Abstract:
A medical device having a forwardly-projecting needle and a selectively-movable needle cap that can be variously positioned to cover all or a portion of the needle, depending upon whether the device is, for example, being transported, aspirated or used to inject a therapeutic fluid. The device can optionally be configured to enable retraction of the needle into the body for safe disposal following use.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to a medical device and more particularly to a medical device such as a non-reusable syringe having a hypodermic needle, preferably a retractable needle, and a needle cap that can be selectively retracted and then repositioned during use to suit the stage of operation of the device prior to patient injection or needle retraction. 
       DESCRIPTION OF RELATED ART 
       [0002]    Accidental needle sticks and the resultant transmission of blood-borne illnesses are a principal cause of concern to medical workers who must handle medical devices such as syringes in all aspects of their use, from unpackaging to disposal, many times per day. Medical devices having forwardly projecting needles are typically provided with a protective needle cap that is removable prior to use. Following use of a device, depending upon its design and construction, the needle is desirably retracted into a position where the needle tip is no longer exposed, thereby preventing reuse. Health care workers are typically cautioned against recapping exposed needles with the protective needle cap following use because of the associated risk of needle stick injury. In some devices, pivotable guards or forwardly slidable sheaths are sometimes provided to cover the needle tip following use and prior to disposal of the device, although those devices also have disadvantages and fail to eliminate needle stick risks. Medical devices with used needles are often simply deposited into “sharps” disposal containers, although this procedure also presents disease risks to health care workers, patients, and downstream handlers of the disposed devices. 
         [0003]    During a typical injection sequence using a conventional hypodermic syringe, for example, the syringe is removed from its sterile packaging and the protective needle cap is removed and either dropped into a trash receptacle or set aside by the health care worker performing the injection. The syringe is then manipulated by the user to insert the exposed needle into a vial to aspirate a desired fluid dosage into the barrel. During aspiration, and depending upon the size of the vial, the length of the exposed portion of the needle, and the angle of insertion, the needle tip can sometimes contact the bottom or side wall of the vial, thereby bending the needle or blunting the needle tip. 
         [0004]    Also, it is not uncommon for a health care worker to draw an injection and then lay the filled syringe down with an uncovered, exposed needle prior to administering the injection. This can occur, for example, where the user lays the syringe down on a tray, table or other surface for a moment while swabbing the injection site or attending to some other matter prior to the injection. During any such occurrence, the needle and needle tip are exposed, with an attendant risk of accidental needle stick to the worker or patient, or accidental contamination of the needle by contact with an unsterile surface prior to the injection. 
         [0005]    A medical device having a forwardly projecting needle is therefore needed that comprises a needle cap or needle cover configured to protect the needle tip prior to use and that can be selectively moved to an alternate position exposing the needle tip and a portion of the needle for some clinically desirably purpose during use. The subject needle cap or needle cover will also desirably be completely removable from the device and disposable prior to use of the device for injecting a therapeutic fluid, and will preferably comprise a retractable needle that is no longer in a forwardly projecting, exposed position following use. The capability for complete removal of the needle cover during administration is desirable so as to clear the site from all unnecessary visual obstructions and provide for safer operation. 
       SUMMARY OF THE INVENTION 
       [0006]    The invention disclosed here is a safe and reliable medical device having a forwardly projecting, preferably retractable, needle and a needle cap that protects the needle from damage or contamination by contact prior to use, that can be selectively retracted to expose a portion of the needle during use, and that can be subsequently repositioned or removed completely during use and prior to needle retraction. Although the invention is primarily described herein in the embodiment of a hypodermic syringe used for injecting a therapeutic fluid directly into a patient, it will be appreciated upon reading this disclosure that similar benefits and advantages are also achievable where the subject medical device is used for injecting into a fluid access port or otherwise configured for other medical applications. The subject invention desirably comprises only a few parts, all of which are easily manufactured and assembled and do not require close tolerances, thus facilitating large volume, low cost production. 
         [0007]    A distinguishing feature of the disclosed invention is a needle cap for a medical device having a forwardly projecting needle, in which the needle cap can be selectively disposed in at least the three following positions, depending on the mode or stage of operation of the device: A pre-use position in which a portion of the needle cap extends forwardly past and circumferentially surrounds the forwardly projecting needle tip; an intermediate position in which the needle cap is moved rearwardly relative to the needle to expose the needle tip and a desired portion of the overall length of the needle; and a final position in which the needle cap is removed entirely from the medical device and is no longer needed. 
