Abstract:
An apparatus was disclosed comprising a housing having a proximal end and a distal end, the housing slidably mounted on a needle shaft below a needle distal tip, the clip having a bridge, a proximal end coupled to the bridge and a distal end coupled to the bridge. The clip is disposed within the housing such that it retains a resilience imparting a biasing force to the clip ends such that the ends grip the needle shaft. When the housing is advanced beyond the needle distal tip, the clip distal end releases to contain the needle distal tip within the housing.

Description:
FIELD OF THE INVENTION 
     This invention relates to the field of medical devices and in particular to a needle safety cover. 
     BACKGROUND 
     Blood borne diseases such as AIDS and Hepatitis present significant risks to medical personnel administering vascular injections. The means by which a patient&#39;s vessel and skin are pierced to either draw or introduce fluids can just as effectively pierce the hands and arms of attending medical personnel. Gloves or similar protective garb may provide some protection, but making such items entirely resistant to needle penetration oftentimes sacrifices the wearer&#39;s mobility and dexterity proportionate to the degree of protection. Therefore, protective wear is not a total answer to the problem. 
     In order to adequately protect medical personnel from inadvertent puncture and wounding, catheter systems have been developed to cover and shield the distal needle point after its withdrawal from the patient. These systems have taken a number of embodiments and have various degrees of elaboration. One such mechanism includes a cylindrical sheath of plastic which telescopes out from the flash chamber to surround the needle shaft, including the distal tip. Such mechanism increases costs of manufacture substantially and may malfunction, especially in a fluid filled environment where it may stick or slip. The need for locking parts under these circumstances also increases risk of failure. Other types of needle caps require moving parts, such as a spring activation, to close off the needle in the cap after its withdrawal. These sometimes combine moving parts with specially tooled needles having two or more separate widths so that the larger circumference and diameter either trips the spring and/or blocks the needle&#39;s removal from the cap. 
     Given that the needle protector, however configured, will be contaminated upon each use, cost-benefit requirements dictate that a desirable shielding system be disposable along with the needle. Furthermore, the system must be quick and easy to use as to present as little imposition as possible to the administration and function of the catheter. Moving parts which may malfunction or stick such as springs and similar biasing mechanisms, as well as telescoping sheaths requiring deployment from the flash chamber, are less desirable in this regard and can drive up the manufacturing cost for a disposable unit. Lathing the needle circumference to alter the circumference over particular segments requires precise tooling and hence substantially added cost. What is desirable is a low cost, easily manufactured needle cover. 
     SUMMARY 
     An apparatus is disclosed comprising a housing having a proximal end and a distal end, the housing slidably mounted on a needle shaft below a needle distal tip, the clip having a bridge, a proximal end coupled to the bridge and a distal end coupled to the bridge. The clip is disposed within the housing such that it retains a resilience imparting a biasing force to the clip ends such that the ends grip the needle shaft. When the housing is advanced beyond the needle distal tip, the clip distal end releases to contain the needle distal tip within the housing. 
     Other features and advantages of the invention will be apparent from the accompanying drawings and from the detailed description that follows below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements and in which: 
     FIG. 1 shows a perspective view of an embodiment of the invention as fit over a needle shaft. 
     FIG. 2 shows a cutaway side view of one embodiment of the invention as fit over a needle shaft. 
     FIG. 3 shows a cutaway side view of one embodiment of the invention as deployed over the distal tip of the needle. 
     FIG. 4 shows a perspective cutaway view of one embodiment of the invention deployed over the distal tip. 
     FIG. 5 shows a perspective view of a clip of one embodiment of the invention. 
     FIG. 6 shows a top view of a flat metal piece prior to its bending to form a clip of one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     FIG. 1 shows one embodiment of the invention where needle cover  10  is mounted upon a needle shaft  15 . In this embodiment, housing  20  for needle cover  10  is barrel shaped. Needle cover  10  is slidably mounted on needle shaft  15  and prior to its deployment, is located back from the needle distal tip (not pictured) such that the shaft extends through housing  20  of the needle cover  10 . For ease of sliding, needle shaft  15  may be lubricated or coated. 
     With reference to FIG. 2, needle shaft  15  and distal tip  22  are illustrated with one embodiment of the invention mounted thereon. In this embodiment, the invention includes housing  20  defining openings  24 ,  26  at the proximal and distal ends, respectively, to accommodate needle shaft  15  extending therethrough. The openings have diameters slightly larger than needle shaft  15  outer diameter so that the housing  20  slides along needle shaft  15  and contacts substantially the entire needle shaft  15  outer circumference. Inside housing  20  are clips  11 ,  12 . In one embodiment, clips  11 ,  12  each having bridge  13  and two legs  16 ,  17  coupled to bridge  13  at opposite ends. In one embodiment, bridge  13  may be arched with the apex of the arch approaching or engaging horizontal walls  30  of housing  20 . Clips  11 ,  12  are loaded into housing  20  under a compressive force which biases legs  16 ,  17  toward needle shaft  15 . In one embodiment, housing  20  is made of a polymer and clips  11  and  12  are loaded as housing  20  is injection molded. Clips  11 ,  12  may be made of resilient material so as to impart a memory upon bending or contorting clips  11 ,  12  into housing  15  when loaded. As such, housing  15  and clips  11 ,  12  can be of a complementary size to accommodate biased clips  11 ,  12  and fit them within the housing. 
