Abstract:
The invention relates to a catheter introducer comprising: a tube-like introducer sheath; an introducer hub having a distal section and a proximal section, wherein the distal section is joined to the proximal end of the introducer sheath and the proximal section defines a chamber; a needle extending through the introducer hub and the introducer sheath and having opposite proximal and distal ends, the distal end forming a needle tip; a needle hub attached to the proximal end of the needle; and a needle safety device slidably arranged on the needle, wherein the needle safety device is retained in the chamber of the introducer hub when the needle extends through the introducer hub and the introducer sheath, and is removable from the introducer hub once the needle tip is received in the needle safety device upon withdrawal of the needle from the introducer sheath.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to India Application No. 1293/DEL/2008, filed May 28, 2008, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a catheter introducer, in particular an over-the-needle peel-away catheter introducer, comprising a tube-like introducer sheath; an introducer hub having a distal section and a proximal section, wherein the distal section is joined to a proximal end of the introducer sheath and the proximal section defines a chamber; a needle extending through the introducer hub and the introducer sheath and having opposite proximal and distal ends, wherein the distal end forms a needle tip; and a needle hub attached to the proximal end of the needle. 
     As used herein, the term “proximal” refers to a location on the device closest to, for example, a clinician using the device. Conversely, the term “distal” refers to a location on the device farthest from the clinician, such as the distal needle tip to be inserted into a patient&#39;s vein. 
     A catheter introducer of the above kind is generally known and typically used to facilitate insertion and placement of a catheter or another medical device into a patient&#39;s vasculature. A conventional peel-away catheter introducer, which is also referred to as a peelable or splittable or a tear-away catheter introducer, comprises a pair of wings extending transversely from the introducer hub. 
     When using the peel-away catheter introducer a clinician grabs the needle hub along with the introducer hub and inserts the distal portions of the needle and of the introducer sheath at a selected site into a patient&#39;s skin. The clinician advances the device until venipuncture has been confirmed, for example, when blood enters a flashback chamber formed in the needle hub. After venipuncture has been confirmed, the clinician advances the distal end portion of the introducer sheath into the patient&#39;s vein and withdraws the needle. With the catheter introducer properly placed, the clinician can then insert a medical device, such as a catheter, into the proximal opening of the introducer sheath and advance the medical device through the introducer sheath until it is properly placed in the patient&#39;s vasculature. After placement of the medical device the clinician withdraws the introducer sheath out of the venipuncture site. The clinician then splits the introducer hub and introducer sheath into two respective separate halves by a combination of twisting and/or pulling apart of the wings along tear lines provided in the introducer hub and introducer sheath until the two halves of the introducer hub and introducer sheath split apart. The clinician can thus remove the introducer hub and introducer sheath while the catheter inserted into the patient&#39;s vein remains in place. 
     Due to the increasing incidence of blood-borne pathogens such as human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) there is a need to protect clinicians or other medical professionals or personnel handling catheter introducers from accidental contact with the sharp needle tip after withdrawal of the needle from the introducer sheath and introducer hub. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a catheter introducer which provides reliable protection against accidental pricking by the needle once the needle has been withdrawn from the introducer sheath and introducer hub. 
     The catheter introducer of the invention comprises a tube-like introducer sheath; an introducer hub having a distal section and a proximal section, wherein the distal section is joined to a proximal end of the introducer sheath and the proximal section defines a chamber; a needle extending through the introducer hub and the introducer sheath and having opposite proximal and distal ends, wherein the distal end forms a needle tip; a needle hub attached to the proximal end of the needle; and a needle safety device slidably arranged on the needle, wherein the needle safety device is retained in the chamber of the introducer hub when the needle extends through the introducer hub and the introducer sheath and is removable from the introducer hub once the needle tip is received in the needle safety device upon withdrawal of the needle from the introducer sheath. 
     The needle safety device is operative as a guard for the needle tip by automatically covering the needle tip during withdrawal of the needle from a patient and subsequently from the introducer sheath. The needle safety device thereby serves to prevent accidental pricking of, for example, a clinician by the needle tip after removal of the needle from the introducer sheath. Hence, the needle can be safely disposed of after use. 
