Syringe assembly

Abstract

The present disclosure relates to a syringe assembly comprising a syringe having a proximal end and a distal end, a needle extending from the distal end of the syringe, and a shield positioned on the syringe to slide between a first position in which a first length of the needle is exposed for filling the syringe, a second position for exposing a second length of the needle, the second length being smaller than the first length, wherein a locking mechanism holds the shield in the first position, the second position, and a third position for covering the needle, wherein the locking mechanism locks the shield in the third position. The syringe assembly according to the present disclosure enables controlling the penetration depth of the cannula for delivering a drug or medicament to a selected target area and prevents the syringe from being reused.

Description

Technical Field

[0001] This invention relates to a syringe having a movable component for modifying the length of an exposed portion of the syringe needle used to aspirate and fill the syringe to inject a drug into a patient. The syringe includes the movable component to change the effective length of the syringe for injection to a desired depth and to provide a needle shield after use. Background Technology

[0002] A needle of 4mm to 6mm length is inserted into the container or vial and aspirated appropriately. The needle length requires the needle to pierce the septum in the vial in a straight line to ensure penetration and reduce the risk of needle bending.

[0003] The insertion of a needle into the patient's skin is primarily determined by the characteristics of the needle itself, rather than the characteristics or structure of the needle support. Needle insertion into the patient's skin is generally divided into three phases, each influencing the injection depth. The first phase corresponds to the initial contact between the needle and the skin, where tissue deforms without piercing the skin surface. The second phase refers to the piercing of the skin and the relaxation of the skin when the needle insertion force ceases. The third phase is one in which the needle is withdrawn, pulling or stretching the skin outwards as the needle is withdrawn.

[0004] The needle length (e.g., a needle with a length of approximately 4 mm to 6 mm) is suitable for injecting medication into a designated target depth in the subcutaneous region. This invention provides a structure that allows the needle to be consistently inserted to the desired target depth. Existing injection devices support the needle or cannula on an axial column extending from the needle hub. This column forms a narrow section and a relatively wide base that does not contact the skin during injection. In other injection delivery devices, the distal side of the needle hub positioned against the injection site may be relatively large and may have a slight taper at the edges. When the cannula is inserted at an angle relative to the surface of the patient's skin, the edges of the needle hub can engage the skin.

[0005] Various injection devices have been manufactured in which the support structure does not contact the skin during injection or needle withdrawal. Other devices have been proposed in which the end face of the device is positioned to contact the skin surface to limit the depth of penetration into the patient.

[0006] Syringe delivery devices facilitate the self-administration of parenteral medications. An example of a delivery device is the pen needle. The needle is a component of a needle-based injection system and comprises a double-ended cannula assembled to a plastic needle hub using adhesive. The needle hub, with internal threads, allows attachment to the pen syringe device. This attachment allows the proximal end of the cannula to penetrate the rubber diaphragm of the drug cartridge, creating a fluid flow path. For many diabetic patients who maintain glycemic control by injecting insulin multiple times daily into subcutaneous (SC) tissue, pen syringe delivery devices have been developed as a convenient and discreet alternative to vials and syringes. Many syringes are commercially available in single-use or reusable configurations, each offering a variety of patient-centered features. The distal pen needle cannula interacts with the delivery site, providing a conduit for delivery. The delivery device and needle are designed to achieve consistent delivery to the target tissue space, minimize leakage of the injected substance, and reduce pain / discomfort and injection-related side effects such as bleeding and bruising. Key design features, needle length / specification, and needle seat geometry, along with the mechanics of the delivery system and injection technology, determine the success of the injection.

[0007] Injections can be administered intradermally, subcutaneously, or intramuscularly (IM). For many types of injectable medications, including insulin, the subcutaneous region is the preferred site for administration.

[0008] Although existing devices are generally suitable for their intended use, there is still a need for improved devices for controlling the penetration depth of catheters used to deliver drugs or medications to selected target areas. Summary of the Invention

[0009] This disclosure relates to a syringe assembly comprising: a syringe having a proximal end and a distal end; a needle extending from the distal end of the syringe; and a shield positioned on the syringe for sliding between a first position, a second position, and a third position, wherein in the first position the needle is exposed to fill a first length of the syringe, the second position exposes a second length of the needle less than the first length, wherein a locking mechanism holds the shield in the first and second positions, and the third position covers the needle, wherein the locking mechanism locks the shield in the third position.

