Abstract:
A Safety Arteriovenous Fistula (AVF) winged safety needle device provides a safety feature including a protective shield with handling wings, which when placed in cooperating relationship, allows accommodation of a blood collection needle and a hub. The Safety AVF provides a reliable and user friendly first releasable locking mechanism in an insertion position and a second unreleaseable locking mechanism in a protected position. The Safety AVF also allows for rotation of the needle after cannulation in order to maximize blood or fluid flow to or from a vessel.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a winged safety needle assembly and, more particularly, to a winged safety needle assembly having a winged cylindrical sheath for substantially reducing sticking accidents from taking place when retracting the needle into the winged cylindrical sheath. Protection of the edge of the needle is achieved by unlocking and sliding the needle along the inner wall of the winged cylindrical sheath.  
         [0003]     2. Discussion of the Related Art  
         [0004]     Proper disposal of used needles is required to avoid needlestick injuries. Used needles may be recapped with the same cover that originally covered the needles before use or by similar covers or tubes before the needle is discarded. This method requires movement of the hands toward the exposed needle and may promote needlestick injuries during the recapping. In addition, needles may also be disposed of by tossing them into nearby refuse containers. However, this creates danger to those who handle the refuse containers.  
         [0005]     Winged intravenous (IV) sets are well known in the art. A typical prior art IV butterfly needle used for the insertion into blood vessels and similar passageways in the body to permit the infusion or withdrawal of sterile fluids or blood is illustrated in  FIG. 8 . The butterfly needle generally has a hollow needle or cannula  30 , a cylindrical hub  20  holding the needle  30  at one end and connected to an IV tube  52  at the opposite end, and a cylindrical housing  10  surrounding the needle with a wing-like extension  50  extending on each side thereof.  
         [0006]     The wings  50  are used to handle the assembly during insertion and withdrawal. For example, the wings of the needle assembly may be folded upwards around the hub to provide a gripping extension for the technician or nurse to use when attempting to insert the needle into the desired vein, artery or other passageway. The wings are also used to stabilize the device while in place by providing a broad surface area of contact with the patient which allows for taping of the device to the patient while discouraging movement, especially rotation, of the device. This assists the technician or nurse in affixing the needle to the patient during the infusion of fluids or medicants.  
         [0007]     A problem typical of butterfly needles as just described is that when the needle is withdrawn from the vein or artery, the sharpened end, now contaminated with blood or other body fluid, remains exposed. The exposed needle can be a source of great danger to the operator or to anyone who might be pricked or scratched. Needle injuries may result in the transmission of diseases such as hepatitis, HIV, or cause other types of infection. A common solution available to the operator was to simply drop the needle and the holder into a trash receptacle. However, a danger to clean up and medical waste disposal personnel continues if the used needles are not rendered harmless in some way. Another solution is to attempt to recap the needle with a safety cover immediately after use. This, however, may in itself cause injury if the operator should accidentally stick themselves during the recapping process. In addition, caps or covers may come loose and expose the used needle.  
         [0008]     Therefore, in order to substantially reduce such sticking accidents various proposals have been made. One such proposal is a winged needle assembly disclosed in U.S. Pat. No. 5,505,711 (hereinafter referred to as the &#39;711 patent). The &#39;711 patent describes an indwelling injector needle assembly having wings including a cannula or needle body, a hub supporting a proximal end of the needle body, a tube in fluid communication with the needle body, a cylindrical holder having a distal end from which the wings protrude, and a latching mechanism. The hub can slide along an inner periphery of the holder between a first position near the distal end of the holder and a second position near a proximal end of the holder. The latching mechanism is formed in and disposed between the hub and the holder so that the hub is inhibited from moving from the first position toward the second position, and vice versa. The needle edge can be retracted within the holder while the wings remain fixed to a patient&#39;s skin.  
         [0009]     However, the winged needle assembly disclosed in the &#39;711 patent has a key disadvantage. The &#39;711 patent discloses a structure that includes a non-rotating needle. A rotateable needle is preferable in order to maximize blood or fluid flow to or from a vessel in which the needle is inserted. The structure of the &#39;711 patent prevents the needle from being rotated after cannulation. The &#39;711 patent also describes a hub supporting the non-rotating needle. The hub has a guide groove formed in a peripheral wall thereof, the groove extending longitudinally of the hub. A cylindrical holder having wings is disposed on the hub. The cylindrical holder has a lug protruding inwardly from an inner peripheral surface of a proximal end thereof. The lug is slidably engaged with the guide groove in the hub so that the hub can be moved relative to the holder between a first position in which the needle body protrudes from a distal end of the cylindrical holder and a second position in which the needle body is retracted so that a pricking edge of the needle body is within the holder. The needle and hub cannot rotate relative to the cylindrical holder due to the lug being slidably engaged with the guide groove in the hub. Therefore the needle cannot be rotated when needed after cannulation in order to maximize blood or fluid flow to or from the vessel.  