     According to one embodiment, a part of the needle safety device is, seen in a radial direction, arranged between the introducer hub and the needle hub. In this way, not only a safe seat of the needle safety device in the chamber of the introducer hub but also a secure connection between the introducer hub and the needle hub are achieved prior to withdrawal of the needle from the introducer sheath. Furthermore, the arrangement of a part of the needle safety device between the introducer hub and the needle hub facilitates a correct positioning of the needle safety device in the introducer hub and thus makes the assembly and ultimately the manufacture of the catheter introducer easier and less expensive. 
     According to a further embodiment, the needle safety device comprises two generally L-shaped extensions formed on opposite sides of the needle safety device, preferably in the region of a proximal end thereof. Each L-shaped extension may have an axial section extending generally in an axial direction at a distance from a base portion or a reinforced jaw portion of the needle safety device. As used herein, the axial direction is defined by the longitudinal axis of the introducer sheath and of the needle extending therethrough. 
     Preferably, the proximal section of the introducer hub is configured to be received between the axial sections and the base portion or the reinforced jaw portions of the needle safety device. 
     According to a further embodiment, the proximal section of the introducer hub is formed from two opposite proximal tube sections extending in the axial direction. Similarly, the needle hub may comprise a main body and two opposite tube sections extending in the axial direction from a distal end of the main body. 
     Preferably, the tube sections of the needle hub are configured to engage between the proximal tube sections of the introducer hub such that the tube sections of the needle hub and the proximal tube sections of the introducer hub together form a substantially closed tube. Because of this substantially closed tube the chamber defined by the proximal section of the introducer hub is also substantially closed, such that the needle safety device received in the chamber is protected from outside influences. This helps to permanently maintain a reliable functioning of the needle safety device. 
     According to a further embodiment, the main body of the needle hub comprises a tube-like portion configured to receive both a base portion of the needle safety device and a portion of the proximal section of the introducer hub. In the assembled state, i.e. prior to withdrawal of the needle, the tube-like portion of the main body of the needle hub hence surrounds a part of the needle safety device as well as a part of the proximal section of the introducer hub, thereby not only protecting the needle safety device but also preventing the introducer hub and consequently the introducer sheath from accidentally splitting into halves. 
     According to a further embodiment, locking means are provided to hold the portion of the proximal section of the introducer hub in place between the axial sections and the base portion or the reinforced jaw portions of the needle safety device. The locking means help to secure the needle safety device at the introducer hub as long as the needle has not been fully withdrawn from the introducer sheath and the needle tip has not been received in the needle safety device. Hence, the needle can move relative to the needle safety device until the needle tip is safely received in the needle safety device. The locking means thus ensure a correct functioning of the needle safety device. 
     According to a further embodiment, locking means are provided to hold the proximal section of the introducer hub in place in the tube-like portion of the needle hub. The locking means ensure a safe connection between the introducer hub and needle hub and thereby prevent the needle from being accidentally withdrawn from the introducer sheath. 
     Preferably, both the locking means operating between the introducer hub and the needle safety device and the locking means operating between the introducer hub and the needle hub comprise a locking protrusion on the respective one part and a corresponding locking depression in the respective other part. For instance, respective locking protrusions may be provided in the region of the proximal ends of the proximal tube sections of the introducer hub, whereas corresponding grooves may be provided at the inner side of the tube-like portion of the needle hub and of the generally L-shaped extensions of the needle safety device. 
     The needle safety device may comprise first and second jaws extending from the base portion in a generally axial direction. 
     According to one embodiment, the first jaw is integrally formed with the base portion and, preferably, substantially rigid. Due to the first jaw being formed integrally with the base portion, the number of parts in the needle safety device is reduced and the simplicity thereof increased. Forming the base portion, and thus preferably also the first jaw, from a plastic material helps to reduce the costs of manufacturing the needle safety device. The first jaw being substantially rigid increases the integrity of the needle safety device. At the same time, a reliable functioning of the needle safety device can be ensured by a suitable deflectability of the second jaw. 
