Patent Description:
Catheters, particularly intravascular (IV) catheters, are used for infusing fluid, such as normal saline solution, various medicaments and total parenteral nutrition, into a patient, withdrawing blood from a patient or monitoring various parameters of the patient's vascular system. Peripheral IV catheters tend to be relatively short, and typically are on the order of about two inches or less in length. The most common type of IV catheter is an over-the-needle peripheral IV catheter.

As its name implies, an over-the-needle catheter is mounted over an introducer needle having a sharp distal tip. At least the distal portion of the catheter tightly engages the outer surface of the needle to prevent peelback of the catheter and thus facilitates insertion of the catheter into the blood vessel. The catheter and the introducer needle are assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter with the bevel of the needle facing up away from the patient's skin.

The catheter and introducer needle assembly is inserted at a shallow angle through the patient's skin into a blood vessel. There are many techniques for inserting such a catheter and introducer needle assembly into a patient. In one insertion technique, the introducer needle and catheter are inserted completely into the blood vessel together. In another technique, the introducer needle is partially withdrawn into the catheter after the initial insertion into the blood vessel. The catheter is then threaded over the needle and inserted completely into the blood vessel.

The clinical utilization of a pointed hollow needle mounted inside a flexible catheter tube is well known in the medical art for the introduction of a catheter. In such a medical instrument, the catheter tube is positioned tightly around the needle in such a way as to allow the needle to slide and telescope along the length of the catheter tube. Before use, the tip of the needle is protruding slightly through the opening of the catheter tube to allow facile penetration through the skin. Upon puncturing of the skin and introduction of the needle, the distal end of the catheter tube is simultaneously brought into place inside the desired target body cavity of the patient, such as the inside of a blood vessel, for example a vein. The needle has then done its duty in assisting the introduction of the catheter and is withdrawn by being pulled backwards through the catheter. Upon release of the needle, the catheter is set in its intended working mode extending over a lengthier period of time and including, for example, periodical administration or infusion of fluids or medications in liquid form, the collection of blood samples and the like.

With regard to over-the-needle catheters, there are mainly two major alternatives. The first one, the open IV catheter system, comprises luer through which the needle is withdrawn after insertion of the catheter into the blood vessel, which is connectable to blood withdrawal or infusion means, as well as an optional port for the same purpose. The second one, the closed IV catheter system, comprises a septum in an catheter hub through which the needle is withdrawn after insertion of the catheter into the blood vessel, closing off the "needle channel" from the environment, and instead has an extension tube extending laterally from the catheter hub, wherein the extension tube is in fluid communication with the catheter hub cavity and the lumen of the catheter positioned in the blood vessel. These two alternatives are accompanied with different problems and benefits.

In recent years, there has been great concern over the contamination of clinicians with a patient's blood and a recognition that "blood contaminated sharps" must be disposed to avoid an accidental needle stick. This concern has arisen because of the advent of currently incurable and fatal diseases, such as Acquired Immunosuppressive Deficiency Syndrome ("AIDS"), hepatitis, etc., which can be transmitted by the exchange of body fluids from an infected person to another person.

As a result of the problem of accidental needlesticks by "blood contaminated sharps", various needle shields have been developed for use in conjunction with intravenous catheters.

In the field of medicine, such as within the field of devices for infusion and injection, it is known to arrange needle tip shielding devices on the injection or infusion needle, said shielding device having the ability to snap in front of the needle tip upon withdrawal of the needle. These needle tip shielding devices have historically been manufactured in stainless steel. After the manufacturing and packing of the devices for infusion and injection, the devices are sterilized for hygenic reasons.

Such a needle tip shielding device is for example disclosed in <CIT>. However, needle tip shielding devices will, when being arranged in for example a catheter hub, scratch and tear the polymeric catheter hub lumen, resulting in a major risk of flushing plastic material into the blood stream of the patient. Additionally, the manufacturing of such shielding devices of stainless steel is cumbersome and costly, since several punching and bending stations have to be used. Additionally, due to the metal sheet of such device, there is a high risk of "drawer effect" on the needle shaft.

