Abstract:
The present invention relates to a safety clip device for shielding and retaining a tip of an introducer needle following insertion of a vascular catheter. The safety clip device includes a sleeve having an interlock system for locking together the sleeve and the catheter adapter. The sleeve houses a safety clip wherein a portion of the introducer needle extends through the safety clip and is pinched between arm portions of the safety clip. As the tip of the introducer needle is withdrawn from the catheter adapter, the tip of the introducer needle is retained in the safety clip, whereafter the safety clip is retained within the sleeve and the sleeve is released from the catheter adapter for safe disposal.

Description:
BACKGROUND OF THE INVENTION 
     This disclosure relates generally to vascular access devices and methods, including hypodermic needles, catheter assemblies, and devices used with catheter assemblies. Generally, vascular access devices are used for communicating fluid with the vascular system of patients. For example, catheters are used for infusing fluid, such as saline solution, various medicaments, and/or total parenteral nutrition, into a patient, withdrawing blood from a patient, and/or monitoring various parameters of the patient&#39;s vascular system. 
     Intravenous (IV) catheter assemblies are among the various types of vascular access devices. Over-the-needle peripheral IV catheters are a common IV catheter configuration. As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. The introducer needle is generally a hypodermic needle coupled to a needle assembly to help guide the needle and to facilitate its cooperation with the catheter. At least the inner surface of the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and thus facilitate insertion of the catheter into the blood vessel. The catheter and the introducer needle are assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter with the bevel of the needle facing up away from the patient&#39;s skin. The catheter and introducer needle are generally inserted at a shallow angle through the patient&#39;s skin into a blood vessel. 
     In order to verify proper placement of the needle and/or catheter in the blood vessel, the clinician generally confirms that there is “flashback” of blood into a flashback chamber associated with a needle assembly. Flashback generally entails the appearance of a small amount of blood which is visible within the needle assembly. This allows a clinician to confirm placement of the catheter within a patient&#39;s blood vessel. Once proper placement of the distal tip of the catheter into the blood vessel is confirmed, the clinician may apply pressure to the blood vessel by pressing down on the patient&#39;s skin over the blood vessel distal of the introducer needle and the catheter. This finger pressure momentarily occludes the vessel, minimizing further blood flow through the introducer needle and the catheter. 
     The clinician may then withdraw the introducer needle from the catheter. The introducer needle may be withdrawn into a needle tip shield or needle shield that covers the needle tip and prevents accidental needle sticks. In general, a needle tip shield includes a housing, a sleeve, or other similar device that is designed such that when the needle is withdrawn from the patient, the needle tip will be trapped/captured within the needle tip shield. The purpose of the needle tip shield is to house the tip of the needle in a secure location, thereby reducing the possibility of needle sticks when the needle and needle tip shield are separated properly from the catheter. The catheter, conversely is left in place to provide intravenous access to the patient. 
     The separation of the needle assembly from the catheter portions of the catheter assembly presents numerous potential hazards to the clinicians and others in the area. As indicated above, there is a risk of accidental needle sticks if the needle tip is not secured properly in a needle tip shield. Additionally, because the needle has been in contact with blood in the patient&#39;s vasculature, blood is often present on the exterior of the needle and is often present inside the lumen of the needle. As the needle is withdrawn, there is a risk that this blood will drip from the needle tip or come into contact with other surfaces to expose clinicians and equipment to blood. Additionally, it has been observed that withdrawing a needle from a catheter assembly often imparts energy to the needle assembly, such as by the intentional or unintentional bending forces applied to the needle during removal. This energy has been observed to cause blood to splatter or spray from the needle as the needle wiggles and shakes with stored energy once it is free from the catheter assembly. While prior needle assemblies have provided needle tip shields to reduce the occurrence of needle sticks, these prior enclosures and clips have not sufficiently addressed the risk that clinicians and equipment may be exposed to blood from the needle without experiencing a needle stick. While the problem of blood exposure from needle tips used in over-the-needle catheters is a common problem, blood exposure risks are also problematic in other uses of hypodermic needles where the needle tip has been in contact with blood. The present disclosure presents systems and methods to significantly limit and/or prevent such blood exposure. 
     BRIEF SUMMARY OF THE INVENTION 
     The systems and methods of the present disclosure have been developed in response to problems and needs in the art that have not yet been finally resolved by currently available vascular access systems and methods. Thus, these systems and methods are developed to provide safer vascular access systems that reduce blood exposure. 