[0010] This disclosure also relates to a syringe assembly comprising: a syringe having a proximal end and a distal end; a needle extending from the distal end of the syringe; and a shield coupled to the syringe for sliding relative to the syringe, the shield having a base coupled to the syringe and a sleeve coupled to the base for sliding relative to the base, the sleeve having a central opening configured to receive the distal end of the syringe, the sleeve being coupled to the base for sliding between a first position, a second position, and a third position. In the first position, the needle is exposed for a first length to fill the syringe; in the second position, a second length of the needle is exposed, which is less than the first length; in the third position, the needle is covered; the base and the shield have locking mechanisms to hold the sleeve in the second position to prevent the shield from sliding toward the proximal end of the syringe while allowing the shield to slide to the third position, and to lock the shield in the third position to cover the distal end of the needle and prevent the shield from sliding toward the proximal end of the syringe.

[0011] This syringe assembly relates to a device for assisting in the aspiration of a syringe and the injection of a drug into a patient at a selected depth. In one embodiment, the syringe includes a needle having a first exposure length for aspirating the syringe and a second exposure length for injecting the substance into the patient at a desired depth. The syringe assembly may also include a movable shield that, after use, moves over the tip of the needle and locks in an extended position to prevent accidental needlesticking.

[0012] In one embodiment, the syringe includes a syringe barrel and a needle or cannula extending from a distal end of the syringe barrel. A movable shield is coupled to the syringe for sliding relative to the syringe. The movable shield slides between a retracted position and an extended position, in which the needle is exposed to a length suitable for filling and aspirating the syringe, and in the extended position, the shield extends at least partially over the needle to limit the exposed length of the needle for injection into the patient. A base forms a mounting member for coupling to the syringe, wherein the movable shield slides relative to the base to slide over at least a portion of the needle that extends from the syringe during aspiration and injection. The movable shield slides from the retracted position relative to the syringe such that the needle has an exposed length capable of piercing a septum on a container or vial to aspirate the syringe. The movable shield can slide to a second position, the second position exposing a selected length of the needle corresponding to a desired penetration depth. After injection, the movable shield slides to a locked position covering the extended portion of the needle after use. The shield and / or the base may include one or more locking mechanisms to lock the shield in an extended position to cover the needle after use.

[0013] In one embodiment, the syringe includes a syringe barrel and a shield configured to slide relative to the syringe from a first position, a second position, and a third position, in which the needle is exposed for a first length, in the second position, the needle is exposed for a second length less than the first length, and in the third position, the shield completely covers the tip of the needle.

[0014] In another embodiment, the syringe includes a syringe barrel, wherein a shield is attached to the distal end of the syringe. An arm forming a connecting member is coupled to the shield for sliding between a retracted position exposing a portion of the needle on the syringe and an extended position covering the needle. The arm is configured to slide on a base coupled to the syringe to hold the shield in one or more selected positions relative to the syringe and the needle on the syringe.

[0015] In one embodiment, the syringe has a shield that slides relative to the syringe between a retracted position, a second position, and an extended position. The retracted position exposes the length of the needle used to fill the syringe and inject medication into a patient to a selected depth. The second position covers only a portion of the needle for injecting medication to a depth less than the depth when the shield is in the first position. In the extended position, the shield covers the needle and is locked in the extended position to prevent the syringe from being reused. A locking mechanism may be included to hold the shield in the second position during use while allowing the shield to slide to the extended position, in which the shield is permanently locked to prevent further movement.

[0016] Another feature of the syringe is a movable shield coupled to a base for sliding relative to the syringe, wherein the base is coupled to the outer surface of the syringe. The shield and / or the base have a locking mechanism for holding the shield in a partially retracted position, in which manual force can be applied to release the shield from the partially retracted position, wherein the shield can slide to an extended position to cover the distal end of the needle and be permanently locked in the extended position.

[0017] These features are essentially achieved by a syringe assembly comprising: a syringe barrel having a proximal end and a distal end; a needle support seat coupled to the distal end of the syringe barrel; and a movable shield member positioned on the syringe barrel. The movable shield member is mounted to slide between a first position where the needle is exposed, a second position where at least a portion of the needle is covered, and a third position where the needle is completely covered by the shield.

[0018] The syringe features a syringe barrel having a proximal end and a distal end, a needle support hub coupled to the distal end of the syringe barrel, and a shield that slides relative to the syringe to cover the distal end of the needle after use and to lock the shield in the extended position to prevent reuse. The shield assembly includes a base coupled to the syringe and has a locking member projecting outward from the base. The shield has a sleeve and an arm, the sleeve being sized to cover the end of the needle, and the arm being coupled to the base to allow the shield to slide relative to the base. The arm includes a first locking member that engages with a locking member of the base to hold the shield in a partially extended position to provide a short needle length. The locking member can be released by pushing the shield or arm distally relative to the syringe to allow the shield to slide past the end of the needle, wherein the locking member on the base engages a second locking member on the arm to lock the arm and the shield in the extended position and to prevent the shield from sliding relative to the syringe in a retracted or proximal direction.

