Variable length injection syringe

Abstract

To provide a device to assist in aspirating a syringe and injecting a medication to a selected depth into a patient.SOLUTION: A syringe assembly includes a syringe barrel (12) having a proximal end and a distal end, a needle hub (20) supporting the needle and coupled to the distal end of the syringe barrel (12). A moveable shield (36) is included for sliding from a first position, where the needle is exposed by a first length, to a second position where the needle is exposed by a second length less than the first length, and a third position covering a distal end of the needle. A locking mechanism (48, 86) is included to retain the shield in the second position while enabling the shield to slide to the third position, and to lock the shield in the third position to prevent re-use of the syringe.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 882,277, filed Aug. 2, 2019, which is hereby incorporated by reference in its entirety. The present invention relates to a syringe having a movable member for changing the length of the exposed portion of a syringe needle for aspirating and filling a syringe for injecting a drug into a patient. The syringe includes a movable member for changing the effective length of the syringe to a desired depth for injection and for shielding the needle after use.

Background Art

[0002] Insert a needle having a length in the range of 4 mm to 6 mm into a container or vial and aspirate. The length of the needle needs to penetrate the septum in the vial in a straight line to ensure penetration and reduce the risk of the needle bending.

[0003] The insertion of the needle into the patient's skin is determined mainly by the characteristics of the needle, rather than the characteristics or structure of the needle support. The insertion of the needle into the patient's skin is generally classified into three stages that affect the injection depth. The first stage corresponds to the initial contact of the skin with the needle and the deformation of the tissue without piercing the skin surface. The second stage shows the piercing of the skin and the relaxation of the skin when the insertion force of the needle stops. The third stage is when the skin is pulled or stretched outward when the needle is withdrawn.

[0004] The length of a needle, such as a needle having a length of about 4 mm to 6 mm, is adapted to inject a drug to a specified target depth in the subcutaneous region. The present invention provides a structure that can consistently insert the needle to a desired target depth. Previous injection devices have a needle or cannula supported by an axial post extending from the hub. The post forms a narrow portion and a relatively wide base that does not contact the skin during injection. In other injection delivery devices, the distal surface of the hub positioned relative to the injection site can be relatively large and can be provided with a slight taper at the end. When the cannula is inserted at an angle relative to the surface of the patient's skin, the end of the hub can engage the skin.

[0005] During needle injection or removal, various injection devices have been manufactured such that the support structure does not contact the skin. Other devices have been proposed to be arranged such that the end face of the device contacts the surface of the skin in order to limit the depth of penetration into the patient.

[0006] Syringe delivery devices facilitate the self-administration of parenteral drugs. An example of a delivery device is a pen needle. The needle is a component of a needle-based injection system and includes a cannula with both ends assembled into a plastic hub using an adhesive. The hub with an internal thread enables the hub to be attached to a pen injection device. The attachment of the needle allows the proximal end of the cannula to penetrate the rubber septum of the drug cartridge to form a fluid flow path. The maintenance of blood glucose control in many diabetic patients is achieved by injecting insulin multiple times daily into the subcutaneous (SC) tissue using a convenient and discreet pen-type syringe delivery device in place of vials and syringes. Many syringes are commercially available in disposable or multi-use configurations, each offering various patient-centered functions. The distal pen needle cannula connects to a delivery site that provides a conduit for delivery. The design of the delivery device and the needle is intended to enable consistent delivery into the target tissue space, minimize leakage of the injected substance, and reduce the pain / discomfort and the impact on the site such as bleeding and bruising associated with the injection. The needle length / gauge and the shape of the hub face, which are the main design features, together with the mechanism of the delivery system and the injection technique, determine the success of the injection.

[0007] Injections can be performed in the intradermal, subcutaneous, and intramuscular (IM) regions of the skin. In many types of injectable drug therapies, including insulin, the SC region is preferred for administration of the injection.

[0008] While conventional devices are generally suitable for their intended use, there remains a need for improved devices for controlling the depth of penetration of the cannula for delivering a drug or agent to a selected target region.

Summary of the Invention

[0009] The present syringe assembly relates to a device for assisting in aspirating a syringe and injecting a drug to a selected depth in a patient. In one embodiment, the syringe includes a needle having a first exposed length for aspirating the syringe and a second exposed length for injecting a substance to a desired depth in the patient. The syringe assembly can also include a movable shield that moves over the end of the needle after use and locks in an extended position to avoid accidental needle sticks.