     A vascular access system may include a needle shielding system. The needle shielding system may include a needle, and in one embodiment, the needle shielding system includes a hypodermic needle. The needle is a tubular shaft with a needle tip on a distal end and an opening on a proximal end. The needle also includes a needle feature, such as a crimp or ferrule, at a location along the exterior of the needle and generally located near the distal end of the needle. The needle feature is attached to the needle in an irreversible manner such that the feature is unable to be removed from the needle. The needle feature is positioned along the exterior of the needle so as to interact with a safety clip as described below. 
     The needle shielding system may include a safety clip positioned around the needle. The safety clip includes a generally cylindrical base wherein a first side of the base is closed and a second side of the base is open. The first side of the base comprises a cannula port such that the needle may slidably extend through the cannula port and into the base of the safety clip. For example, in one embodiment the cannula port has an inner diameter is that is greater than the outer diameter of the needle shaft but is less than the outer diameter of the needle feature such that the needle may translate through the cannula port, but the needle feature may not translate through the cannula port. 
     The safety clip base further comprises at least one arm, wherein the arm extends distally from the base in an orientation parallel to the needle. The safety clip further comprises a flap that extends perpendicularly from the distal end of the arm such that the flap pinches the tubular shaft of the needle. This biases the arm and the flap of the base in a radially outward direction. The base of the safety clip further comprises at least one barb which extends radially outward from the base so as to interact with a complementary barb catch as located on the interior of a sleeve. The safety clip is positioned within a sleeve as described below. 
     The needle shielding system may also include a sleeve which is generally tubular and houses the safety clip. The sleeve includes a proximal and a distal opening. The safety clip is housed within the sleeve and the arm of the safety clip extends from the sleeve through the distal opening. Additionally, the proximal end of the needle shaft extends through the proximal opening. However, the proximal opening of the sleeve does not permit the base of the safety clip to exit the sleeve. For example, in one embodiment the proximal end opening of the sleeve has an inner diameter that is less than the outer diameter of the safety clip but that is greater than the outer diameter of the needle shaft. The outer diameter of the safety clip base is slightly less that the inner diameter of the sleeve such that the safety clip may translate within the sleeve in a slidable fashion. The sleeve may also include a complementary barb catch on the interior surface of the sleeve. As such, the barb of the safety clip base may interact with the barb catch of the sleeve in an irreversible manner such that the safety clip is locked within the interior of the sleeve. This process is described in detail below. 
     The sleeve may also include a hinged interlock flange wherein a section of the sleeve is cut such that a window is formed. The window may have three unattached sides and one hinged side such that the remaining hinged cut-out is an interlock flange. The interlock flange may hinge outwardly from the outer surface of the sleeve and interact with an interlock mate as located on the inner surface of a catheter adapter. The interlock flange may include an interlock finger for engaging an interlock mate and may also include a safety clip contact for maintaining contact with the at least one arm of the safety clip. For example, in one embodiment, the proximal end of the sleeve comprises a complementary barb catch located on the interior surface of the sleeve. The distal end of the sleeve is cut such that an interlock flange is hingedly attached to the sleeve. In this same embodiment, the cut in the sleeve results in a window being formed. The window is generally rectangular having three unattached sides and a fourth attached side comprising a hinge. The hinge attaches the interlock flange to the fourth side of the window. The interlock flange of this embodiment further comprises an interlock finger extending outwardly from the outer surface of the interlock flange. The interlock finger compatibly engages an interlock mate as formed on the inner surface of a catheter adapter. The interlock flange further comprises a safety clip contact that extends inwardly from the inner surface of the interlock flange and maintains contact with the arm of the safety clip. For example, in one embodiment the safety clip contact and the interlock finger are molded extensions of the interlock flange. The safety clip contact maintains contact with the outer surface of the at least one arm of the safety clip and the outwardly biased arm of the safety clip outwardly biases the interlock flange. As such, the interlock finger is securely locked within the interlock mate as formed on the interior surface of the catheter adapter. The engaged interlock finger and interlock mate provide support for the sleeve and the catheter adapter as described below. 
     The needle shielding system may also include a catheter adapter. The catheter adapter comprises an opening adapted to receive the sleeve such that the interlock finger of the interlock flange may compatibly engage an interlock mate as formed on the interior surface of the catheter adapter. The catheter adapter may also include a catheter. The catheter is attached to the distal end of the catheter adapter and configured such that the needle and the needle feature are positioned in the catheter. As such, the needle is positioned to aid in insertion of the catheter into a patient. The catheter adapter has an inner diameter that is slightly greater than the outer diameter of the sleeve. As such, the sleeve may be inserted into the catheter adapter in a compatible manner. For example, in one embodiment the sleeve is fitted into the catheter adapter. As inserted, the interlock finger of the interlock flange compatibly engages the interlock mate as formed on the interior surface of the catheter adapter. In this same embodiment, the needle is housed within the catheter such that the tip of the needle extends distally beyond the distal end of the catheter. In this embodiment, the sleeve and the catheter adapter are locked together and supported by the engaged interlock finger and interlock mate. 
