Abstract:
A medical device attachable to the front of a conventional syringe and having a hub assembly selectively attachable to the syringe, a nose projecting forwardly from the hub assembly, a rearwardly biased needle retraction mechanism seated inside the nose, a retractable needle projecting forwardly of the nose, and a fluid flow path from the fluid chamber through the hub assembly, nose, needle retraction assembly and needle, wherein the needle is retracted into the nose and a retraction tube external to the syringe by rotating the syringe relative to the nose.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. 119(e) of the earlier filing date of U.S. Provisional Patent Application No. 61/737,263 filed Dec. 14, 2012. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the use of conventional syringes in combination with a newly disclosed frontal attachment having a retractable needle. The invention relates more particularly to a medical device comprising in combination a needle, nose and hub assembly attachable to a conventional syringe preferably having a forwardly facing luer lock connector. The subject device has a needle retraction mechanism that is activated by rotating the syringe barrel relative to the nose of the device to retract the needle from a patient and propel it into the nose and a retraction tube that is part of the hub assembly. 
     2. Description of Related Art 
     Conventional syringes comprising a generally cylindrical barrel, a fixed needle projecting forwardly from the barrel, and a plunger slidably disposed inside the barrel through an opening in the rear of the barrel are well known. More recently, syringes have been made with a luer connector on the front of the barrel to which a needle hub is attachable to allow needles of different gauges or sizes to be used with a commonly configured barrel. 
     Even more recently, in an effort to control the spread of blood-borne pathogens and the incidence of contamination by contact with either exposed needles or bodily fluids, syringes having fixed or changeable needles have been designed to embody various “safety” elements. Such “safety” elements should desirably include a retractable needle, but many products marketed as having “safety” elements include, for example, covers or guards that are manually operated by medical personnel administering an injection to shield or cover the needle tip following removal of the needle from a patient. 
     Some previously disclosed needle retraction systems without changeable needles are activated either manually or automatically by application of a force upon completion of an injection to force the needle and needle tip back inside a retraction chamber. The only known syringe having a changeable, retractable needle does not have a conventional luer lock connection, and the retraction mechanism is activated by the application of a forwardly directed force to the plunger handle following removal of the needle from a patient, thereby exposing the needle and also exposing the user to the risk of needle-stick injury. 
     U.S. Pub. No. 2006/0155244 to Popov discloses a venipuncture device that rotates a port unit following needle retraction. The retraction chamber is disposed inside the medical device, is not part of the frontal attachment and remains stable while the port unit is moved rotationally relative to the retraction chamber following needle retraction. The frontal attachment disclosed there cannot be used with a generic luer lock syringe. 
     Although many advancements in syringe technology have been made in recent years, a frontal attachment device is needed that can be used with a standard syringe having a conventional luer lock connector, that offers the advantages of a changeable needle in combination with the advantages of a retractable needle providing sufficient retraction force to retract the needle while inserted into a patient, and that can be activated by the application of a rotational force to the syringe barrel while stabilizing the nose without applying a forwardly directed force to the plunger or the needle. 
     SUMMARY OF THE INVENTION 
     A medical device is disclosed that comprises a hub assembly selectively attachable to the front of a conventional syringe, a nose projecting forwardly from the hub assembly, a rearwardly biased needle retraction mechanism seated inside the nose, a retractable needle projecting forwardly of the nose, and a fluid flow path from the fluid chamber through the hub assembly, nose, needle retraction mechanism and needle, wherein the needle is retracted following use into the nose and a retraction tube external to the syringe by rotating the syringe relative to the nose. As used throughout this disclosure, the terms “attachable,” “detachable” and “changeable” are generally used to characterize frontal attachments, such as needles or needle/hub combinations, that are selectively attachable to, detachable from, or otherwise changeable in relation to a syringe for purposes such as, without limitation, selecting a particular gauge needle for a particular clinical use. 
     A medical device as disclosed here can be configured to be attachable to the front of a conventional syringe having a luer lock connector. If desired, a medical device as disclosed here can also be made with a snap-on or other attachment mechanism instead of a conventional luer lock connector provided that the syringe with which it is used is cooperatively configured. A medical device as disclosed here desirably comprises a needle that is retractable, and retraction is activated by applying rotational rather than axial force to the syringe barrel. A satisfactory medical device as disclosed here desirably has sufficient retraction force to retract a needle that is still inserted into a patient&#39;s body and thereby prevents exposure of the contaminated needle to others. A medical device as disclosed here desirably utilizes a retraction tube that is not embodied in the syringe or plunger handle, and is instead part of the attachable hub assembly. 