[0010] A syringe in one embodiment includes a syringe barrel and a needle or cannula extending from the distal end of the syringe barrel. The movable shield is engaged with the syringe to slide relative to the syringe. The movable shield slides between a retracted position where the needle is exposed by a length suitable for filling and aspirating the syringe and an extended position that extends at least partially over the needle to limit the exposed length of the needle for injecting the patient. The base forms an attachment member for coupling to the syringe, and the movable shield slides relative to the base and slides over at least a portion of the needle extending from the syringe during aspiration and injection. The movable shield slides relative to the syringe from the retracted position such that the needle has an exposed length that can penetrate the septum of a container or vial for aspirating the syringe. The movable shield can slide to a second position that exposes a selected length of the needle corresponding to a desired penetration depth. When the injection is complete, the movable shield slides to an extended position and a locked position that covers the needle after use. The shield and / or the base can include one or more locking mechanisms for locking the shield in the extended position to cover the needle after use.

[0011] In one embodiment, the syringe includes a shield coupled to the syringe to slide relative to the syringe from a first position where the needle is exposed by a first length, through a second position where the needle is exposed by a second length less than the first length, to a third position where the shield completely covers the tip of the needle.

[0012] In another embodiment, the syringe includes a syringe barrel having a shield attached to the distal end of the syringe. The arm forming the connecting member is coupled to the shield to slide the shield between a retracted position that exposes the length of the needle on the syringe and an extended position that covers 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 syringe's needle.

[0013] In one embodiment, the syringe has a shield that slides relative to the syringe between a retracted position for filling the syringe and exposing the length of the needle for injecting a drug into a patient to a selected depth, a second position that covers only a portion of the needle for injecting the drug to a shallower depth than when the shield is in the first position, and an extended position where the shield covers the needle and locks in the extended position to prevent reuse of the syringe. A locking mechanism can be included to hold the shield in the second position during use while allowing the shield to slide to the extended position where the shield is permanently locked to prevent further movement of the shield.

[0014] Another feature of the syringe is a movable shield coupled to the base for sliding movement relative to the syringe with the base coupled to the outer surface of the syringe. The shield and / or the base have a locking mechanism for holding the shield partially in the retracted position, and the locking mechanism releases the shield partially from the retracted position by applying manual force to the shield, and the shield can slide to the extended position where it covers the distal end of the needle and locks permanently in the extended position.

[0015] The features are basically achieved by a syringe assembly comprising a syringe barrel having a proximal end and a distal end, a needle bearing hub coupled to the distal end of the syringe barrel, and a movable shield member disposed on the syringe barrel. The movable shield member is attached 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.

[0016] The syringe features a syringe barrel having a proximal end and a distal end, a needle bearing 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 lock the shield in an extended position to prevent reuse. The shield assembly includes a base coupled to the syringe and having a locking member projecting outwardly from the base. The shield has a sleeve dimensioned to cover the end of the needle and an arm that couples to the base to enable the shield to slide relative to the base. The arm includes a first locking member that mates with a locking member of the base to partially hold the shield in an extended position to provide a short needle length. The locking member can be released by pushing the shield or the arm distally relative to the syringe to slide the shield beyond the end of the needle, which causes the locking member on the base to engage a second locking member of the arm to lock the arm and the shield in the extended position and prevent the shield from being retracted or slid proximally relative to the syringe.

[0017] A method is provided for aspirating and filling a syringe assembly, preparing the syringe assembly for use, and preventing reuse of the syringe. The method comprises providing a syringe having a proximal end and a distal end, a needle bearing hub coupled to the distal end of the syringe, and a movable shield coupled to the syringe. The shield is in a first position that exposes a first length of a needle having a first length for filling the syringe. The shield slides to a second position to expose a second portion of the needle having a second length less than the first length for injecting the drug into the patient, and 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 reuse of the syringe.

[0018] These and other features of the invention will become apparent from the following detailed description of the invention, which, in conjunction with the drawings, discloses various embodiments of the invention.

Brief Description of the Drawings

[0019] The following is a brief description of the drawings.