A softer needle shielding device could be used to avoid such scratching. For instance, a plastic needle shield would not scratch the plastic of the catheter hub. However, the softer material characteristics of such a needle shield could also create the risk of it being able to slide over the stopper close to the needle tip, and off the needle. <CIT> discloses a prior art catheter assembly.

Hence, a soft needle shield assembly with decreased risk of undue needle shield assembly release with regard to a IV catheter system, is desired.

Accordingly, the present invention preferably seeks to mitigate, alleviate or eliminate one or more of the above-identified deficiencies in the art and disadvantages singly or in any combination and solves at least the above mentioned problems by providing: an IV catheter system comprising a catheter hub, said catheter hub comprising: a tubular catheter, having a lumen, attached to a catheter hub body at its proximal end, with a catheter hub cavity in fluid communication with the lumen of the tubular catheter; a needle hub, said needle hub comprising: a needle extending distally from a needle hub body, said needle having a bulge and a high friction surface at its distal end zone; a needle shield comprising at least one resilient arm extending distally from a base plate, said base plate having a through hole for receiving the needle there through; wherein the needle hub is arranged in the catheter hub, such that the needle is slidingly arranged through the lumen of said catheter, such that the needle may be withdrawn proximally from the catheter hub; wherein the needle shield is arranged in the catheter hub cavity in a retained manner through cooperation between the needle shield and an inner wall of the catheter hub in said catheter hub cavity, and onto the needle, such that the at least one arm rests upon and is spring loaded by the needle, and the needle is slidingly arranged within the through hole of the base plate, in an assembled state; and wherein the outer diameter of the needle bulge is larger than the inner diameter of the through hole of the base plate when the needle hub is withdrawn from the catheter hub to release the needle shield from the catheter hub and the at least one arm will cover the tip of the needle in a released state: and such needle hub.

The invention is defined in claims <NUM>,<NUM>. Advantageous features of the invention are defined in the dependent claims.

These and other aspects, features and advantages of which the invention is capable will be apparent and elucidated from the following description of non-limiting embodiments of the present invention, reference being made to the accompanying drawings, in which.

Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings in order for those skilled in the art to be able to carry out the invention. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Furthermore, the terminology used in the detailed description of the particular embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. More specifically, the term "proximal" refers to a location or direction of items or parts of items, during normal use of the IV catheter system disclosed herein, is closest to the user, i.e. the clinician, and farthest away from the patient receiving the IV catheter system. Similarly, the term "distal" refers to a location or direction of items or parts of items, during normal use of the IV catheter system disclosed herein, is closest to the patient and farthest away from the clinician. The term "laterally" refers to the direction away from the central axis of the IV catheter system, such that at least a vector component perpendicular to the central axis of the IV catheter system, wherein the needle and catheter of the assembled IV catheter system coincides with the central axis of the IV catheter system.

In accordance with Fig. 1a, one embodiment of a catheter hub <NUM> of an open IV catheter system is illustrated. The catheter hub <NUM> comprises a longitudinal and tubular catheter <NUM> at its distal end. The catheter <NUM> is, in accordance with above, intended to be inserted into a blood vessel of a patient. The catheter <NUM> is attached to a catheter hub body <NUM> at its proximal end, such that the catheter extends distally from the catheter hub body <NUM>. The lumen of the catheter <NUM> is in fluid communication with a distal catheter hub cavity <NUM>. The catheter hub body <NUM> is preferably made through injection molding, and then of a rigid plastic material suitable for injection molding and connection and interaction with other parts of the system. Such a suitable material is polycarbonate or a copolymer of polycarbonate and polyester.