     A satisfactory hub assembly for use in the invention as disclosed here comprises a hub disposed forwardly of the plunger, a retraction tube laterally spaced apart from the hub, and a frame member interconnecting the hub and the retraction tube in substantially fixed, laterally spaced-apart relation to each other. A medical device made in accordance with the invention desirably further comprises a nose projecting forwardly from the hub and is attached to the frame so as to permit the hub assembly to move laterally in relation to the nose between a first position axially aligned with the hub and a second position axially aligned with the retraction tube. A rearwardly biased needle retraction mechanism comprising a needle holder and retraction spring is desirably seated inside the nose; and a retractable needle projects forwardly of the nose. A fluid flow path is thereby provided from the fluid chamber of a syringe through the hub, nose, needle retraction assembly and needle; and an annular fluid seal is desirably disposed around a portion of the fluid flow path between the hub and the nose. 
     Following an injection using a syringe provided with the medical device disclosed here, a clinician administering the injection desirably grasps a stabilizer tab provided at the nose of the device with the thumb and finger or fingers of one hand to stabilize the body and nose, and with the other hand, rotates the syringe barrel in a clockwise direction (the same direction in which the barrel is rotated during attachment of the syringe to the device prior to use). As the body and nose are stabilized, the syringe barrel and the attached hub assembly are rotated relative to the nose, which first causes the hub to slide laterally out of coaxial alignment with the head of the needle holder. As the hub slides out of engagement with the rearwardly biased needle holder, preferably in a curvilinear arc, a portion of the frame member disposed between and connecting the hub to the laterally spaced-apart retraction tube comes into abutting engagement with the needle holder to continue holding the retraction spring in its compressed position. The needle holder remains rearwardly biased until such time as a forwardly facing opening into the retraction tube sufficiently approaches coaxial alignment with the needle holder to allow the compressed retraction spring to propel the needle holder rearwardly into the retraction tube. As this occurs, the needle holder also carries the attached needle rearwardly to a fully retracted position where the needle is released from the patient and the needle tip no longer projects forwardly from the nose. 
     In this way, the medical device disclosed here is configured to convert rotational motion of the syringe to curvilinear translational realignment of the nose and the needle holder from coaxial alignment with the hub to coaxial alignment with the retraction tube. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The apparatus of the invention is further described and explained in relation to the following drawings wherein: 
         FIG. 1  is a side elevation view of one embodiment of a syringe having selectively attached to its front end one embodiment of a medical device comprising in combination a nose, a needle or cannula projecting forwardly of the nose, a needle retraction mechanism seated inside the nose, and a hub assembly; 
         FIG. 2  is a cross-sectional view of the apparatus of  FIG. 1  taken along line  2 - 2  of  FIG. 9 ; 
         FIG. 3  is an exploded perspective view of the apparatus of  FIG. 1 ; 
         FIG. 4  is an enlarged detail view of the attachable medical device of  FIG. 1 ; 
         FIG. 5  is a side elevation view of the apparatus of  FIG. 1  with the syringe plunger advanced to the post-injection position and the hub assembly rotated clockwise relative to the nose; 
         FIG. 6  is a cross-sectional view of the apparatus of  FIG. 5  taken along line  6 - 6  of  FIG. 10 ; 
         FIG. 7  is a side elevation view of the apparatus of  FIG. 5  with the plunger advanced to the post-injection position and the hub assembly rotated further clockwise relative to the nose; 
         FIG. 8  is a cross-sectional view of the apparatus of  FIG. 5  taken along line  6 - 6  of  FIG. 10 ; 
         FIG. 9  is a front elevation view of the apparatus of  FIG. 1 ; 
         FIG. 10  is a front elevation view of the apparatus of  FIG. 5 ; 
         FIG. 11  is a front elevation view of the apparatus of  FIG. 7 ; 
         FIG. 12  is a rear elevation view of the apparatus of  FIG. 1 ; 
         FIG. 13  is a rear elevation view of the apparatus of  FIG. 5 ; 
         FIG. 14  is a rear elevation view of the apparatus of  FIG. 7 ; and 
         FIGS. 15-17  are right, left side and front elevation views, respectively, of the medical device of  FIG. 1 , with a needle cover installed prior to use. 
     
    
    
     Like reference numerals are used to describe like features in all Figures of the drawings. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1 and 2  depict an assembled combination  20  of syringe barrel  24 , having a luer lock connector  47 ,  49  disposed at the front end and a plunger handle  28  with plunger seal  44  slidably engaging the inside wall of syringe barrel  24 , and a satisfactory medical device  22  of the invention having a hub assembly  48  that is attached to luer lock connector  47 ,  49  so as to establish fluid communication between fluid chamber  46  of syringe barrel  24  and needle  32 . Plunger handle  28  extends rearwardly from an opening in the back of syringe barrel  24  and is positioned relative to syringe barrel  24  as it could be prior to the injection of a fluid disposed inside fluid chamber  46  into a patient if tip  60  of needle  32  were inserted into the patient, recognizing that the position of plunger seal  44  relative to barrel  24  will depend upon the amount of fluid that is drawn into fluid chamber  46 . The injection force is applied to a fluid disposed inside fluid chamber  46  through plunger handle  28  by depressing thumb cap  30  of plunger handle  28  while stabilizing syringe barrel  24  by applying oppositely directed finger force to the forwardly facing surfaces of outwardly projecting flanges  26 . 