     The needle shielding system is actuated following insertion of the catheter into a patient. The actuation occurs as the needle tip is withdrawn from the catheter in a proximal direction. As such, the needle and needle feature are removed from the catheter and into the lumen of the catheter adapter. As the needle tip is drawn into the interior of the catheter adapter, the needle tip translates proximally beyond the flap of the safety clip arm. At that point, the flap no longer pinches the shaft of the needle. At this point the arm of the safety clip collapses inwardly such that the flap is moved into a position generally perpendicular to the needle and distal to the location of the needle tip. At this point, the flap covers the needle tip, preventing the needle tip from exiting the safety clip beyond the flap. As the proximal end of the needle&#39;s shaft translates in a proximal direction, the needle is drawn further into the interior of the safety clip until the needle feature catches on the cannula port. At this time the needle and the safety clip are drawn together into the interior of the sleeve. 
     As the needle and the safety clip are drawn into the interior of the sleeve, the flap of the safety clip arm is drawn proximally past the safety clip contact. As such, the safety clip contact no longer contacts the at least one arm of the safety clip. At that point, the interlock flange relaxes inwardly, disengaging the interlock finger from the interlock mate. As the interlock finger disengages from the interlock mate, the barb of the safety clip base is simultaneously engaged by the complimentary barb mate. This irreversibly locks the safety clip within the sleeve. With the interlock finger disengaged from the interlock mate, the sleeve, and the enclosed needle and safety clip, are no longer supported by the catheter adapter and may be removed from the catheter adapter for safe disposal. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       In order that the manner in which the above-recited and other features and advantages of the invention are obtained will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. These drawings depict only typical embodiments of the invention and are not therefore to be considered to limit the scope of the invention. 
         FIG. 1  is a cross-sectional view of a vascular access system, incorporating a safety clip, prior to insertion of the catheter into a patient. 
         FIG. 2  is a cross section view of a vascular access system incorporating a safety clip following insertion of the catheter into a patient. 
         FIG. 3  is a cross-sectional view of a vascular access system having the needle tip withdrawn into the lumen of the safety clip. 
         FIG. 4  is a cross-sectional view of a vascular access system having the safety clip withdrawn into the lumen of the sleeve. 
         FIG. 5  is a cross section view of a vascular access system having the needle, safety clip, and sleeve members withdrawn from the catheter adapter. 
         FIG. 6  is a cross-sectional view of a safety clip as housed within a sleeve. 
         FIG. 7  is a perspective view of a sleeve retaining a needle and safety clip following removal of the sleeve from the catheter adapter. 
         FIG. 8  is a cross-sectional view of a vascular access system, incorporating a safety clip, prior to insertion of the catheter into a patient. 
         FIG. 9  is a cross-sectional view of a safety clip and needle being withdrawn into a sleeve member. 
         FIG. 10  is a cross-sectional view of a sleeve retaining a needle and safety clip following removal of the sleeve from the catheter adapter. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The presently preferred embodiments of the present invention will be best understood by reference to the drawings, wherein like reference numbers indicate identical or functionally similar elements. It will be readily understood that the components of the present invention, as generally described and illustrated in the figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description, as represented in the figures, is not intended to limit the scope of the invention as claimed, but is merely representative of presently preferred embodiments of the invention. 
     Referring now to  FIG. 1 , a vascular access system  10  is illustrated comprising a needle  12 , a catheter adapter  14 , a sleeve  16  and a safety clip  18 . The needle  12  may include a hypodermic needle having a tubular shaft or body and a needle feature  20  positioned towards the distal end of the needle  12 . The needle feature  20  may include a ferrule or crimp designed to interact with safety clip  18  (discussed in detail below). In one specific embodiment the needle  12  is a hypodermic needle and the needle feature  20  is a ferrule. The needle feature  20  is positioned along the needle  12  such that the needle feature  20  and the needle tip  22  may be jointly retained within the safety clip  18  during removal of the needle  12  from the needle shielding assembly  10 . 