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

[0021] The syringe assembly of the present invention refers to a syringe having a needle or cannula for injecting a drug or other substance into a patient. The terms needle and cannula are used interchangeably herein and refer to a thin tubular member having a sharp end for insertion into the injection site of interest. The distal direction is the direction towards the injection end of the syringe assembly, and 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, and the radial direction refers to the direction perpendicular to the axial direction.

[0022] The syringe is configured to inject a drug into a patient at a selected depth depending on the drug and the intended depth of penetration. The dermal layer of an adult generally has a thickness of about 2-3 mm, and thus the depth of intradermal injection ranges up to about 3 mm measured from the outer surface of the skin. The thickness of the subcutaneous layer varies depending on the age, gender, body mass index (BMI) of the patient, and the part of the body where the injection is made. The subcutaneous region has an average thickness of about 7 mm - about 15 mm. Insulin can preferably be delivered to the subcutaneous region.

[0023] The syringe is suitable for use in the method of injection and the method of injecting a drug into a patient. The description of the embodiments should not be regarded as limiting the present invention. The present disclosure is intended to enable those skilled in the art to practice the described variations of the present invention without departing from the scope of the present invention. The numerical limitations in this specification and the claims are to be understood as being limited by the modifier "about", and small departures that result in equivalent results are within the scope of the present invention. Features disclosed in relation to one embodiment or independent claim or limitations of dependent claims may be combined with another embodiment or different independent claim without departing from the scope of the present invention.

[0024] This disclosure, in its application, is not limited to the details of the configurations shown in the following description or the arrangements of components shown in the drawings. The embodiments of this specification can be modified, implemented, or executed in various ways. Also, it should be understood that the expressions and terms used in this specification are for the purpose of explanation and should not be regarded as limiting. The use of "including", "comprising", or "having" and their variants in this specification means including additional items in addition to the items listed thereafter and their equivalents. Unless otherwise specifically limited, the terms "connected", "coupled", and "mounted" in this specification, and their variants, are used in a broad sense and include direct and indirect connections, couplings, and attachments. Additionally, the terms "connected" and "coupled" and their variants are not limited to physical or mechanical connections or couplings. Further, terms such as up, down, below, above, etc. are relative and are for the purpose of assisting illustration but are not limiting. Embodiments are not intended to be mutually exclusive, and the features of one embodiment can be combined with other embodiments as long as they do not conflict with each other. Terms of degree such as "substantially", "about", and "approximately" are understood by those skilled in the art to refer to a reasonable range around and including a given value, as well as a range outside the given value, for example, the general tolerance ranges associated with the manufacture, assembly, and use of the embodiments. The term "substantially" when referring to a structure or property includes a property that is mostly or completely present within the structure. Distal refers to the direction or position towards the patient end of the needle, and proximal refers to the direction or position away from the patient end of the needle and towards the user of the syringe.

[0025] Referring to the drawings, the syringe assembly 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 the substance contained in the syringe assembly.

[0026] The needle hub 20 is coupled to the distal end 16 of the syringe barrel 12 as shown in FIG. 1. The needle hub 20 includes a syringe and a needle 22 that extends axially from the needle hub. The needle hub 20 is configured to couple to the distal end of the syringe barrel 12. In the illustrated embodiment, the needle hub 20 has a substantially cylindrical body 24 having a proximal end 26 with a radially extending flange 28 that extends outwardly and a distal end 30.

[0027] The needle shield assembly 32 is coupled to the syringe and slides from the initial storage position shown in FIG. 5 to the intermediate position shown in FIG. 7 and then to the extended position that covers the distal end of the needle after use shown in FIG. 8, preventing reuse of the syringe and preventing accidental needle sticks. The needle shield assembly 32 includes a base 34 for coupling to the syringe and a movable shield 36 for covering the needle after use. In the illustrated embodiment, the movable shield 36 slides relative to the base 34 and relative to the syringe 12.