     The second jaw may include a strip of material having spring-like properties, for example a strip of sheet metal or a strip of a suitable plastic material. Because of the first and second jaws being made from two separate parts, the needle safety device can easily be adapted to needles of different thicknesses. Furthermore, due to its simple design the needle safety device and, thus, the entire catheter introducer can be manufactured at low cost. Due to its spring-like properties the second jaw may be deflected against a restoring force by the needle extending all the way through the needle safety device, such that the second jaw snaps in front of the needle tip as soon as the needle tip is moved in between the two jaws, thereby safely guarding the needle tip. 
     According to an alternative embodiment that can also be manufactured at low cost, the first and second jaws may be formed integrally with the base portion, wherein preferably both jaws have spring-like properties. 
     The second jaw may have a distal end section which extends towards the first jaw such that it sits on the needle when the needle extends through the needle safety device, thereby deflecting the second jaw outwardly against a restoring force, and blocks the needle tip from protruding from the needle safety device when the needle tip is received between the jaws, thereby safely guarding the needle tip in the needle safety device. 
     According to a further embodiment, an elastic element, in particular a tension ring, surrounds the first and second jaws in order to positively collapse the jaws when the needle tip is received between the jaws. Preferably, the elastic element and the jaws are configured such that the second jaw can be spread away from the first jaw against a restoring force of the elastic element in order to allow the needle to extend all the way through the needle safety device. 
     Due to the elastic element exerting its restoring force on the second jaw in the deflected state of the second jaw, which is the state in which the catheter introducer is typically shelved prior to use, the elastic element ensures that the spread-apart jaws will snap together and guard the needle tip upon withdrawal of the needle from the introducer sheath even after a longer shelf time, thereby continuously ensuring a correct functioning of the needle safety device. In addition, the elastic element prevents the jaws from becoming loose when the needle safety device slides along the needle, thereby further adding to a correct functioning of the needle safety device. Furthermore, the elastic element helps prevent the needle tip from protruding sideways out of the needle safety device, thereby further increasing the protective function of the needle safety device. 
     According to a further embodiment, the needle extends through an axial bore in the base portion of the needle safety device, wherein the cross section of the bore is adapted to the main profile of the needle, and the needle has an enlargement near the needle tip rendering the outer diameter of the needle, seen in at least one direction, greater than the diameter of the bore. The enlargement prevents the needle safety device from sliding off the needle when the needle tip is received between the jaws, thereby even further improving the protective function of the needle safety device. 
     Further subject matter of the invention is a needle safety device for guarding the tip of a needle of a medical apparatus, for example a catheter introducer of the above-described type or an intravenous catheter apparatus, which comprises a base portion and two jaws extending therefrom and defining an axial direction and two generally L-shaped extensions formed on opposite sides of the needle safety device, wherein each L-shaped extension has an axial section extending generally in the axial direction at a distance from the base portion or from reinforced portions of the jaws. Apart from that, the needle safety device may be configured similar to the needle safety device of the above-described catheter introducer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred embodiments of the invention are described in the following description and in the accompanying drawings. 
         FIGS. 1   a  to  1   c  show ( a ) a first longitudinal sectional view of a catheter introducer according to the invention, ( b ) a second longitudinal sectional view of the catheter introducer, and ( c ) an enlargement of a portion of  FIG. 1   a;    
         FIGS. 2   a  and  2   b  show perspective views of an introducer hub of the catheter introducer of  FIG. 1  and of the introducer hub attached to an introducer sheath; 
         FIGS. 3   a  and  3   b  show ( a ) a perspective view of a needle hub of the catheter introducer of  FIG. 1  and ( b ) a side view of the needle hub attached to a needle; 
         FIGS. 4   a  to  4   f  show ( a ) a perspective view of a needle safety device of the catheter introducer of  FIG. 1 , ( b ) a longitudinal sectional view of the needle safety device, ( c ) a side view of the needle safety device, ( d ) a plan view of the needle safety device, ( e ) a side view of the needle safety device guarding the tip of a needle, and ( f ) a longitudinal sectional view of the needle safety device guarding the needle tip; and 
         FIGS. 5   a  to  5   f  show ( a ) a perspective view, ( b ) a side view, ( c ) a longitudinal sectional view, and ( d ) a plan view of an alternative needle safety device for the catheter introducer of  FIG. 1 , and ( e ) a side view and ( f ) a longitudinal sectional view of the needle safety device guarding the tip of a needle. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIGS. 1   a  and  1   b  show longitudinal sectional views of an over-the-needle peel-away catheter introducer of the invention. The catheter introducer comprises a tube-like introducer sheath  10  having a proximal end region  12  that is joined to an introducer hub  14 . 
