the syringe  12  prior to delivering the syringe  12  to the point of use. Further, needle  22  of the prefilled syringe  12  is generally covered with a protective cap  20  immediately after the filling of the syringe  12  with medicament to protect the needle  22  during handling prior to use.  
         [0027]    Referring still to FIG. 2, it can be seen that the guard body  16  is formed with as a hollow cylinder, open at both its proximal and distal ends. For the present invention, as shown, the guard body  16  is sized large enough to be slid over the hollow needle  22  and syringe barrel  24  of the prefilled syringe  12 . As shown, a flat  30  is formed at the proximal end of the guard body  16  to allow the finger flange  26  of the prefilled syringe  12  to seat against the guard body  16 . Clips  32   a, b  extend from the guard body  16  to hold and lock the guard body  16  against the finger flange  26  of the prefilled syringe  12  when the device  10  is installed on the prefilled syringe  12 . As shown, a beveled surface on each clip  32   a, b  allows the finger flange  26  to pass the clips  32   a, b  and a slot on the flat  30 . As further shown, a replacement finger flange  34  is formed at the proximal end of the guard body  16  to aid in depressing the plunger  28  during an injection. As shown in FIG. 1, once the syringe  12  and guard body  16  are locked together, the finger flange  26  of the prefilled syringe  12  is no longer functional as a finger flange.  
         [0028]    Referring back to FIG. 2, it can be seen that the guard  14  is also formed as a hollow cylinder defining a longitudinal axis  36 . As shown, a substantially cylindrical aperture  38  extends through the guard  14  sized large enough to allow the cap  20  of the syringe  12  to be passed through the aperture  38 . Preferably, the distal end of the guard  14  is tapered, as shown. Importantly, the cylindrical guard  14  is sized to allow the guard  14  to be inserted into the distal end of the guard body  16 . With this combination of structure, the guard body  16  can be disposed over the guard  14  allowing reciprocal movement between the guard  14  and guard body  16 , as shown in FIG. 1.  
         [0029]    Referring back to FIG. 2, a coil spring  18  is provided for the device  10  to urge the guard  14  in a distal direction, relative to the guard body  16 . As shown, the spring  18  is sized to allow for insertion of the spring  18  into the distal end of the guard body  16 . A ledge  40  is formed in the guard body  16  to seat the proximal end of the spring  18 . As shown, the distal end of the spring  18  seats against the edge of the guard at the proximal end of the guard  14 .  
         [0030]    Referring now with cross reference to FIGS. 1 and 2, it can be seen that the guard  14  is formed with a pair of substantially identical plugs  42   a, b  extending outwardly from the axis  36 . Further, the guard body  16  is formed with a pair of substantially identical linear slots  44   a, b  that each extend through the cylindrical wall of the guard body  16 . As shown, the guard  14  can be disposed within the guard body  16 , with each plug  42  inserted into a respective slot  44 . Specifically, the distal end of the guard can be deformed slightly and then pressed into the proximal end of the guard body. As shown, each linear slot  44  is aligned substantially parallel to the longitudinal axis  36  and is formed with a proximal end  46  and a distal end  48 . Further, each slot  44  is formed with a latching cutout  50  positioned between the proximal end  46  and the distal end  48 , and a locking cutout  52  positioned at the distal end  48 .  
         [0031]    Referring now with cross reference to FIGS. 2 and 3, it can be seen that the proximal end of a guard  14  is formed with a pair of tabs  54   a, b  that extend outwardly from the axis  36 . Further, with cross reference to FIGS. 2 and 4, it can be seen that the distal end of the guard body  16  is formed with a pair of grooves  56   a, b  that extend into the inner wall of the cylindrical guard body  16 . The tabs  54  and grooves  56  are positioned on the guard  14  and guard body  16  so that when the plugs  42  of the guard  14  are positioned in the locking cutouts  52  of the slots  44 , the tabs  54  will each be inserted into a respective groove  56 . It is to be appreciated that when the tabs  54  are inserted into the grooves  56  they will limit rotation of the guard  14  relative to the guard body  16 .  
         [0032]    The operation of the device  10  can best be appreciated with reference to FIGS.  5 A-D. FIG. 5A shows that in accordance with the present invention, the device  10  is initially configured with the plugs  42  of the guard  14  located in the slots  44  of the guard body  16  and positioned at the latching cutout  50 . While the device  10  is in this configuration, the distal end of the prefilled syringe  12  (with cap  20  installed) is inserted into the proximal end of the guard body  16  until the cap  20  extends distally from the guard  14 . FIG. 5B shows the device  10  installed on the syringe  12  after removal of the cap  20 . As shown, after removal of the cap  20 , a small portion (tip) of needle  22  extends distally from the guard  14 . This small extension allows the tip of the needle  22  to be accurately located on the patient for the injection.  
         [0033]    Next, as shown in FIG. 5C, the needle  22  is inserted into the body of the patient  58  until the guard  14  contacts the patient  58 . The syringe  12  and guard body  16  can be further translated towards the patient  58 , inserting the needle  22  to the proper penetration depth. Thus, the guard body  16  moves relative to the guard  14  during insertion of the needle  22  into the patient  58 . By cross referencing FIGS. 5B and 5C it can be seen that during the penetration of the patient  58  with the needle  22 , the plugs  42  are directed from the latching cutouts  50 , into the linear track of the slots  44  and towards the proximal end  46  of each linear track. Once the needle  22  is inserted into the patient  58  at the proper depth, fluid medicament can be injected into the patient  58  by depressing the plunger  28  of the syringe  12 .  
         [0034]    With cross reference to FIGS. 5C and 5D, it can be seen that during the withdrawal of the needle  22  from the patient  58 , the needle  22 , guard body  16  and syringe  12  move in a proximal direction relative to the guard  14 . Specifically, the spring  18  (shown in FIG. 2) expands to hold the guard  14  against the patient  58  while the needle  22  is withdrawn. During the withdrawal of the needle  22  from the patient  58 , the spring  18  (shown in FIG. 2) expands to translate the plugs  42  along the linear slots  44  towards the distal end  48  of the linear slots  44 .  
         [0035]    After the needle  22  is completely withdrawn from the patient  58 , the syringe  12  and the needle  22  are pulled away from the body of the patient  58 . During this movement, the spring  18  (shown in FIG. 2) continues to expand causing the guard  14  and plugs  42  to move distally until the plugs  42   a, b  reach the distal end  48  of each slot  44   a, b . At the distal end  48  of the slots  44 , a guide ramp  60  formed in each slot  44  causes the plug  42  to move azimuthally (with respect to the axis  36 ) and axially into the locking cutout  52 . Thus, the guard  14  rotates relative to the guard body  16  as the plugs  42  move from the linear portion of each slot  44  into the locking cutout  52 . This rotation allows the tabs  54  (shown in FIG. 3) formed in the proximal end of the guard  14  to insert into the grooves  56  (shown in FIG. 4) formed in the distal end of the guard body  16 . Accordingly, when the plug  42  is in the locking cutout  52 , as shown in FIG. 5D, axial movement of the guard  14  relative to guard body  16  and syringe  12  is blocked by the locking cutout  52  while rotational movement of the guard  14  relative to guard body  16  and syringe  12  is blocked by the interaction of the tabs  54  and grooves  56 . Importantly, in this configuration, the guard  14  is locked over the hollow needle  22  of the syringe  12  to protect against accidental needle sticks or inadvertent re-use.  
         [0036]    While the particular devices and methods as herein shown and disclosed in detail are fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that they are merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.