[0028] Referring to FIGS. 3 and 4, the base 34 is configured to couple to the syringe and allow the shield 36 to slide relative to the base 34 and relative to the syringe and needle. The base 34 in the illustrated embodiment is coupled to the syringe hub 20 by snapping onto the radial flange 28. The base 34 forms an attachment structure for coupling the shield and the shield to the syringe to slide relative to different positions of the syringe and the needle. The base 34 includes a body 38 and an attachment 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 axially relative to the syringe and the base. The sleeve 40 has a configuration for coupling to the syringe barrel 12. In the illustrated embodiment, the sleeve 40 has a substantially cylindrical shape with a central opening having dimensions for coupling 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 coupled to the syringe in a manner that allows the shield to rotate to a position selected by the user on the syringe. In one embodiment, the sleeve 40 is fixed to the syringe barrel 12 by a suitable mechanical mechanism or by adhesion such as an adhesive or welding.

[0029] The base 34 includes a pair of spaced side walls 42 that form a longitudinal passage 43 or gap for receiving the shield and allow the shield to slide longitudinally within the passage 43. The side walls 42 have upper ends with inwardly projecting flanges 44 that extend longitudinally. A bottom wall 46 extends between the side walls 42 that form the passage 43 and forms an open portion between the side walls 42 that are open at the upper end of the base. The flange 44, side walls 42, and bottom wall 46 capture the shield 36 for sliding movement relative to the syringe and the needle.

[0030] A lock mechanism is included in base 34 for holding a shield in one or more selected positions relative to the base and syringe. In the illustrated embodiment, the lock mechanism is in the form of a latch that holds shield 36 in a selected position that allows the latch to be released and the shield to slide to another position in the proximal direction. The lock mechanism in the illustrated embodiment is a spring-biased finger 48 having a proximal end connected to base 34 by spring hinge 50, whereby finger 48 bends inwardly toward bottom wall 46 of base 34 and it is possible to bias finger 48 outwardly from the bottom wall of the base. Finger 48 has a distal end having a tab 52 having a distal surface 54 and a proximal surface 56. As shown in FIG. 4, distal surface 54 defines the leading surface of finger 48. Proximal surface 56 in the illustrated embodiment is inclined relative to the longitudinal axis of base 34 and slopes outwardly in the distal direction. The substantially flat end surface 56 of tab 52 is shown substantially parallel to the longitudinal axis of finger 48 and the longitudinal axis of base 34.

[0031] Sleeve 40 is configured to couple base 34 to the syringe and attach shield 36 to slide relative to the base and syringe. Sleeve 40 has a longitudinally extending central opening 60 dimensioned to receive the distal end of the syringe. A coupling mechanism is included in central opening 60 as shown in FIG. 4 for coupling sleeve 40 to the syringe. The coupling mechanism can be one or more detents 62 on the inner surface of the sleeve that project inwardly to engage and capture flange 28 of the needle hub. Detents 62 are spaced longitudinally from end wall 63 and form recess 65 to receive and capture flange 28 of syringe barrel 12. In one embodiment, the coupling mechanism can be a snap connection that inhibits or prevents separation of base 34 from syringe barrel 12 and needle hub 20. Detents 62 shown in FIG. 4 can have angled or inclined proximal surfaces for sliding over radial flange 28 of the syringe. In other embodiments, the coupling mechanism can be an annular ring that forms a snap or interference connection.

[0032] The sleeve 40 in the illustrated embodiment has an open proximal end for receiving 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 has a shape and dimensions for receiving the distal end of the needle hub through which the needle can extend distally from the distal end of the sleeve. The passageway 60 can open at the distal end as shown in FIG. 4, and the distal end 30 of the needle hub can project 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 can be slightly recessed relative to the distal end of the sleeve. In other embodiments, the sleeve can have an end wall having an opening sized to allow the needle to pass through and contact the distal end of the needle hub.

[0033] The shield 36 as shown in FIG. 2 has an open axial passageway 64 having a shield body 37 that is substantially cylindrical in shape, and an open proximal end 66 and a distal end wall 68. The end wall 68 has a central opening 70 sized to allow the needle to extend through the shield 36, fill and aspirate the syringe, and inject the drug into the patient for a length sufficient to do so. The open proximal end 66 is sized to receive the distal end of the sleeve 40, and the end of the sleeve 40 can slide within the open proximal end 66 as shown in FIG. 5.