     The needle  12  extends through the radial center of the needle shielding assembly  10  along a generally horizontal axis  24  and is directly housed within the safety clip  18 . The safety clip  18  is positioned generally within the lumen of the sleeve  16  and comprises a base  26  and at least one arm  28 . The arm  28  extends from the base  26  and is generally parallel to the needle  12 . A flap  30  extends inwardly from the distal end of the arm  28  whereby the flap  30  maintains contact with the shaft of the needle  12 . The flap  30  may comprise any design useful in interacting with and containing the needle tip  22 . For example, in one embodiment the flap  30  is designed such that a terminal portion of the flap  30  curls towards the base  26  of the safety clip  18 . In another embodiment, the safety clip base  26  comprises two arms  28  and  28   a . Each arm  28  and  28   a  comprises a flap. A first flap  30  of the first arm  28  comprises an inwardly curled terminal end. A second flap  30   a  of the second arm  28   a  comprises an inward or outwardly curled terminal end. The first and second arm  28 ,  28   a  are configured such that the first arm  28  is shorter than the second arm  28   a . As such, the second flap  30   a  may be positioned to overlap the first flap  30  when the needle tip  22  is withdrawn past the flaps  30  and  30   a  of the safety clip  18 . 
     The base  26  of the safety clip  18  further comprises at least one barb  32 . The barb  32  is positioned on the external surface of the base  26  and designed to compatibly engage a barb catch  34  as located on the interior surface of the sleeve  16  towards the proximal end of the sleeve  16 . The base  26  of the safety clip  18  further comprises a cannula port  38  on the proximal end of the base  26 . The cannula port  38  comprises an inner diameter that is slightly larger that the outer diameter of the needle  12  shaft such that the needle  12  may slidably translate through the cannula port  38 . However, the inner diameter of the cannula port  38  is slightly smaller than the outer diameter of the needle feature  20  such that the needle feature  20  may not translate through the cannula port  38 . 
     The safety clip  18  is partially housed within the lumen of the sleeve  16 . For example, the base  26  is entirely housed within the sleeve  16 , the arm  28  is partially housed within the sleeve  16 , and the flap  30  is entirely not housed within the sleeve  16 . The sleeve  16  is generally tubular and comprises a lumen wherein the safety clip  18  is partially housed. The sleeve  16  has an outer diameter that is selected to be slightly less than the inner diameter  32  of the catheter adapter  14 . As such, the sleeve  16  may be inserted into the lumen of the catheter adapter  14 . The sleeve  16  further comprises a first end and a second end, the first end having a cannula port  36 . The cannula port  36  comprises an inner diameter that is slightly greater than the outer diameter of the needle  12  shaft. As such, the needle  12  may slidably translate through the cannula port  36 . However, the inner diameter of the cannula port  36  is smaller than the outer diameter of the safety clip base  26 . Thus, the base  26  of the safety clip  18  may not translate through the cannula port  36 , but rather is retained within the sleeve  16 . The second end of the sleeve  16  is generally open such that the needle  12  and the at least one arm  28  of the safety clip  18  extend beyond the second end of the sleeve  16  and into the lumen of the catheter adapter  14 . 
     The sleeve  16  further comprises a barb catch  34  located on the interior surface of the sleeve  16  near the first end of the sleeve  16 . The barb catch  34  comprises a recessed channel of a width and depth designed to compatibly receive the barb  32  of the safety clip. The base  26  of the safety clip  18  is configured to minimize the tolerance between the barb  32  and the inner surface of the sleeve  16  such that the inner surface of the sleeve  16  inwardly biases the barb  32 . As the base  26  of the safety clip  26  is drawn towards the first end of the sleeve  16 , the barb  32  is drawn into the barb catch  34 . At this point, the inward bias of the barb  32  is released such that the barb  32  relaxes outwardly and engages the barb catch  34 . Once engaged, the one-way compatibility of the barb  32  and the barb catch  34  prevent the safety clip  18  from exiting the opening of the second end of the sleeve  16 . 
     The sleeve  16  further comprises an interlock flange  40  hingedly attached to the sleeve  16 , as an appendage of the sleeve  16 . In one embodiment, the interlock flange  40  comprises a section of the sleeve  16  that has been completely freed on three sides such that the interlock flange  40  forms a hinged window of the sleeve  16 . The interlock flange  40  may be any length and therefore any portion of the sleeve  16  necessary to perform the function of interlocking the sleeve  16  and the catheter adapter  14 . 
     The interlock flange  40  includes a hinge  42  formed by removing a portion of the sleeve&#39;s  16  exterior material such that a recess is formed between the sleeve  16  and the interlock flange  40 . The hinge  42  is formed on the outer surface of the sleeve such that the interlock flange  40  may be outwardly biased with regard to the generally horizontal axis  24 . The interlock flange  40  further comprises an interlock finger  44  located at the non-hinged end of the interlock flange  40  positioned on the outer surface of the interlock flange  40 . The interlock finger  44  comprises a generally ramped shape and is configured to compatibly engage an interlock mate  50  as formed on the inner surface  52  of the catheter adapter  14 . The interlock finger  44  extends radially outward from the outer surface of the interlock flange  40  and, therefore, also extends outwardly beyond the outer surface of the sleeve  16 . 