In one embodiment in accordance with figure 1a, an open connector <NUM> is provided on a catheter hub body <NUM>. The open connector <NUM> extends laterally from the catheter hub body <NUM>. The open connector <NUM> may for example be tubular. The open connector <NUM> may be a luer fitting, such as a luer lock or luer slip, adapted to receive a syringe or tubing set in a known manner. The open connector <NUM> may have a lid, such as an injection port cap. The lid may be spring force operated. The open connector <NUM> connects to a bifunctional valve <NUM> in the distal catheter hub cavity <NUM>, such that a tube or syringe may be connected to the tube connector <NUM> allowing for infusion through the open tube connector <NUM> into a proximal catheter hub cavity <NUM>, further to the catheter <NUM> and finally into the blood stream of the patient, when there is no needle through the bifunctional valve <NUM> and catheter <NUM>. The distal catheter hub cavity <NUM> ends proximally in a bifunctional valve <NUM>. This bifunctional valve <NUM> has a central through-channel, which may be penetrated by a needle <NUM> of a needle hub <NUM>, in accordance with Fig. 1a. When the needle <NUM> has been withdrawn from the catheter hub <NUM>, the bifunctional valve <NUM> will keep said through channel open, such that the distal catheter hub cavity <NUM> is in contact with the proximal catheter hub cavity <NUM>. Furthermore, the bifunctional valve <NUM> is preferably of a suitable rubber material or silicone. On the proximal side of the bifunctional valve <NUM> a proximal catheter hub cavity <NUM> is located. The proximal catheter hub cavity <NUM> is formed by the tubular wall of the catheter hub body <NUM> and a distal end wall in form of the proximal end wall of the bifunctional valve <NUM>. This proximal catheter hub cavity <NUM>, extending distally into the catheter hub body <NUM>, is adapted in size and shape to house the needle shield <NUM>, as disclosed in Fig. 1a.

The needle hub <NUM> comprises a needle <NUM> extending distally from a needle hub body <NUM> with a needle shaft <NUM>, a needle tip <NUM>, a bulge <NUM> and a high friction surface part <NUM> at its distal end zone, as seen in <FIG>. The high friction surface part <NUM> may at least partly be applied on the bulge <NUM> and/or proximally of the bulge <NUM>, i.e. closer to the needle hub body <NUM> than the bulge <NUM>. The high friction surface part <NUM> may also cover the bulge <NUM>, and extend proximally and/or distally of the bulge <NUM>. To facilitate skin penetration, the high friction surface part <NUM> does however not cover the needle tip <NUM> and/or the part of the needle <NUM> extending distally beyond a catheter on an IV catheter system in a ready-to-use state.

The needle bulge <NUM> is a short section of the needle, where the radius of the bulge <NUM> is larger than that of the needle shaft <NUM>. This may be achieved by a slight local deformation of the needle shaft <NUM>. By a slight flattening of two opposing sides of the needle shaft <NUM>, perpendicular to the length axis of the needle shaft <NUM>, increased radius transitions between the flattened areas will protrude distally from the needle shaft and provide the bumps of the needle bulge <NUM>, as seen in <FIG>. The needle bulge <NUM> may also be obtained by for example providing the needle shaft <NUM> with a weld.

The needle bulge <NUM> area has a high friction surface part <NUM>, covering at least the needle bulge <NUM>, and may extend proximally and/or distally of the bulge <NUM> along the needle shaft <NUM>.

In one embodiment in accordance with <FIG>, a needle system <NUM> is provided comprising a needle hub <NUM>, wherein the needle hub <NUM> comprises a needle <NUM> extending distally from a needle hub body <NUM> with the needle bulge <NUM> at its distal end zone having a high friction surface part <NUM>.

