Abstract:
A pre-slit injection site ( 34 ) includes a housing ( 40 ) with a flow path therethrough. A first end ( 42 ) of the housing ( 40 ) carries a pre-slit septum ( 52 ). One form of a blunt cannula ( 98 ), usable with the injection site ( 34 ), carries a locking member ( 100 ). When the pre-slit injection site ( 34 ) slidably receives the blunt cannula ( 98 ), the locking member ( 100 ) latches to the injection site ( 34 ) and creates a mechanically coupled unit. Another form of the cannula ( 280 ) includes a tube having a tapered distal end region ( 298 ) and having elongate discharge slots ( 294 ) for reducing contact surface area and for directing the flow laterally out of the cannula. The cannula may also include a rounded lead post ( 330 ), an annular barb ( 394 ), and axially oriented grooves ( 268 ).

Description:
This is a continuation of U.S. patent application Ser. No. 08/695,040 filed Aug. 9, 1996, which was a continuation of U.S. patent application Ser. No. 07/325,617 filed Mar. 17, 1989 (now abandoned) which is a continuation-in-part of U.S. patent application Ser. No. 07/217,004, filed Jul. 8, 1988, now abandoned is a continuation-in-part of U.S. patent application Ser. No. 07/147,414, filed Jan. 25, 1988 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The invention pertains to coupling systems usable to transfer materials from one flow conduit to another. More particularly, the invention pertains to two-part coupling members with a first part including a pre-slit septum and second part including a blunt cannula. The pre-slit septum slidably receives the blunt cannula to effect the coupling. 
     BACKGROUND OF THE INVENTION 
     Injection sites usable with pointed cannulae have long been known. For example, such sites can be formed with a housing having a fluid flow path therein. A septum is positioned in the housing closing the fluid flow path. 
     One injection site usable with a piercing cannula is disclosed in U.S. Pat. No. 4,412,573 to Zbed entitled “Injection Site.” The Zbed patent is assigned to the assignee of the present invention. 
     The pointed cannula can be forced through the septum into fluid flow communication with the flow path in the housing. Known injection sites usable with a piercing cannula can be physically damaged by repetitive piercing caused by the sharp cannula. This damage, known as coring or laceration, can result in subsequent leakage. 
     Due to problems associated with infectious agents, personnel using such pointed cannulae do so with great care. Notwithstanding careful and prudent practice, from time to time, accidents do occur and individuals using such pointed cannulae jab themselves. 
     Injection sites usable with a blunt cannula are also known. For example, U.S. Pat. No. 4,197,848 issued to Garrett, et al., entitled “Closed Urinary Irrigation Site” and assigned to the assignee of the present invention discloses one such injection site. That injection site is a relatively low pressure device having a relatively thin, molded, sealing member. The sealing member has an opening therethrough. 
     A blunt cannulae can be forced through the sealing member placing the cannulae into fluid flow communication with a fluid flow pathway in the injection site. 
     Injection sites of the type noted above usable with a blunt cannula have the advantage that the blunt cannula will not pierce the skin of a user. On the other hand, it is important that the pre-alit injection site reseal with enough force that fluids do not ooze therefrom and that airborne particulate matter, bacterial or viral matter do not enter therethrough. 
     Hence, there continues to be a need for a pre-slit injection site which can be used with a variety of solutions and over a range of fluid pressures. Further, there continues to be a need for such a pre-slit injection site which will reliably reseal even after many insertions of the blunt cannula. 
     Such an injection site should be able to receive a large number of insertions of the cannula without displaying reseal failure. Such an injection site should provide for improved alignment of the cannula on insertion. Improved alignment will result in less chance of damage to the injection site after repeated insertions of the cannula. Preferably, the injection site would also be usable with a pointed cannula. Preferably, a pre-slit injection site usable with a blunt cannula will provide a reasonable level of insertion force such that health care personnel will readily be able to insert the blunt cannula, yet the cannula will not easily fall from or drop out of contact with the septum. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, an easily wipeable injection site usable with a blunt cannula is provided. The injection site includes a housing which defines a fluid flow channel therethrough. The housing has a first and a second end. 
     A flexible sealing member is carried by the housing for sealing the first end. The sealing member has a resealable opening therein. The sealing member also is formed with a curved exterior peripheral surface such that the blunt cannula can be sealingly inserted through the opening and placed in fluid flow communication with the flow path. Further, the blunt cannula can be removed from the opening with a sealing member then interacting with the housing so as to reseal the opening. 
     The housing can also be formed with the first end including an annular channel underlying the sealing member. The sealing member is subjected to radially directed forces by a tapered surface of the first end of the housing. These forces tend to reseal the opening in the sealing member. 
     The sealing member can be a cylindrically shaped rubber member. The first end of the housing can include an interior tapered surface for receiving the sealing member and for applying the radially directed forces to the sealing member. 
     A retaining member carried by the first end of the housing can be used to retain the sealing member within the housing. The retaining member can be generally U-shaped. Alternately, the retaining member can be formed as a coiled spring. 
     The retaining member applies axially directed forces to the sealing member. In one embodiment of the invention, the retaining member deflects the sealing member and forms a curved exterior peripheral surface thereon. The curved exterior peripheral surface is an easily wipeable surface. 
     The retaining member deflects or distorts the upper and lower peripheral edges slightly as a result of applying axial forces thereto. When the blunt cannula is inserted into the slit in the sealing member, an annular interior peripheral region of the sealing member deforms further and fills, at least in part, the annular channel. 
     Deformation of this annular peripheral region results in an insertion force in a range of 2.0 pounds (0.7564 kilograms) to 5.0 pounds (1.891 kilograms). Preferably, the insertion force will have a value of the order of 2.0 pounds (0.7564 kilograms). 
     The resealable opening in the sealing member can extend entirely through that member. Alternately, the resealable opening can extend only partway therethrough. In this embodiment, the end of the blunt cannula will be used to tear through the remainder of the sealing member. 
     The sealing member can be formed in two parts. An exterior cylindrical portion can be slit completely. An interior cylindrical unslit portion can be provided to seal the site until the blunt cannula is inserted therethrough the first time. 
     The interior surface of the first end can be formed with the taper in a range on the order of 5 degrees to 20 degrees. Preferably, the interior surface will have a taper on the order of 12 degrees. This tapered surface permits the use of a cylindrically shaped sealing member. 
     To provide for leak-free insertion, the length of the slit in the sealing member must be less than one-half the circumference of the cannula being inserted therethrough. Hence, the slit length may exceed the diameter of the cannula being inserted. In addition, the slit length must be great enough, given the elastic limit of the sealing member, to prevent tearing during insertion. 
     Further, in accordance with the invention, a coupling system for coupling first and second fluid flow members together is provided. The coupling system includes an injection site which is affixed to the first fluid flow member. The injection site includes a housing. The housing has a fluid flow path therethrough. 
     A sealing member is carried by the housing. The sealing member has a resealable opening therein. 
     An annular retaining member is carried by the housing and cooperates with the housing to retain the sealing member therein. Radially directed forces are applied to the sealing member by the housing, thereby urging the opening into a resealed condition. 
     A blunt cannula, affixed to second fluid flow member, has a fluid flow path therethrough. The cannula carries a locking member for lockingly engaging the housing when the cannula extends through the opening of the sealing member. When so positioned, the two fluid flow members are placed into fluid flow communication. 
     The locking member can include a luer-type twist lock fitting. Alternately, the locking member can include slidably engageable members which are responsive to axial movement of the injection site and the cannula toward one another. 
     In accordance with further aspects of this invention, the blunt cannula may be provided with features that facilitate insertion into the injection site, enhance fluid flow or dispersion, increase tug resistance, and reduce kickback. 
