Abstract:
A cap assembly is disclosed for use with a lock solution delivery device. The cap assembly includes a housing defining a receptacle and having an inlet end and an outlet end. A plunger is movable axially within the receptacle from a retracted position to an advanced position and is rotatably supported within the receptacle from a first position to a second position. The plunger includes an axial extension configured to non-rotatably engage a syringe connected to the inlet end of the housing. The plunger is positioned to move from the first position to the second position in response to rotatable detachment of a syringe from the inlet end of the housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/008,482, filed on Dec. 20, 2007, which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to lock solution delivery devices for use with indwelling catheter assemblies and, more particularly, to a cap assembly for use with a prefilled lock solution syringe for delivering a lock solution to an indwelling catheter assembly. 
     2. Description of Related Art 
     Indwelling catheter assemblies are commonly used to deliver medication to patients who require treatment over an extended period of time. Typically, an indwelling catheter assembly is inserted into a patient&#39;s vasculature and is secured to the body, e.g., the arm, of the patient. When a medication is required to be given to the patient, a syringe is secured to the catheter assembly via a reusable connector/valve, and medication is injected into the patient from the syringe through the valve/connector and through the catheter assembly. 
     Typically, the valve/connector includes a valve member which is pressed forwardly by the syringe during attachment of the syringe to the valve/connector, to open the valve/connector and facilitate delivery of the medication into the catheter assembly. When the syringe is removed from the valve/connector, the valve member returns to its sealed position. As the valve member returns to its sealed position, a vacuum may be drawn within the catheter assembly creating retrograde blood flow into the catheter assembly from the patient. 
     Syringes for delivering lock and/or flush solutions to catheter assemblies are well known. Generally, a syringe having a lock and/or flush solution is attached to the valve/connector and catheter assembly after medication has been injected into the patient. By injecting a lock and/or flush solution through the catheter assembly after a medication injection, any medication remaining in the catheter is flushed from the catheter and delivered to the patient and any blood drawn into the catheter assembly after removal of the medicament syringe is also flushed from the catheter assembly. However, upon removal of the lock solution syringe from the catheter assembly, the valve member of the valve/connector again returns to its sealed position and blood may be once again drawn into the catheter assembly. When blood is drawn into the catheter assembly, if the blood stagnates, the blood will eventually clot and occlude the catheter assembly. Further, stagnant blood provides a food source for planktonic bacteria which may lead to bio-film formation and a catheter-related bloodstream infection. 
     There are various types of valves/connectors that are designed to impart a positive displacement of fluid into the catheter assembly upon removal of the lock solution syringe. However, at times, an effective amount of positive displacement fluid to eliminate the existence of retrograde blood flow into the catheter assembly is not achievable. This may be partially due to the limited amount of fluid capable of being displaced by known valves/connectors which may be less than 1 mL. Furthermore, these valves/connectors are reusable and have been susceptible to bacterial contamination. 
     Accordingly, a need exists in the medical arts for an improved device for effectively flushing and locking a catheter assembly after injection of a medication into the catheter assembly which can be removed from the catheter assembly without drawing blood into the catheter assembly. 
     SUMMARY 
     A cap assembly is disclosed for use with a lock solution delivery device which includes a housing defining a receptacle and having an inlet end and an outlet end. The inlet end defines an opening and is adapted to releasably and rotatably engage a syringe. The outlet end defines an outlet conduit and is adapted to releasably engage an indwelling catheter assembly. A plunger is axially movably positioned within the receptacle from a retracted position to an advanced position and is rotatably supported within the receptacle from a first position to a second position. The plunger includes an axial extension configured to non-rotatably engage a syringe connected to the inlet end of the housing. The plunger assembly includes at least one protrusion and the housing includes at least one slot dimensioned to slidably receive the at least one protrusion. The at least one protrusion is misaligned with the at least one slot when the plunger is in the first position to retain the plunger in the retracted position and the at least one protrusion is aligned with the at least one slot when the plunger is in the second position to facilitate movement of the plunger from the retracted position to the advanced position. In one embodiment, a biasing member is positioned within the receptacle to urge the plunger towards the advanced position. The biasing member may include a coil spring. In one embodiment, the plunger is positioned to move from the first position to the second position in response to rotatable detachment of a syringe from the inlet end of the housing. The distal end of the plunger may have a cylindrical portion which is movably received within a cylindrical portion of the receptacle. The cylindrical portion of the plunger includes at least one annular sealing rib positioned to slidable and sealingly engage an inner wall of the cylindrical portion of the receptacle. 
     The at least one slot may include a plurality of longitudinal slots formed in a stepped portion of the housing. Each slot is dimensioned to slidably receive one of the at least one protrusions. A proximal surface of the stepped portion defines a shoulder, wherein the at least one protrusion rests on the shoulder when the plunger is in the first position. In one embodiment, the at least one protrusion includes a plurality of radially extending fingers formed on the plunger. Each of the radially extending fingers is aligned with a respective one of the plurality of longitudinal slots when the plunger is in the second position. 