The needle shield <NUM> comprises a base plate <NUM>. The base plate <NUM> is provided with a hole <NUM>, extending there through, i.e. from the proximal side of the base plate <NUM> to the distal side of the base plate <NUM>. Preferably, the hole <NUM> is arranged centrally on the base plate <NUM>, such that arrangement of needle <NUM> through said hole <NUM> is facilitated while the needle <NUM> is arranged in accordance with the ready position of the catheter instrument. At least one resilient arm <NUM> is extending distally from an attachment point at said base plate <NUM>. Preferably, due to manufacturing reasons, the attachment point is located at the periphery of the base plate <NUM>. The resilient arm <NUM> has a resting state, from which it may be urged to yield free passage for the needle <NUM> through said hole <NUM> in an axial direction of said base plate <NUM> in a tension state. This released resting state is disclosed in <FIG>. The resilient arm <NUM> is in its tension state when the catheter instrument <NUM> is in its ready position, in accordance with Fig. 1a. The resilient arm <NUM> is adapted for clamping a needle tip <NUM> of a needle <NUM> extending through the hole <NUM> when the resilient arm <NUM> is in said resting state. For this reason, a straight imaginary line extending longitudinally through said hole <NUM> in the axial direction of said base plate <NUM> coincides with said at least one resilient arm <NUM> when said resilient arm <NUM> is in said resting state.

The needle shield <NUM> may comprise one, two, three or more tongues <NUM>, which extend proximally from the lateral circular periphery of the base plate <NUM>. The tongues <NUM> are, in accordance with above, resilient, whereby they are resiliently striving from a compressed state towards an expanded state. In the assembled state within the proximal catheter hub cavity <NUM>, the tongues <NUM> are somewhat compressed, to exercise a force on the inner walls of the catheter hub <NUM>. The needle shield <NUM> is thereby held therein, i.e. a constant spatial relationship between the needle shield <NUM> and the catheter hub <NUM> is provided. A plurality of tongues <NUM> may be evenly spread at the periphery of the base plate <NUM>, whereby each tongue <NUM> is contacting the inner surface of the catheter hub <NUM> with essentially the same force.

The tongues <NUM> may comprise a protuberance <NUM> extending in a direction essentially perpendicular to the central axis or laterally of the needle shield <NUM>. When the tongues <NUM> are provided with protuberances <NUM>, the diameter of the base plate <NUM> in a transversal plane intersecting the protuberances <NUM> may be greater than the diameter of the proximal catheter hub cavity <NUM>, and specifically the proximal opening thereof, along a transversal plane. Then the needle shield <NUM> may be compressed, due to the flexibility of the tongues <NUM>, such that it may be inserted into the proximal catheter hub cavity <NUM> in a compressed state. In the inserted position, the protuberances <NUM> on the tongues <NUM> then exerts a retaining radially outwards directed pressure on the inner wall of the proximal catheter hub cavity <NUM>. The ridge <NUM> of at the opening of the proximal catheter hub cavity <NUM> then maintains the needle shield <NUM> within the cavity, until the needle <NUM> bulge <NUM> pulls the stopping element proximally to the needle shield, whereby the pressure of the protuberances <NUM> on the inner walls of the proximal catheter hub cavity <NUM> is overcome and the also the protuberances <NUM> are pressed inwardly beyond the ridge <NUM> to safely release the needle shield <NUM> from the proximal catheter hub cavity <NUM>. To facilitate interaction between the needle shield <NUM> and the proximal catheter hub cavity <NUM>, the ridge <NUM> is somewhat slanting distally and/or proximally. The protuberances <NUM> are in the same way slanting distally and/or proximally. Preferably the slanting of the protuberances is sharper in the proximal direction than in the distal direction, whereby the needle shield <NUM> may be smoothly inserted into the proximal catheter hub cavity <NUM>, retained with a snap action when the proximal side of the protuberances pass distally beyond the ridge <NUM>, and also maintained more securely due to the sharper slanting at the proximal zone.

In one embodiment in accordance with <FIG>, a shielded needle system <NUM> is provided comprising a needle hub <NUM> and a needle shield <NUM>. The needle hub <NUM> comprises a needle <NUM> extending distally from a needle hub body <NUM> with the needle bulge <NUM> at its distal end zone having a high friction surface part <NUM>. The needle shield <NUM> is mounted on the needle, the needle shaft <NUM> extending through the hole of the needle shield base plate, the base plate being at the proximal end and the at least on resilient arm <NUM> at the distal end. The needle shield is mounted on the needle and located between the needle hub <NUM> and needle bulge <NUM>.