         [0008]    In one embodiment, the subject needle cap is desirably hollow and generally cylindrical with both ends open, is releasably attachable in a first position relative to a front portion of a medical device, is configured to be moveable rearwardly from the first position to a second position relative to the front portion of the medical device to expose a portion of a forwardly extending needle for a clinical procedure such as aspirating a therapeutic fluid, is forwardly movable back to the first position following the clinical procedure to recap and protect the needle, and is completely releasable and removable from the device prior to a clinical procedure such as administering an injection. Where the medical device is also provided with a needle retraction mechanism, the needle can be retracted following completion of the clinical procedure to prevent re-use or accidental needle sticks. 
         [0009]    In one embodiment of the subject medical device, the selectively retractable needle cap and the body comprise cooperatively configured interfering structures that resist premature or unintended rearward sliding movement of the needle cap relative to the body. 
         [0010]    In one embodiment of the subject medical device, the selectively retractable needle cap and the body comprise cooperatively-configured interfering structures that resist accidental or premature separation of the needle cap from the body. 
         [0011]    In one embodiment of the subject medical device, the selectively retractable needle cap comprises manually-operated latch features configured to resist premature or accidental movement or removal of the needle cap until the latch features are released by the user. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The apparatus of the invention is further described and explained in relation to the following drawings wherein: 
           [0013]      FIG. 1  is a side elevation view of one embodiment of the subject medical device with a needle cap covering a forwardly projecting needle; 
           [0014]      FIG. 2  is a front perspective view of the device as depicted in  FIG. 1 ; 
           [0015]      FIG. 3  is a front elevation view of the device of  FIG. 1 ; 
           [0016]      FIG. 4  is a cross-sectional side elevation view along line  4 - 4  of  FIG. 3 ; 
           [0017]      FIG. 5  is a detail view of the area identified as “5” within  FIG. 4 ; 
           [0018]      FIG. 6  is an exploded perspective view of device of  FIG. 2 ; 
           [0019]      FIG. 7  is the side elevation view of the device of  FIG. 2  with the needle cap in the retracted position; 
           [0020]      FIG. 8  is a front perspective view of the device as in  FIG. 7 ; 
           [0021]      FIG. 9  is a cross-sectional side elevation view of the device of  FIG. 7 ; 
           [0022]      FIG. 10  is a side elevation view of the device of  FIG. 7  with a vial of therapeutic fluid and a transparent barrel; 
           [0023]      FIG. 11  is a side elevation view of the device of  FIG. 10  with a needle inserted into the vial. 
           [0024]      FIG. 12  is a side elevation view of the device of  FIG. 11  showing therapeutic fluid being drawn into the barrel. 
           [0025]      FIG. 13  is a side elevation view of the device of  FIG. 12  showing therapeudic fluid in the barrel and the needle cap having been returned to its initial position. 
           [0026]      FIG. 14  is a side elevation view of the device of  FIG. 7  with the needle cap removed. 
           [0027]      FIG. 15  is a side elevation view of the device of  FIG. 14  near the completion of an injection. 
           [0028]      FIG. 16  is a front perspective view of the device of  FIG. 15 ; 
           [0029]      FIG. 17  is a cross-sectional side elevation view of the device of  FIG. 15 ; 
           [0030]      FIG. 18  is a side view of the device of  FIG. 15  with the needle retracted into the body of the syringe; 
           [0031]      FIG. 19  is a front perspective view of the device of  FIG. 18 ; 
           [0032]      FIG. 20  is a cross-sectional side elevation view of the device of  FIG. 18 ; 
           [0033]      FIG. 21  is a side elevation view of another embodiment of the subject medical device with the needle cap covering a forwardly projecting needle; 
           [0034]      FIG. 22  is a front elevation view of the device of  FIG. 21 ; 
           [0035]      FIG. 23  is a cross-section view taken along line  23 - 23  of  FIG. 22 ; and 
           [0036]      FIG. 24  is a detail view of the area identified as “24” within  FIG. 23 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    Referring to  FIG. 1 , a medical device  10  is illustrated in this embodiment as syringe  20 . Although medical device  10  can take many different forms, a syringe having a retractable needle as further disclosed and described, for example, in U.S. Pat. No. 7,351,224 is believed to be useful for practicing the present invention after being specially adapted consistent with the teachings of this specification and the accompanying drawings. 