     Furthermore, the catheter introducer comprises a needle  16  having a distal end that forms a needle tip  18  and a proximal end that is attached to a needle hub  20 . 
     Prior to use of the catheter introducer, the needle hub  20  is connected to the introducer hub  14  such that the needle  16  extends all the way through the introducer hub  14  and the introducer sheath  10  and the needle tip  18  protrudes beyond a distal end of the introducer sheath  10 . 
     In order to prevent accidental pricking by the needle tip  18  prior to use of the catheter introducer, an elongate cap  22  or protective tube is mounted to the introducer hub  14 , which covers the length of the introducer sheath  10  and also the needle tip  18  protruding therefrom. 
     As can be seen in more detail from  FIG. 2 , the introducer hub  14  includes a distal section  24  and a proximal section  26 . The distal section  24  has smaller inner and outer diameters than the proximal section  26  and is joined to the proximal end region  12  of the introducer sheath  10 . 
     In the transition region between the distal section  24  and the proximal section  26  a funnel-like structure  28  is formed in the introducer hub  14 , which helps to facilitate the introducing of a medical device, for example a catheter, into the introducer sheath  10  after the introducer sheath  10  has been inserted into the vein of a patient. Furthermore, two wings  30  extend transversely from the introducer hub  14  in the transition region between the distal section  24  and the proximal section  26 . 
     Both the distal section  24  and the proximal section  26  of the introducer hub  14  are formed from pairs of opposite axially extending tube sections  32 ,  34  which define first and second halves of the introducer hub  14 . Prior to use, the first and second halves of the introducer hub  14  are connected to each other by the funnel-like structure  28 . 
     Once a medical device, such as a catheter, has been introduced through the introducer sheath  10  into a patient&#39;s vein, the person handling the catheter introducer, for example a clinician, withdraws the introducer sheath  10  from the venipuncture site. By a combination of twisting and/or pulling apart of the wings  30  the clinician then splits the introducer hub  14  into its two separate halves, thereby also tearing the introducer sheath  10 , such that the introducer hub  14  and the introducer sheath  10  can be removed from the catheter. In order to facilitate the breaking of the introducer hub  14  into its two halves, tear lines  36  may be provided in the funnel-like structure  28  and also in the introducer sheath  10 . 
     As can be seen in  FIG. 3 , the needle hub  16  comprises a main body  38  and two opposite tube sections  40  which extend in an axial direction from a distal end of the main body  38 . The tube sections  40  of the needle hub  20  are configured to engage between the proximal tube sections  34  of the introducer hub  14  such that the proximal tube sections  34  of the introducer hub  14  and the tube sections  40  of the needle hub  20  form a substantially closed tube. 
     To this end, the tube sections  40  of the needle hub  20  and the proximal tube sections  34  of the introducer hub  14  have substantially the same length and curvature, and the tube sections  40  of the needle hub  20  have a width corresponding to the gap between the proximal tube sections  34  of the introducer hub  14 . 
     Referring again to  FIGS. 1   a  and  1   b , the proximal tube sections  34  of the introducer hub  14  and the tube sections  40  of the needle hub  20  together form a chamber  42  for a needle safety device  44  which is slidably arranged on the needle  16 . 
     As shown in  FIG. 4 , the needle safety device  44  comprises a main part  46 , a clip  48  and a tension ring  50 . 
