Abstract:
A solid blunt and a needle assembly having a solid blunt. The solid blunt helps to prevent accidental needle sticks. In one exemplary embodiment, a solid blunt has an outer dimension (e.g. outer diameter) which is nearly equal to an inner dimension (e.g. inner diameter) of a cannula of a needle which is configured to contain the solid blunt. In one example, the solid blunt substantially blocks fluid flow in a first circumferential portion of an inner diameter of the cannula and allows fluid flow in a second circumferential portion of the inner diameter. The solid blunt is typically capable of longitudinal movement through the cannula and is prevented from moving substantially in a direction perpendicular to the longitudinal movement. A needle assembly, in another exemplary embodiment, includes a solid blunt, a cannula and a clip which couples slidably the solid blunt to a frame which is coupled to the cannula. The present invention may be used with medical devices including needles, introducers and catheters and other devices as well.

Description:
[0001]    This is a continuation of Ser. No. 09/221,272, filed on Dec. 23, 1998, entitled, SOLID BLUNT FOR A NEEDLE ASSEMBLY. 
     
    
     
       BACKGROUND FOR THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to medical devices and other similar devices and in particular to medical devices such as intravenous catheters and syringes which include a hollow needle having a sharp distal end for piercing an object, such as the skin of a patient.  
           [0004]    2. Background of the Invention  
           [0005]    The existence of infectious diseases has highlighted the danger to which medical personnel may be exposed when treating patients by means of catheter devices and syringes where a sharp needle point is used to pierce the skin of the patient. In order to protect medical personnel against inadvertent needle stick, a number of solutions have been developed whereby a protective mechanism, incorporated within a catheter or syringe, prevents physical contact with the sharp needle point after use and hence protects against inadvertent needle stick. Many of the developed solutions are complicated. For example, some developments utilize the retraction of the needle within a housing once the needle has been used. Other developments utilize blunts which are contained within the cannula of the hollow needle.  
           [0006]    These blunts come in two principal forms: hollow blunts which are hollow tubes concentrically disposed within the circular shaft of a hollow needle, and solid blunts. Hollow blunt designs require that an exit hole be provided at a proximal location to allow blood to exit the blunt and enter a flash chamber, the use of which is well known in the art. In order for blood flashback to be seen as quickly as possible, the exit hole needs to be located just proximal to the butt end of the needle. Thus, hollow blunts require extra machining or manufacturing steps in order to produce a satisfactory hollow blunt. Solid rod blunts are typically cylindrical rods which have an outer diameter which is sufficiently smaller than the inner diameter of the shaft of the cannula of the needle in order to allow clearance for fluid flow all around the diameter of the solid rod blunt. While some prior art designs have included grooves in the solid rod blunt, these solid rod blunts nevertheless position the wall of the blunt (the outside diameter of the blunt) some distance from the inner diameter of the shaft of the cannula.  
           [0007]    [0007]FIG. 1A illustrates an example of a prior art solid blunt  103  within the shaft  105  of the needle assembly  101 . The needle  107  includes a hollow opening  109  and a sharp tip  107  at the end of the opening. The needle assembly  101  is shown in FIG. 1A before its use. In this situation, the solid rod blunt  103  is disposed entirely within the shaft of the needle  105  such that the sharp point  107  can pierce an object, such as the skin of a patient. After use, the solid rod blunt  103  is advanced longitudinally along the longitudinal axis  120  shown in FIG. 1B such that the end  111  of the solid blunt  103  extends beyond the opening of the shaft  105 , thereby to some extent covering the sharp tip  107  so that a user of the needle may not receive an accidental needle stick. As is well known in the art, a clip or other mechanism holds the solid blunt rod  103  relative to the shaft  105 , preventing it from moving longitudinally along the axis  120  once the blunt  103  has been extended beyond the opening. However, as shown in FIG. 1C, it is also possible for the solid blunt  103  to move perpendicularly to the longitudinal axis  120  and this tends to increase the gap between the blunt and the sharp tip which tends to increase the likelihood of an accidental needle stick or skive. FIG. 1C shows a cross-sectional view of the assembly  101  shown in FIG. 1B at the line  1 C- 1 C shown in FIG. 1B. As can be seen from FIG. 1C, there is a considerable gap  109   a  between the inner diameter of the shaft  105  and the outer diameter of the solid blunt rod  103 . This makes it possible for the rod to move up and down along the axis  130  which is perpendicular to the longitudinal axis  120  shown in FIG. 1B. As a result, it is possible for the blunt  103  to be pushed away from the sharp tip  107  even when it is extended out beyond the tip  107  as shown in FIG. 1B. As a result, even though the blunt may be advanced longitudinally beyond the end of the sharp tip of the needle, the gap between the wall of the blunt and the sharp tip may be so large that the sharp point is permitted to scratch or skive a person&#39;s skin. Naturally, the solid blunt must provide space around its circumference in order to permit fluid flow, and thus it would appear that a gap  109   a  is required.  