     In one embodiment, the axial extension defines a fluid channel. A resilient valve member may be formed on the axial extension adjacent an outlet end of the fluid channel of the axial extension to prevent fluid from entering the cap assembly during shipping and/or transportation of the cap assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the presently disclosed cap assembly for use with a prefilled lock solution syringe are disclosed herein with reference to the drawings wherein: 
         FIG. 1  is a side cross-sectional view of one embodiment of the presently disclosed cap assembly, with the plunger in a retracted position, shown connected to the distal end of a fluid delivery device; 
         FIG. 2  is a cross-sectional view taken along section lines  2 - 2  of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the cap assembly shown in  FIG. 1  taken along section lines  3 - 3  of  FIG. 1 ; 
         FIG. 4  is a side cross-sectional view of the cap assembly shown in  FIG. 1  with the plunger in an advanced position; and 
         FIG. 5  is a side cross-sectional view of an alternative embodiment of the plunger of the presently disclosed cap assembly. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the presently disclosed cap assembly for use with a prefilled lock solution syringe will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements in each of the several views. In this description, the term proximally is generally used to indicate the relative nearness of a referenced item to a clinician using the assembly and the term distal is used to indicate the remoteness of a referenced item to a clinician using the device. 
     Referring to  FIG. 1 , cap assembly  10  includes a housing  12 , a plunger assembly  14  and a biasing member  16 . Housing  12  includes an inlet connector  18  defining an inlet opening  20 , an outlet connector  22 , and an outlet conduit  24 . Housing  12  also defines a receptacle  26  for movably receiving plunger assembly  14  as will be discussed in further detail below. Inlet connector  18  includes a female luer-type connector which is configured to engage the distal end of a fluid delivery device  28 , e.g., a syringe. Outlet connector  22  includes a male luer-type connector which is configured to releasably engage an indwelling catheter assembly (not shown). 
     Referring also to  FIG. 1 , housing  12  includes an inner wall  30  which defines receptacle  26 . A central portion of inner wall  30  defines a stepped portion  32 . Stepped portion  32  defines an annular shoulder  34  ( FIG. 3 ) and a plurality of spaced longitudinal slots  36  ( FIG. 3 ). Spaced longitudinal slots  36  are dimensioned to slidably receive radially extending fingers or tabs  38  as will be discussed in further detail below. Although four slots  36  and tabs  38  are shown ( FIG. 3 ), one or more slots  36  and tabs  38  may be provided. 
     Plunger assembly  14  includes a plunger body  40  and a plunger head  42  which are secured together using known fastening techniques, e.g., adhesives, welding interlocking structure, etc., to define an integral assembly  14 . It is also envisioned that plunger assembly  14  may be of unitary construction. Plunger body  40  has a proximal end  40   a  defining an axial extension  44  and a bell-shaped body portion  46 . Radial fingers or tabs  38  extend radially from a distal end of body  40  and are positioned to rest on shoulder  34  of housing  12  ( FIG. 3 ) when plunger assembly  14  is in a retracted position. Radial fingers  38  are also dimensioned to be slidably received in longitudinal slots  36  formed along inner housing wall  30  of housing  12 . Axial extension  44  of plunger body  40  is dimensioned to extend into a delivery channel  28   a  of delivery device  28  ( FIG. 1 ) and defines a T-shaped channel  46 . Channel  46  allows fluid to flow from delivery device  28  into receptacle  26  of housing  12  when axial extension  44  is positioned in delivery channel  28   a  of delivery device  28 . It is envisioned that channel  46  may have other configurations such as Y-shaped, F-shaped, or any other configuration that allows fluid to flow from delivery device  28  into receptacle  26 . As illustrated in  FIG. 3 , axial extension  44  has a non-circular outer geometry which is illustrated as being substantially triangular, although other non-circular configurations are envisioned, e.g., square, rectangular, trapezoidal, etc. The outer geometry of axial extension  44  should be such that when axial extension  44  of plunger assembly  14  is received in delivery channel  28   a  of delivery device  28 , delivery device  28  and plunger assembly  14  are rotatably fixed together. 
     Plunger head  42  is substantially cylindrical and is dimensioned to be slidably received within a cylindrical portion  50  of housing  12 . An outer wall  42   a  of plunger head  42  includes one or more annular sealing ribs  52  which are positioned to sealingly engage an inner wall of cylindrical portion  50  of housing  12  as plunger assembly  14  moves from its retracted position ( FIG. 1 ) to its advanced position ( FIG. 4 ). Movement of plunger head  42  through cylindrical portion  50  of housing  12  forces fluid located within cylindrical portion  50  through outlet conduit  24  into an indwelling catheter assembly (not shown). 