The high friction surface part <NUM> is intended to cover the needle bulge <NUM>, and extending proximally and possibly distally of the bulge <NUM>, along the needle shaft <NUM>. The length of the high friction surface part <NUM>, from its distal end to its proximal end, may vary due to factors such as the diameter of the needle, but is in the range of <NUM> to <NUM>, preferably <NUM> to <NUM>. The friction coefficient between the normally polished steel alloy of the needle and a fatter plastic can be lower than <NUM> (µs). This is a positive property for optimal operation of the needle shield, ensuring smooth and quiet needle movement through the through hole of the needle shield base plate <NUM>. However, the modulus of elasticity of a polymer body such as the needle shield <NUM>, is low (polymer (PC) <NUM> MPa or (LCP) <NUM> MPa), resulting in that with a polished (low friction) needle bulge, there is a risk of the needle shield <NUM> deforming enough to be forced past the needle bulge <NUM>. By providing a high friction surface part <NUM> on the needle bulge <NUM>, the friction coefficient is increased up to <NUM>-fold between the needle shield <NUM> and the high friction surface part <NUM> of the needle bulge <NUM>. This greatly increases the force required for the needle shield <NUM> to be forced past the needle bulge <NUM>. The surface roughness of a polished needle for medical purposes is <NUM> Ra. Hence, the surface roughness of the high friction surface part <NUM> is selected to be above <NUM> Ra, such as <NUM> to <NUM> Ra, and as defined in the invention, <NUM> to <NUM> Ra, and even more preferably from <NUM> to <NUM> Ra, such as <NUM> to <NUM> Ra. In this way, the surface roughness is adapted not to interact with the catheter, upon withdrawal of the needle hub <NUM> from the catheter hub <NUM>, while simultaneously allowing for increased interaction between the needle shield <NUM> and the needle <NUM> of the needle hub <NUM>, and more precisely the bulge <NUM> and the needle shield <NUM>, such that needle shield <NUM> will be better retained on the needle <NUM>.

By extending the high friction surface part <NUM> along the needle shaft <NUM>, proximally of the needle bulge <NUM>, the needle shield <NUM> will be subjected to high friction contact with the needle shaft <NUM> already before the needle shield base plate <NUM> interacts with the needle bulge <NUM>. This is even more pronounced if the needle shield <NUM> experiences any lateral force or is tilting slightly in relation to the length axis of the needle shaft <NUM>. This will result in increased drag between the needle shield <NUM> and the needle shaft <NUM> just before the needle shield base plate <NUM> makes contact with the needle bulge <NUM>, providing part of the force required to release the needle shield <NUM> from the catheter hub <NUM>, making it easier for the needle bulge <NUM> to release the needle shield <NUM>.

The high friction surface part <NUM> can be achieved by processes, such as sandblasting, etching (chemical process), erosion, electron beam surface treatment, plasma treatment, electrical discharge machining and laser texturing. Optionally, the high friction surface part <NUM> could be achieved by adding a surface layer or surface film, such as a high-friction coating or layer, on the area of the high friction surface part <NUM>.