[0019] A method is provided for aspirating and filling a syringe assembly, preparing the syringe assembly for use, and preventing the syringe from being reused. The method includes providing a syringe having a proximal end and a distal end, a needle support hub coupled to the distal end of the syringe, and a movable shield coupled to the syringe. The shield is in a first position, thereby exposing a first length of a needle having a first length for filling the syringe. The shield slides to a second position, thereby exposing a second portion of the needle having a second length less than the first length for injecting medication into a patient, wherein the shield is releasably held in the second position. The shield then slides to a third extended position to cover the end of the needle and locks in the extended position to prevent the syringe from being reused.

[0020] These and other features of the invention will become apparent from the following detailed description of the invention, which discloses various embodiments of the syringe in conjunction with the accompanying drawings. Attached Figure Description

[0021] The following is a brief description of the accompanying drawings, in which:

[0022] Figure 1 A side view of the syringe assembly in one embodiment;

[0023] Figure 2 for Figure 1 Side view of the shield assembly;

[0024] Figure 3Side view of the base of the protective shield assembly;

[0025] Figure 4 A cross-sectional view of the base of the protective shield assembly;

[0026] Figure 5 This is a side view of the shield in its initial position.

[0027] Figure 6 For being in Figure 5 A partial sectional side view of the protective shield in its position;

[0028] Figure 7 A partial sectional side view of the shield in its partially extended position;

[0029] Figure 8 A partial cross-sectional side view of the shield in its extended position covering the needle; and

[0030] Figure 9 This is a side view of the shield in another embodiment. Detailed Implementation

[0031] The syringe assembly of the present invention refers to a syringe having a needle or cannula for injecting drugs or other substances into a patient. The terms needle and cannula are used interchangeably herein to refer to a thin tubular member having a sharp end for insertion into an injection site in a subject. The distal direction is the direction toward the injection end of the syringe assembly, while the proximal direction is the opposite direction. The axial direction refers to the direction along or parallel to the longitudinal axis of the needle and needle hub, while the radial direction refers to the direction perpendicular to the axial direction.

[0032] The syringe is configured to inject the drug into the patient at a selected depth based on the medication and the expected penetration depth. The endodermis in adults is typically about 2 to 3 mm thick, allowing for intradermal injection depths up to about 3 mm when measured from the outer surface of the skin. The thickness of the subcutaneous layer varies depending on the patient's age, sex, body mass index (BMI), and the site of injection. The subcutaneous region has an average thickness of about 7 mm to about 15 mm. Insulin can be delivered to the subcutaneous region.

[0033] The syringe is suitable for use in methods of injection and for administering medication to a patient. The description of the embodiments is not intended to be limiting. This disclosure is intended to enable those skilled in the art to practice variations of the described syringe without departing from the scope of the invention. In the specification and claims, numerical limitations herein are to be understood as being limited by the modifier “about” so that minor deviations from producing equivalent results are within the scope of the invention. Features or limitations of dependent claims disclosed in an embodiment or independent claim may be combined in another embodiment or with different independent claims without departing from the scope of the invention.

[0034] The application of this disclosure is not limited to the construction and arrangement details of the components set forth in the following description or illustrated in the accompanying drawings. The embodiments described herein can be modified, practiced, or performed in various ways. Moreover, it will be understood that the wording and terminology used herein are for descriptive purposes only and should not be considered limiting. The use of the terms “comprising,” “including,” or “having,” and their variations, is intended to cover the items listed thereafter and their equivalents and additional items. Unless otherwise limited, the terms “connection,” “link,” and “installation,” and their variations, are used extensively herein and cover direct and indirect connections, links, and installations. Furthermore, the terms “connection” and “link,” and their variations, are not limited to physical or mechanical connections or links. Further, terms such as upper, lower, bottom, and top are relative and are for illustrative purposes only, not limiting. Embodiments are not mutually exclusive, so features of one embodiment can be combined with other embodiments, provided they do not contradict each other. For example, the degree terms “generally,” “approximately,” and “approximately” are understood by those skilled in the art to refer to a reasonable range around and encompassing a given value, as well as ranges outside the given value, such as general tolerances associated with the manufacture, assembly, and use of the embodiment. When referring to a structure or feature, the term “generally” includes features that are present in most or all of the structure. Distal refers to the direction or location toward the patient end of the needle, while proximal refers to the direction or location away from the patient end of the needle and toward the user of the syringe.