[0034] The shield 36 includes an arm 72 that is attached to the side surface of the shield 36, extends in the proximal direction of the shield, and is radially spaced outward from the wall of the shield with respect to the central axis of the shield 36. The arm 72 is coupled to the base 34 and is configured to slide relative to the base and the syringe to guide the shield during longitudinal movement of the shield. In the illustrated embodiment, the arm 72 has a distal end 74 coupled to the side wall of the shield 36 and a proximal end 76. The thumb tab 78 is formed at the proximal end 76 for manipulating the shield and manually pushing the shield distally relative to the syringe and the needle. The rib 80 projects from the opposite side of the arm and extends longitudinally for mating with the flange 44 of the side wall 42 of the base 34. The flange 44 contacts the upper surface of the rib 80 to capture the arm 72 within the open passage 43 of the base formed by the side wall 42, the flange 44, and the bottom wall 46. The arm is slidable longitudinally within the passage 43 relative to the base and relative to the syringe and the needle. In the illustrated embodiment, the arm 72 has a substantially straight distal portion 82 and an angled proximal portion 84.

[0035] The arm 72 includes a locking member that mates with a locking member of the base 34 to hold the shield in a selected position relative to the base and the syringe, cover the distal end of the needle after use, and lock the shield in an extended position to prevent reuse of the syringe. The locking member includes a mechanism that mates with the spring finger 48 of the base 34. The locking mechanism is disposed at the distal end of the arm 72 near the shield 36 to hold the shield in a first position and to release the shield when a force is applied to the end of the arm to allow the arm to slide distally within the base. The locking mechanism in the illustrated embodiment has a recess 86 for mating with the tab 52 of the spring finger 48. The recess 86 in one embodiment is formed by a first detent 88 and a second detent 90 spaced from the first detent 88. In other embodiments, the recess can be formed on the surface of the arm. The locking mechanism is formed by the detent 88, the recess 86, and the detent 90.

[0036] The first detent 88 is spaced from the distal surface 91 of the radial rib 93 extending from the shield 36, as shown in FIG. 2, to form a recessed region 95. The first detent 88 has a distal face 92 inclined with respect to the longitudinal axis of the arm 72 and a rear proximal face 94. The proximal face 94 is shown to be an inclination that complements the inclination of the surface 54 of the spring finger 48, but the proximal face can be substantially perpendicular to the face of the arm. The proximal face 94 has a shape and configuration for mating with the distal surface 54 of the finger 48. The second detent 90 has a configuration that forms a recess 86 and is spaced from the first detent 88 by a distance to receive the tab 52 of the finger. The second detent 90 has a distal face 96 and a proximal face 98.

[0037] The second detent 90 can have an appropriate configuration that enables the tab 52 of the finger 48 to slide over the second detent 90 by applying sufficient force in the distal direction to the arm. The distal face 96 of the detent 90 has a surface configured to enable the finger to slide distally over the detent. The rear proximal face 98 of the detent 90 can have an appropriate configuration to limit the sliding of the arm on the finger 48 in the proximal direction toward the proximal end of the base and to resist sliding in the proximal direction. In the illustrated embodiment, the second detent 90 has a rounded distal face 96 and a rounded proximal face 98 for sliding over the spring finger 48 when a force is applied in the distal direction. The recess 86 is configured to receive the tab 52 of the spring finger 48 when the shield 36 and the arm 72 are in an intermediate position relative to the base and the syringe, as shown in FIG. 7 relative to the initial position shown in FIG. 6.

[0038] The second locking member of the arm engages the spring finger 48 and locks the arm in the extended position to cover the distal end of the needle after use. The second locking member includes a projection or detent 100 spaced from the first locking mechanism and disposed proximal to the first locking mechanism toward the proximal end of the arm. The detent 100 has an inclined distal surface 102 and a proximal surface 104. The inclined distal surface 102 has a length that allows the spring finger 48 to slide upwardly on the surface of the distal surface by applying an axial force to the proximal end of the arm 72. The proximal surface 104 in the illustrated embodiment engages the tab 52 of the spring finger 48 and is angled to prevent the arm 72 from sliding rearward in the proximal direction relative to the base 34 and the syringe and to lock the shield in the extended position to cover the tip of the needle. The arm 72 has a longitudinal length that slides distally relative to the syringe and has a distance to cover the distal end of the needle.