     In particular, one embodiment of the cannula includes a tube with a plurality of elongate discharge slots adjacent the distal end. The fluid changes direction as it passes laterally through the slots and out of the tube. The flow area of the slots exceeds the flow area inside the tube. This slot structure enhances fluid flow and inspersion characteristics. In addition, the slots decrease the contact surface area on the tube exterior so as to facilitate insertion. 
     In a further modification, the cannula includes a lead post on the tube distal end to guide the cannula through the slit in the injection site. 
     In another cannula embodiment, the tube is generally cylindrical and the fluid discharges directly from an open end of the tube. The exterior surface of the tube is provided with grooves to reduce the contact surface area. 
     In still another cannula embodiment, the tube has a cylindrical portion and a tapered distal end portion which are each about equal in length. The taper facilitates insertion, and the remaining cylindrical portion reduced kickback. 
     In yet another embodiment, the cannula includes an annular barb which functions to reduce kickback. 
     Other advantages of a blunt plastic cannula in accordance with the invention, relative to conventional steel needles include a higher fluid flow rate capacity and a simpler one-piece plastic design. 
     Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention and the embodiments thereof, from the claims and from the accompanying drawings in which the details for the invention are fully and completely disclosed as a part of this specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view, partly in section, of a prior art pre-slit injection site and an associated blunt cannula; 
     FIG. 2A is a view in perspective of a catheter positioned in the hand of a patient with a pre-slit injection site in accordance with the present invention positioned adjacent thereto; 
     FIG. 2B is a perspective view of the catheter of FIG. 2A with a pre-slit injection site in accordance with the present invention rotatably affixed thereto; 
     FIG. 3 is an enlarged side elevational view in a section of a pre-slit injection site in accordance with the present invention formed on a body having a luer twist-lock type connector for coupling to a catheter; 
     FIG. 4A is an exploded view of a pre-slit injection site, a shielded blunt cannula and a syringe prior to being coupled together; 
     FIG. 4B is an enlarged, side elevational view in section of the pre-slit injection site, the shielded blunt cannula and the syringe of FIG. 4A coupled together to form a sealed fluid flow system; 
     FIG. 5A is a view in perspective of a pre-slit injection site prior to engaging a blunt cannula carrying a locking member; 
     FIG. 5B is an enlarged side elevational view, partly broken away, illustrating the interrelationship between the pre-slit injection site and the blunt cannula of FIG. 5A; 
     FIG. 6 is an overall view of a container, an associated solution administration set and a pre-slit injection site in accordance with the present invention; 
     FIG. 7 is an enlarged side elevational view, partly broken away illustrating the relationship between selected elements of FIG. 6; 
     FIG. 8 is a side elevational view, partly broken away illustrating an alternate shielded cannula in accordance with the present invention; 
     FIG. 9 is a side elevational view, partly in section, of a pre-slit injection site mounted on a fragment of a solution container; 
     FIG. 10 is a side elevational view of a fragment of a solution container carrying, as a single port, a pre-slit injection site; 
     FIG. 11 is a side elevational view of the injection site and the fragmentary container of FIG. 10 prior to being engaged with a shielded cannula carried by a syringe; 
     FIG. 12 is an enlarged side elevational view, partly in section, of a coupling system with a pre-slit injection site partly coupled to a blunt cannula; 
     FIG. 13 is an enlarged side elevational view, partly in section, of the coupling system of FIG. 12 subsequent to engagement of the two coupling members; 
     FIG. 14 is a side elevational view, partly broken away, of a spike connector carrying a pre-slit injection site in accordance with the present invention; 
     FIG. 15 is an enlarged side elevational view of a Y-connector in section carrying a pre-slit injection site in accordance with the present invention; 
     FIG. 16 is an enlarged fragmentary side elevational view in section of a coupling member carrying a pre-slit injection site where the slit extends only partway through the septum; 
     FIG. 17 is a perspective view of a burette solution administration set carrying a pre-slit injection site in accordance with the present invention; 
     FIG. 18 is a view of part of a burette solution administration set carrying a pre-slit injection site being coupled to a shielded blunt cannula; 
     FIG. 19 is a step in the method of making a pre-slit injection site in accordance with the present invention; 
     FIG. 20 is another step in the method of making a pre-slit injection site in accordance with the present invention; 
     FIG. 21 is an initial phase of a final step in making a pre-slit injection site in accordance with the present invention; 
     FIG. 22 is an intermediate phase of the final step in a method of making a pre-slit injection site in accordance with the present invention; 
     FIG. 23 is a final phase of the final step in a method of making a pre-slit injection site in accordance with the present invention; 
     FIG. 24 illustrates an initial phase in an alternate step of making a pre-slit injection site in accordance with the present invention; 
     FIG. 25 illustrates a final phase of the alternate step in a method of making an injection site in accordance with the present invention; 
     FIG. 26 illustrates yet another alternate step in a method of making a pre-slit injection site in accordance with the present invention; 
     FIG. 27 is an enlarged, fragmentary cross-sectional view of another embodiment of an injection site in accordance with the present invention; 
     FIG. 28 is a cross-section view taken generally along the plane  28 — 28  in FIG. 27; 
     FIG. 29 is an end view of another embodiment of the cannula in accordance with the present invention; 
     FIG. 30 is a cross-section view taken generally along the plane  30 — 30  in FIG. 29; 
     FIG. 31 is an end view of another embodiment of the cannula in accordance with the present invention; 
     FIG. 32 is a cross-sectional view taken generally along the plane  32 — 32  in FIG. 31; 
     FIG. 33 is a cross-sectional view taken generally along the plane  33 — 33  in FIG. 32; 
     FIG. 34 is an end view of another embodiment of the cannula in accordance with the present invention; 
     FIG. 35 is a fragmentary, side elevational view of the embodiment of the cannula illustrated in FIG. 34; 
     FIG. 36 is a cross-sectional view taken generally along the plane  36 — 36  in FIG. 34; 
     FIG. 37 is a cross-sectional view taken generally along the plane  37 — 37  in FIG. 36; 
     FIG. 38 is an end view of another embodiment of the cannula according to the present invention; 
     FIG. 39 is a cross-sectional view taken generally along the plane  39 — 39  in FIG. 38; 
     FIG. 40 is a cross-sectional view taken generally along the plane  40 — 40  in FIG. 39; 
     FIG. 41 is an and view of another embodiment of the cannula according to the present invention; 
     FIG. 42 is a cross-sectional view taken generally along the plane  42 — 42  in FIG. 41; 
     FIG. 43 is an end view of another embodiment of the cannula according to the present invention; 
     FIG. 44 is a cross-sectional view taken generally along the plane  44 — 44  in FIG. 43; and 
     FIG. 45 is a view in section of another insertion member for a blunt cannula. 
     FIG. 46 is a perspective view of another embodiment of a blunt cannula embodying the present invention. 
     FIG. 47 is a perspective view of a blunt cannula shield or tip protector. 
     FIG. 48 is a perspective view of a heparin lock embodying the present invention. 
     FIG. 49 is a side elevational view of the heparin lock of FIG. 48 in joined relationship with a blunt cannula device of alternative construction embodying the present invention. 
     FIG. 50 is a cross-sectional view of the heparin lock of FIG. 48 in joined relationship with a blunt cannula device of further alternative construction embodying the present invention. 
     FIG. 51 is a cross-sectional view of a pre-slit in-line injection site embodying the present invention in joined relationship with a blunt cannula shown in side elevational view. 
     FIG. 52 is a perspective view of the alternative blunt cannula device of FIG. 49 in joined and locked relationship with the pre-slit in-line injection site depicted in FIG.  51 . 
     FIG. 53 is a perspective view, partially broken away, depicting the combination of a syringe and an alternative blunt cannula device of the present invention for injecting or removing liquid through a pre-slit in-line injection site, such as depicted in FIG.  51 . 
     FIG. 54 is a perspective view of a blunt cannula shield or tip protector for attachment over the end of the blunt cannula device such as depicted in FIG.  53 . 