[0035] Referring to the accompanying drawings, the syringe 10 includes a syringe barrel 12 having a proximal end 14 and a distal end 16. The proximal end 14 receives a movable plunger 18 and a stopper for dispensing a substance contained in the syringe assembly.

[0036] like Figure 1As shown, needle hub 20 is coupled to the distal end 16 of syringe barrel 12. Needle hub 20 includes a needle 22 extending axially from needle hub and syringe. Needle hub 20 is configured for coupling to the distal end of syringe barrel 12. In the illustrated embodiment, needle hub 20 has a generally cylindrical body 24 having a proximal end 26 and a distal end 30, the proximal end 26 having an outwardly extending radial flange 28.

[0037] Needle shield assembly 32 is connected to the syringe for use in... Figure 5 The initial retraction position shown slides to Figure 7 The middle position shown, and up to Figure 8 The extended position shown is intended to cover the distal end of the needle after use to prevent the syringe from being reused and to prevent accidental needle pricks. The needle guard assembly 32 includes a base 34 for attachment to the syringe and a movable guard 36 for covering the needle after use. In the illustrated embodiment, the movable guard 36 slides relative to the base 34 and relative to the syringe 12.

[0038] refer to Figure 3 and 4 The base 34 is configured for attachment to the syringe and for allowing the shield 36 to slide relative to the base 34 and relative to the syringe and needle. In the illustrated embodiment, the base 34 is attached to the syringe needle seat 20 by snapping onto a radial flange 28. The base 34 forms a mounting structure for the shield and for attaching the shield to the syringe to slide to different positions on the syringe and relative to the needle. The base 34 includes a body 38 and a mounting member shown as a cylindrical sleeve 40. The body 38 is configured to receive and attach to the shield such that the shield can slide longitudinally relative to the syringe and the base. The sleeve 40 has a configuration for attachment to the syringe barrel 12. In the illustrated embodiment, the sleeve 40 has a generally cylindrical shape with a central opening sized for attachment to the syringe barrel. The sleeve 40 is attached to the syringe barrel to resist axial movement and separation of the sleeve relative to the syringe barrel 12 during normal use. The sleeve 40 can be directly attached to the syringe in such a way that the cover can be rotated on the syringe to a position selected by the user. In one embodiment, the sleeve 40 is secured to the syringe barrel 12 by a suitable mechanical mechanism or by a combination such as adhesive or welding.

[0039] The base 34 includes a pair of spaced-apart sidewalls 42 forming a longitudinal channel 43 or gap for receiving a shield and allowing the shield to slide longitudinally within the channel 43. Each sidewall 42 has an inwardly projecting flange 44 extending longitudinally at its apex. A bottom wall 46 extends between the sidewalls 42 forming the channel 43 to form an opening between the sidewalls 42 that opens toward the apex of the base. The flange 44, sidewalls 42, and bottom wall 46 capture the shield 36 for sliding relative to the syringe and needle.

[0040] The base 34 includes a locking mechanism for holding the shield 36 in one or more selected positions relative to the base and the syringe. In the illustrated embodiment, the locking mechanism is in the form of a latch to hold the shield 36 in a selected position, in which the latch can be released to allow the shield to slide proximally to another position. In the illustrated embodiment, the locking mechanism is a spring-biased finger 48 having a proximal end connected to the base 34 via a spring hinge 50, allowing the finger 48 to bend inward toward the bottom wall 46 of the base 34 and to be biased outward away from the bottom wall of the base. The finger 48 has a distal end with a tab 52 having a distal side 54 and a proximal side 56. Figure 4 As shown, the distal surface 54 defines the front of the finger 48. In the illustrated embodiment, the proximal surface 56 is inclined relative to the longitudinal axis of the base 34 and tilted outward in the distal direction. The generally flat end face 56 of the tab 52 is shown to be generally parallel to the longitudinal axis of the finger 48 and the longitudinal axis of the base 34.

[0041] Sleeve 40 is configured to connect base 34 to syringe and mount shield 36 for sliding relative to base and syringe. Sleeve 40 has a longitudinally extending central opening 60 sized to receive the distal end of syringe. Figure 4 The central opening 60 shown includes a coupling mechanism for attaching the sleeve 40 to the syringe. The coupling mechanism may be one or more pawls 62 on the inner surface of the sleeve, the pawls 62 projecting inward to engage and capture the flange 28 on the needle hub. The pawls 62 are longitudinally spaced from the end wall 63 to form a groove 65 to receive and capture the flange 28 on the syringe barrel 12. In one embodiment, the coupling mechanism may be a snap-fit ​​connector that prevents or avoids separation of the base 34 from the syringe barrel 12 and the needle hub 20. Figure 4 As shown, the pawl 62 may have an angled or inclined proximal side to slide over the radial flange 28 of the syringe. In other embodiments, the coupling mechanism may be an annular ring that can form a snap-fit ​​or interference fit.