The needle shield <NUM> is intended to be arranged on the needle <NUM> of the needle hub <NUM>, which in turn is intended to be arranged in the catheter hub <NUM>. In such assembled state, in accordance with Fig. 1a, the needle <NUM> penetrates the bifunctional valve <NUM>, and extends through the catheter <NUM>. Preferably, the needle <NUM> extends just beyond the distal end of the catheter <NUM>, such that skin and blood vessel penetration is facilitated. In that position, the needle shield <NUM> is arranged in the proximal catheter hub cavity <NUM>, with arms <NUM> thereof forced laterally by needle <NUM>. The needle shield <NUM> preferably does not extend proximally of the proximal end of the catheter hub <NUM>, but is instead entirely housed in the proximal catheter hub cavity <NUM> of the catheter hub <NUM>. In this way, the needle hub body <NUM> of the needle hub <NUM> may cooperate with the catheter hub body <NUM> of the catheter hub <NUM>, without intermediary structures, such as the needle shield <NUM>. This may be accomplished through a distal connective flange <NUM> on the needle hub <NUM>. The distal connective flange <NUM> may then house the distal end of the catheter body <NUM> of the catheter hub <NUM>. This connection may be a snap fit. Alternatively, the needle hub body <NUM> has a distal cavity for housing a part of the needle shield <NUM>, while still being adapted to be connectable to the catheter hub body <NUM>. In this position the needle shield <NUM> is held in place in the proximal catheter hub cavity <NUM> through interaction between a needle shield base plate <NUM> and the inner tubular wall of the catheter hub body <NUM>. This may be accomplished by tongues <NUM>, extending laterally of the base plate <NUM>, being flexed somewhat inwardly to exercise a lateral pressure on the inner tubular wall of the catheter hub body <NUM> inside the proximal catheter hub cavity <NUM>. To further increase the cooperation between the periphery of the needle shield <NUM> and the catheter hub <NUM> a circumferential ridge <NUM> may be formed at the opening of the proximal catheter hub cavity <NUM>. The base plate <NUM> is provided with a centrally arranged through hole, such that the needle <NUM> may run freely therein.

When withdrawing the needle hub <NUM> from the catheter hub <NUM>, after the catheter <NUM> has been securely placed inside the blood vessel of the patient, the needle hub <NUM> will firstly be disconnected from the cooperation between the catheter hub body <NUM> and the needle hub body <NUM>, such as through release of the connective flange <NUM> from the circumference of the catheter body <NUM>. Then the needle <NUM> travels proximally within the catheter <NUM>, until the needle tip <NUM> of the needle <NUM> exits the catheter <NUM> and enters the catheter hub body <NUM>. When entering the catheter hub body <NUM>, the needle tip <NUM> of the needle <NUM> will continue proximally into the distal catheter hub cavity <NUM> and further through the bifunctional valve <NUM>. When the needle tip <NUM> of the needle <NUM> exits the bifunctional valve <NUM> on the proximal side thereof, the needle tip <NUM> of the needle <NUM> enters the proximal catheter hub cavity <NUM> of the catheter hub <NUM>, wherein the needle shield <NUM> is securingly interacting with the inner tubular wall of the catheter hub body <NUM>. When the needle tip <NUM> of the needle <NUM> passes proximally of the arms <NUM>, the arms <NUM> will snap centrally to cover the needle tip <NUM> of the needle <NUM>. This may be further facilitated by hooked tips <NUM> on the arms <NUM>, Just subsequently to the snapping of the arms <NUM> in front of the tip of the needle <NUM>, a the high friction surface part <NUM> surrounding the bulge <NUM> on the needle <NUM> contacts the distal side of the needle shield <NUM> base plate <NUM>. Thus, the withdrawal of the needle hub <NUM> further proximally will safely pull out the needle shield <NUM> from the proximal catheter hub cavity <NUM>. This is accomplished by adapting the retaining action from tongues <NUM>, such that the retaining force from these is overcome by a suitable withdrawal force. The high friction surface part <NUM> of the needle bulge <NUM> will ensure that the suitable withdrawing force is applied to the needle shield <NUM>, to ensure safe release the needle shield from the proximal catheter hub cavity <NUM>. Then the needle hub is separated from the catheter hub, and the needle shield <NUM> is securely arranged on the tip of the needle <NUM> to prohibit and prevent accidental needle stick, as can be seen in <FIG>, <FIG>. When the needle tip <NUM> of the needle <NUM> has exited the proximal side of the bifunctional valve <NUM>, the bifunctional valve <NUM> will provide an open connection between the distal catheter hub cavity <NUM> and the proximal catheter hub cavity <NUM>. At the same time, the bifunctional valve <NUM> will open up the connection between the open connector <NUM> and the proximal catheter hub cavity <NUM>.