     During or following the injection, a clinician administering the injection can grasp the textured surfaces of outwardly projecting stabilizer tab  38  of medical device  22  to stabilize medical device  22  and rotate syringe barrel  24 , preferably in a clockwise direction (as viewed from the back of assembled combination  20 ), relative to stabilizer tab  38  of nose  35  (best seen in  FIG. 4 ). Although medical device  22  of the invention can be made so as to permit rotation of syringe barrel  24  in either a clockwise or counter-clockwise direction relative to stabilizer tab  38  of nose  35  to achieve needle retraction, one or more mechanical barriers to counter-clockwise rotation of syringe barrel  24  are desirably provided to avoid accidentally unthreading luer lock connector  47 ,  49  of syringe barrel  20  from nose  35 . 
     Satisfactory structural elements for use in combination  20  and in medical device  22  of the invention are further described and explained in relation to  FIGS. 1-4 . Medical device  22  as shown comprises nose  35 , a retraction mechanism further comprising a needle holder  95  ( FIG. 4 ) and a compressed retraction spring  50  seated inside nose  35 , and hub assembly  48  comprising hub  72 , frame member  74 , retraction tube  42  further comprising retraction cavity  86 , and an annular fluid seal such as fluid seal  56  that is desirably disposed between nose  35  and hub  72 , preferably inside a recess  76  in the forwardly facing portion of hub  72 . A plurality of radially projecting locking wedges  70 , diametrically opposed as shown, or other similarly effective engagement elements are provided at the rear of hub  72  to facilitate locking engagement with locking leer connector  47 ,  49  of syringe barrel  24 . 
     Referring to  FIG. 4 , needle holder  95  as shown comprises elongated cylindrical shaft portion  34 , a larger diameter head  65 , which is seated against an annular shoulder inside substantially cylindrical body  36  of nose when the retraction mechanism is seated inside nose  35  prior to attaching nose  35  to hub assembly  48  as further described below. Prior to seating needle holder  95  inside body  36  of nose  35 , retraction spring  50  is desirably compressed (spring  50  is shown compressed in  FIGS. 2-4  and relaxed in  FIG. 8 ) between an annular nose  39  near the front of body  36  (best seen in  FIG. 8 ) and annular shoulder  64  ( FIG. 4 ) on the forwardly facing surface of head  65  of needle holder  95 . The length of cylindrical shaft portion  34  of needle holder  95  is desirably such that the forwardly extending end of shaft portion  34  will project slightly beyond the front of body  36  as seen in  FIG. 1 . 
     As shown, nose  35  further comprises substantially cylindrical body  36  having a rearwardly facing collar  92 , and an outwardly projecting stabilizer tab  38  with textured gripping elements  40 . Body  36  of nose  35  desirably further comprises an attachment tab  100  ( FIG. 6 ) projecting radially outward below the longitudinal axis through interior cavity  62  that has a rearwardly projecting, split cylindrical boss  58  configured to snap into a cooperatively aligned orifice  68  in frame member  74  of hub assembly  48 . Nose  35  is thereby rotatably attached to hub assembly  48  with the axis of rotation offset being offset from the longitudinal axes through hub  72  and retraction tube  42  so as to define an arc through which hub assembly  48  can be moved translationally from a first position characterized by coaxial alignment of hub  72  with body.  36  to a second position characterized by coaxial alignment of retraction tube  42  with body  36  to initiate retraction following injection. Although the structural elements as disclosed are satisfactory for rotatably mounting nose  35  in relation to hub assembly  48 , it will be appreciated by those of ordinary skill in the art upon reading this disclosure that other structural elements and configurations can be substituted for those particularly disclosed here to achieve the same functionality within the scope of the invention. Broadly stated, such functionality comprises rotating a syringe barrel following injection to move the barrel translationally relative to a nose portion comprising a retraction mechanism to initiate retraction of a needle from a patient into a cavity inside a retraction tube so that the tip of the needle no longer projects forwardly of the barrel. 