[0042] In the illustrated embodiment, the sleeve 40 has an open proximal end to receive the distal end of the needle hub and the radial flange 28 when the base 34 is coupled to the needle hub or syringe. In one embodiment, the sleeve is shaped and sized to receive the distal end of the needle hub, wherein the needle can extend distally from the distal end of the sleeve. Figure 4 As shown, the channel 60 may be open at its distal end, wherein the distal end 30 of the needle hub may protrude from the distal end of the sleeve 40. In one embodiment, the sleeve 40 has a longitudinal length that complements the length of the needle hub, such that the distal end 30 of the needle hub is aligned with the distal end of the sleeve. Alternatively, the distal end 30 of the needle hub may be slightly recessed relative to the distal end of the sleeve. In other embodiments, the sleeve may have an end wall with an opening that contacts the distal end of the needle hub, wherein the opening is sized to allow a needle to pass through.

[0043] like Figure 2 As shown, the shield 36 has a shield body 37 having a generally cylindrical shape and an open axial channel 64 having an open proximal end 66 and a distal end wall 68. The end wall 68 has a central opening 70 sized to allow a needle to extend sufficiently through the shield 36 to fill and aspirate the syringe and inject medication into the patient. The open proximal end 66 is sized to receive the distal end of a sleeve 40, wherein the end of the sleeve 40 can slide into the open proximal end 66, as... Figure 5 As shown in the image.

[0044] The shield 36 includes an arm 72 attached to one side of the shield 36 and extending proximally along the shield, and radially spaced outward from the shield wall relative to the central axis of the shield 36. The arm 72 is configured to engage with a base 34 and slide relative to the base and syringe to guide the shield during longitudinal movement. In the illustrated embodiment, the arm 72 has a distal end 74 and a proximal end 76 engaged with a sidewall of the shield 36. A thumb tab 78 is formed on the proximal end 76 for manipulating the shield and manually pushing it distally relative to the syringe and needle. A rib 80 projects from the opposite side of the arm and extends longitudinally to engage with a flange 44 on a sidewall 42 of the base 34. The flange 44 contacts the top surface of the rib 80 to capture the arm 72 in an open channel 43 formed by the sidewall 42, the flange 44, and the bottom wall 46 of the base. The arm is capable of sliding longitudinally relative to the syringe and needle within the channel 43. In the illustrated embodiment, the arm 72 has a generally straight distal portion 82 and an angled proximal portion 84.

[0045] Arm 72 includes a locking member that engages with a locking member on base 34 to hold the shield in a selected position relative to the base and syringe, and to lock the shield in an extended position to cover the distal end of the needle after use and to prevent the syringe from being reused. The locking member includes a mechanism that engages with spring fingers 48 of base 34. The locking mechanism is positioned near the shield 36 at the distal end of arm 72 to hold the shield in a first position and to release the shield when force is applied to the end of the arm, allowing the arm to slide distally within the base. In the illustrated embodiment, the locking mechanism has a recessed portion 86 for engaging with a tab 52 on spring fingers 48. In one embodiment, the recessed portion 86 is formed by a first pawl 88 and a second pawl 90 spaced apart from the first pawl 88. In other embodiments, the recessed portion may be formed in the surface of the arm. The locking mechanism is formed by the pawl 88, the recess 86, and the pawl 90.

[0046] like Figure 2 As shown, the first pawl 88 is spaced from the distal surface 91 of the radial rib 93 extending from the guard 36 to form a recessed region 95. The first pawl 88 has a forward distal surface 92 and a tail proximal surface 94 inclined relative to the longitudinal axis of the arm 72. The proximal surface 94 is shown to have an inclination complementary to the inclination of the surface 54 of the spring finger 48, but the proximal surface may be substantially perpendicular to the face of the arm. The proximal surface 94 has a shape and configuration for engaging with the distal surface 54 of the finger 48. The second pawl 90 is configured to form a recessed portion 86 and is spaced apart from the first pawl 88 to receive the tab 52 of the finger. The second pawl 90 has a forward distal surface 96 and a proximal surface 98.