In one embodiment in accordance with <FIG>, a tube connector <NUM> is provided on catheter hub body <NUM>. The tube connector <NUM> extends laterally from the catheter hub body <NUM>. The tube connector <NUM> has a lumen in fluid communication with the distal catheter hub cavity <NUM>, such that a tube <NUM> may be connected to the tube connector <NUM> to allow for infusion from the tube <NUM> into the tube connector <NUM>, further into distal catheter hub cavity <NUM> to catheter <NUM>, and finally into the blood stream of the patient. The tube connector <NUM> may for example be tubular. A suitable material for the tube <NUM> is polyvinyl chloride or ethylene vinyl acetate. The catheter distal catheter hub cavity <NUM> ends proximally in a septum <NUM>. This septum <NUM> has a central through channel, which may be penetrated by a needle <NUM> of a needle hub <NUM>, in accordance with <FIG>. When the needle <NUM> has been withdrawn from the catheter hub <NUM>, the septum <NUM> will close said through channel, such that the distal catheter hub cavity <NUM> is marked off from the surroundings in the proximal direction. For this reason, the septum <NUM> is preferably of a suitable rubber material or silicone. On the proximal side of the septum <NUM> a proximal catheter hub cavity <NUM> is located. The proximal catheter hub cavity <NUM> is formed by the tubular wall of the catheter hub body <NUM> and a distal end wall in form of the proximal end wall of the septum <NUM>. This proximal catheter hub cavity <NUM>, extending distally into the catheter hub body <NUM>, is adapted in size and shape to house the needle shield <NUM>.

According to one embodiment, the needle shield <NUM> may be made of a plastic material. Preferably, the plastic material has a suitable combination, for its intended purpose, of tenacity, rigidity, fatigue resistance, elasticity, and creep deformation resistance. A suitable plastic material has a high creep deformation resistance, i.e. it has a low tendency to slowly move or deform permanently under the influence of an applied external pressure. Hence, a catheter system of the present invention, comprising needle shield <NUM>, may be stored in the assembled ready mode for a prolonged time without extensive creep deformation of the arms <NUM> or the tongues <NUM>. Advantages of a plastic needle shield <NUM> include the highly reduced tendency, in comparison to metal, of release of e.g. microscopic plastic chips by the scraping of the plastic catheter hub <NUM>, when the needle shield <NUM>, is ejected from the former upon withdrawal of the needle <NUM>. Accordingly, the tendency for formation of scrape marks, which may result in leakage through the affected connector, is greatly reduced. In addition, a plastic needle tip <NUM> shielding device may be easily color coded or transparent, depending on its particular application.

The needle shield <NUM> is a monolithic or homogenous injection molded needle shielding <NUM>, made of a molded plastic material. Due to the specific configuration of the different parts of the needle shield <NUM> according to the embodiments of the present invention, the needle shield <NUM> may be molded, such as injection molded, into one homogenous, i.e. monolithic, piece and/or one integral unit, without interfaces in between the different parts thereof. Advantages of a monolithic needle shield <NUM> include a lower production cost in comparison to other devices made of more than one part that has to be assembled. The needle shield <NUM> may in this respect be made of a thermoplastic polymer. The thermoplastic polymer could be crystalline, amorphous, or comprising crystalline and amorphous alternating regions. A creep resistance of the thermoplastic polymer of choice may preferably be at least <NUM> MPa (ISO <NUM>, ASTM D638). Suitable plastics for the needle shield <NUM> may be selected from the group comprising of polyoxymethylene (POM), polybutylen terephthalate (PBTP), polymethyl methacrylate (PMMA), acrylonitrile butadiene styrene (ABS), styrene acrylonitrile (SAN), acrylonitrile styrene acrylate (ASA), polystyrene (PS), styrene butadiene (SB), liquid crystal polymer (LCP), polyamide (PA), polysulfone (PSU), polyetherimide (PEI), polycarbonate (PC), polyphenylene oxide (PPO), and/or PPO/SB, and co- and terpolymers thereof. These polymers have specifically the advantages of providing enhanced storing capacity, even in strained state, and excellent cooperation abilities with regard to the catheter hub, due to the excellent structure memory of these polymers.