     Finally, the interlock flange  40  comprises a safety clip contact  46  located at the non-hinged end of the interlock flange  40 . The safety clip contact  46  is positioned on the inner surface of the interlock flange  40  so as to be opposite the interlock finger  44 . The safety clip contact  46  comprises an inward extension of the interlock flange  40  which maintains contact with the arm  28   a  of the safety clip  18  in a pinching manner. Thus, the interlock flange  40  is outwardly biased by the pinching arm  28   a  of the safety clip  18 . The outward bias of the interlock flange  40  secures the interlock finger  44  within the interlock mate  50  such that the sleeve  16  and the catheter adapter  14  are interlocked. 
     The catheter adapter  14  is generally tubular with an opening at the first end, the first end being adapted to support the sleeve  16  such that the inner diameter of the first end of the catheter adapter  14  is slightly greater than the outer diameter of the sleeve  16 . The catheter adapter further comprises a second which forms a catheter  54 . The catheter  54  comprises a flexible tube with a first end and a second end, the first end being housed within the opening of the second end of the catheter adapter  14 . The first end of the catheter  54  has an opening adapted to receive the needle  12  and the needle feature  20 . The first end of the catheter  54  is secured within the opening of the second end of the catheter adapter  14  in a fluid tight manner. The second end of the catheter  54  has an opening adapted to permit the needle tip  22  to extend beyond the catheter  54 . The outer surface of the catheter&#39;s  54  second end is tapered towards the needle tip  22  so as to facilitate insertion of the catheter  54  into a patient. 
     In one embodiment, the second end of the sleeve  16  is housed within the catheter adapter  14 . The sleeve  16  is locked within the catheter adapter  14  via an engagement of the interlock mate  50  by the interlock finger  44  of the outwardly biased interlock flange  40 . In this same embodiment, the interlock flange  40  is outwardly biased by the pinching interaction of the safety clip contact  46  and the safety clip arm  28   a . The safety clip arm  28   a  is outwardly biased due to the pinching interaction of the flap  30   a  and the shaft of the needle  12 . 
     Referring now to  FIGS. 2-5 , the needle shielding assembly  10  is illustrated following insertion of the catheter  54  into a patient (not shown) wherein the needle  12  is being removed from the catheter  54  in a proximal direction  60 . Referring to  FIG. 2 , as the needle  12  is removed in a proximal direction  60 , the needle feature  20  passes under the first flap  30   a  and the second flap  30 . At this point, the first arm  28   a  and the second arm  28  are further biased outward to accommodate the passage of the needle feature  20 . Referring to  FIG. 3 , as the needle  12  continues in the proximal direction  60 , the needle tip  22  is drawn past the first flap  30   a . At this point, the first flap  30   a  relaxes radially inward such that the first flap  30   a  no longer pinches the shaft of the needle  12 . In this position, the first flap  30   a  acts as a blockade in preventing the needle tip  22  from advancing beyond the first flap  30   a  in a direction opposite to the proximal direction  60 . As the needle  12  is further drawn in the proximal direction  60 , the needle tip  22  is drawn past the second flap  30 . At this point, the second flap  30  relaxes radially inward such that the second flap  30  no longer pinches the shaft of the needle  12 . In this position, the second flap  30  acts as a blockade in preventing the needle tip  22  form advancing beyond the second flap  30  in a direction opposite to the proximal direction  60 . 
     At this point, the needle  12  and needle feature  20  are entirely within the lumen of the safety clip  18 . As such, the needle feature  20  is positioned against the cannula port  38  of the safety clip  18 . In this position, the needle feature  20  is prevented from translating in a proximal direction  60  beyond the cannula port  38  due to the diameter of the cannula port  38  being smaller than the outer diameter of the needle feature  20 . Therefore, as the needle  12  is drawn in a proximal direction  60 , the needle feature  20  binds on the cannula port  38  and the safety clip  18  translates with the needle  12  and needle feature  20  in a proximal direction  60 . 