     The main part  46  is made from a plastic material and comprises a base portion  52  and an elongate portion  54  forming a first jaw  55 . The base portion  52  is of substantially cylindrical shape and has a bore  56  extending therethrough in the axial direction for receiving the needle  16 . 
     The elongate portion  54  is of semi-cylindrical shape and extends from the base portion  52  in the axial direction. The elongate portion  52  has a groove  58  formed in its flat side  60 , which extends in the axial direction along the entire length of the elongate portion  54  and forms an extension of the bore  56  in the base portion  52 . While the bore  56  has a generally circular cross section that is adapted to the main outer profile of the needle  16 , the groove  58  has a generally semi-circular cross section. 
     The clip  48  is formed from a strip of sheet metal having spring-like properties, such as steel or the like. Alternatively, the clip  48  could be formed from a plastic material which has suitable spring-like properties. 
     The clip  48  forms a second jaw  62  and comprises a base section  64  and a deflectable section  66 . The base section  64  includes an axial section part  68  and a radial section part  70 . It is adapted to engage with the base portion  52  of the main part  46  such that the axial section part  68  lies against the outer surface of the base portion  52  while the radial section part  70  lies against a rear or proximal end face of the base portion  52 , when the clip  48  is attached to the main part  46 . In order to ensure a correct positioning of the main part  46  and the clip  48 , the base portion  52  is provided with a guide  74  for the clip  48 . 
     The clip  48  is secured to the main part  46  by means of a heat sealing connection. To this end, the main part  46  initially has a pillar or pin  76  formed at its proximal end face and extending generally in the axial direction. The clip  48  has a corresponding opening  78  formed in its radial section part  70  for receiving the pillar or pin  76  when the clip  48  is mounted on the main part  46 . Once the clip  48  has been brought into its correct position relative to the main part  46 , the pillar or pin  76  extending through the opening  78  of the clip  48  is deformed by heat and/or pressure in order to increase the diameter of the pillar or pin  76 . By making the diameter of the pillar or pin  76  larger than the diameter of the opening  78 , the clip  48  is safely fixed at the main part  46 . Alternatively, the clip  48  could be secured to the main part  46  by means of gluing or welding or any other suitable type of connection. 
     The base section  64  of the clip  48  passes into the deflectable section  66  via a step-like bending of the sheet metal strip. The deflectable section  66  includes a straight section part  80  which is reinforced by two elongate wings  82  that extend on either side of the straight section part  80  and are bent inwards, i.e. towards the elongate portion  54 , by an angle of substantially 90°. In a relaxed state of the clip  48  mounted on the main part  46  ( FIGS. 4   b  and  4   c ), the straight section part  80  does not exactly extend in the axial direction, but is bent slightly towards the elongate portion  54  of the main part  46 . 
     In the region of its distal end, the straight section part  80  passes into a head section part  84  which extends beyond the free end of the elongate portion  54  of the main part  46 . The head section part  84  has a generally V-like shape with the peak of the V pointing in the axial direction and the free leg  86  of the V extending towards the elongate portion  54 . 
     The tension ring  50  surrounds the elongate portion  54  of the main part  46  and the straight section part  80  of the clip  48  in the region of the elongate wings  82 . The tension ring  50  is made from a material having elastic properties, for example rubber. The tension ring  50  is configured so that the deflectable section  66  of the clip  48  is deflected against a restoring force of the tension ring  50 , when the needle  16  extends all the way through the needle safety device  44 . This situation is called the deflected state of the needle safety device  44  and is shown in  FIG. 1   b.    
     When the needle  16  does not extend all the way through the needle safety device  44  ( FIGS. 4   e  and  4   f ) or when there is no needle  16  at all ( FIGS. 4   b  and  4   c ), the deflectable section  66  of the clip  48  is drawn towards the elongate portion  54  of the main part  46  by the tension ring  50 . In this situation, which is referred to as the collapsed state of the needle safety device  44 , the head section part  84  of the clip  48  overlaps with or extends over at least a portion of the distal end face  90  of the elongate portion  54 , thereby preventing the needle tip  18  from protruding out of the needle safety device  44  at the distal end thereof. 