         [0010]     As can be seen, what is needed is a winged safety needle device that allows for rotation of the needle after cannulation in order to maximize blood or fluid flow to or from the vessel, and provides for a reliable and user friendly first releasable locking mechanism in an insertion position and a second unreleasable locking mechanism in a protected position.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  illustrates an exploded view of the Safety AVF needle according to an embodiment of the present invention;  
         [0012]      FIG. 2  illustrates a winged sheath according to an embodiment of the present invention;  
         [0013]      FIG. 3   a  illustrates a PC hub with a pair of flexible extension arms in a pre-assembled state according to an embodiment of the present invention;  
         [0014]      FIG. 3   b  illustrates a PC hub with a pair of flexible extension arms in an assembled state according to an embodiment of the present invention;  
         [0015]      FIG. 4  illustrates a cannulation procedure of the Safety AVF needle according to an embodiment of the present invention;  
         [0016]      FIG. 5  illustrates a view showing an orientation of a cannula bevel according to an embodiment of the present invention;  
         [0017]      FIG. 6  illustrates a retraction procedure of the Safety AVF needle according to an embodiment of the present invention;  
         [0018]      FIG. 7  illustrates multiple views of the Safety AVF needle according to an embodiment of the present invention; and  
         [0019]      FIG. 8  illustrates a prior art intravenous butterfly needle.  
     
    
     DETAILED DESCRIPTION  
       [0020]     The Safety Arteriovenous Fistula (AVF) needle assembly  100  as shown in  FIG. 1 , is a retractable winged safety needle device having a needle holder  110  (referred to as a polycarbonate (PC) hub), a needle or cannula  120 , and a winged sheath  130 . Referring to  FIGS. 1, 3   a , and  3   b  the PC hub  110  is tubular, may be made of a polycarbonate material, and holds a proximal end of the needle or cannula  120  at the distal end. The needle or cannula  120  is hollow and has a beveled edge  121  at the distal end. The base  122  or proximal portion of the hollow needle  120  is fixed to and supported by a conical shaped head  119  of the PC hub  110 . A polyvinyl chloride (PVC) tube  140  for use in fluid administration is slid over the proximal end of the PC hub  110 , providing a fluid tight seal.  
         [0021]     The PC hub  110  has the conical shaped head  119  at the distal end and a stopper  111  at the proximal end for tube  140  bonding. Furthermore, the PC hub  110  has a pair of flexible extension arms  115  located approximately in the center of the PC hub  110  and extending toward the conical shaped head  119  at the distal end that serve as a key component to provide for a first releasable locking mechanism and a second unreleasable locking mechanism. The conical shaped head  119  serves to stabilize the PC hub  110  and the needle  120  during a cannulation procedure.  
         [0022]     Referring to  FIG. 3   a , the PC hub  110  including the conical shaped head  119  and the pair of flexible extension arms  115  is shown in a pre-assembled state, i.e., before insertion into the winged sheath  130 . A cross-sectional width (X 2 ) of the tips  116  of the flexible extension arms is greater than a cross-sectional width (X 1 ) of the conical shaped head  119  and a cross-sectional width (X 3 ) of a proximal portion  117  of the flexible extension arms  115  such that X 2 &gt;X 1 &gt;X 3 . The cross-sectional width (X 3 ) of the proximal portion  117  of the flexible extension arms  115  being less than the cross-sectional width (X 1 ) of the conical shaped head  119  allows for a smooth needle retraction.  
         [0023]     Referring to  FIG. 3   b , the PC hub  110  including the conical shaped head  119  and the pair of flexible extension arms  115  is shown in an assembled state, i.e., after insertion into the winged sheath  130 . A cross-sectional width (X 2 ) of the tips  116  of the flexible extension arms may remain greater than or equal to a cross-sectional width (X 1 ) of the conical shaped head  119  and a cross-sectional width (X 3 ) of the proximal portion  117  of the flexible extension arms  115  such that X 2 ≧X 1 &gt;X 3 . Also shown, a gap (G 1 ) may remain between a base of the tips  116  of the flexible extension arms and the PC hub  110  when the flexible extension arms  115  are flexed inward in the assembled state. The gap (G 1 ) also allows for a smooth needle retraction.  