[0047] The second pawl 90 may be suitably configured to allow the tab 52 of the finger 48 to slide past the second pawl 90 by applying sufficient force to the arm in the distal direction. The distal surface 96 of the pawl 90 has a surface configured to allow the finger to slide past the pawl in the distal direction. The proximal surface 98 of the pawl 90 may be suitably configured to restrict the proximal end of the arm toward the base from sliding past the finger 48 in the proximal direction, thus resisting sliding in the proximal direction. In the illustrated embodiment, the second pawl 90 has a rounded distal surface 96 and a rounded proximal surface 98 to slide past the spring finger 48 when force is applied in the distal direction. The recess 86 is configured such that the shield 36 and the arm 72 are positioned relative to the base and the syringe in a position similar to... Figure 7 The intermediate position shown is the receiving tab 52 of the spring finger 48, the intermediate position being relative to Figure 6 The initial position is shown in the figure.

[0048] A second locking member on the arm engages with the spring finger 48 to lock the arm in the extended position after use, covering the distal end of the needle. The second locking member includes a protrusion or pawl 100 spaced apart from the first locking mechanism and positioned proximal to the first locking mechanism toward the proximal end of the arm. The pawl 100 has an inclined distal side 102 and a proximal side 104. The inclined distal side 102 is of a length such that the spring finger 48 can be slid upwards onto the surface of the distal side by applying an axial force to the proximal end of the arm 72. In the illustrated embodiment, the proximal side 104 is angled to engage the tab 52 of the spring finger 48 and to prevent the arm 72 from sliding backwards proximally relative to the base 34 and the syringe, thereby locking the guard in the extended position to cover the tip of the needle. The arm 72 has a longitudinal length to slide a distance distally relative to the syringe to cover the distal end of the needle.

[0049] During use, such as Figure 5 As shown, the base 34 is coupled to the syringe, wherein the base 34 is connected to the distal end of the syringe and the shield 36 is in the retracted position. In the retracted position, the distal end of the body of the sleeve 40 is received in the open proximal end of the shield 36. Figure 5 and Figure 6 As shown, the needle protrudes a certain distance from the distal end of the shield for filling the syringe and injecting medication into the patient. When the shield 36 is in the proximal position relative to the syringe, the tab 56 of the spring finger 48 is received in the recessed area 95 of the shield. In one embodiment, when the shield is in... Figure 5 and Figure 6 In the initial retracted proximal position shown, the needle has an exposed length of approximately 6-8 mm extending from the distal end of the shield 36. In one embodiment, the needle has an exposed length of approximately 6 mm when the shield is in the proximal retracted position. In the retracted position, the tab 52 of the spring finger 48 is positioned anterior to or distal to the pawl 88 to hold the shield in the retracted position. Figure 5 and 6 The construction utilizes a syringe in which a shield 36 forms a limiter to restrict the penetration depth of the exposed needle length. When the shield is in... Figure 6 In the proximal position shown, the needle 22 has an exposed length extending from the shield to allow filling of the syringe by piercing the septum of the vial. Needle lengths less than 6 mm are generally difficult to use for filling vials because the needle length may not be sufficient to pierce the septum, especially when the needle is inserted at an angle. Therefore, in the illustrated embodiment, the needle has an exposed length of at least 6 mm when the shield is in the proximal position.

[0050] After filling the syringe, the shield 36 can slide to the proximal end of the arm 72 by the user pushing it distally. Figure 7The second intermediate position is shown. The inclined front surface 92 of the pawl 88 slides over the proximal side 56 of the tab 52 of the spring finger 48, thereby deflecting the spring finger toward the base, wherein the tab 52 snaps into the groove 86. Sliding the tab 52 into the groove 86 can provide the user with an auditory or tactile sensation to provide the shield in place. Figure 7 The indication in the second intermediate position shown. In one embodiment, when the shield is in Figure 7 When in the middle position, the exposed length of the needle extending from the shield is approximately 4 mm to approximately 5 mm, and typically approximately 4 mm. In other embodiments, when the shield is in... Figure 7 When in the intermediate position, the needle has an exposed length of approximately 3-5 mm. The exposed length of the needle is determined by the position of the recess 86 relative to the arm. The needle guard also forms a limiter to restrict the axial length of the exposed portion of the needle during injection. The recess 86 captures the tab 52 on the finger 48 with sufficient resistance to hold the guard and arm in the intermediate position during use.

[0051] After injection, the arm 72 is pushed forward distally relative to the syringe, wherein the tab 52 separates from the recessed position 86 and slides past the second pawl 90. The pawl 100 slides past the spring-loaded tab 52 to... Figure 8 The position shown is such that the shield slides to cover the distal end of the needle. The proximal portion 84 of the arm 72 is angled relative to the distal portion 82 to allow the shield to move off-center from the needle, as shown. Figure 8 As shown, this is done so that the distal end of the needle is no longer aligned with the opening 70 in the end wall of the shroud. The distal side 54 of the tab 52 engages the proximal side of the pawl 100 to lock the shroud in the extended position to cover the end of the needle and prevent the syringe from being reused.