         [0038]    Syringe  20  is desirably shipped in a sterile package that is opened shortly before use. Upon removal from the package, syringe  20  will initially be configured substantially as depicted in  FIGS. 1-5 . Syringe  20  comprises as its principal parts barrel  30 , plunger  40 , needle assembly  50  and needle cap  60 . Barrel  30  desirably comprises an elongate tubular bore  32  with a forwardly facing annular shoulder  33 , oppositely disposed transversely projecting finger flanges  34 , a forwardly facing nozzle tube  35  and a rearwardly facing opening  36  surrounded by substantially cylindrical collar  38 . 
         [0039]    Plunger  40  comprises a forward portion  41  (see  FIG. 4 ) which is initially positioned within barrel  30 , a rearward portion  44  extending beyond cylindrical collar  38  and a thumb grip  46 . Referring to  FIG. 6 , plunger  40  also comprises needle retraction cavity  42  and plunger seal  48 . Plunger seal  48  further comprises annular sealing ring  482  and elastomeric web  484 . Rearwardly facing thumb grip  46  is desirably provided opposite elastomeric web  484  for use in moving plunger  40  in coaxial sliding relationship to the inside wall of barrel  30  during use of syringe  20 . Plunger  40  is desirably moved rearwardly relative to barrel  30  to draw a therapeutic fluid into barrel  30  and is moved forwardly relative to barrel  30  to expel a therapeutic fluid from syringe  20 . 
         [0040]    In the initial position illustrated in  FIGS. 1-5 , needle assembly  50  is covered by needle cap  60 . However, components of needle assembly  50  are illustrated in  FIG. 6 . Needle assembly  50  comprises needle  52 , with needle tip  522 ; needle holder  54 , further comprising rearward annular ring  542  and rearwardly-facing head  544 ; retraction spring  56 ; and torroidal retainer member  58 . 
         [0041]    Needle cap  60  preferably comprises hollow body  62  and tapered nose tube  64 , which is surrounded by a plurality of circumferentially spaced, longitudinally extending ribs  66 . A rearward end of hollow body  62  comprises an annular rib  68 . A preferred embodiment of needle cap  60  is distinguished from typical prior art devices by comprising both a rearward opening  63  and forward opening  65 . 
         [0042]    Referring to  FIG. 5 , additional components of needle cap  60  and barrel  30  are visible in cross section. A forward annular inward projection  622  and a rearward annular inward projection  624  are disposed on the inside wall of hollow body  62  and desirably define annular recess  626  between them. An annular outward projection  357  is disposed on the outside surface of hollow body  35 . Annular inward projections  622 ,  624  and recess  626  are configured to cooperate with annular outward projection  357  of nozzle tube  35  to form a detent mechanism that provides resistance tending to prevent needle cap  60  from sliding forwardly relative to nozzle tube  35  (and becoming disengaged from barrel  30 ) or from sliding rearwardly (and prematurely exposing needle tip  522 ) prior to use of syringe  20 . 
         [0043]    In  FIGS. 1-5 , needle cap  60  is illustrated in its pre-use position where nose tube  64  of needle cap  60  is preferably configured to extend forwardly beyond needle  52  and needle tip  522 . In this position needle cap  60  helps protect needle tip  522  from damage or contamination by contact prior to use and helps protect health care workers and patients from accidental needle sticks and the associated risk of infection or disease. 
         [0044]    With conventional syringes and needle caps, the needle cap must be completely removed from the syringe to perform any procedure using the needle, including, for example, aspirating a therapeutic fluid from a vial. As the needle is inserted into a vial, the full length of the forwardly projecting part of the needle is exposed. As a result, the needle can be easily contaminated, bent, or damaged by contact with the inside wall or inside bottom surface of the vial. 