     Referring to  FIG. 4 , the safety clip  18  translates with the needle  12  in a proximal direction  60  until such time that the second flap  30  translates proximally beyond the first safety clip contact  46 . At this point, the first safety clip contact  46  breaks contact with the first arm  28   a  and the first interlock flange  40  relaxes inwardly, disengaging the first interlock finger  44  from the respective interlock mate  50  of the catheter adapter  14 . Upon further translation of the safety clip  18 , the first flap  30   a  translates proximally beyond the second safety clip contact  46   a . At this point, the second safety clip contact  46   a  breaks contact with the second arm  28  and the second interlock flange  40   a  relaxes inwardly, disengaging the second interlock finger  44   a  from the respective interlock mate  50  of the catheter adapter  14 . At this point, the barb  32  engages the barb catch  34  in an irreversible manner such that the safety clip  18  is locked within the sleeve  16 . Furthermore, in this locked position, the safety clip base  26  abuts the cannula port  36  of the sleeve  16 . As such, the larger diameter safety clip base  26  is unable to translate beyond the smaller diameter cannula port  36  thereby preventing the safety clip  18  from further translation in a proximal direction  60 . 
     Referring now to  FIG. 5 , the safety clip  18  is locked within the lumen of the sleeve  16 , and the sleeve  16  is no longer interlocked with the catheter adapter  14 . Thus, with both interlock fingers  44  and  44   a  disengaged from their respective interlock mates  50 , additional translation of the needle in a proximal direction  60  withdraws the released sleeve  16  from the lumen of the catheter adapter  14 . At this point, the needle tip  22  is safely locked within the safety clip  18  and the sleeve  16 , and may be removed from the vascular access system  10  and disposed. 
     Referring now to  FIG. 6 , an embodiment of the sleeve  70  and the safety clip  72  is illustrated. The base  74  of the safety clip  72  is modified to include a pair of alignment clips  76  to control alignment of the safety clip  72  within the sleeve  70 . The safety clip  72  comprises a base  74 , at least one arm  80 , at least one flap  82 , a cannula port  84 , a barb  32  and a pair of alignment clips  76 . The base  74  is generally tubular with a first end having a cannula port  84  and a second end being generally open. The base  74  further comprises at least one arm  80  extending laterally from the second end of the base  74 . The arm  80  extends from the base in a generally horizontal axis  24  and terminates in a flap  82 . The base  74  further includes a barb  32 . The barb  32  comprises a partially cutout, flapped portion of the base  74  where three sides of the barb  32  are unattached to the base  74  and the fourth side is attached to the base  74 . The barb  32  is outwardly biased such that the barb  32  opens towards the second end of the base  74 . As such, the unattached end of the barb  32  may irreversibly engage the barb catch  34  of the sleeve  70 . 
     Each alignment clip  76  comprises a partially cutout, flapped portion of the base  74 . Each alignment clip  76  is outwardly biased such that the free end  86  of each alignment clips  76  opens towards the cannula port  84 . The free end of each alignment clip  76  interacts with an alignment channel  78  of the sleeve  70  to prevent a rotation of the safety clip  72  with respect to the sleeve  70 . As such, the alignment clip  72  ensures proper alignment of the barb  32  and the barb catch  34 . Additionally, the alignment clip  72  ensures proper alignment of the arm  80  and the safety clip contact  46  of the sleeve  70 . 
     The sleeve  70  is generally tubular with an opening on both a first end  96  and a second end  102 . The sleeve  70  further comprises a first inner diameter  90  and a second inner diameter  100 . The first inner diameter  90  approximates the outer diameter  98  of the safety clip base  74  such that the safety clip  72  is slidably housed within the sleeve  70 . The sleeve  70  further includes a pair of alignment channels  78  comprising a recessed groove on the inner surface  92  of the sleeve  70 . The alignment channels  78  are defined by a groove depth and groove width selected to accommodate translation of the alignment clips  76  through the alignment channels  78 . The alignment channels  78  include a first end  62  and a second end  64 , the first end  62  having an opening and the second end  64  having a clip catch  94 . The clip catch  94  provides a closure of the alignment channel  78  such that the alignment channel  78  ends at a point prior to the first end  96  of the sleeve  70 . The clip catch  94  interacts with the free end  86  of each alignment clip  76  to prevent the safety clip  72  from exiting the first end  96  of the sleeve  70 . The position of the clip catch  94  is selected so as to coordinate the simultaneous interactions of the alignment clip  76  with the clip catch  94 , and the barb  32  with the barb catch  34 . Therefore, as the safety clip  72  is drawn towards the first end  96  of the sleeve  70 , both interactions occur simultaneously and the safety clip  72  is locked in place within the sleeve  70 . 