     FIG. 55 is a cross-sectional view of an alternative blunt cannula device particularly suited for attachment to a syringe as shown in FIG.  53 . 
     FIG. 56 is a perspective view of the blunt cannula device shown in FIG. 53 in joined relationship with the pre-slit injection site shown in FIG.  51 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While this invention is susceptible of embodiment in many different forms, there are shown in the drawing and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
     A prior art pre-slit injection site  10  and associated blunt cannula  12  are illustrated in FIG.  1 . The prior art injection site  10  has a cylindrical housing  14  with a fluid flow path  16  therethrough. A first end  18  of the housing  14  is closed with a relatively thin disc-shaped resealable member  20 . The member  20  has a resealable opening  22  therein. 
     The member  20  is a molded septum with an integrally formed skirt  20   a.  The skirt  20   a  is oriented generally perpendicular to the portion of the septum with the opening  22 . 
     The cannula  12  includes a body portion  24  which carries at a first end a hollow, cylindrical, blunt piercing member  26 . As the cannula  12  is moved in a direction  28  toward the first end  18  of the injection site  10 , the member  26  slidably engages the opening  22 . The sealing member  20  is then deformed adjacent the opening  22  and the number  26  extends into the flow path  16 . A fluid flow path through the cannula  12  will then be in fluid flow communication with the flow path  16  via the hollow piercing member  26 . 
     In contradistinction to the prior art pre-slit injection site  10  of FIG. 1, FIGS. 2A and 2B illustrate a pre-slit injection site  34  being coupled to a peripheral venous catheter  36 . The catheter  36  is shown in fluid flow communication with a vein in a hand H of a patient. The catheter  36  carries at a proximal end  38  a luer-type female twist lock connector  41 . 
     The pre-slit injection site  34  is formed with a cylindrical housing  40  having a first end  42  and a second end  44 . 
     Carried by the housing  40 , adjacent the second end  44  is a hollow cylindrical fluid flow member  46 . The member  46  slidably engages a receiving member in the housing  38  of the catheter  36 , thereby providing a sterile fluid flow coupling as is well known and conventional. 
     A plurality of internal male luer-type threads  48  is carried by the housing  40  adjacent the second end  44 . The threads  48  will engage the flange member  41  when the injection site  34  is rotated in a direction  50 . When so coupled together, the catheter  36  and the injection site  40  provide a sealed coupling through which fluids may be injected into the vein of the hand H. 
     FIG. 3 illustrates, in section, further details of the injection site  34 . A resealable septum  52  is carried by the first end  42  of the housing  40 . The septum  52  includes first and second spaced apart surfaces  54  and  56  respectively. The surface  54  has been forced into a dome-like shape by annular, U-shaped, swaged end members  58  carried by the first end  42 . The dome-like shape of the surface  54  can extend beyond a surface  42   a  of the first end  42 . This facilitates cleaning the surface  54 . 
     The septum  52  has a generally cylindrical shape. The septum  52  can be formed of a latex or synthetic rubber material. Alternately, the septum can be formed of a thermoplastic elastomer. The material used for the septum  52  should be non-toxic and sterilizable such as by means of radiation, steam or Ethylene Oxide. 
     Because the septum  52  is generally cylindrical in shape, it can be die-cut from a sheet, cut from an extruded rod or molded. The septum  52  can have an exemplary diameter on the order of 0.30 inches (0.762 centimeters). The height of the septum  52  can be, for example, on the order of 0.125 inches (0.3175 centimeters). 
     The first end  42  is also formed with a tapered interior surface  60  which terminates in an annular channel  62 . The tapered interior surface  60  has a taper in a range of 5 degrees to 20 degrees. Preferably, the taper will be on the order of 12 degrees. With the indicated size of the above noted exemplary septum  52  and a 12 degree taper, diametric resealing compression of the septum  52  adjacent the channel  62  is on the order of 10%. 
     The channel  62  is bounded in part by a septum supporting ridge  62   a.  The channel  62  can typically have a depth in a range of 0.050-0.070 inches (0.127-0.1778 centimeters). 
     A peripheral surface  64  of the septum  52  slidably engages the tapered interior surface  60  as the septum  52  slides into the first end  42 . The annular channel  62  which underlies the interior peripheral surface  56  of the septum  52  is provided to permit the septum  52  to deform when a blunt cannula is inserted through an opening  66  therein. 
     The housing  40  is also formed with a fluid flow path  68  such that fluids injected via a blunt cannula inserted through the resealable opening  66  can flow into the catheter  36  for delivery to hand H of the patient. 
     The swaged end members  58  apply axial forces to the septum  52  thereby creating the domed exterior peripheral surface  54 . The axial forces applied by the end members  58  slightly deform the regions  52   a  and  52   b.  In contradistinction, the tapered internal surface  60  applies radially directed forces to the septum  52 , thereby forcing the opening  66  into a resealed condition. 
     In an alternate embodiment, the surface  52  could be formed as a flat, as opposed to a domed, surface. 
     Once the injection site  34  is lockingly engaged with the catheter  36 , a sealed system is formed through which fluids can be infused into the catheter  36 . The resealable septum  52  closes the fluid flow path  68 . 
     FIGS. 4A and 4B illustrate in combination the injection site  34 , a blunt shielded cannula  80  and a syringe of a conventional type  82 . The syringe  82 , as is well known, can be formed with a cylindrical hollow end  84  which carries a male luer-type twist lock thread  86 . A hollow centrally located cylindrical fluid flow member  88  is in fluid flow communication with an interior region  90  of the syringe  82 . 
     The shielded blunt cannula  80  carries at a first end  92  a female luer twist-lock flange  94 . The flange  94  will slidably engage the threads  86  of the end  84 . Hence, the shielded blunt cannula  80  can be locked to the syringe  82  forming a closed fluid flow pathway. The shielded cannula  80  could alternately be formed fixedly attached to the syringe  82 . 
     The shielded blunt cannula  80  carries a cylindrical hollow protective shield  96  which surrounds a centrally located hollow, elongated cylindrical blunt piercing member  98 . The cylindrical blunt piercing member  98  has a total length on the order of three times the thickness of the septum  52  in order to ensure complete penetration. The cylindrical blunt piercing member  98  has a diameter on the order of ⅓ the diameter of the septum  52 . The shield  96  is desirable and useful for maintaining the piercing member  98  in an aseptic condition by preventing touch contamination prior to the shielded cannula  80  engaging the pre-slit septum  52 . Also, the shield helps to align the piercing member with the pre-slit septum. 
     The cylindrical blunt piercing member  98  can slidably engage the pre-slit septum  52 , best illustrated in FIG. 4B, thereby extending through the preformed opening  66  therein. As illustrated in FIG. 4B, when the piercing member  98  slidably engages and pierces the septum  52 , the region  52   a  deforms by expanding into and filling, at least in part, the annular channel  62 . 
     The deformation facilitates insertion of the piercing member  98  through the slit  66 . Subsequent to the piercing member  98  slidably engaging the injection site  34 , the interior region  90  of the syringe  82  is in fluid flow communication with the flow path  68  of the injection site  34  via flow paths  88   a  and  98   a  respectively of the syringe and the blunt piercing member  98 . 
     In this engagement condition, the septum  52  seals completely around the piercing member  98 . Hence, exterior gases, liquids or airborne matter will be excluded from the channel  68 . 
     Subsequent to infusing fluid from the syringe  82  into the fluid flow pathway  68 , hence into the catheter  36  and the hand H of the patient, the syringe  82  with lockingly engaged shielded cannula  80  can be slidably withdrawn from the injection site  34 . Subsequent to this withdrawal, the septum  52  reseals the opening  66  therein. 