           [0008]    From the above discussion, it can be seen that it is desirable to provide an improved solid blunt which better protects a user of a needle.  
         SUMMARY OF THE INVENTION  
         [0009]    The present invention provides a solid blunt which helps to prevent accidental needle sticks. The present invention also provides a needle assembly having a solid blunt.  
           [0010]    In one exemplary embodiment, a solid blunt has an outer dimension (e.g. outer diameter) which is nearly equal to an inner dimension (e.g. inner diameter) of a cannula of a needle which is configured to contain the solid blunt.  
           [0011]    In one example, the solid blunt substantially blocks fluid flow along a first circumferential portion of an inner diameter of the cannula and allows fluid flow in a second circumferential portion of the inner diameter. The solid blunt is typically capable of longitudinal movement through the cannula and is prevented from moving substantially in a direction perpendicular to the longitudinal movement.  
           [0012]    A needle assembly, in another exemplary embodiment, includes a solid blunt, a cannula, and a clip which couples the solid blunt to a frame which is coupled to the cannula. The clip allows the solid blunt to move longitudinally between at least two positions and the clip prevents the solid blunt from rotating within the shaft of the needle. The solid blunt itself is effectively lodged within the shaft of the needle so that it cannot move substantially in a direction perpendicular to the longitudinal movement of the solid blunt.  
           [0013]    The present invention may be used with medical devices, including needles, catheter assemblies and introducers for catheters and other devices as well.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements.  
         [0015]    [0015]FIG. 1A shows a cross-sectional view of a prior art blunt within a needle shaft. This view depicts the typical position of the blunt relative to the shaft and tip of the needle before use of the needle.  
         [0016]    [0016]FIG. 1B shows a cross-sectional view of a prior art needle assembly having a blunt which is extended beyond the tip of the needle after use of the needle.  
         [0017]    [0017]FIG. 1C shows a cross-sectional view of a solid blunt within a needle shaft; this cross-sectional view is taken along the line  1 C- 1 C shown in FIG. 1B.  
         [0018]    [0018]FIGS. 2A, 2B,  2 C, and  2 D show cross-sectional views of four examples of solid blunts according to the present invention.  
         [0019]    [0019]FIGS. 3A, 3B,  3 C, and  3 D show cross-sectional views of the blunts shown respectively in FIGS. 2A, 2B,  2 C, and  2 D within the shaft of a needle. FIGS. 3A, 3B,  3 C, and  3 D also illustrate the relative position of portions of the blunt and the sharp tip  311  of the needle and blunt assembly.  
         [0020]    [0020]FIG. 3E shows the perspective side view of a needle and blunt assembly according to the present invention.  
         [0021]    [0021]FIG. 4A shows another cross-sectional view of an example of a specific solid blunt according to the present invention.  
         [0022]    [0022]FIG. 4B shows another example of a specific solid blunt according to the present invention.  
         [0023]    [0023]FIGS. 5A and 5B show cross-sectional views of an example of a catheter assembly which may use a solid blunt according to the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0024]    The present invention provides various examples of solid blunts and needle assemblies containing solid blunts. The following description and drawings are illustrative of the invention and are not to be construed as limiting the invention. Numerous specific details are described to provide a thorough understanding of the invention. For example, very specific geometries and dimensions are provided for purposes of illustrating the invention. In certain instances, well known or conventional details are not described in order to not unnecessarily obscure the present invention in detail.  