Contacting smooth shapes of two bodies, such as a needle shield <NUM> mounted in a catheter hub <NUM>, may result in a significant attraction between these bodies, especially if the contact area is large and they are pressed together. The underlying basis for this type of attraction include intermolecular attraction between the molecules of the two bodies, in which molecular van der Waals interactions and surface tension of the two bodies are important factors. Covalent bond formation between closely interacting surfaces may also contribute to the attraction. Such covalent bond formation, and other types of attraction between two surfaces, may also result upon radiation treatment, such as radiation treatment of e.g. catheter instrument to sterilize these. This type of attraction may become noticeable when the needle shield <NUM> is about to be released from the catheter hub <NUM>. The force needed to release the needle shield <NUM> from the catheter hub <NUM> then becomes significantly higher than expected. This effect, which may be referred to as "the attraction effect", may even adventure the intended function of the needle tip <NUM> shielding device if relying on e.g. an automatic release of a part of the device, such as a spring biased arm or the like, from a part of the catheter hub. The needle shield <NUM> is kept in contact with the catheter hub <NUM> in the assembled state via at least one interface surface between the needle shield <NUM> and the catheter hub <NUM>. Thus, in one embodiment the surface of the needle shield <NUM> being in contact with the inner lumen of the catheter hub is of a different polymeric material than the polymeric material of the catheter hub. Here, the high friction surface part <NUM> of the needle bulge <NUM> provides extra safety, since it makes it possible to exert additional pulling force on the needle shield in case of such attraction.

Claim 1:
An IV catheter system comprising:
a catheter hub (<NUM>), said catheter hub comprising: a tubular catheter (<NUM>), having a lumen, attached to a catheter hub body (<NUM>) at its proximal end, with a catheter hub cavity (<NUM>, <NUM>) in fluid communication with the lumen of the tubular catheter (<NUM>);
a needle hub (<NUM>), said needle hub (<NUM>) comprising: a needle (<NUM>) extending distally from a needle hub body (<NUM>), said needle (<NUM>) having a bulge (<NUM>) and a high friction surface part (<NUM>) at its distal end zone,
wherein the high friction surface part (<NUM>) is applied at least on the bulge (<NUM>) and extends proximally and distally of the bulge (<NUM>) along a section of the metal alloy of a needle shaft (<NUM>) and has a surface roughness in a range of <NUM> to <NUM> Ra;
a needle shield (<NUM>) made from a polymer with a low modulus of elasticity comprising at least one resilient arm (<NUM>) extending distally from a base plate (<NUM>), said base plate (<NUM>) having a through hole for receiving the needle (<NUM>) there through;
wherein the needle hub (<NUM>) is arranged in the catheter hub (<NUM>), such that the needle (<NUM>) is slidingly arranged through the lumen of said catheter (<NUM>), such that the needle (<NUM>) may be withdrawn proximally from the catheter hub (<NUM>);
wherein the needle shield (<NUM>) is arranged in the catheter hub cavity (<NUM>, <NUM>) in a retained manner through cooperation between the needle shield (<NUM>) and an inner wall of the catheter hub (<NUM>) in said catheter hub cavity (<NUM>, <NUM>), and onto the needle (<NUM>), such that the at least one arm (<NUM>) rests upon and is spring loaded by the needle (<NUM>), and the needle (<NUM>) is slidingly arranged within the through hole of the base plate (<NUM>), in an assembled state; and
wherein the outer diameter of the needle bulge (<NUM>) is larger than the inner diameter of the through hole of the base plate (<NUM>) such that when the needle hub (<NUM>) is withdrawn from the catheter hub (<NUM>), the contact between the needle bulge (<NUM>) and the base plate (<NUM>) provides force to release the needle shield (<NUM>) from the catheter hub (<NUM>) with the at least one resilient arm (<NUM>) covering the tip of the needle (<NUM>) in a released state.