     As has been mentioned above, the bore  56  provided in the base portion  52  of the main part  46  of the needle safety device  44  is adapted to the main outer profile of the needle  16 . As is indicated in  FIG. 3   b , the needle  16  is provided with an enlargement  92  near the needle tip  18 , which renders the outer diameter of the needle  16 , seen in at least one direction, greater than the diameter of the bore  56 . The enlargement  92  prevents the needle safety device  44  from sliding off the needle  16  when the needle tip  18  is received between the first and second jaws  55 ,  62  as is shown in  FIGS. 4   e  and  4   f.    
     As illustrated in  FIGS. 4   a  and  4   d , two generally L-shaped extensions  94  are formed on opposite sides of the needle safety device  44  in the proximal region of the base portion  52  of the main part  46 . Each L-shaped extension  94  has an axial section  96  which extends in the axial direction at a distance from the base portion  52  of the needle safety device  44 . 
     The L-shaped extensions  94  are dimensioned such that proximal end portions  98  of the proximal tube sections  34  of the introducer hub  14  are tightly received between the axial section  96  of the L-shaped extensions and the base portion  52  of the needle safety device  44  when the needle safety device  44  is received in the chamber  42  defined by the tube sections  34 ,  44  of the introducer hub  14  and the needle hub  20 , as shown in  FIGS. 1   a  and  1   c.    
     In order to retain the proximal tube sections  34  of the introducer hub  14  in engagement with the L-shaped extensions  94  of the needle safety device  44 , locking grooves  100  are provided in the inner surfaces of the axial sections  96  of the L-shaped extensions  94  and corresponding locking protrusions  102  are provided at the outer surfaces of the proximal tube sections  34  of the introducer hub  14  ( FIGS. 1   c  and  2 ). 
     As is best seen in  FIG. 3 , the tube sections  40  of the needle hub  20  pass into a tube-like portion  104  of the main body  38  of the needle hub  20 . The tube-like portion  104  is configured to receive not only the base portion  52  of the needle safety device  44  but also a part of the proximal tube sections  34  of the introducer hub  14  ( FIGS. 1   a  and  1   c ). 
     In order to secure the proximal tube sections  34  of the introducer hub  14  in the tube-like portion  104  of the needle hub  20 , locking grooves  106  are provided in the inner surface of the tube-like portion  104  of the needle hub  20  ( FIG. 3 ) and corresponding locking protrusions  108  are formed at the outer surface of the proximal tube sections  34  of the introducer hub  14  in a distance distal from the locking protrusions  102  provided for engagement with the needle safety device  44  ( FIGS. 1   c  and  2 ). 
     The engagement of the locking protrusions  108  with the locking grooves  106  prevents the needle hub  20  from being accidentally released from the introducer hub  14 . 
     At the same time, the locking engagement of the locking protrusions  102  with the locking grooves  100  secures the needle safety device  44  at the introducer hub  14 , thereby preventing the needle safety device  44  from being accidentally withdrawn from the introducer hub  14  before the needle tip  18  has been received between the first and second jaws  55 ,  62  of the needle safety device  44 . 
       FIG. 5  shows an alternative embodiment of a needle safety device  44 . 
     Similar to the embodiment of  FIG. 4  the needle safety device  44  shown in  FIG. 5  comprises a main part  46  and a tension ring  50 . However, in contrast to the embodiment of  FIG. 4 , the needle safety device  44  shown in  FIG. 5  does not have any separate clip  48 . Instead, the main part  46  comprises a base portion  52  and two elongate portions  110 ,  112  that extend from the base portion  52  generally in the axial direction to form the first and second jaws  55 ,  62 . 
     The base portion  52  and the two elongate portions  110 ,  112  are integrally formed and made, for example, from a plastic material. The base portion  52  is of substantially cylindrical shape and has a bore  56  extending therethrough in the axial direction for receiving the needle  16 . The bore  56  has a generally circular cross section that is adapted to the main outer profile of the needle  16 . 