         [0025]    Generally, a solid blunt according to the present invention has an outer dimension, such as an outer diameter, which is nearly equal to (e.g. just less than) an inner dimension, such as an inner diameter, of a cannula of a needle which is configured to contain the solid blunt. At least a portion of the solid blunt having this outer dimension is configured to be positioned near a sharp tip of the needle when the blunt is positioned to protect against needle skiving, such as when the blunt is extended longitudinally out beyond the opening of the needle. The solid blunt is formed in a manner to provide a fluid flow through a fluid path of sufficient size while positioning the surface of the blunt (e.g. the outside diameter) as close to the sharp point of the needle (e.g. inside diameter) as possible. Thus, at least a portion of the solid blunt may substantially block fluid flow along a first circumferential portion of an inner diameter of the cannula while allowing fluid flow in a second circumferential portion of the inner diameter. A typical blunt according to the present invention may be capable of longitudinal movement through the cannula but be prevented from moving substantially in a direction which is perpendicular to the longitudinal movement. By being prevented from moving in this perpendicular direction, the outside dimension of the blunt will be positioned close to the sharp point of the needle and thereby reduce the likelihood that the sharp point will scratch or skive a person&#39;s skin.  
         [0026]    [0026]FIG. 2A shows an example of a solid blunt  201  which has one particular geometry which resembles the letter “D” in the cross-sectional view of the solid blunt  201 . This solid blunt  201  includes an outer circumferential portion or surface  203  and an upper flat portion  209 . The solid interior  205  of the blunt extends from the circumferential portion  203  beyond the centerline  207  and up to the flat portion  209 . The centerline  207  is designed to be the central diameter of a cannula which receives the solid blunt  201 .  
         [0027]    [0027]FIG. 3A shows an example of a needle assembly  301  which includes the solid blunt  201  and the shaft  303  of a needle. The solid blunt is disposed within the shaft of the needle  303  such that the bulk of the solid blunt is positioned near the needle&#39;s sharp tip  311  which is shown diagrammatically in the cross-sectional view of FIG. 3A. As can be seen from FIG. 3A, the circumferential portion  203  of the outer surface of the solid blunt is closely positioned to the inner diameter  307  of the shaft  303 . Thus very little gap  309  exists between the blunt  201  and the shaft  303  along at least a first circumferential portion of the inner diameter of the shaft  303 . However, fluid flow is allowed to occur through the opening  305  which exists above the solid blunt  201  as shown in FIG. 3A. The blunt  201  includes material at or above the centerline  207  as shown in FIG. 3A so that the blunt cannot move substantially in a perpendicular direction relative to the longitudinal movement of the blunt  201  within the shaft  303 . That is, by having solid material of the blunt at or above the centerline of the shaft  303 , the blunt resists movement in this perpendicular direction.  
         [0028]    [0028]FIG. 2B shows another example of a particular geometry of a solid blunt according to the present invention. This particular geometry is referred to as a pie-slice shaped solid blunt due to the fact that the cross-section of the blunt as shown in FIG. 2B resembles a pie slice. The blunt  211  of FIG. 2B includes a first circumferential portion or outer surface  213  and a second circumferential portion or outer surface  215 . Each of these circumferential portions are designed to come in close contact with the inner diameter of the shaft  303  as shown in FIG. 3B. In one case, the outer diameter of the blunt is nearly equal to (but just less than) the inner diameter of shaft  303 . Thus, only a very small gap exists between the portion  213  and the inner diameter  307  of the shaft  303  as shown in FIG. 3B. The solid interior  219  of the blunt  211  extends from one circumferential portion to the other circumferential portion, thereby resisting perpendicular movement of the blunt. FIG. 2B shows in its cross-sectional view a particular geometry in which the sides  217  a and  217  b are straight. It will be appreciated that alternatively the sides  217  a and  217  b may be either concave or convex.  