     The opening  66  will repeatedly reseal, when the piercing member  98  is removed, provided that the pressure (in the septum  52  of the opening  66 ) created by interaction of the septum material properties and compression supplied by the housing exceeds the pressure challenge of the fluid contained within. Blunt cannula do not haphazardly core, lacerate, or otherwise damage the sealing interface  66  as conventional needles do, thereby allowing repeatable resealability. However, septum material properties, thickness, and compression allow resealability for a finite number of conventional needle insertions. The combination injection site  34  and catheter  36  then return to its pre-infusion, sealed condition. 
     FIGS. 5A and 5B illustrate the pre-slit injection site  34  used in combination with a blunt cannula  80   a.  The cannula  80   a  includes a hollow body portion  92   a  with a luer flange  94   a,  a piercing member  98   a,  and manually operable elongated locking members  10   a  and  10   b.  Alternately, a tubing member could be affixed to the hollow body portion  92 . 
     Curved end regions  10   c  of the members  100   a  and  100   b  slidably engage the second end  44  of the housing  40  when the piercing member  98   a  of the blunt cannula  80   a  has been forced through the preformed opening  66 , best illustrated in FIG.  5 B. The embodiment illustrated in FIGS. 5A and 5B has the advantage that the infusion cannula  80   a  cannot accidentally disengage from the pre-slit septum  34  during the fluid infusion process. It will be understood that while spring-like deflecting members  102   a  and  100   b  are illustrated in FIGS. 5A and 5B that other forms of locking members are within the spirit and scope of the present invention. 
     FIG. 6 illustrates an alternate pre-slit injection site  34   a.  A tubing member  102  can be fixedly attached to the cylindrical hollow fluid flow member  46 . The embodiment  34   a  of FIG. 6 utilizes the same structure for the septum  52  including the tapered surface  60  and the underlying annular channel  62  as does the embodiment  34  in FIG.  3 . The shielded cannula  80  can be utilized with the injection site  34   a  as previously described. 
     In the event that it is desirable to infuse solution from a container  104  with a connectional port  106 , a fluid administration set  110  of a conventional variety may be utilized. The set  110  includes a spike connector  112  at a first end. The spike connector  112  is designed to pierce the port  106  of the container  104 . The set  110  can also carry a slidably engageable connector  114  of a known type at a second end. As illustrated in FIG. 7, the connector  114  can slidably engage the hollow cylindrical member  92  of the shielded cannula  80 , thereby placing the interior fluid of the container  104  into fluid communication with the tubing member  102 . 
     FIG. 8 illustrates yet another alternate  100   b  to the shielded cannula  80 . The piercing member  98  carries a tubing member  118  fixedly attached thereto. The tubing member  118  could be coupled at a second end to a container such as the container  104 . 
     The present pre-slit injection site can be directly affixed to a container  120  as illustrated in FIG.  9 . The container  120  includes a rigid hollow cylindrical access port  122  affixed thereto. The access port  122  includes a fluid flow channel  124  in fluid flow communication with the interior of the container  120 . Sealingly affixed to the port  122  is a pre-slit injection site  126 . 
     The site  126  includes a cylindrical housing  128  which carries at a first end  130  a septum  132  with a slit  134  formed therein. The first end  130  has been swaged to form an annular U-shaped retaining member  136 . The retaining member  136  in turn forms a domed exterior peripheral surface  138  on the septum  132 . 
     The first end  130  also includes a tapered interior force applying surface  140  and an annular channel  142  underlying the septum  132 . As discussed previously, the channel  142  provides a space into which the septum  132  can deform when a blunt cannula is forced through the resealable opening  134 . 
     Further, as illustrated in FIG. 9, the injection site  126  can be covered by a removable cover  146  of a type used with the conventional port  106  of the bag  104 . 
     While the bag  120  is illustrated formed with two ports, the conventional pierceable port  106  and the pre-slit injection site  126 , it will be understood that as an alternate (FIG.  10 ), a container  150  could be formed which includes only the pre-slit injection port  126 . The removable cover  146  could be used in combination with the container  150 . 
     As illustrated in FIG. 11, the pre-slit injection site  126  can be utilized for the purpose of injecting fluid from the syringe  82 , coupled to the shielded cannula  80 , into the container  150 . When so utilized, the blunt piercing member  98  is used to place the interior fluid containing region  90  of the syringe into fluid flow communication with the interior of the container  150 . 
     FIGS. 12 and 13 illustrate a fluid flow coupling system  151  having as a first element a pre-slit injection site  126   a.  The site  126   a  is the same as the site  126  except for a plurality of exterior threads  153  formed on an exterior peripheral surface  155  of the housing  128   a.  A second element of the coupling system  151  is a shielded blunt cannula  157 . 
     The shielded blunt cannula  157  is sealingly affixed to a flexible tubing member  159  by means of a proximal hollow cylindrical member  161 . The member  161  extends into a hollow cylindrical shield  163  to form a blunt piercing member  165 . 
     The shield  163  carries, on an interior peripheral surface, a set of coupling threads  165 . The threads  165  match the threads  153 . 
     The two connector elements  126   a  and  157  slidably engage one another when the shielded cannula  157  moves in an axial direction  167  toward the injection site  126   a.  The blunt piercing member  165  penetrates the septum  132   a.    
     The coupling member  157  can then be rotated in a direction  169  such the interior set of threads  165  carried thereon engages the exterior set of threads  153 . As a result, the two coupling members  126   a  and  157  are lockingly engaged together with the insertion member  165  extending through the opening  134   a  in the septum  132   a.  Hence, fluids can flow from the container  150   a  via the connector system  126   a  and  157  through the tubing member  159  to the recipient. 
     Injection sites of the type described above are also usable in connection with other fluid flow coupling components. For example, with respect to FIG. 14, a pre-slit injection site  160  of the type described above can be used in combination with a spike connector  162  of a conventional variety. Spike connectors such as the spike connector  162  can be used to pierce conventional ports such as the port  106  of the container  104  (FIG.  6 ). When the spike connector  162  is so used, the pre-slit injection site  160  can then be utilized for the purpose of coupling to other fluid administration sets. 
     The injection site  160  illustrates an alternate fore of swaging the first end  42   c  for the purpose of retaining the septum  52   c  therein. The first end  42   c  can be swaged so as to form an annularly shaped, spiral, spring-like member  164 . The member  164  has a free end  164   a  which engages the exterior dome-shaped peripheral surface  54   c  of the septum  52   c.  The spiral, spring-like swaged member  164  will tend to uncoil, thereby continuously applying axial force to the septum  52   c  and maintaining the domed exterior peripheral surface  54   c.    
     In yet another alternate, FIG. 15 illustrates a pre-slit injection site  166  formed in a Y-junction member  168 . The Y-junction member  168  is fixedly attached to first and second tubing members  170  and  172  respectively. 
     As an alternate to forming the slit  66   d  completely through the septum  52   d,  as illustrated in FIG. 16, a slit  66   e  can be formed only partly through the septum  52   e.  Such a structure has the further advantage that, until used for the first time, the septum  52   e  is completely sealed. 
     The septum  52   e  can be formed in two parts. One part can have a slit, such as the slit  66   e,  extending entirely therethrough. A second part can be formed without a slit. These two parts can be located adjacent one another in the first end  42   e  of the injection site. 
     The slit  66   e  may be longer on the top of the septum than the bottom. This feature aids blunt cannula alignment with the slit upon insertion, and aids resealability by minimizing the critical slit sealing interface area. 
     In accordance with the present invention, the slit could have a length with a range on the order of 0.03 inches (0.0762 centimeters) to 0.150 inches (0.381 centimeters). Preferably, a slit length on the order of 0.07 inches (0.1778 centimeters) will be used in combination with a blunt cannula having a diameter on the order of 0.1 inches (0.254 centimeters). 
     When initially used, the blunt cannula piercing member, such as the member  98 , will be forced through the slit  66   a.  The lower peripheral surface  56   e  will then be punctured, providing access for the blunt cannula piercing member  98  into the fluid flow pathway  68   e.    