[0052] Figure 9 Another embodiment shown includes a shield 110 similar to that of the previous embodiment. The shield 110 includes an arm 112 and a sleeve 114 coupled to the arm, the sleeve 114 being used to cover the end of the needle as in the previous embodiment. As in the previous embodiment, the shield 110 is coupled to a base 34 for sliding linearly relative to the syringe and needle on the base. The sleeve 114 has an open proximal end 116 and an open distal end 118, the proximal end 116 having dimensions for receiving the distal end of the needle hub of the syringe, and the distal end 118 for allowing the needle to protrude a certain distance for injecting medication into the patient.

[0053] Figure 9The arm 112 in this embodiment is similar to the arm in the previous embodiment, except that it includes more than one set of pawls forming a locking mechanism for positioning the shield in a selected position relative to the needle hub and the needle to expose different lengths of the needle according to the expected penetration depth of the needle. The arm 112 has a first locking mechanism 120 at its distal end and a second locking mechanism 122 spaced proximally from the first locking mechanism 120. The first and second locking mechanisms are configured to engage with the spring finger 48 to hold the shield in a selected position relative to the base 34 and the syringe. The first locking mechanism 120 includes a distal pawl 124 and a proximal pawl 126 spaced apart to form a groove 128. The distal pawl 124 has an inclined distal front side 130 for sliding over the spring finger and a proximal tail side for preventing the shield from sliding proximally relative to the base. The groove 128 is sized to receive the tabs of the spring finger to hold the shield in a selected position during use. The second locking mechanism 122 is similar and includes a distal pawl 132 and a proximal pawl 134 forming a groove 136. The pawls are generally similar in that they capture the tabs of the spring fingers and hold the shield in a selected position relative to the base and the syringe.

[0054] During use, the shield 110 is received in the opening in the base 34 and positioned in a retracted position to expose a first length of the needle, allowing for aspiration and filling of the syringe with medication. The syringe can be used by inserting the needle into the patient to inject medication to a depth corresponding to the exposed length of the needle. The shield is retracted to a first extended position by sliding the shield distally relative to the syringe until the spring-loaded finger engages in the recess 128 to hold the shield in a partially extended position, thus exposing a shorter length of needle than the initial exposed length. For example, the initial exposed length of the needle may be approximately 6 mm, and in the partially extended position, the exposed length of the needle may be approximately 4 mm. The shield can be extended to a second position in which the finger is received in the recess 136 of the second locking mechanism 122 to expose an even shorter length of needle, which is less than the initial exposed length and less than the length when the spring-loaded finger is received in the recess of the first locking mechanism 120. When the spring-loaded finger is received in the recess of the second locking mechanism, the exposed length of the needle may be, for example, approximately 2 mm. After use, the shield slides to the extended distal position, where the shield covers the end of the needle, and the proximal locking pawl 138 locks the arm and shield in the extended position to prevent reuse in a manner similar to the previous embodiment.

[0055] The foregoing embodiments and advantages are exemplary and not intended to limit the scope of the invention. The descriptions of alternative embodiments are illustrative and do not limit the scope of the invention. Various modifications, substitutions, and variations will be apparent to those skilled in the art and fall within the scope of the invention. It should be particularly noted that different embodiments and features of the claims can be combined with each other, provided they do not contradict each other. Therefore, all such modifications are intended to be included within the scope of the invention as defined in the appended claims and their equivalents.

Claims

1. A syringe assembly, the syringe assembly comprising: A syringe having a proximal end and a distal end, and a needle extending from the distal end of the syringe; as well as A shield, positioned on the syringe, is slidable between a first position, a second position, and a third position, in which the needle is exposed for a first length to fill the syringe; the second position exposes a second length of the needle, which is less than the first length; a locking mechanism holds the shield in the first and second positions; and the third position covers the needle, wherein the locking mechanism locks the shield in the third position. A base having a sleeve and a body, the sleeve having a first longitudinal channel for engagement with the syringe, the body for movably receiving the shield, the body having a second longitudinal channel and spring-biased fingers in the second longitudinal channel, the spring-biased fingers having a distal end extending toward a distal end of the base and configured to be bent inward relative to the base; The shield has an arm extending from the proximal end of the shield, the arm being received in the second longitudinal channel of the body for sliding relative to the base, the arm having a recessed portion on the inner surface at the distal end of the arm for receiving the distal end of the spring-biased finger of the base to hold the shield in a second position.