         [0029]    [0029]FIG. 2C shows another specific geometry of a solid blunt according to the present invention. The solid blunt  221  shown in the cross-sectional view of FIG. 2C includes a cut-out region  229 . Even with the cut-out region, a solid portion  223 of the blunt  221  extends beyond the centerline  231  of the shaft  303  as shown in FIG. 3C. Accordingly, the solid blunt  221  will resist perpendicular movement as described above. The outer circumferential portion  225  of the solid blunt  221  has a diameter which is nearly equal to (but just less than) the diameter of the shaft  303  and thus very little space or gap  309  exists between the outer surface of the solid blunt and the inner diameter  307  of the shaft  303 . Also as shown in FIG. 3C, the blunt is positioned relative to the sharp tip  311  so that a majority of the solid blunt material will be disposed next to the sharp tip  311 .  
         [0030]    [0030]FIG. 2D shows another example of a particular geometry of a solid blunt according to the present invention. In the cross-sectional view of FIG.  2 D, the blunt  241  includes a D-shaped cut-out  249  in the upper surface  251  of the blunt. Sufficient solid material  245  of the blunt is at or above the centerline  247  of the shaft  303  as shown in FIG. 3D. The outer circumferential portion  243  of the blunt  241  is sized relative to the inner diameter of the shaft  303  such that very little gap  309   c  exists between the inner diameter of the shaft  303  and the outer circumference of the blunt  241 . The blunt  241  is positioned relative to the sharp tip  311  so that most of its solid material will be positioned near the tip  311 .  
         [0031]    [0031]FIG. 3E shows a side perspective view of the assembly  301  shown in FIG. 3A. The cross-sectional view of FIG. 3A is shown by line  3 A- 3 A of FIG. 3E. The needle assembly  301 , as shown in FIG. 3E, includes the solid blunt  201  which is disposed within the hollow inner diameter of the cannula formed by the shaft  303 . The inner diameter  307  of the shaft  303  is nearly equal to (but just less than) the outer diameter of the blunt  201  such that the gap  309  is very small. The gap  305  between the top of the solid blunt  201  and the inner diameter  307  provides a sufficient fluid path through the shaft  303  when the needle is used,. On the other hand, the close proximity between the outer circumferential portion  203  of the blunt  201  and its corresponding inner circumferential portion of the shaft  303  is such that fluid flow through the gap  309  is relatively restricted. The centerline  207  of the shaft  303  is shown relative to the solid blunt  201 . It can be seen that a portion of the solid material of the solid blunt is at or above the centerline, thereby preventing the blunt from moving perpendicularly along the perpendicular direction  357  shown in FIG. 3E. The blunt is capable of moving longitudinally along the longitudinal axis  353  under control of a conventional clip or other device (not shown) which is coupled to the blunt  201 . This device, such as a clip, may be attached directly to the blunt or through an intermediary piece which may have a different profile such as the rod  351  shown in FIG. 3E. The rod  351  does not need to perform the functions of the solid blunt  201  and thus may have a different geometry than the solid blunt  201 . The required geometry of the solid blunt  201  should exist around portions of the blunt that will be near the sharp tip  311 . The clip or other device which controls and positions the solid blunt  201  may be similar to those devices in the prior art, such as those shown in U.S. Pat. Nos. 5,009,642, or 5,540,662, or 4,828,547, or 5,743,882. These clips or devices, using conventional mechanisms, allow for the blunt to move longitudinally but prevent the blunt from moving circularly (e.g. rotating) within the shaft  303 ; this circular direction is shown by the arrow  355  shown in FIG. 3E. Thus by using a conventional clip or other device for retaining and controlling the movement longitudinally of the blunt  201 , the blunt  201  may be prevented from rotating (and thus stay positioned properly relative to the sharp tip  311 ) while also allowing for longitudinal movement along the axis  353  as shown in FIG. 3E. The geometric configuration of the blunt according to the present invention will also prevent perpendicular movement along the axis  357  as shown in FIG. 3E.  