     The sleeve  70  further comprises a second inner diameter  100  located at the second end  102  of the sleeve  70 . The second inner diameter  100  is greater than the first inner diameter  90  such that the inner surface  92  of the sleeve  70  is tapered from the first inner diameter  90  to the second inner diameter  100 . The tapered portion of the inner surface  92  thereby provides clearance for the safety clip arm  80  to bias outwardly when the arm  80  and the flap  82  are positioned beyond the second end  102  of the sleeve  70 . The sleeve further comprises a pair of interlock flanges  40 . Each interlock flange  40  includes an interlock finger  44  and a safety clip contact  46  as described in the previous embodiment (see  FIGS. 1-5  above). 
     Referring now to  FIG. 7 , the needle shielding assembly  10  is shown following removal of the sleeve  70  from the catheter adapter  14 . As illustrated, the needle  12  and the safety clip flaps  82  and  82   a  have been retracted into the lumen of the sleeve  70 . The first and second flaps  82  and  82   a  are in a closed position such that the needle tip  22  is enclosed within the safety clip. The interlock flanges  40  are relaxed inwardly such that the interlock fingers  44  have disengaged from the interlock mate of the catheter adapter  14 . The safety clip contacts  46  and  46   a  are positioned in front of the safety clip flaps  82  and  82   a  thereby further securing the safety clip within the sleeve  70 . 
     Referring now to  FIGS. 8-10 , an embodiment of the needle shielding assembly  110  is illustrated. The needle shielding assembly  110  includes a needle  12 , a catheter adapter  112 , a sleeve  114 , and a safety clip  116 . In this embodiment, the safety clip  116  is modified to include at least one arm  134  having an interlock flange  130  at the distal end of the arm  134 . The interlock flange  130  includes a flap  138  extending inwardly from the distal end  140  of the interlock flange  130 . As positioned, the free end  142  of the flap  138  pinches the shaft of the needle  12  to apply a slight pressure to the outer surface  144  of the needle  12 . As such, the presence of the needle  12  outwardly biases the interlock flange  130 . The interlock flange  130  further comprises an interlock finger  132  extending outward from the distal end  140  of the interlock flange  130 . The interlock finger  132  is positioned in a direction generally opposite to the flap  138  such that the interlock finger  132  forms an interface  146  with the inner surface of the interlock ring  118 . The flap  138  may be linear or contoured to provide effective shielding and retention of the needle tip  22  as well as retention of any residual fluids exuded from the needle tip  22  following use of the needle  12 . 
     The catheter adapter  112  includes an interlock ring  118 . The interlock ring  118  is positioned at the opening of the first end  122  of the catheter adapter  112  and comprises an inward, annular extension of the inner surface  120  of the catheter adapter  112 . The depth and width of the interlock ring  118  is selected so as to provide a compatible surface for engaging the interlock finger  132  of the interlock flange  130 . The interlock flange  130  is outwardly biased by the presence of the needle  12 , such that the needle  12  is pinched by the free end  142  of the flap  138  resulting in an outward displacement of the interlock flange  130 . As such, the interlock finger  132  engages the interlock ring  118  and forms an interface  146  between the interlock finger  132  and the interlock ring  118 . Thus, the catheter adapter  112  and the sleeve  114  are supported and locked together by this interface. 
     The sleeve  114  is modified to include at least one interlock finger channel  150  formed on the inner surface  152  of the sleeve  114 . The interlock finger channel  150  is a recessed groove formed on the inner surface  152  of sleeve  114 . The interlock finger channel  150  extends from the distal end  154  of the sleeve  114  to the proximal end  156  of the sleeve  114 , and terminates in an interlock finger catch  158 . The interlock finger catch  158  is the terminal end of the interlock finger channel  150  and is located at a point prior to the proximal end  156  of the sleeve  114 . The interlock finger channel  150  is designed to compatibly receive the interlock finger  132  of the safety clip  116 . The interlock finger  132  translates within the interlock finger channel  150  from the distal end  154  of the sleeve  114  to the proximal end  156  of the sleeve  114 . At one point, the interlock finger  132  engages the interlock finger catch  158  and the safety clip  116  is prevented from further retraction into the sleeve  114 . The location of the interlock finger catch  158  is selected so as to coordinate the simultaneous interaction of the interlock finger  132  with the interlock finger catch  158 , and the barb  32  with the barb catch  34 . As such, when the safety clip  116  is drawn towards the proximal end  156  of the sleeve  114 , both interactions occur simultaneously and the safety clip  116  is locked in place within the sleeve  114 . 
