Abstract:
A device for expelling a fluid through a needle mounted on a hub includes an elongated luer member that has a distal portion dimensioned to engage the needle hub to provide fluid communication between the luer member and the needle. An adapter anchors the luer member within the device. Slidingly mounted on the adapter is a cylindrical-shaped inverted plunger that is movable thereon between an advanced position and a withdrawn position. A needle guard is biased by a biasing member to extend distally from the luer member when the plunger is in the advanced position. The guard is selectively engageable with the plunger to be retracted to expose the distal portion of the luer member for fluid engagement with the needle hub when the plunger is moved to the withdrawn position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/505,015, “Syringe Guard with Selected Needle Configurations”, filed on Jul. 17, 2009, now U.S. Pat. No. 8,246,599, which is a continuation of U.S. patent application Ser. No. 11/055,415, “Syringe Guard with Selected Needle Configurations”, filed on Feb. 10, 2005, issued as U.S. Pat. No. 7,666,168, which is a continuation-in-part of U.S. patent application Ser. No. 10/983,108, “Passively Guarded, Fillable Injection Syringe”, filed on Nov. 5, 2004, issued as U.S. Pat. No. 7,198,617. This application hereby expressly incorporates by reference herein the entire disclosures of each of the above-listed prior applications. 
    
    
     FIELD OF THE INVENTION 
     The present invention pertains generally to devices for providing injections with needles. More particularly, the present invention pertains to protective devices for receiving needles prior to the administration of an injection. The present invention is particularly, but not exclusively, useful for passively covering and protecting the needle of an injection syringe after its use. 
     BACKGROUND OF THE INVENTION 
     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. 
     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 worker&#39;s lost time, and the associated tracking and administrative costs, can be considerable. 
     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 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 reuses a contaminated needle on a patient. 
     One particular type of syringe that is prone to needle stick injuries is the fillable injection syringe. In overview, these fillable injection syringes are designed to be filled with a medicament from a medicament vial by the same user that administers an injection. Heretofore, a typical procedure has involved removing a cap that covers the sharp needle tip of the fillable injection syringe. With the needle exposed, the needle tip is inserted into a vial containing medicament. This step generally occurs just prior to an injection. Next, the plunger is depressed to void the syringe chamber of air. With the syringe voided, the plunger is retracted to draw a specified quantity of medicament into the syringe chamber. Once the medicament has been loaded into the syringe, the needle is then inserted into a patient and the plunger is depressed to inject the medicament into the patient. After the injection, the needle is removed from the patient and often must be manually recapped to protect the contaminated needle. After recapping, it is often difficult to distinguish between used and unused syringes. 
     Fillable injection syringes and needles are often obtained separately. Typically, the syringes are available for use with different sized needles. This allows doctors to obtain and store fewer syringes. Then, when an injection is needed, a desired needle is simply mounted on a syringe. 
     In light of the above, it is an object of the present invention to provide a device that passively covers and protects a needle after first filling the device with medicament and then injecting the medicament into a patient. It is another object of the present invention to provide a device which guards the needle prior to an injection procedure and uses the same guard to passively guard the needle after an injection procedure. It is still another object of the present invention to provide a device in which the position of the needle guard is controlled and regulated by plunger movements that are required in a typical fill and inject procedure. It is yet another object of the present invention to provide a device having an integral mechanism that prevents reuse of the syringe (after use and contamination) by disabling the plunger at the completion of an injection procedure. Still another object of the present invention is to provide such a device for use with commercially available needles. Still another object of the invention is to provide a device with a needle guard that is movable to allow mounting of a needle on the device before use. Yet another object of the present invention is to provide a protective device for a medical syringe that is easy to use, relatively simple to implement, and comparatively cost effective. 
     SUMMARY OF THE INVENTION 
     A device for expelling a fluid, such as a medicament, through a hypodermic needle mounted on a hub includes an extended luer member that has a proximal portion, a distal portion and a fluid conduit extending along an axis therebetween. The distal portion of the extended luer member is dimensioned to engage the needle hub to provide fluid communication between the fluid conduit and the needle. When engaged, the needle extends away from the distal portion of the luer member to a sharp needle tip at its own distal end. Additionally, the device includes an adapter for anchoring the proximal portion of the luer member. The adapter includes a substantially cylindrical-shaped wall surrounding a cavity bounded by an open distal end and a proximal end substantially covered by a base. Slidingly mounted on the adapter is a cylindrical-shaped inverted plunger that is movable thereon between an advanced position and a withdrawn position. When the plunger is in the withdrawn position, a fluid chamber is created between the plunger and the adapter base. Specifically, the chamber is formed by a seal engaging the proximal portion of the luer member which is slidingly received by the plunger to form a fluid tight boundary for the fluid chamber. For the present invention, a tube-shaped needle guard having a lumen is biased by a biasing member such as a spring to extend distally from the distal portion of the luer member when the plunger is in the advanced position. The guard is selectively engageable with the plunger to be retracted into the adapter cavity and over the elongated luer member to expose the distal portion of the luer member for fluid engagement with the needle hub when the plunger is moved to the withdrawn position. 