         [0032]    [0032]FIGS. 4A and 4B show respectively particular examples of the D-shaped solid blunt and the pie-slice shaped solid blunt according to the present invention. These particular figures and the following tables provide various specific examples for dimensions which are specified in the following tables. In particular, Table A below specifies examples for particular dimensions of the D-shaped blunt relative to certain specific needle shafts. Similarly, Table B shows examples of specific dimensions for the pie-slice shaped blunt of FIG. 4B. The tables show the nominal inner diameter (ID) of the needle and show the nominal outer diameter (OD) of the blunt. It can be seen that the OD of the blunt is less than but nearly equal to the ID of the needle. In a typical case, the OD of the blunt is 0.002 inches less than the ID of the blunt. The labels on the FIGS. 4A and 4B represent the same labeled dimensions in the Tables A and B (for example, “A” in FIG. 4A is a dimension shown in the column A [“Nominal Blunt OD”] of Table A). These examples of FIGS. 4A and 4B assume a cylindrical shape for the needle&#39;s shaft and the blunt so that a diameter may be used to describe the relative dimensions. It will be appreciated that other geometries for the needle and blunt may be used with the present invention; for example, a needle and a blunt each having triangular or elliptical cross-sections may be used where a dimension of the blunt nearly equals a dimension of the needle.  
                                     TABLE A                           Nominal           Nominal   Blunt OD   B Flat       Needle ID   A   Location                                0.050   .0475   .029       0.038   .036   .021       0.030   .028   .018       0.023   .021   .012       0.017   .015   .009       0.014   .012   .007                  
 
         [0033]    [0033]                                   TABLE B                           Nominal                       Nominal   Blunt       Needle   OD       ID   A   B Base   C   D (Ref)   E (Ref)                   0.050    .0475   0.0450   0.0122   0.0172   0.0573       0.038   .036   0.0319   0.0048   0.0110   0.0400       0.030   .028   0.0237   0.0024   0.0082   0.0300       0.023   .021   0.0181   0.0018   0.0060   0.0225       0.017   .015   0.0132   0.0018   0.0045   0.0165       0.014   .012   0.0103   0.0012   0.0035   0.0130                    
         [0034]    [0034]FIGS. 5A and 5B show an example of a catheter system  501  of the invention. It will be appreciated that the solid blunt of the present invention may be used with various different types of catheter systems and that FIGS. 5A and 5B show merely one example of such a system. The catheter system  501  includes a needle  502 , a catheter hub  503 , a solid D-shaped blunt  504 , and a needle frame  507 . The catheter hub  503  includes a tube  506  which surrounds the needle  502 . The catheter hub  503  also includes a hub interconnect portion  503   a  which includes a section  503   b  disposed to engage a notch on the clip  511 . FIG. 5A shows the catheter system set before the needle is used so that the blunt is within the shaft of the needle. The solid blunt  504  is disposed within the shaft of the needle  502  and will extend beyond the opening of the needle  502  and beyond the sharp tip  505  of the needle  502  after the needle is used in accordance with conventional operating mechanisms for moving blunts. FIG. 5B shows the catheter system after the needle is used. The needle frame  507  is coupled to a flash chamber  509  and is also coupled by means of a slidable joint to the end  515  of the blunt  504 . The end  515  is coupled to the clip  511  so that when the catheter hub  503  is pulled away from the needle frame  507 , the blunt  504  is pulled out (so that it extends out beyond the sharp tip  505 ) by the interaction between the hub at  503   a  and the clip at  511  and the lower portion of the needle frame  507 . This lower portion of the needle frame  507  engages a portion of the clip  511  as shown in FIG. 5B after the catheter hub  503  has been pulled away from the needle frame  507 . This engagement between the lower portion of the needle frame  507  and the clip will keep the blunt extended out beyond the sharp tip  505  as shown in FIG. 5B. Blood or other fluids which enter the opening of the needle  502  travel along the top of the solid blunt  504  along the line  513 towards the flash chamber  509 . It will be appreciated that the solid blunts of the present invention may be used with various different needle assemblies having various different types of clips and other mechanisms for positioning the solid blunt and for allowing for longitudinal movement of the solid blunt relative to the shaft of the needle.  
         [0035]    In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.