     The elongate portions  110 ,  112  each have a proximal section  114  and a distal section  116 . While the proximal sections  114  extend generally parallel to each other, the distal sections  116  are inclined towards each other in the collapsed state of the needle safety device  44  ( FIGS. 5   e  and  5   f ) or when no needle  16  extends through the needle safety device  44  ( FIGS. 5   a  to  5   d ). 
     The distal section  116  of the second jaw  62  passes into a head section part  84  which extends beyond the free end of the first jaw  55 . The head section part  84  includes an end section  118  which extends in a radial direction towards the first jaw  55 . The length of the end section  118  is such that it covers at least a portion of the free end of the first jaw  55  when the needle safety device  44  is in its collapsed state in order to prevent the needle tip  18  from protruding out of the needle safety device  44  ( FIGS. 5   e  and  50 . 
     The tension ring  50  surrounds the first and second jaws  55 ,  62  in the region of their distal sections  116 . The tension ring  50  is made from a material having elastic properties, for example rubber. The tension ring  50  is configured so that the first and second jaws  55 ,  62  are deflected against a restoring force of the tension ring  50 , when the needle  16  extends all the way through the needle safety device  44 . 
     Two generally L-shaped extensions  94  are formed on opposite sides of the needle safety device  44 . The L-shaped extensions  94  emerge from reinforced portions  120  of the first and second jaws  55 ,  62  in the proximal end region of the first and second jaws  55 ,  62 . Each L-shaped extension  94  has an axial section  96  which extends in the axial direction at a distance from the respective reinforced portion  120 . 
     The L-shaped extensions  94  are dimensioned such that proximal end portions  98  of the proximal tube sections  34  of the introducer hub  14  are tightly received between the axial sections  96  of the L-shaped extensions and the reinforced portions  120  of the needle safety device  44  when the needle safety device  44  is received in the chamber  42  defined by the tube sections  34 ,  44  of the introducer hub  14  and the needle hub  20 , as shown in  FIGS. 1   a  and  1   c.    
     Contrary to the embodiment of  FIG. 4 , the L-shaped extensions  94  of the needle safety device  44  shown in  FIG. 5  do not have any locking grooves  100  in the inner surfaces of the axial sections  96  of the L-shaped extensions  94 . Instead, the reinforced portions  120  are provided with locking shoulders  122  for retaining the proximal tube sections  34  of the introducer hub  14  between the axial sections  96  of the L-shaped extensions and the reinforced portions  120  of the needle safety device  44 . Accordingly, the proximal tube sections  34  of the introducer hub  14  should be provided with corresponding locking means at their inner surfaces, for example suitable depressions. 
     LIST OF REFERENCE NUMERALS 
     
         
           10  introducer sheath 
           12  proximal end region 
           14  introducer hub 
           16  needle 
           18  needle tip 
           20  needle hub 
           22  elongate cap 
           24  distal section 
           26  proximal section 
           28  funnel-like structure 
           30  wing 
           32  distal tube section 
           34  proximal tube section 
           36  tear line 
           38  main body 
           40  tube section 
           42  chamber 
           44  needle safety device 
           46  main part 
           48  clip 
           50  tension ring 
           52  base portion 
           54  elongate portion 
           55  first jaw 
           56  bore 
           58  groove 
           60  flat side 
           62  second jaw 
           64  base section 
           66  deflectable section 
           68  axial section part 
           70  radial section part 
           74  guide 
           76  pin 
           78  opening 
           80  straight section part 
           82  wing 
           84  head section part 
           86  free leg 
           90  end face 
           92  enlargement 
           94  L-shaped extension 
           96  axial section 
           98  proximal end portion 
           100  locking groove 
           102  locking protrusion 
           104  tube-like portion 
           106  locking groove 
           108  locking protrusion 
           110  elongate portion 
           112  elongate portion 
           114  proximal section 
           116  distal section 
           118  end section 
           120  reinforced portion 
           122  locking shoulder