     In greater structural detail, the luer member includes a head section that engages the adapter. The head section is connected to a shaft section which extends distally from the head section along the axis to a shaft end that is spaced from the head section by a shaft length that is at least as long as the length of the adapter. Therefore, the luer member extends through the cavity and the open distal end of the adapter. As the extremity of the distal portion of the luer member, the shaft end is dimensioned for engagement with the needle hub. Engagement between the needle hub and shaft end may be achieved through a number of known methods. For instance, the needle hub may include a circumferential protrusion that fits into a corresponding circular groove on the shaft end. Alternatively, the needle hub may include male or female threadings to allow the hub to be screwed into reciprocal threadings on the shaft end. Or, more simply, the needle hub may be slipped snugly onto the shaft end. 
     As described in greater detail below, a mechanism provides selective engagement between the plunger and guard during the course of an injection procedure. More specifically, the plunger movements that are required to expose the distal portion of the extended luer member for mounting a needle thereon, to fill the fluid chamber, and to dispense a fluid from the fluid chamber also function to control the position of the guard. In functional overview, prior to an injection procedure, the guard is locked in an extended position distal of the luer member and can only be unlocked by a movement of the plunger. Once unlocked, the guard can be retracted to expose the distal portion of the luer member. This allows the needle hub to be mounted on the distal portion of the luer member, and in addition, allows the needle to be inserted into a medicament vial to fill the fluid chamber and to be inserted into a patient for an injection. When the plunger is withdrawn proximally relative to the adapter to create the fluid chamber, the plunger and guard engage one another, and the guard moves proximally to expose the distal portion of the luer member and a needle mounted thereon. On the other hand, when the plunger is advanced (i.e. moved distally), the plunger releases the guard. Once released, the guard is free to move distally under the influence of the spring. As a consequence of this interaction, after the plunger is depressed to complete an injection, the guard is released and allowed to move distally to its extended position to cover and protect the needle. 
     In operation, the plunger is initially located in an advanced position relative to the adapter. Next, the plunger is withdrawn proximally which causes the plunger to engage the guard and to move the guard proximally with the plunger to a retracted position. With the guard retracted, the next step is to mount the needle hub onto the exposed shaft end of the luer member. Then the distal tip of the needle may be inserted into a medicament vial. At this point, the plunger can be depressed to expel air into the vial and void the fluid chamber. During plunger advancement, the plunger operatively disengages the guard. Thus, distal movement of the guard is only prevented by the contact between the guard and the vial. Next, the plunger can be withdrawn to fill the fluid chamber with medicament. During this plunger withdrawal, the plunger again engages and retracts the guard. Thus, when the needle is removed from the vial, the distal tip of the needle remains unguarded and exposed. The syringe is now ready for an injection. 