     Pre-slit injection sites of the type described above can be utilized in combination with burette solution administration sets. One such set  176  is illustrated in FIG.  17 . The set  176  includes a pre-slit injection site  178  of the type described above. The injection site  178  is affixed to an exterior planar surface  180  of the burette  182 . A removable cover  184  can be used to maintain the injection site  178  in an aseptic condition until blunt cannula  186  or  188  is inserted therethrough. 
     FIGS. 19 through 23 disclose a method of making a pre-slit injection site in accordance with the present invention. In a first step, a housing  200  is provided. The housing  200  has an interior tapered surface  202  at a first end  202   a  thereof. The interior peripheral surface terminates in an annular channel  204 . A cylindrical septum  206  can be provided adjacent the end  200   a.    
     In a second step, the septum  206  can be forced into the end  202   a  of the housing  200  and slightly deformed by the tapered peripheral surface  202  using an axially moving die  210 . When positioned by the die  210 , the septum  206  is located adjacent an internal annular right  212  which bounds the annular channel  204 . 
     In a third step, a second die  214  can be utilized to swage the end  200   a  into spiral-shaped, spring-like members  200   b  which apply axially directed forces against an exterior peripheral surface  206   a  of the septum  206 . The axially directed forces form the flat surface  206   a  into a domed exterior peripheral surface  206   b  as illustrated in FIG.  23 . 
     Simultaneously, with swaging the end members  200   a  so as to lock the septum  206  into the housing  200  and to form the domed exterior peripheral surface  206   b,  a knife  216  can be utilized to form a slit in the septum  206 . Alternatively, the slit may be cut by a separate die in a separate step. If the septum  206  is formed as an extrusion, the slit can be created during the extrusion process. If the septum  206  is formed by stamping from a rubber sheet, the slit can be cut during the stamping process. If the septum  206  is formed by compression molding, the slit can be cut during the trimming process. 
     In order to extrude the slit into rod, a flat pin extrusion bushing can be used. A trailing ribbon may be attached to the bushing. The ribbon would prevent curing material across the slit. The ribbon or wire could be placed in the rod core and later stripped out leaving a slit. An inert substance, such as silicon oil, could be coextruded in the center of the rod to prevent curing across the slit and provide lubrication and a visible target for cannula insertion. 
     FIGS. 24 and 25 illustrate alternate swaging steps wherein a die  220  moving axially toward the housing  200  swages the end region  200   a  so as to form an annular U-shaped region  200   c  and the exterior domed peripheral surface  206   c.    
     The dies  214  or  220  can be formed with various alternate shaped swaging surfaces  224 , as illustrated in FIG. 26, depending on the precise shape of the end swage which is desired. It will be understood that all such variations in the swaging operation are within the spirit and scope of the present invention. 
     The injection site configuration need not be limited to the configurations depicted in FIGS. 3 through 5B,  9 , and  12  through  16 . Rather, several configurations could be constructed without departing from the scope of this invention. Any such configuration would provide a flexible pre-slit sealing member captured in a chousing which provides compression to create a seal against pressure and a void region to accommodate deformed portions of the sealing member material only when the material is deformed or displaced by a blunt cannula piercing member. One such possible configuration is depicted in FIGS. 27 and 28. 
     FIGS. 29 and 30 illustrate a tapered cannula structure  250  which is an alternate to the tapered cannula  98 . The cannula  250  includes a proximal end  252  with an interior region  254 . The region  254  is in part bounded by an internal peripheral wall  256  which is formed with a standard luer taper. The tapered cannula  250  can be formed with a luer-type coupling flange  257  at the proximal end so as to be releasably connectable to the syringe  82  as was the tapered cannula  98  previously discussed. 
     Extending from the proximal end  252  is a cylindrical tube having a cylindrical mid-region  258  and a distal end member  260 . The member  260  has a generally elongated, cylindrical shape with an exterior side wall  262 . A centrally located, cylindrical, internal fluid flow path  264  extends through the distal end member  260  and mid-region  258  in fluid flow communication with the interior region  254 . 
     The distal end of the end member  260  has a tapered exterior surface  266 . The tapered exterior surface  266  minimizes insertion force as the cannula  250  is being forced through a slit of a septum, such as the slit  66  in the septum  52 . The angle of taper of the surface  266  is preferably in a range between 1 to 15 degrees. 
     The member  260  is also provided with a plurality of elongated grooves  268 . The grooves  268  in the exterior wall of the member  260  decrease the surface area of contact at the cannula/septum interface during insertion of the cannula into the injection site  34 . This reduced exterior contact surface area decreases the frictional component of the insertion force. 
     In one embodiment, the tapered blunt cannula  250  may have overall insertion length, corresponding to combined axial lengths of mid-region  258  and end member  260 , on the order of 0.375 inches (0.9525 centimeters). 
     An alternate cannula structure  280  is illustrated in FIGS. 31,  32  and  33 . The cannula structure  280  includes a proximal end region  282  corresponding to the end region  252  of the cannula  250 . The region  282  includes a luer flange  283 . The cannula  280  also includes a central, elongated, cylindrical region  288 . 
     The central region  288  carries at a distal end thereof an elongated cylindrical end member  290 . The member  290  includes an exterior, peripheral, cylindrical surface  292  (FIG.  31 ). The surface  292  is interrupted by a plurality of spaced-apart, elongated slots or apertures  294 . The slots  294  are defined by first and second spaced-apart, elongated, parallel side surfaces  294   a  and  294   b.  Each of the slots terminates in an end surface  294   c  at the central region  288 . 
     A fluid flow path  294   d  extends through the cannula  280 . The flow path  294   d  is in fluid flow communication with the slots  294 . 
     Between the slots  294 , at a distal end of the region  290 , the exterior surface  292  terminates in tapered end regions  298  to facilitate insertion of the cannula into a pre-slit injection site. The slots  294  themselves also function to decrease the surface contact area, and this further minimizes the insertion force. 
     The slots  294  are oriented substantially 90 degrees apart around a longitudinal axis  300 . The slots  294  increase the internal flow path cross-section. This increases the fluid flow rate. 
     The slots  294  also provide for enhanced dispersion characteristics owing to the fluid flowing radially out through the slots  294 . This radial flow, effecting as change in fluid flow direction of about 90 degrees, promotes flushing and dispersion of fluid through the injection site  34 . 
     Another embodiment of a blunt cannula  310  is illustrated in FIGS. 34 through 37. The cannula  310  is formed with an enlarged proximal connection region  312  corresponding to the region  252  of the cannula  250 . The region  312  includes a luer flange  313  and a central fluid flow region  314 . 
     An intermediate, cylindrical region  318  extends from the proximal connection region  312 . The cylindrical intermediate region  318  includes a fluid flow path  320  in communication with the fluid flow region  314 . 
     The end region  324  extends from the region  318  and includes a first cylindrical portion  326  into which the fluid flow path  320  extends. The region  326  terminates in a tapered exterior surface  328 . The tapered exterior surface  328  merges with a centrally located lead post or guide post  330 . The lead post  330  terminates in a hemispherical end surface  332 . 
     The lead post  330  helps locate the septum slit  66  prior to insertion and facilitates penetration of the septum slit  66  by the cannula. The lead post  330  facilitates insertion by providing a very low insertion force at the beginning of the insertion step as the cannula is pushed through the slit, such as the slit  66 . 
     In a preferred embodiment, the guide post  330  can have a length on the order of 0.060 inches (0.1524 centimeters) and a diameter on the order of 0.050 inches (0.127 centimeters). 
     The end region  318  includes a novel structure for increasing the flow rate and enhancing dispersion characteristics. In particular, the region  318  includes three radially oriented slots  338 . Each slot  338  has sides  339   a  and  339   b  which each lie along a radius of the cylindrical portion  326  as best illustrated in FIG.  37 . The fluid flowing through the cannula  310  undergoes a change in direction (of up to about 90 degrees relative to the cannula center line  337 ) in the slots  338 . This change in direction increases fluid dispersion. Further, since the slots  338  open radially, fluid flow can be maintained even if the end surface  332  of the cannula is pushed up against any material in the system in which the cannula is inserted. 