         [0024]     Referring to  FIG. 2 , the winged sheath  130  is a cylindrical structure with a hollow interior. The winged sheath  130  may be made of a polymeric material such as a polyethylene, or any other suitable material. The winged sheath  130  is axially slideable on the PC hub  110  and may have a constant inner diameter (defining the hollow interior). At the distal end of the sheath, a pair of wings  131   a ,  131   b  are positioned for use in grasping the device when squeezed together (see also  FIG. 4 ) and for adhering the device to a patient&#39;s skin during infusion, haemodialysis, apheresis, and blood collection when laying flat (see also  FIG. 5 ). The flexible wings  131   a ,  131   b , may be integrally formed with the body of the supporting cylinder of the winged sheath  130  on both sides thereof, and the shape of the wings  131   a ,  131   b , is not particularly limited. The wings  131   a ,  131   b  are preferably provided on the cylinder body to form one plane as shown in  FIG. 1 ,  FIG. 2 , and  FIG. 5 .  
         [0025]     The first releasable locking mechanism will now be described according to embodiments of the present invention. Referring to  FIG. 2 ,  FIG. 3   a ,  FIG. 3   b , and  FIG. 7  the winged sheath  130  may have a front linear groove  132  located on the interior surface at the distal end that may accept the tips  116  of the flexible extension arms  115  of the PC hub  110 , may allow for 360 degree rotation of the PC hub  110  with the attached extension arms  115  within the winged sheath  130 , and may function as part of the first releasable locking mechanism. The flexible extension arms  115  of the PC hub  110  partially spring outward allowing the tips  116  of the flexible arms  115  to releasably seat in the front linear groove  132  (see  FIG. 7   a ).  
         [0026]     Alternative embodiments of the present invention may achieve 360 degree rotation of the PC hub  110  with the attached extension arms  115  within the winged sheath  130  without the use of a front linear groove  132  located on the interior surface. In such an embodiment the absence of a front linear groove  132  would prevent the tips  116  of the flexible extension arms  115  from partially springing outward and functioning as part of the first releasable locking mechanism.  
         [0027]     Alternative embodiments of the present invention may include an inner circumferential rib  141  provided at the inner distal surface of the winged sheath  130 . The inner circumferential rib  141  in combination with a locking tab  130  described below may functioning as part of the first releasable locking mechanism.  
         [0028]     The locking tab  135  with a projection  137  located at approximately the center of the winged sheath can be selectively placed in a locked or unlocked position. The locking tab  135  is attached to the side of the winged sheath  130  by a hinge  136  so that when in an unlocked position, it remains attached thereto. In the locked position the projection  137  of the locking tab  135  fits into a slot  138  in the winged sheath  130 . The projection  137  extends through the slot  138  into the hollow interior portion of the winged sheath  130  to abut against the proximal portion  117  of the flexible extension arms  115  of the PC hub  110  to prevent retraction of the PC hub  110  with needle or cannula  120  with respect to the winged sheath  130 . The projection  137  of the locking tab  135  will cover at least 180 degrees or half of the inner circumferential diameter of the winged sheath  130  to abut against the proximal portion  117  of the flexible extension arms  115  (see  FIGS. 7   a ,  7   b ,  7   c ).  
         [0029]     The first locking mechanism may consist of the locking tab  135  with the projection  137  abutting against the proximal portion  117  of the flexible extension arms  115  in conjunction with the tips  116  of the flexible arms  115  releasably seating in the front linear groove  132 . In an alternative embodiment of the present invention, the first locking mechanism may consist of the locking tab  135  with the projection  137  abutting against the proximal portion  117  of the flexible extension arms  115  in conjunction with the tips  116  of the flexible arms  115  abutting against the inner circumferential rib  141  provided at the inner distal surface of the winged sheath  130 .  
         [0030]     Referring to  FIG. 5 , the Safety AVF needle assembly  100  also includes a rotational feature that allows the PC hub  110  with attached needle or cannula  120  to rotate 360 degrees within the winged sheath  130 . This feature allows the cannula bevel  121  orientation within the fistula or graft to be ascertained and adjusted.  