     To inject a medicament into a patient, the distal tip of the needle is inserted into the patient and the plunger depressed. This distal advancement of the plunger releases the guard. Once released, the guard is free to move distally under the influence of the spring. Thus, as the needle is withdrawn from the patient, the needle retracts proximally into the guard, which remains in contact with the patient&#39;s skin. Once the syringe has been removed from the patient, the plunger and adapter can be advanced distally relative to the syringe body to lock the guard in place. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a perspective view of a device for expelling a fluid through a hypodermic needle mounted on a hub, shown in its initial configuration; 
         FIG. 2  is a perspective view of a hypodermic needle mounted on a hub for use with the device of  FIG. 1 ; 
         FIG. 3A  is a sectional view of the syringe as seen along line  3 - 3  in  FIG. 1 , shown after a needle has been mounted on the luer member and with the guard locked over the needle&#39;s distal tip; 
         FIG. 3B  is a sectional view of the syringe as in  FIG. 3A , shown after a plunger movement has unlocked and distally retracted the guard; 
         FIG. 3C  is a sectional view of the syringe as in  FIG. 3A , shown after the needle&#39;s distal tip has been inserted into an object (i.e. medicament vial or patient) and thereafter the plunger has been advanced proximally; 
         FIG. 3D  is a sectional view of the syringe as in  FIG. 3A , shown after the plunger and adapter have been advanced distally relative to the syringe body to lock the guard in position and prevent inadvertent reuse of the syringe; 
         FIG. 4A  is a sectional view of the syringe as seen along line  4 - 4  in  FIG. 1 , shown after a needle has been mounted on the luer member and with the guard locked over the needle&#39;s distal tip; 
         FIG. 4B  is a sectional view of the syringe as in  FIG. 3A , shown after a plunger movement has unlocked and distally retracted the guard; 
         FIG. 4C  is a sectional view of the syringe as in  FIG. 3A , shown after the needle&#39;s distal tip has been inserted into an object (i.e. medicament vial or patient) and thereafter the plunger has been advanced proximally; and 
         FIG. 4D  is a sectional view of the syringe as in  FIG. 3A , shown after the plunger and adapter have been advanced distally relative to the syringe body to lock the guard in position and prevent inadvertent reuse of the syringe. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to  FIG. 1 , a syringe device for expelling a fluid through a needle mounted on a hub is shown and generally designated  10 . As shown in  FIG. 1 , the device  10  includes a substantially cylindrical syringe body  12  that is centered on an axis  14  and formed with a finger grip  16  at its proximal end.  FIG. 1  further shows that the device  10  includes an adapter  18  sized to fit within the syringe body  12 . The adapter  18  includes a cylindrical portion that is also centered on the axis  14 . For the device  10 , a substantially cylindrical needle guard  20  is provided and positioned co-axially with both the syringe body  12  and adapter  18 . The guard  20  is sized to fit within the adapter  18 . It can be further seen that the device  10  includes a plunger  22  that is formed with a grip flange  24  at its proximal end. 
     Referring to  FIG. 2 , a straight, elongated hypodermic needle  26  is shown extending from a sharp needle tip  28  to a needle hub  30 . As best seen in  FIG. 3A , the needle  26  may be mounted to the passively guarded, fillable injection device  10 . Specifically, the device  10  includes a luer member  32  that receives and engages the needle hub  30 . The luer member  32  has a proximal portion or head  34 . Extending distally from the head  34  is a substantially cylindrical shaft  36  centered on the axis  14 . The needle hub  30  is mounted to the luer member  32  at the shaft&#39;s distal portion or distal shaft end  38 . Additionally, the head  34  has a proximal side  33  and a distal side  35  that engages the adapter  18 . Circumferentially-spaced truss-like webs  40  are provided on the luer member  32  to reinforce the connection between the shaft  36  and the head  34 . Furthermore, the luer member  32  includes a pipe-like conduit  39  that extends from the proximal side  33  of the head  34  to the shaft end  38 . When the needle hub  30  is frictionally mounted on the shaft end  38 , the needle hub  30  and luer member  32  are sealed together to establish fluid communication between the needle  26  and the conduit  39 . 
     As shown in  FIG. 3A , the adapter  18  engages the luer member  32  about the webs  40  thereby preventing rotational movement therebetween. The adapter  18  includes a substantially cylindrical wall  42  that is centered on the axis  14  and forms a cavity  43 . The wall  42  extends from a proximal end  44  substantially covered by a base  45  to an open distal end  46 . At its proximal end  44 , the adapter  18  has a narrow circumference and is designed to engage the distal side  35  of the head  34  of the luer member  32 . At its distal end  46 , the adapter  18  has a broad circumference and is designed to engage the plunger  22  and receive the guard  20 . As can be seen in  FIG. 3A , the adapter  18  also includes two oppositely positioned, axially aligned slits  48 . 
     As best seen in  FIG. 3A , the adapter  18  is sized to allow the cylindrical guard  20  to move along the axis  14  into and out of the adapter cavity  43 . Specifically, the guard  20  may be moved between an extended position  49  (shown in  FIGS. 3A and 4A ) to a retracted position  53  (shown in  FIGS. 3B and 4B ). Structurally, the guard  20  is a shell forming a lumen  51  that extends between an open proximal end  50  and an open distal end  52 . The guard  20  includes abutments  54  that extend radially outward from the proximal end  50 . 
     Also in  FIG. 3A , it can be seen that the inverted plunger  22  has a substantially cylindrical side member  56  that extends from a closed proximal plate member  58  to an open distal edge  60 . Structurally, the cylindrical side member  56  surrounds a fluid chamber  62  and is slidingly mounted on the proximal end  44  of the adapter  18 .  FIG. 3A  further shows that the plunger  22  is formed with tangs  64  that extend radially inward (i.e. toward the axis  14 ) and distally from the cylindrical side member  56  of the plunger  22 . 