     Another embodiment of the tapered cannula of the present invention is illustrated in FIGS. 38 through 40 and is designated generally therein by reference numeral  340 . The cannula  340  includes a proximal end  342  which can include a luer coupling flange  344  for cooperating with a suitable mating structure on a syringe. The proximal end  342  also defines an interior region  346 . 
     Extending from the proximal end  342  is a generally cylindrical mid-region  348 . Extending from the mid-region  348  is an end member or region  350  which includes a tapered surface  352 . 
     The distal end of the end region  352  terminates in a blunt, arcuate end surface  356 . Defined within the mid-region  348  and end region  350  is an internal fluid flow channel  354  which communicates with the interior region  346 . Fluid discharges from the flow channel  354  via grooves or apertures  358  in the end region  350 . The change in direction of the fluid flow as the fluid passes from the interior channel  354  through the apertures  358  improves fluid dispersion with respect to mixing or flushing in the system downstream of the cannula (e.g., the injection site, drug vial, etc.). The apertures  358  may also function to increase withdrawal force or tug resistance. 
     Moreover, since the fluid passes radially out through the apertures  358 , fluid flow through the cannula  340  can be maintained even when the distal end surface  356  of the cannula is bottomed out or pushed against any material in the system in which the cannula is inserted. 
     The structure of the cannula  340  is adapted to be constructed with a minimal lead post length (i.e., the portion of the cannula distal end between the end surface  356  and the interior flow channel  354 ). Further, the design accommodates the use of a minimal tip diameter, minimal taper angle, and minimal cannula diameter. The minimization of these parameters results in a decrease in the peak insertion force required to properly install the cannula in the injection site. 
     Preferably, the total cross-sectional flow area through the three apertures  358  is about three times the cross-sectional flow area of the interior channel  354 . This enhances the flow rate capability compared with a simple open ended cylindrical flow channel of equal length. 
     The design of the cannula  340  also is effective in reducing or limiting “kick back” or recoil of the cannula after insertion. The resilient material of the septum in an injection site can subject the cannula to forces tending to push the cannula back out of the septum. The kick back forces on the cannula  340  are minimized by the provision of the generally cylindrical mid-region  348 . 
     Another embodiment of the cannula of the present invention is illustrated in FIGS. 41 and 42 wherein the cannula embodiment is designated generally therein by the reference numeral  360 . The cannula  360  includes a proximal end  362  defining an interior region  364  and having a luer flange  366  for connection to a suitable mating engaging structure. 
     A generally cylindrical mid-region  366  extends from the proximal end  362 , and an end region  368  extends from the mid-region  366 . As with the previous embodiment of the cannula  340  illustrated in FIGS. 38 through 40, the embodiment of the cannula  360  minimizes kick back or recoil owing to the provision of a substantially cylindrical mid-region  366 . This design also increases withdrawal or tug resistance. 
     A generally cylindrical internal flow channel  370  extends through the end region  368  and mid-region  366  in communication with the interior region  364  of the proximal end region  362 . The end region  368  is provided with a tapered surface  372 . The design permits the use of a very small taper to minimize the insertion force. 
     Further, the design permits the cannula  360  to be constructed with a small tip diameter, small taper angle, and small cannula diameter so as to reduce the peak insertion force. 
     Another embodiment of the cannula of the present invention is illustrated in FIGS. 43 through 44 and is designated generally therein by reference numberal  380 . The cannula  380  includes a proximal end  382  with a luer flange  384 . An interior fluid flow region  386  is defined on the interior of the proximal end  382 . 
     Extending from the proximal end  382  is a aid-region  388 . A distal end region  390  extends from the mid-region  388 . An internal fluid flow channel or path  392  extends through the end region  390  and mid-region  388 , and is in communication with the interior flow region  386 . 
     The end region  390  has an exterior tapered surface  394 . This facilitates insertion of the cannula into the injection site. In contrast, the mid-region  388  is generally cylindrical so as to minimize kick back and increase the withdrawal force or tug resistance. 
     Further, to provide even greater withdrawal force, the mid-region  388  includes an annular barb  396 . The barb  396  has a sufficient radius so as to preclude damage to the septum of the injection site and so as to accommodate molding in a straight draw tool. The maximum diameter of the annular barb  396  may typically be on the order of 0.02 inches (0.0508 centimeters) greater than the diameter of the cylindrical mid-region  388 . Although the barb  396  functions to prevent inadvertent removal of the cannula  380  from the septum of the injection site, removal of the cannula  380  can still be achieved by entering a sufficiently great axially directed removal force on the cannula  380 . 
     Still another embodiment is illustrated in FIG. 45 which includes a blunt tapered cannula insertion member  400  for insertion into a pre-slit injection site, the cannula  400  having a distal end region  402  with a tapered exterior surface which in the preferred embodiment is an approximately 8 degrees taper. The defined aperture  404  for fluid flow is disposed at the end  406  of the distal end region  402 . The end  406  includes a radiused tip defined by a radius of approximately 0.01 inch (0.025 centimeters). The radiused tip reduces insertion force, assists in locating the slit in the injection site and in addition has the practical advantage of facilitating complete filling of the cannula mold cavity. 
     The tapered surface of the distal end region  402  has an axial length of approximately 0.10 inch in the preferred embodiment. Adjacent to the tapered distal end region is a generally cylindrical region  408  for entering into the injection site behind the distal end region  402 , thereby reducing kick back during insertion. The generally cylindrical region  408  has a small draft angle such as about one-half degree. 
     The force required to insert any of the above-discussed embodiments of the blunt tapered cannula into the septum of the injection site depends upon a number factors: friction at the cannula/septum interface, cannula diameter, cannula taper angle, and degree of septum compression. The cannula/septum interface friction is, in turn, dependent upon lubrication, if any, material properties, and surface finish. It will be understood that the friction at the cannula/septum interface can be reduced by providing a smoother surface finish on the cannula (e.g., by sand blasting the cannula exterior surface) or by molding the cannula so as to produce a matte finish. Conventional lubricants can also be used to further reduce the friction and thereby lower the insertion force required. 
     In the embodiments of the cannulae described herein, the aid-region and the tapered distal end region may be alternatively characterized as together forming at least one tube defining a fluid flow path therein with the tube having a distal end region for penetrating the injection site. 
     In preferred contemplated embodiments, the exterior surface of the distal end region may have a taper angle as small as between 1 and 15 degrees. 
     Further, a locking means, such as the locking arms  100   a  and  100   b  discussed with reference to FIGS. 5A and 5B, may be provided on the cannula embodiments illustrated in FIGS. 29 through 44 to permit the cannulae to be releasably locked to the injection site. 
     The above described insertion members, usable as part of a blunt cannula, are preferably molded of a plastic formulation including silicone or other lubricant. The use of silicone or other lubricant increases the ease of insertion of that member into the pre-slit injection site. 
     FIG. 46 shows a blunt cannula member, generally at  410 , for use with the pre-slit injection sites disclosed herein. The blunt cannula member  410  generally has a hollow cylindrical portion  412  and a blunt cannula portion  414 . The blunt cannula member  410  is preferably of one-piece molded, rigid plastic, with a through bore  416  extending through the blunt cannula portion and communicating with the hollow cylindrical portion. 
     The hollow cylindrical portion has a pair of opposed raised flanges or threads  418  for threaded engagement with other devices, for example, syringes, administration sets and the like. Internally, the hollow cylindrical portion  412  may also be adapted for attachment to other devices. For example, the internal surface of the cylindrical portion may define a tapered female luer surface for interfitting with the standard male luer connectors utilized in many medical devices, as is well known in the medical field. The hollow cylindrical portion  412  may also include a pair of opposed flat surfaces  420  for cooperation with a tip protector or shield such as depicted in FIG. 47, which is described below. 