[0039] In use, base 34 is coupled to the syringe as shown in FIG. 5, base 34 is connected to the distal end of the syringe, and shield 36 is in the retracted position. In the retracted position, the distal end of the body of sleeve 40 is received within the proximal open end of shield 36. As shown in FIGS. 5 and 6, the needle projects a distance from the distal end of the shield for filling the syringe and injecting a drug into a patient. Tab 56 of spring finger 48 is received within recessed region 95 of shield 36 when shield 36 is in a proximal position relative to the syringe. In one embodiment, the needle has an exposed length of about 6-8 mm extending from the distal end of shield 36 when the shield is in the initial retracted proximal position shown in FIGS. 5 and 6. In one embodiment, the needle has an exposed length of about 6 mm when the shield is in the proximal retracted position. In the retracted position, tab 52 of spring finger 48 is positioned forward or distally of detent 88 to hold the shield in the retracted position. The syringe can be used in the configurations of FIGS. 5 and 6 where shield 36 forms a limiter that limits the penetration depth of the exposed length of the needle. Needle 22 has an exposed length extending from the shield when the shield is in the proximal position shown in FIG. 6, allowing the syringe to be filled by penetrating the septum of the vial. A needle length of less than 6 mm is generally difficult to fill from a vial because the needle length may not be sufficient to penetrate the septum, especially when the needle penetrates the septum at an angle. Thus, in the illustrated embodiment, the needle has an exposed length of at least 6 mm when the shield is in the proximal position.

[0040] After filling the syringe, the shield 36 can be slid to the second intermediate position shown in FIG. 7 by the user pushing the proximal end of the arm 72 distally. The inclined distal face 92 of the detent 88 slides on the proximal face 56 of the tab 52 of the spring finger 48, thereby deflecting the spring finger toward the base and causing the tab 52 to snap into the recess 86. Sliding the tab 52 into the recess 86 can provide an audible or tactile indication to the user that the shield is in the second intermediate position shown in FIG. 7. In one embodiment, the exposed length of the needle extending from the shield is from about 4 mm to about 5 mm, and typically about 4 mm when the shield is in the intermediate position of FIG. 7. In other embodiments, the needle has an exposed length of about 3 - 5 mm when the shield is in the intermediate position of FIG. 7. The exposed length of the needle is determined by the position of the recess 86 relative to the arm. The needle shield also forms a limiter that restricts the axial length of the exposed portion of the needle during injection. The recess 86 captures the tab 52 of the finger 48 with sufficient resistance to hold the shield and the arm in the intermediate position during use.

[0041] After injection, the arm 72 is pushed forward distally relative to the syringe, the tab 52 separates from the recess position 86 and slides over the second detent 90. The detent 100 slides on the tab 52 of the spring finger to the position shown in FIG. 8, and the shield slides to a position covering the distal end of the needle. The proximal portion 84 of the arm 72 is at an angle relative to the distal portion 82 to move the shield away from the center of the needle as shown in FIG. 8, such that the distal tip of the needle is no longer aligned with the opening 66 in the end wall of the shield. The distal face 54 of the tab 52 engages the proximal face of the detent 100 to cover the end of the needle and lock the shield in the extended position to prevent reuse of the syringe.

[0042] Another embodiment shown in FIG. 9 includes a shield 110 similar to the shield of the previous embodiment. The shield 110 includes an arm 112 and a sleeve 114 coupled to the arm to cover the end of the needle, similar to the previous embodiment. The shield 110 is coupled to the base 34 to slide linearly on the base with respect to the syringe and the needle, similar to the previous embodiment. The sleeve 114 has an open proximal end 116 sized to receive the distal end of the needle hub of the syringe and an open distal end 118 to allow the needle to project a distance for injecting the drug into the patient.

[0043] The arm 112 in the embodiment of FIG. 9 is similar to the arm of the previous embodiment, except that it includes two or more sets of detents that form a locking mechanism for positioning the shield at a selected position relative to the needle hub and needle to expose needles of different lengths depending on the intended penetration depth of the needle. The arm 112 has a first locking mechanism 120 at the distal end of the arm 112 and a second locking mechanism 122 spaced proximally from the first locking mechanism 120. The first and second locking mechanisms are configured to mate with the spring fingers 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 detent 124 and a proximal detent 126 spaced apart to form a recess 128. The distal detent 124 has an inclined distal face 130 of the tip for sliding on the spring finger and a proximal face of the rear end to prevent the shield from sliding proximally relative to the base. The recess 128 is sized to receive the tab 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 detent 132 and a proximal detent 134 that form a recess 136. The detents capture the tab of the spring finger and are substantially similar to holding the shield in a selected position relative to the base and the syringe.