     Biasing member  16  which is shown as a coil spring is positioned within receptacle  26  between a proximal shoulder  60  of housing  12  and radial fingers  38 . Biasing member  16  urges plunger assembly  14  distally within receptacle  26  such that when radial fingers  38  are misaligned with longitudinal slots  36 , radial fingers  38  rest on shoulders  34  of stepped portion  32  of housing  12 , and when radial fingers  38  are aligned with longitudinal slots  36 , biasing member  16  urges plunger assembly  14  from its retracted position ( FIG. 1 ) to its advanced position ( FIG. 4 ). 
     In use, cap assembly  10  is attached to a syringe  28  including a locking solution. It is envisioned that cap assembly  10  and syringe  28  may be preassembled. It is also envisioned that cap assembly  10  may be prefilled with a locking solution and further include a means for selectively closing the distal end of outlet conduit  24  and/or the proximal end of inlet connector  18  such as by attaching a removable luer cap. When cap assembly  10  is secured to syringe  28 , axial extension  44  is received within delivery channel  28   a  of syringe  28 . As discussed above, axial extension  44  and delivery channel  28   a  have non-circular configurations to rotatably fix axial extension  44  to syringe  28  ( FIG. 2 ). In this condition, radial fingers  38  are misaligned with longitudinal slots  36  such that radial fingers  38  are seated on shoulders  34  ( FIG. 3 ) and plunger assembly  14  is retained in its retracted position ( FIG. 1 ). Distal connector  22  can be connected to an indwelling catheter assembly (not shown) and fluid can be injected from syringe  28 , through cap assembly  10  into the indwelling catheter assembly (not shown) along the path indicated by arrows “A” in  FIG. 1 . When this occurs, locking fluid will fill cap assembly  10  and flow into the indwelling catheter assembly to force medicament and/or blood positioned within the catheter assembly into the patient. Additionally, fluid can be aspirated from the indwelling catheter assembly (not shown), through cap assembly  10  into syringe  28  in the reverse direction of path “A”. When syringe is subsequently separated from cap assembly  10  by rotating syringe  28  in relation to cap assembly  10  in the direction indicated by arrow “C” ( FIG. 2 ), axial extension  44 , which is rotatably fixed to syringe  28 , will rotate to rotate plunger assembly  14  within receptacle  26 . When plunger assembly  14  rotates, radial fingers  38  are rotated over shoulders  34  in the direction indicated by arrows “B” in  FIG. 3  into alignment with longitudinal slots  36 . When radial fingers  38  move into alignment with longitudinal slots  36 , biasing member  16  moves plunger assembly  14  to its advanced position ( FIG. 4 ) to force fluid from cylindrical portion  50  of housing  12  through outlet conduit  24  into the indwelling catheter assembly (not shown). As such, blood is not withdrawn into the indwelling catheter assembly when syringe  28  is separated from housing  12  of cap assembly  10 . Furthermore, plunger assembly  14  is also capable of displacing large amounts of fluid, for example 1-2 mL or more, from cylindrical portion  50  of housing  12  into the indwelling catheter assembly (not shown). Cap assembly  10  remains attached to the indwelling catheter until it is desired to inject a medicament into the catheter assembly or withdraw blood from a patient. Then, it can be removed from the catheter assembly and the flushing/locking process described above can be repeated after medicament administration or blood withdrawal. 
       FIG. 5  illustrates an alternate embodiment of the presently disclosed plunger assembly shown generally as  114 . Plunger assembly  114  is substantially similar to plunger assembly  14  except that plunger assembly  114  further includes a resilient valve or sealing element  114   a  formed at the outlet end of T-shaped channel  146 . Resilient valve  114   a  may be in the form of a slit-type valve. Resilient valve  114   a  remains closed until a predetermined positive or negative pressure is created in channel  146 , such as by actuating syringe  28  ( FIG. 1 ). When the predetermined positive pressure is reached in channel  146 , resilient valve  114   a  flexes outwardly to allow fluid to flow from channel  146  into the housing receptacle (see  FIG. 1 ). When the predetermined negative pressure is reached in channel  146 , resilient valve  114   a  flexes inwardly to allow fluid flow from the housing receptacle into channel  146 . Furthermore, a proximal end of resilient valve  114   a  may be in contact with the distal end of syringe  28  to prevent fluid from flowing through the gap that may exist between the outside surface of axial extension  144  and the wall of delivery channel  28   a . Plunger assembly  114  prevents lock solution from entering the receptacle of the cap assembly during transportation and storage of the syringe and cap assembly when the two parts are preassembled. A removable cover (not shown) may be provided to seal outlet conduit  24  to guard or prevent contaminants from entering the cap assembly prior to use. 
     It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.