     The blunt cannula portion  414  extends generally axially from the hollow cylindrical portion  410 . The cannula portion is generally cylindrical throughout the greater part of its length, with a tapered end portion  424 , which narrows to the blunt end edge  426 . 
     FIG. 47 is an enlarged view of a hollow shield or tip protector  428  for covering and protecting a blunt cannula, such as, for example, the blunt cannula portion  414  of blunt cannula member  410  shown at FIG. 46 or other blunt cannulae as disclosed herein. The shield  428  has a generally elongated housing  430 , which is open at one end for receiving the blunt cannula. At the open end, the interior surface  432  of the shield generally corresponds to the shape of the exterior surface of the blunt cannula portion  412 , i.e., it is generally cylindrical, with a pair of opposed flat surfaces  434  matching the flat surfaces  420  of the blunt cannula device  410 . Further, either surfaces  432  or  434  can be provided with standing ribs to control the depth of insertion of the blunt cannula portion  414  into housing  430 . The matching flat surfaces of the shield and the blunt cannula device allow a user to secure the blunt cannula onto a syringe or similar device, for example, without exposing the cannula portion  414  to touch contamination. When access to the blunt cannula is required, the shield may simply be slidably removed from the cannula. As can be appreciated, the outer surface of the shield  428  can be shaped in such a manner or provided with a roughened finish to assist the user in gripping or removing shield  428  from the cannula. 
     Typically, the blunt cannula  410  or other blunt cannula device and shield  428  would be provided in a joined sterile configuration. The shield  428  can be provided with channels to facilitate gas sterilization. The user preferably leaves the shield on to prevent inadvertent contamination when attaching the blunt cannula to the mating product, e.g., the male luer fitting of a syringe or administration set. The matching flat surfaces  432  of the shield and  420  of the blunt cannula act as a wrench to allow any twisting force applied to the shield to be transmitted to the cannula, e.g., for threading the cannula onto a luer lock device or for applying a twisting force in making a luer slip connection. 
     FIG. 48 shows what is commonly referred to as a heparin lock, generally at  436 , employing a pre-slit injection site  442  and other features of the present invention. The heparin lock  436  may be attached, for example, to the end of a venous catheter. 
     During intravenous therapy, it is not unusual for the administration of liquid to be interrupted from time to time. Instead of performing a new catheterization procedure each time administration is to be restarted, it is often preferable to utilize the same catheter, thus reducing the number of catheterization procedures, more colloquially referred to as the number of “sticks,” and reducing the trauma and risk associated with each such procedure. 
     To maintain the patency of the catheter during interruption, and prevent blood from clotting and clogging the catheter, it is a common practice to attach an injection site over the catheter and fill the catheter with heparin or other anticoagulant. The heparin lock  436  shown in FIG. 48 is for attaching to a patient&#39;s catheter for maintaining patency of the catheter during interruption in fluid flow. 
     The heparin lock  436 , also shown in FIGS. 49 and 50, has a first end portion  438  in the form of a male luer connector for sealingly engaging a complementary female tapered luer surface on the patient&#39;s catheter (see cross-sectional view in FIG.  50 ). The other end of the heparin lock  436  includes a pre-slit injection site  442  of the type previously discussed in detail. An axial fluid flow passageway  444  communicates between the pre-slit injection site and the end of the male luer for fluid flow therebetween. 
     The tapered exterior surface of the male luer  438  is substantially surrounded by generally cylindrical gripping collar  446 . Threads  448  are provided on the interior surface of the collar for threadedly engaging a standard luer lock connector, as is often found on intravenous catheter devices. The exterior surface of the collar  446  is generally arcuate in cross-sectional shape (as best seen in FIGS.  49  and  50 ), to provide a gripping surface. The surface curves generally outwardly in a direction toward the pre-slit injection site  442 . This allows the nurse, physician or attending staff member to grip the heparin lock and to reduce any force exerted during entry of a blunt cannula into the pre-slit injection site from being transmitted to the venous catheter. For improvement in the gripping, a series of axial grooves  450  are provided in the exterior surface of the collar  446 . 
     In accordance with other aspects of the present invention, the heparin lock includes features which allow attachment to various styles or types of blunt cannulae. For example, as best seen in FIG. 48, threads  452  are provided on the exterior surface of the cannula for threaded locking engagement to a blunt cannula device of the type having an interiorly threaded sleeve or shield, such as depicted in FIG.  50 . The heparin lock  436  also includes a generally radially-extending shoulder  454  for locking retention, of resilient gripping fingers on a blunt cannula device of the type shown in FIG.  49 . 
     As a safety measure, and to prevent staff confusion of an injection site of the present invention with other injection sites which are for use with needles, a visual identifier is also provided with the heparin lock of FIG.  48 . Such an identifier may also be provided with the other pre-slit injection site devices described above. The identifier may take the form of any unique color or configuration which allows the staff member to determine that the heparin lock  436  embodies the present invention and is intended for Use with blunt cannula. In the preferred embodiment, however, the visual identifier comprises a distinct color identifier and, more particularly, is a brightly colored ring  456  (FIG. 48) circumscribing the pre-slit injection site  442 . While the color selected may vary depending on application, it should be a color which is distinct from and in contrast to the color of any plastic used in the manufacture of the heparin lock. 
     As noted earlier, the heparin lock  436  depicted in FIG. 48 may be used with a variety of styles or types of blunt end cannula devices. For example, the heparin lock may be used with a bare blunt end cannula, such as that depicted in FIG. 46, which does not lock onto to the heparin lock. Alternatively, as shown in FIG. 49, the heparin lock may be used in combination with a blunt cannula device  458  which utilizes a pair of resilient gripping fingers  460  for retaining the blunt cannula in joined relationship with the heparin lock. The blunt cannula device  458  depicted in FIG. 49 has a generally cylindrical, hollow base or body portion  462  and a blunt cannula portion  464  substantially as described earlier in connection with FIG. 46 or with the other figures of the present inventions. A fluid flow path  463  extends through the blunt cannula portion and communicates with a female luer connection  465  defined in the hollow body portion for fluid flow through the blunt cannula device. Flanges or threads  467  on the body portion permit the attachment of a male luer lock connector to the blunt cannula device. 
     Each of the gripping fingers  460  is mounted to the body portion of the blunt cannula device by an intermediate radially extending wall portion  466 . The gripping fingers have radially inwardly directed retention means  468  at one end for engaging against radial shoulder  454 , and gripping means  470  at the other end for squeezing and spreading the retention means to release the blunt cannula device from the heparin lock. In the as-molded condition, the gripping fingers are biased radially inwardly, toward the blunt cannula portion  464 . Because of the natural resilience of the plastic, the retention end of the fingers may be spread by squeezing the gripping end of the fingers. The natural resilience will hold the retention means in the lock position (shown in FIG. 49) until manually released. 
     When used in combination with a heparin lock such as depicted in FIG. 48, the blunt cannula device  458  may be attached by simply pushing the blunt cannula into the pre-slit injection site  442 . A forward facing tapered surface  472  (FIG. 49) in front of the threads engages a similar tapered surface  474  on the retention means  468  so as to naturally spread the fingers  460  apart as the blunt cannula is forced into the pre-slit injection site. After the blunt cannula is inserted into pre-slit injection site sufficiently far so that the retention means are beyond the radial shoulder  454 , the gripping fingers will snap inwardly behind the shoulder, holding the blunt cannula in the position depicted in FIG.  49 . To withdraw the blunt cannula, the user need simply squeeze the gripping end  470  of the handles, which will spread the retention means of the fingers and release the blunt cannula device from the heparin lock. 