2. The syringe assembly of claim 1, wherein the recessed portion is configured to lock the shield in the second position and allow the shield to slide to the third position, and to lock the shield in the third position to cover the needle and prevent the shield from sliding toward the proximal end of the syringe.

3. The syringe assembly of claim 2, wherein the base is coupled to a needle hub on the distal end of the syringe, and wherein the base is rotatable relative to the syringe.

4. A syringe assembly, the syringe assembly comprising: A syringe having a proximal end and a distal end, and a needle extending from the distal end of the syringe; A shield, positioned on the syringe, is slidable between a first position, a second position, and a third position, in which the needle is exposed for a first length to fill the syringe; the second position exposes a second length of the needle, which is less than the first length; a locking mechanism holds the shield in the first and second positions; and the third position covers the needle, wherein the locking mechanism locks the shield in the third position. and A base having a sleeve and a body for coupling to the syringe, the base having a longitudinal channel and spring-biased fingers in the longitudinal channel, the spring-biased fingers having a distal end extending toward a distal end of the base and configured to be bent inward relative to the base; The shield has an arm extending from the proximal end of the shield, the arm being received in the longitudinal channel of the base for sliding relative to the base, the arm having a recessed portion on the inner surface at the distal end of the arm for receiving the distal end of the spring-biased finger of the base to hold the shield in a second position. The spring-biased fingers of the locking mechanism on the base engage with the arm of the shield to: hold the shield in the first position; The shield is held in the second position, in which the shield can be released from the spring-biased finger; and the shield is locked in the third position to prevent the shield from moving proximally relative to the syringe.

5. The syringe assembly of claim 4, wherein the spring-biased finger is biased outward from the base for engaging the arm of the shield.

6. The syringe assembly of claim 5, wherein the spring-biased finger has a spring hinge at a proximal end of the base for biasing the spring-biased finger outward from the base.

7. The syringe assembly of claim 4, wherein the arm includes a plurality of spaced-apart pawls on the inner surface of the arm, and the spring-biased fingers on the base are used to selectively engage one of the pawls on the arm to hold the shield in the first, second, and third positions.

8. A syringe assembly, the syringe assembly comprising: A syringe having a proximal end and a distal end, and a needle extending from the distal end of the syringe; A shield, positioned on the syringe, is slidable between a first position, a second position, and a third position, in which the needle is exposed for a first length to fill the syringe; the second position exposes a second length of the needle, which is less than the first length; a locking mechanism holds the shield in the first and second positions; and the third position covers the needle, wherein the locking mechanism locks the shield in the third position. A base having a sleeve and a body for coupling to the syringe, the base having a longitudinal channel and spring-biased fingers in the longitudinal channel, the spring-biased fingers having a distal end extending toward a distal end of the base and configured to be bent inward relative to the base; The shield has an arm extending from the proximal end of the shield, the arm being received in the longitudinal channel of the body for sliding relative to the base, the arm having a recessed portion on the inner surface at the distal end of the arm for receiving the distal end of the spring-biased finger of the base to hold the shield in a second position. The arm includes a plurality of spaced-apart pawls on its inner surface, and the spring-biased fingers on the base are configured to selectively engage one of the pawls on the arm to hold the shield in a first position, a second position, and a third position; and The plurality of pawls on the arm include: a first pawl at the distal end of the arm, wherein the spring-biased fingers of the base releasably engage the first pawl to hold the shield in a first position in which the needle is exposed at the first length; and a second pawl spaced proximally from the first pawl, wherein the spring-biased fingers of the base engage the second pawl on the arm to hold the shield in a second position, and wherein the second pawl slides past the spring-biased fingers of the base to a position to lock the shield in a third position, whereby the body of the shield covers the distal end of the needle.

9. The syringe assembly of claim 8, wherein the first pawl has a proximal side and an inclined distal side, the first pawl being configured to engage the spring-biased finger of the base and prevent the shield from sliding proximally relative to the syringe; and the second pawl is spaced proximally from the first pawl and defines the recessed portion to hold the shield in a second position, the second pawl having an inclined distal side to allow the shield to slide distally relative to the syringe to a third position; and the third pawl is on the inner surface of the arm at the proximal end of the arm.

10. The syringe assembly according to claim 9, characterized in that, The third pawl has a proximal surface and an inclined distal surface that slides over the spring-biased finger, the proximal surface being oriented to engage the distal end of the spring-biased finger of the base to lock the shield in the extended third position.

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