         [0031]     In an embodiment of the present invention, the winged sheath  130  having front linear groove  132  located on the interior surface at the distal end accepts the tips  116  of the flexible extension arms  115  of the PC hub  110 , and allows for 360 degree rotation of the PC hub  110  with the flexible extension arms  115  within the winged sheath  130 . A black dot may be stamped or marked on the distal exterior surface of the conical surface  119  of the hub  110  and is visible from above when facing up (see  FIG. 5 ) to indicate the cannula bevel  121  is facing up within the fistula or graft. Alternatively, a red dot may be stamped or marked on the distal exterior surface of the conical surface  119  of the hub  110  and is visible from above when facing up (not visible as shown in  FIG. 5 ) to indicate the cannula bevel  121  is facing down within the fistula or graft. This mechanism allows the handling of the Safety AVF needle assembly  100  of the present invention to be simplified. For example, after inserting the needle  120  with the beveled surface  121  facing up into a blood vessel (the black dot on the distal exterior surface of the conical surface  119  of the hub  110  is visible when facing up as shown in  FIG. 5 ), the beveled edge  121  may be made to face down by simply rotating the hub  110  until the red dot on the distal exterior surface of the conical surface  119  of the hub  110  is visible when facing up. The needle  120  may then be retained in that state (not shown in  FIG. 5 ). The ability to adjust the orientation (0-360 degrees) of the cannula bevel  121  within a vessel allows a technician to adjust for maximum fluid flow. For example, due to the various shapes and sizes of blood vessels, direction of fluid flows, and other particularities, etc., it is beneficial to be able to rotate the cannula  120  to maximize flow.  
         [0032]     In contrast, some prior art winged retention needles have the disadvantage that the rotational operation thereof is troublesome. An assembly with a hollow needle directly affixed to a winged portion requires the entire assembly, needle and wings, to be rotated as one. For example, if a bevel edge surface is facing up upon insertion into a blood vessel, the entire winged needle assembly would need to be rotated by a half rotation so that the bevel edge surface would be faced down. If the wings have been previously secured to the patient with tape, the tape would have to be removed prior to rotation.  
         [0033]     The second releasable locking mechanism will now be described according to embodiments of the present invention. Referring to  FIG. 2 ,  FIG. 3   a ,  FIG. 3   b , and  FIG. 7  the winged sheath  130  has a slot  133  located through the interior/exterior surface and extending ⅔ of the circumference of the proximal end of the winged sheath  130 . The slot  133  may accept the tips  116  of the flexible extension arms  115  of the PC hub  110  to provide for the second unreleasable locking mechanism. The flexible extension arms  115  of the PC hub  110  fully spring outward allowing the tips  116  to unreleasably seat in the slot  133  (see view  7   d ).  
         [0034]     In addition, an inner circumferential rib  139  is provided at the inner proximal surface of the winged sheath  130 . The inner circumferential rib  139  abuts against the tips  116  of the flexible extension arms  115  in the second unreleasable (final) locked position to prevent the PC hub  110  from being pulled out of the winged sheath  130 . Referring to  FIG. 3   b , the inner diameter of the inner circumferential rib  139  may be larger than the width X 3  and smaller than the width X 2 . This allows for smooth retraction of the PC hub  110  into the winged sheath  130 . Otherwise the base  117  of the flexible extension arms  115  will abut against the inner circumferential rib  139 , the needle  120  may not be retracted within the winged sheath  130 , and the tips  116  of the flexible arm  115  may not seat into the slot  133 .  
         [0035]     It should be noted that a width (W 1 ) of the slot  138  in the winged sheath  130  that accommodates the projection  137  from the locking tab  135  is smaller than a width (W 2 ) of the slot  133  located at the proximal end of the winged sheath  130  to prevent the tips  116  of the flexible extension arms  115  from seating in the W 1  slot  138  (width of W 1  and W 2  are not shown, see view  7   d  for view of tips  116  seating in slot  133 ).  
         [0036]     Operation of the Safety AVF needle  100  will now be described according to embodiments of the present invention. In the insertion position, the needle  120  is exposed through the distal end of the sheath  130  and may be held in this position according to two mechanisms. First, the flexible extension arms  115  of the PC hub  110  partially spring outward allowing the tips  116  to releasably seat in the front linear groove  132  when the PC hub  110  is pushed to the distal end of the sheath  130 , and second, the projection  137  of the locking tab  135  abuts against the proximal portion  117  of the flexible extension arms  115 .  
         [0037]     Referring to  FIG. 6  and  FIG. 7 , when the needle  120  is to be withdrawn, the locking tab  135  is disengaged and the PC hub  110 /needle  120  are pulled in a proximal direction (releasing the tips  116  of the extension arms  115  from the front groove  132 ). PC hub  110 /needle  120  are drawn proximally until the tips  116  of the flexible extension arms  115  are pulled to the proximal end of the sheath  130  wherein the tips  116  will fully spring outward and unreleasably seat in the slot  133 . It should be noted that the locking tab  135  is used only for maintaining the locked relationship between the sheath  130  and PC hub  110  in the insertion position (see view  7   a  and view  7   b ) and not in the protection position (see view  7   d ).  
         [0038]     While the description above refers to particular embodiments of the present invention, it will be understood that many modifications may be made without departing from the spirit thereof. The accompanying claims are intended to cover such modifications as would fall within the true scope and spirit of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.