     As shown in  FIG. 3 , a syringe suitable for use with medical device  22  of the invention can comprise barrel  24  with radially projecting flanges  26  disposed along the rear portion of barrel  24 , an engagement structure such as luer lock connector  47 ,  49  attachable to hub assembly  48 , plunger seal  44  attached to mounting boss  88  of plunger handle  28 , and a thumb cap  30  to facilitate the application of a forwardly directed force to plunger handle  28  relative to barrel  24  during injection. As shown, tapered luer member  49  comprising a substantially cylindrical bore  51  cooperates with annular collar  47  having internal threads  51  disposed in spaced-apart relation to tapered luer member  49  to form luer lock connector  47 ,  49  that is engageable with locking wedges  70  of hub  72  to provide a fluid-tight seal between hub  72  and syringe barrel  24 . When combination  20  is assembled as shown in  FIG. 1 , a continuous fluid flow path is formed from fluid chamber  46  ( FIG. 2 ) through interior  84  of hub  72 , interior  66  of fluid seal  56 , interior  94  of needle holder  95 , and needle  32  ( FIG. 4 ). 
     Referring to  FIGS. 5 and 6 , the assembled combination  20  is again shown, but this time with plunger handle  28  advanced relative to syringe barrel  24  to the point it will be following an injection, when plunger seal  44  has forced the fluid out of fluid chamber  46  as previously shown and described in relation to  FIGS. 1 and 2 . This is the position in which plunger handle  28  will desirably remain relative to syringe barrel  24  during activation of the retraction mechanism and retraction of needle  32 . By comparing the position of retraction tube  42  in  FIG. 5  to that shown in  FIG. 1 , it is apparent that rotation of barrel  24  and retraction tube  42  relative to stabilization tab  38  of nose  35  has already been initiated. 
     Referring to  FIGS. 7 and 8 , the assembled combination  20  is again shown, and by comparing the position of retraction tube  42  in  FIG. 7  to that shown in  FIG. 5 , it is apparent that rotation of barrel  24  and retraction tube  42  relative to stabilization tab  38  of nose  35  has continued to a point where retraction has occurred, and retraction spring  50  has propelled needle holder  95  in retraction tube  42  to a position where no portion of needle  32  is exposed forwardly of body  36 . 
       FIG. 9  depicts the relative positions of the components of combination  20  as in  FIG. 1 , but viewed from the front.  FIG. 12  depicts the relative positions of the components of combination  20  as in  FIG. 1 , but viewed from the rear. 
       FIG. 10  depicts the relative positions of the components of combination  20  as in  FIG. 5 , but viewed from the front, with arrow  102  showing the direction of rotation of frame member  74  of hub assembly  48  relative to stabilization tab  38 .  FIG. 13  depicts the relative positions of the components of combination  20  as in  FIG. 5 , but viewed from the rear, with arrow  106  showing the direction of rotation of retraction tube  42  and syringe flanges  26  relative to stabilization tab  38 . 
       FIG. 11  depicts the relative positions of the components of combination  20  as in  FIG. 5 , but viewed from the front, with arrow  104  showing the direction of rotation of frame member  74  of hub assembly  48  relative to stabilization tab  38 .  FIG. 14  depicts the relative positions of the components of combination  20  as in  FIG. 5 , but viewed from the rear, with arrow  108  showing the direction of rotation of retraction tube  42  and syringe flanges  26  relative to stabilization tab  38 . 
     Nose  35 , needle holder  95 , hub assembly  48 , syringe barrel  24  and plunger handle  28  are all desirably moldable from a suitable moldable polymeric material. Such materials and molding methods are believed to be well known to those of ordinary skill in the art. Similarly, it will be appreciated by those of skill in the art of syringe design and manufacture that a medical device such as medical device  22  disclosed here can be used with syringes that are either pre-filled or not, and that may comprise component portions made of glass or other suitable materials for particular applications. Similarly, it will be appreciated that fluid seal  56  and plunger seal  44  are desirably made of a rubbery or elastomeric polymeric material of the types commonly known for use in such medical applications. Similarly, it will be appreciated that materials used in the fabrication of this and other medical devices must be approved by the relevant regulatory authorities for use in such devices. Retraction spring  50  and needle  32  as disclosed are desirably made of stainless steel or any other similarly effective material. A needle cover  37  for medical device  22  is shown in  FIGS. 15-17  for use with needle  32  while it is disposed in the forwardly projecting position prior to use, and it will be appreciated by those of skill in the art that such needle covers  37  are needed to protect needle  32  from contamination or damage during shipment and storage, and can be designed and fabricated using known technology. 
     Other alterations and modifications of the invention will likewise become apparent to those of ordinary skill in the art upon reading this specification in view of the accompanying drawings, and it is intended that the scope of the invention disclosed herein be limited only by the broadest interpretation of the appended claims to which the inventors are legally entitled.