     It can be seen in  FIG. 3A , that the device  10  includes an elastomeric seal  66  that is attached onto the proximal end  34  of the luer member  32 . Specifically, the seal  66  is press fitted onto the proximal end  34  of the luer member  32 . As shown, the seal  66  has a generally fusiform or spindle-like shape and is formed with a through-hole  68 . When the open distal edge  60  of the plunger  22  is slid over the luer member  32  and adapter  18 , the seal  66  compresses between the luer member  32  and the cylindrical side member  56  of the plunger  22  to establish sealed fluid communication between the fluid chamber  62  and the conduit  39  of the luer member  32 . When the needle hub  30  is mounted on the luer member  32  to establish fluid communication between the needle  26  and the conduit  39 , the plunger  22  can be moved to a withdrawn position  61  (shown in  FIGS. 3B and 4B ) to draw fluid through the needle  26  and into the chamber  62 . Furthermore, the plunger  22  can be moved to an advanced position  63  (shown in  FIGS. 3C and 4C ) to expel fluid from the chamber  62  through the needle tip  28 . 
     As further shown in  FIG. 3A , the syringe body  12  extends from an open proximal end  70  to an open distal end  71 . Positioned at the proximal end  70 , the finger grip  16  includes a recess  72  sized to receive the grip flange  24  of the plunger  22 . Functionally, the plunger  22  can be advanced distally after an injection until the grip flange  24  is positioned in the recess  72 . Once the grip flange  24  is positioned in the recess  72  it cannot be removed; therefore, subsequent movement of the plunger  22  relative to the syringe body  12  is effectively prevented. 
     Turning to  FIG. 4A , other features of the device  10  may be seen. Specifically, the adapter  18  is shown having cam levers  74  positioned at its distal end  46 . The cam levers  74  are in a biased position  76  in which the plunger  22  forces them to be coincident with the rest of the cylindrical wall  42 . However, the cam levers  74  mechanically prefer a relaxed position  78  (shown in  FIG. 4B ) in which the distal ends  80  of the cam lever  74  extend radially outward from the cylindrical wall  42 . 
     As shown in  FIG. 4A , the guard  20  has hinges  82 . Similar to the cam levers  74  of the adapter  18 , the hinges  82  of the guard  20  have a relaxed position  84  in which the proximal ends  86  of the hinges  82  extend radially outward from the rest of the guard  20 . The biased position  88  of the hinges  82  is shown in  FIG. 4B . 
     As further shown in  FIG. 4A , the syringe body  12  can also include flanges  90  at its distal end  71 . The flanges  90  extend distally and radially inward from the cylindrical portion  92  of the syringe body  12 . Their purpose is discussed below. 
     By cross-referencing  FIGS. 3A-D  and  4 A-D, it can be seen that the device  10  includes a mechanism to lock the guard  20  in an extended position  49  covering the needle tip  28  prior to an injection procedure. Once locked, the guard  20  can only be unlocked by movement of the plunger  22 . As previously discussed, the adapter  18  is formed with cam levers  74  having distal lever ends  80 . Comparing  FIG. 4A  with  FIG. 4B , it can be seen that the cam levers  74  are deflectable by the cylindrical side member  56  of the plunger  22  from a relaxed position  78  ( FIG. 4B ) to a biased position  76  ( FIG. 4A ). In the relaxed position  78  ( FIG. 4B ), the cam levers  74  extend radially outward from the remaining cylindrical section of the adapter  18 . On the other hand, as shown in  FIG. 3A , in the biased (i.e. deflected) position  76 , the cam levers  74  are coincident with the remaining cylindrical wall  42  of the adapter  18 . When the plunger  22  is in the advanced position  63  shown in  FIG. 4A , the cylindrical side member  56  of the plunger  22  contacts the cam levers  74  and deflects them into the biased position  76 . As shown in  FIG. 4A , when the cam levers  74  are in the biased position  76 , the lever ends  80  engage the proximal ends  86  of the hinges  82  of the guard  20  and prevents proximal movement of the guard  20 . When the plunger  22  is in its withdrawn position  61  as shown in  FIGS. 3B and 4B , the cam lever  74  relaxes into its undeflected, outward position  78  (as shown in  FIG. 4B ) and allows the guard  20  to move proximally. 