     Clip legs  16 ,  17  terminate in tabs  25  which define a semicircular circumference to fit around needle shaft  15 . This allows for a more close fit of tabs  25  to the needle shaft  15  increasing their grip thereon. In one embodiment, tab ends (not pictured) are not equivalent lengths, rather one is shorter than the other. The resulting arc, of the defined circumference therefore is eccentric. Such configuration allows for a greater ability to grip needle shaft  15  when legs  16 ,  17  are contorted to engage needle shaft  15  at an angle to bridge  13  less then 90 degrees, providing for greater constrictive force, imparting greater potential energy to the bias resilience than engaging needle shaft  15  at a 90 degree angle where legs  16 ,  17  are directed toward needle shaft  15 . The angular engagement of legs  16 ,  17  of the opposing tabs at the proximal end of housing  20  also provide greater restrictive force opposing advancement of housing  20  toward distal end  22  of needle shaft  15 , thus obstructing removal of housing  20  over distal tip  22  when legs  16  have deployed over distal tip  22 . 
     FIG. 3 shows the result of sliding housing  20  over distal tip  22  of the needle shaft  15 . As tabs  25  of front legs  16  of clips  13  are biased against the needle shaft, advancing the cover  10  over distal tip  22  and past the point of contact with tabs  25  of front legs  16 , causes legs  16  to release with resilient force to fit over distal tip  22 . In another embodiment, the two opposing legs  16  and tab ends  25  may meet and rest on each other—either eliminating or so constricting the area between tabs  25  to a size smaller than the needle outer diameter, including the outer diameter at the distal tip  22 , so that reinsertion through front opening  24  is blocked. 
     As the front legs  16  deploy, by resilient force, over distal tip  15  to block its reinsertion through opening  24 , rear legs  17 , given their obtuse angles to needle shaft  15 , inhibit further frontal movement of housing  20  toward distal tip  22  thus preventing removal of the housing  20  over distal tip  22  and obstructing sliding housing  20  too far forward on needle shaft  15 , thus falling off distal tip  22 . 
     FIG. 4 shows an embodiment of the invention, where housing  20  is barrel shaped having a cylindrical configuration. Transparent windows  35  on opposing sides of the housing allow the user to view inside to determine if distal point  22  is contained therein, and thus blocked from reinsertion through opening  24 . In one embodiment, windows  35  are located at a point equivalent to the distance distal point  22  would occupy upon deployment of clip legs  16 . Inability to view distal tip  22  could then indicate clip legs  16  had not deployed and distal tip  22  could still re-emerge from distal opening  24  of the housing. 
     The housing is made from materials and in manners known in the art for catheter accessories such as polyurethane and other polymer materials. It may be injection molded in accordance with the practice of the art. Metal reinforcing may be used to provide further support and strength within the polymer mix or the injection molding process. 
     FIG. 5 shows a metal clip  11 . Clip  11  is bent at two ends to form legs  16  and  17 , according to methods known in the art. In one embodiment bridge  13  is arched to provide greater biasing force to legs  16  and  17 . Another embodiment allows the bridge  13  to remain substantially horizontal in relation to shaft  15  while legs  16 ,  17  are bent to form an angle to bridge  13  of less than 90 degrees and the biasing force imparted is analogous to a hinging force at the point of connection between bridge  13  and legs  16 ,  17  which impels legs  16 ,  17  to return to a straight or substantially perpendicular orientation with respect to bridge  13 . Heat treatment of legs  16 , 17  may be used to provide the biasing memory and hinge resilience. Clip legs  16 ,  17  culminate in tabs  25  which define a semicircular circumferential surface for gripping needle shaft  15 . In one embodiment, tabs  25  on each clip  11 , 12  define a semicircular circumference with sides not equivalent in length, and thus define an eccentric semicircle. Where clips  11 ,  12  engage needle shaft  15  using hinged legs  16 ,  17 , thus meeting needle shaft  15  to create a hinge angle less than 90 degrees, the irregular tab lengths serve to keep the surface area gripping needle shaft  15  relatively constant and ensure a complete fit, with the longer tab side length directing the tabs along the circumference of the needle shaft  15  to the center of the tabs at the semicircle apex thus providing sufficient support to avoid slippage. 
     FIG. 6 illustrates clip  11  in a flat view before bending, illustrating tabs  25  and the semicircular space  40  they define to receive the needle shaft. Bending of legs  16 ,  17  where tabs  25  are located may be done by heat treatment to impart biasing memory and, in one embodiment, to arch bridge  13 . In one embodiment, the bending can also be accomplished by a foreslide machine. Clips may be pressed or stamped from sheets. The clips may be made of any suitable metal alloy known in the art. In one embodiment, these are stainless steel. 
     In the preceding detailed description, the invention is described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.