     The heparin lock of FIG. 48 is also useful with a blunt cannula device  475  having an internally threaded shield or sleeve, such as depicted in FIG.  50 . FIG. 50 illustrates the blunt cannula device  475  as it first enters the pre-slit injection site  442  of the heparin lock and prior to engagement with the heparin lock threads  452 . The blunt cannula device shown in FIG. 50 has a generally cylindrical outer wall  476  and a transverse end wall  478 . A blunt cannula  480  extends through the end wall. The blunt cannula may be constructed in generally the same manner as the blunt cannula portion depicted in FIG. 46 or in accordance with the other embodiments of the present invention. 
     The cylindrical outer wall  476  preferably extends beyond the tip end of the blunt cannula to protect the cannula against inadvertent touch contamination. The interior surface of the cylindrical wall is preferably threaded at  482  for threadedly engaging the device to which the blunt cannula is attached, such as the heparin lock depicted in FIG.  48 . As noted above, FIG. 50 depicts the blunt cannula device  475  at an initial entry position. Further insertion of the blunt cannula and simultaneous turning of the blunt cannula device results in threaded locking engagement between the blunt cannula device  475  and the heparin lock. 
     The blunt cannula  480  of the blunt cannula device  475  is in fluid communication with an entry port, generally defined by wall  484 , which extends in the opposite direction of the blunt cannula, from the other side of the transverse wall. The entry port is for attachment to other devices such as syringes, tubing, administration sets or the like, and may take such form as is appropriate for the particular device to which it is attached. The entry port  484  preferably has a tapered inner surface for receiving a standard male luer fitting of a syringe or the like, and may include external threads or flanges  485  for attachment to a luer lock. Another embodiment provides the entry port  484  as having a tapered inner surface for receiving a tubing fit. A fluid passageway  486  extends continuously through the entry port and the cannula portion for flow therebetween. 
     FIG. 51 shows, in cross-sectional view, a further alternative device  492  which may employ the pre-slit injection site of the present invention. The pre-slit injection site device  492  depicted in FIG. 51 is an in-line device, preferably for adding medication to a fluid stream, removing a sample from a fluid stream, or similar application. The device depicted in FIG. 51 has a fluid entry port  494  at one end, a fluid exit port  496  at the other end, and a fluid passageway  498  communicating directly between the entry and exit ports. The inlet and outlet may have such additional features as are useful connecting the injection site device within a fluid flow path. As depicted, the inlet defines a slightly tapered female surface and the outlet defines a similarly female tapered surface which are preferably joined by solvent bonding a similar attachment to plastic tubing of an administration set, extension set or the like. Standard luer fittings or surfaces could also be provided at the inlet or outlet, as desired. 
     For injecting liquid into the fluid stream or sampling the fluid stream, the device has a side channel  496  which communicates between a pre-slit septum  502  made and assembled in accordance with the present invention, and the fluid passageway  498 . The septum  502  is made as described above, and mounted and held in position by a swaged-over wall  504 , as previously described, which may include a colored identifier ring around the septum. 
     In accordance with the present invention, a blunt cannula, such as cannula  506 , may be inserted through the pre-slit septum for injecting fluid into the liquid stream flowing between the inlet and outlet, or for taking samples of the fluid stream. 
     The in-line injection site device  492  shown in FIG. 51 may be used in combination with a bare blunt cannula, such as that depicted in FIG. 51, or may be used in combination with the blunt cannula device  458 , depicted in FIG. 49, when a locking relationship between the blunt cannula and injection site is desired. 
     As depicted, for example, in FIG. 52, the blunt cannula device  458  may be attached in a secure locking relationship to the in-line injection site  492 . As shown there, the in-line injection site has a radially extending shoulder  508  on each side of the housing, for engaging against the retention means  468  on the end of the resilient gripping fingers  460 . As with the heparin lock, the in-line injection site also includes a generally tapered surface  510  defined on the exterior surface for spreading the retention means as the blunt cannula is inserted into the injection site. As was described above, insertion of the blunt cannula into the injection site results in the retention means being spread by the tapered surface  510  and, as the blunt cannula is inserted farther, the retention means snap into a locking position behind the radial shoulder  508 . In this arrangement, the blunt cannula is securely locked onto the injection site and inadvertent withdrawal is thus prevented. To remove the blunt cannula from the in-line injection site, the gripping ends  470  of the resilient fingers are squeezed, causing spreading of the retention means  468  and release from the injection site. The cannula may then be simply removed by withdrawing it from the injection site. 
     FIG. 53 depicts yet a further embodiment of the present invention. That figure depicts a blunt cannula device  512  embodying the present invention in combination with a syringe  514 . The blunt cannula device  512  has a generally cylindrical outer wall  516  which encloses and substantially protects a blunt cannula portion  518 . The blunt cannula portion is attached to and extends from an intermediate transverse interior wall  520 . The blunt cannula device  512  may be attached to a syringe in various ways. As depicted, however, the syringe  514  has a glass barrel wall which is tightly press fit into one end of the cylindrical outer wall, extending therewithin to the transverse wall  520 . 
     Although various syringes nay be used in connection with the blunt cannula device  512  without departing from the present invention, the syringe depicted in FIG. 53 is of the type prefilled with a medical liquid such as heparin. Although it does not form a part of the present invention, for purposes of completeness, the syringe depicted in FIG. 53 has a pair of resilient pistons  522  spaced apart, with the fluid to be dispensed contained between the pistons. A plunger rod  524  pushes the pistons forward until the forward most piston engages against an entry port  526  which extends in a direction opposite the blunt cannula  518 . The forwardmost piston has a frangible portion, which is pierced by the entry port, releasing the liquid contained between the pistons for expulsion through the blunt cannula. 
     In accordance with the present invention, the blunt cannula portion  518  is substantially protected from inadvertent touch contamination by the outer cylindrical wall  516 . To permit the blunt cannula to be used, however, with the in-line injection site  492  or a similar device, a pair of opposed, generally U-shaped recesses  528  are provided in the cylindrical wall for receiving the inlet and outlet portions  494 ,  496  of the in-line injection site when the cannula is attached to it. This arrangement is depicted in a perspective view in FIG.  56 . As shown there, the blunt cannula device  512  may be attached to the in-line injection site by inserting the blunt cannula portion into the pre-slit injection site, with the U-shaped recesses  528  receive the inlet and outlet portions  494 ,  496  of the in-line injection site, thus allowing the bare cannula to be inserted sufficiently far into the pre-slit injection site. 
     FIG. 54 shows a shield or tip protector  530  for a blunt cannula device of the type shown in FIG.  53 . The tip protector  530  has a generally cylindrical outer wall  532  with raised ribs  534  for gripping. The cylindrical wall is sized to slip over the end cylindrical wall  514  of the blunt cannula device  512 , and is sufficiently long to extend beyond the U-shaped recesses to completely enclose and protect the blunt cannula  518  during shipping, storing and between uses, if so desired. 
     Concentrically disposed within the cylindrical wall  532 , the tip protector has an axially extending, hollow tube  536  for slidably receiving the blunt cannula  518  therewithin. The shield or tip protector  530  would typically be attached to the blunt cannula device  512  during manufacture, and removed when the syringe and blunt cannula device are used. If so desired, it may be reattached between uses to protect the cannula from any further contamination. 
     FIG. 55 is an alternative embodiment of the blunt cannula device shown in FIG. 53, and is depicted without a syringe attached to it. As shown in FIG. 55, the blunt cannula device  538  similarly has a cylindrical outer wall  540 , a transverse intermediate inner wall  542 , a blunt cannula  544  extending axially from the transverse intermediate wall and an entry port  546  extending in the opposite direction from the blunt cannula. The essential difference between this embodiment and the one shown in FIG. 53 is the absence of U-shaped recesses for use with an in-line injection site such as depicted in FIG.  56 . For ease of attachment to an injection site, the inner surface of the cylindrical wall is preferably tapered at  548 . 
     From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the novel concept of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.