     As an additional locking mechanism, the syringe body  12  may be moved relative to the adapter  18  to deflect the cam levers  74  of the adapter  18  with its flanges  90 . As shown in  FIG. 4D , the flanges  90  are moved toward the adapter  18  when the plunger  22  and adapter  18  are fully pushed into the syringe body  12 . As a result, the flanges  90  contact and force the cam levers  74  of the adapter  18  to the biased position  76  to lock the device  10  to prevent any further proximal movement of the needle guard  20 . This prevents inadvertent reuse of the device  10 . 
     Operation 
     Initially, the device  10  is provided without a needle  26 . To mount a needle  26  on the device  10 , the needle guard  20  is first moved to the retracted position  53  by withdrawing the plunger  22 . Then the needle hub  30  is frictionally engaged with the shaft end  38  of the luer member  32  as can be understood from  FIGS. 3B and 4B . After mounting the needle hub  30  on the shaft end  38 , the needle guard  20  is allowed to move to its extended position  49  to cover the needle  26  by moving the plunger  22  to its advanced position  63  as shown in  FIG. 3A . As further shown in  FIG. 3A  the tangs  64  of the plunger  22  extend through the slits  48  in the adapter  18  to engage the abutments  54  and retract the guard  20  when the plunger  22  is withdrawn. 
     From  FIG. 4A , it can be seen that the cylindrical side member  56  of the plunger  22  holds the cam levers  74  deflected inward to lock the guard  20  and prevent proximal movement of the guard  20 . As illustrated by  FIGS. 3A-B  and  4 A-B, use of the device  10  begins by withdrawing the plunger  22 . Such proximal movement of the plunger  22  has several effects. Specifically, as shown in  FIGS. 4A and 4B , initial proximal movement of the plunger  22  allows the cam levers  74  to relax outwardly from the axis  14  and unlock the guard  20  for proximal movement. As shown in  FIGS. 3A and 3B , additional proximal movement of the plunger  22  engages the tangs  64  with the abutments  54 , causing the guard  20  to be retracted with the plunger  22 . Also, withdrawal of the plunger  22  draws air (or other fluid) through the needle  26  and into the fluid chamber  62 . 
     Once the guard  20  has been retracted as shown in  FIGS. 3B and 48 , the next step is to insert the exposed distal needle tip  28  into a medicament vial (illustrated by surface  94  in  FIGS. 3C and 4C ). At this point, the plunger  22  can be depressed as shown in  FIGS. 3C and 4C  to expel air into the vial and void the fluid chamber  62 . Comparing  FIGS. 3B and 4B  with  FIGS. 3C and 4C , it can be seen that during its advance the plunger  22  disengages the guard  20 . Thus, as illustrated by  FIGS. 3C and 4C , after advancing the plunger  22 , distal movement of the guard  20  is only prevented by the contact between the distal end  52  of the guard  20  and the surface  94 . Next, the plunger  22  can be withdrawn to fill the chamber  62  with medicament fluid  95  (note  FIGS. 3B and 4B  are representative of the configuration of the device  10  after the chamber  62  is filled with medicament  95 ). From  FIG. 3B , it can be seen that during withdrawal of the plunger  22 , the tangs  64  reengage the abutments  54 . The result is that the plunger  22  engages the guard  20  and prevents distal advancement of the guard  20 . As illustrated by  FIGS. 3B and 4B , when the needle  26  is removed from the vial, the distal tip  28  of the needle  26  remains unguarded and exposed. The device  10  is now ready for an injection. 
     As illustrated by  FIGS. 3C and 4C , to inject a medicament into a patient, the distal tip  28  of the needle  26  is inserted into the patient (represented by surface  94 ) and the plunger  22  is depressed. As shown in  FIG. 3C , the distal advancement of the plunger  22  releases the guard  20 . Once released, the guard  20  is free to move distally under the influence of a coil spring  96  that is interposed between the guard  20  and the adapter  18 . Thus, as the needle  26  is withdrawn from the patient, the needle  26  retracts proximally into the guard  20  which remains in contact with the patient&#39;s skin (represented by surface  94 ).  FIGS. 3A and 4A  are representative of the device  10  after the needle  26  has been withdrawn from the patient and the needle  26  has passively retracted into the guard  20 . 
     Once the device  10  has been removed from the patient, the plunger  22  and the adapter  18  can be advanced distally relative to the syringe body  12  to lock the guard  20  in place ( FIG. 4D ).  FIGS. 3D and 4D  also show that this places the grip flange  24  of the plunger  22  in the recess  72  formed in the syringe body  12 . Functionally, once the device  10  is in the configuration shown in  FIGS. 3D and 4D , the plunger  22  is disabled and the guard  20  completely covers the hollow needle  26  to protect the user from unwanted needle sticks and prevents inadvertent reuse of the device  10 . 
     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.