[0044] In use, the shield 110 is received in the opening of the base 34 and is placed in the retracted position to expose a first length of the needle that can be drawn into the syringe and filled with drug. The syringe can be used by inserting the needle into a patient and injecting the drug to a depth corresponding to the exposed length of the needle. The shield is stored in the first extended position by sliding the shield distally relative to the syringe until the spring fingers snap into the recesses 128, and the shield can be held in the partially extended position to expose a length of the needle that is shorter than the initial exposed length. By way of example, the initial exposed length of the needle can be about 6 mm, and the exposed length of the needle can be about 4 mm in the partially extended position. The shield is extended to a second position where the fingers are received in the recesses 128 of the second locking mechanism 122 to expose a shorter length of the needle that is less than the initial length and less than the length when the spring fingers are received in the recesses of the first locking mechanism 120. The exposed length of the needle when the spring fingers are received in the recesses of the second locking mechanism can be, for example, about 2 mm. After use, the shield slides to the extended distal position where the shield covers the end of the needle and the proximal lock detent 138 locks the arm and shield in the extended position to prevent reuse in a manner similar to the previous embodiment.

[0045] The foregoing embodiments, and advantages, are merely illustrative and should not be construed as limiting the scope of the invention. The description of alternative embodiments is intended to be illustrative and not limiting of the scope of the invention. Various modifications, alternatives, and variations will be apparent to those skilled in the art and are intended to be included 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 as long as they do not conflict with each other. Accordingly, all such modifications are intended to be included within the scope of the invention as defined by the appended claims, and their equivalents.

Claims

1. 1. A 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 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 has a central opening configured to receive the distal end of the syringe, the sleeve coupled to the base to slide between a first position exposing the needle a first length for filling the syringe, a second position exposing a second length of the needle that is shorter than the first length, and a third position covering the needle; The syringe assembly, wherein the base and the shield have a locking mechanism for retaining the sleeve in the second position, preventing the shield from sliding toward the proximal end of the syringe while allowing the shield to slide to the third position, and locking 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.

2. The syringe assembly of claim 1 , wherein the shield has a distal end with an opening for receiving the needle and with dimensions smaller than an outer dimension of the syringe.

3. the sleeve includes an arm extending axially from the sleeve and coupled to the base for sliding axially relative to the base; the shield locking member includes a first detent projecting from the arm toward the base; the locking member of the base comprises a finger biased toward the arm to engage the first detent to retain the sleeve in the second position, the first detent being slidable distally over the finger; 2. The syringe assembly of claim 1, wherein the locking member of the shield includes a second detent projecting from the arm toward the base for engaging the finger and capturing the sleeve in the third position.

4. 1. A method for aspirating and filling a syringe, comprising: providing a syringe assembly comprising a syringe having a proximal end and a distal end and a needle coupled to the distal end of the syringe; a shield coupled to the syringe and slidable from a first position exposing a first length of the needle to a second position exposing a second length of the needle that is shorter than the first length, and to a third position covering the tip of the needle; the shield includes a locking mechanism for holding the shield in the second position, preventing the shield from sliding onto the syringe toward the proximal end of the syringe while allowing the shield to slide to the third position, and locking the shield in the third position, covering the distal end of the needle and preventing the shield from sliding toward the proximal end of the syringe; sliding the shield from the first position to the second position to inject into a patient to a depth corresponding to the second length; sliding the shield to the third position and locking the shield in the third position.

5. The method of claim 4 , wherein the shield has a distal end with an opening for receiving the needle and with dimensions smaller than an outer dimension of the syringe.

6. a sleeve including an arm extending axially from the sleeve and coupled to the base for sliding axially relative to the base; the shield locking member includes a first detent projecting from the arm toward the base; a locking member on the base including a finger biased toward the arm for engaging the first detent to retain the sleeve in the second position, the first detent being slidable distally over the finger; 5. The method of claim 4, wherein the locking member of the shield comprises a second detent projecting from the arm toward the base and engaging the finger to capture the sleeve in the third position.

Images