         [0045]      FIGS. 7-9  illustrate one significant advantage of the present invention that is made possible by the fact that needle cap  60 —unlike most syringe caps—is desirably open on both ends. With two open ends, it becomes possible to move needle cap  60  rearwardly relative to nozzle tube  35  to expose needle tip  522  and a portion of needle  52  during a procedure such as aspirating a therapeutic fluid into barrel  30 . A user (not shown) can grasp needle cap  60  and move it rearwardly relative to nozzle tube  35  until rearward open end  63  of needle cap  60  contacts and abuts forwardly facing annular shoulder  33  of barrel  30 , thereby simultaneously exposing the needle tip  522  and a portion of needle  52  sufficient to permit aspiration into barrel  30  without fully exposing all of needle  52 . 
         [0046]    As shown in  FIGS. 10-12 , the user can then insert the exposed portion of needle  52  into a vial  90  to aspirate therapeutic fluid  92  into barrel  30  by moving plunger  40  rearwardly. By limiting the extent to which the forwardly projecting portion of the needle is exposed, the risk of damage to the needle is greatly reduced. Also, because vials are typically inverted during aspiration, limiting the extent of needle exposure means the user is less likely to inadvertently draw air into barrel  30  where the vial is only partially full of therapeutic fluid  92  and also contains an airspace  94 . 
         [0047]    Following aspiration, and referring to  FIG. 13 , the needle cap can be returned to its original position by grasping hollow body  62  and moving it forwardly relative to nozzle tube  35  until it again reaches the original position, where it is held by the detent mechanism previously described. In this state, syringe  20  contains therapeutic fluid  92  but needle  52  and needle tip  522  are protected by needle cap  60  while awaiting injection. 
         [0048]    Referring to  FIG. 14 , when the user is ready to perform an injection, needle cap  60  can be completely removed from the front of syringe  20  by grasping hollow body  62  and carefully moving needle cap  60  forwardly relative to hollow body  35  with sufficient force to overcome the detent mechanism. The needle cap  60  can be discarded if a retractable needle syringe is being used, since needle  52  will retract into retraction cavity  42  after injection. 
         [0049]    Figures  FIGS. 15-17  illustrate syringe  20  with needle cap  60  removed, in the process of in injection. At this stage, plunger  40  has been advanced almost to the point of completing the injection, Further forward movement of plunger  40  will complete the injection and initiate retraction of needle  52  as described below. 
         [0050]    Referring again to  FIGS. 4-6 , a preferred needle retraction mechanism for syringe  20  is illustrated. Needle holder  54  is seated inside hollow body  35  of syringe  20 . In an initial position, needle retraction spring  56  is compressed in an annular space defined between the outside of needle holder  54  and the inside wall of hollow body  35 . Needle retraction spring  56  is held in compression by torroidal retainer member  58  disposed around the rearwardly facing head  542  of needle holder  54 . In an initial condition of plunger  40 , annular sealing ring  482  and a transversely disposed elastomeric web  484  prevent fluid from entering needle retraction cavity  42  defined inside plunger  40 . 
         [0051]    After therapeutic fluid is expelled, continued forward movement of plunger  40  relative to barrel  30  and will cause elastomeric web  484  to contact pointed head  544  of needle holder  54 . This contact will cause pointed head  544  to stretch and then puncture elastomeric web  484 . The continued forward movement of plunger  30  also forces torroidal retainer member  58  forwardly into annular space  356  inside hollow body  35 . The forward movement of retainer member  58  into annular space  356  allows the rearwardly-directed biasing force of compressed spring  56  to drive needle holder  54  rearwardly into needle retraction cavity  42  of plunger  40 , thereby causing needle  52  to retract. After needle  52  has been retracted into retraction cavity  42 , syringe  20  is ready for disposal into a suitable receptacle (not shown). 
         [0052]      FIGS. 21-24  illustrate another embodiment of the invention. In this embodiment needle cap  80  comprises a fulcrum mechanism  82  which further comprises finger pads  822  near its forward end and cap release latches  824  near its rearward end. Referring to  FIG. 19 , depressing finger pads  822  as indicated by arrow  84  causes cap release latches  824  to flex outwardly as indicated by arrow  86 . The outward movement of cap release latches  824  allows inwardly facing projection  826  to clear blocking member  72  disposed on or near the front end of syringe barrel  70  and allows removal of needle cap  80  from syringe barrel  70 . Otherwise, this embodiment will be seen by those of ordinary skill in the art to function much as previously described for the prior embodiment. 
         [0053]    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 inventor(s) and/or Applicant are legally entitled.