     The sleeve  114  is further modified to minimize the tolerance between the inner surface  152  of the sleeve  114  and the barb  32  of the safety clip  116 . As such, the barb  32  maintains contact with the inner surface  152  of the sleeve  114 . The interaction of the barb  32  and the inner surface  152  of the sleeve  114  prevents the safety clip  116  from translating towards, or exiting, the distal end  154  of the sleeve  114 . Therefore, the safety clip  116  is only able to translate towards, and exit through, the proximal end  156  of the sleeve  114 . The one-way movement of the safety clip  116  further secures the locked position of the sleeve  114  and the catheter adapter  112 , and prevents any disruption of the interface  146 . 
     The interlock finger channel  150  and engaged interlock finger  132  may also provide radial alignment of the safety clip  116  within the sleeve  114 . The distal end  154  of the sleeve  114  is further modified to provide a tapered opening  160 . The tapered opening  160  provides clearance for the outwardly biased interlock flanges  130 . Therefore, the interlock flanges  130  may be outwardly biased without contacting or pivoting on the inner surface  152  of the sleeve  114 . 
     The needle shielding assembly  110  is actuated following insertion of the catheter  54  into the patient. Following catheterization, the needle  12  is removed from the catheter  54  in a proximal direction  60 . As the needle  12  is removed, the needle feature  20  passes under the first and second flaps  138 . The first and second interlock flanges  130  are further biased outwardly to by the passage of the needle feature  20 . As the needle  12  continues in the proximal direction  60 , the needle tip  22  is drawn past the first and second flaps  138 . At this point, the first and second interlock flanges  130  relax inwardly, shielding the needle tip  22 . Additionally, the inwardly relaxed interlock flanges  130  release the first and second interlock fingers  132  from the interlock ring  118 . As such, interlock fingers  132  become disengaged from the interlock ring  118 , and the sleeve  114  and the catheter adapter  112  are no longer connected together. 
     At this point, the needle feature  20  abuts the cannula port  84  of the safety clip  116 . As such, the larger diameter needle feature  20  is prevented from translating in a proximal direction  60  beyond the smaller diameter cannula port  84 . Therefore, as the needle  12  is drawn in a proximal direction  60 , the needle feature  20  binds on the cannula port  84 , causing the safety clip  116  to translate with the needle  12  in a proximal direction  60 . 
     As the needle  12  and the safety clip  116  translate in a proximal direction  60 , the interlock fingers  132  engage the interlock channels  150 . At this point, the interlock fingers  132  translate within the interlock channels  150  in a proximal direction  60 . The interlock fingers  132  continue to translate through the interlock channels  150  until the interlock fingers  132  contact the interlock finger catch  158 . At this point the safety clip  116  and enclosed needle  12  are prevented from further movement in the proximal direction  60 . As the interlock fingers  132  travel through the interlock channels  150 , the tapered opening  160  of the sleeve  114  inwardly bias the flaps  138 . As such, the flaps  138  are brought into a position such that the flaps  138  overlap one another and are closed in front of the needle tip  22 . In this position, the flaps  138  shield the needle tip  22  and further enclose the needle tip  22  within the safety clip  116 . 
     With the flaps  138  closed and shielding the needle tip  22 , the safety clip  116  continues to translate in a proximal direction  60  until the interlock fingers  132  initiate contact with the interlock finger catch  158  of the interlock channels  150 . Simultaneous with this contact, the barbs  32  engage their respective barb catch  34  thereby locking the safety clip  116 , and the enclosed needle tip  22 , within the lumen of the sleeve  114 . 
     Various modifications to the needle shield assemblies of the present invention are possible while staying within the same inventive concept. For example, the needle shield assemblies can be used to protect the tip of a cannula in an IV catheter, a stylet in a long anesthesia needle, a catheter adapter, and other such medical devices. The cross section of the needle shield assembly and/or tubular housing can be of other shapes such as square, rectangular, triangular, oval, polygonal, and the like. The feature of the needle can be non-symmetrical and formed other than by crimping the shaft or affixing a ferrule. Any structure may be used to provide an interlock and interlock mate. The needle shield may include one or more blood stabilizing materials to further limit the risk of blood exposure. The blood stabilizing material may be disposed on one or more internal or external surfaces of the sleeve, the safety clip and/or needle shield assembly. Additionally or alternatively, the blood stabilizing material may be incorporated as a solid or semi-solid ring having a passage through which the needle closely passes. The blood stabilizing material may be a coagulant, an absorbent, or another material for stabilizing the blood to reduce the exposure risk. Similarly, the blood stabilizing material may be a liquid, a solid, a gel, a powder, granular, or any other consistency appropriate for its use. The blood stabilizing material may be disposed in a porous membrane or container that allows the blood to enter while preventing the exit of the blood stabilizing material. Further, any element of any embodiment described above may be combined in any number or orientation with any other element of any embodiment. 
     The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.