Syringe with automatically triggered safety sleeve

[0001] The field of the invention relates to syringe safety systems and in particular to syringe shield systems for protection against needle puncture.

Brief Description of the Prior Art [0002] Syringes are well known medical devices for administering drugs, narcotic drugs and vaccines to patients. Filled syringes are generally considered to be those filled by the pharmaceutical manufacturer with a specific dose of the drug, pharmaceutical agent or vaccine for distribution to the end user. They usually consist of a glass container containing a drug, narcotic drug or vaccine, and a piston slidably mounted inside the cylinder. The distal end of the cylinder comprises a needle cannula or the like attached thereto or a needle cannula connector attached like a Luer connector. The proximal end of the syringe has an integral flange and is open, allowing the plunger and stem assembly to be positioned. The plunger and plunger assembly allows the user to manually apply force to the plunger to deliver drug, narcotic or vaccine through a needle cannula or other punching device. The healthcare professional or patient grasps the collar and puts pressure on the mandrel with his thumb.

[0003] The use of a pointed punch element entails several types of hazard. As long as the syringe is not in use, its contents are protected by a sterile cover, which also prevents accidental needle pricking. When the needle is exposed, there is a risk of accidental needle sticking after use when the needle is contaminated, of accidental needle sticking when the syringe has not been removed correctly, and the risk of accidental or intended reuse. To avoid such accidents, many of the hypodermic syringes contain various protective covers. Some of them consider telescopic shields around the syringe barrel, others consider individual glass cylinders. The telescopic covers can be moved between the retraction position in which the needle is exposed for use in the extended position in which the needle is surrounded by the cover.

[0004] US 6,159,184 describes a telescopic cover at which the user is expected to determine the end of drug delivery and then push the cover with the other hand until it is closed in the housing. Sampson et al. Demonstrated this approach in earlier patents such as US 6,004,296, US 4,425,120 and US 4,573,976 also regarding filled syringes.

[0005] US 4,923,447 by Morgan discloses a sheath assembly for spring actuated hypodermic syringes. Release of the spring and release of the safety elements depends on the action of the user.

[0006] It is usually desirable to lock the needle guard in a safe position, and many prior art solutions include such locks. Some such systems, such as those disclosed in USPat. Nos. 5,201,708, 5,242,240 and US5,318,538 Martin, have been designed to allow the shield to be withdrawn from their locked, extended positions.

[0007] Another solution is presented in US 6,613,022 by Doyle, in which the user detaches the pre-stressed spring by moving the pusher near the end of the delivery position. The user is expected to loosen the finger grip to allow the telescopic cover, which in this case is outside the housing, move forward and lock.

[0008] The safety guard can be triggered by various means. In US 6,613,022, the pusher must reach a certain position relative to the housing; in patent application 20030050607 by Gagnieux, the user places increasing pressure on the pusher to achieve the same effect.

Summary of the invention [0009] The present invention relates to an injection device consisting of:

a housing having a proximal and distal end, the distal end having an opening;

a cylinder chamber within the housing, the cylinder chamber having a proximal and distal end;

a needle cannula attached to the distal end of the cylinder chamber or means for attaching the needle cannula to the distal end; piston inside the cylinder chamber;

a pusher connected to the piston;

a cover connected to the housing and slidably between the retracted position and the extended position;

means moving the shield from the retracted position to the extended position; and sensing elements capable of moving with said pusher and in sliding contact with said cylinder chamber or the inner surface of said housing, the sensing elements being arranged to detect the end of the cylinder or housing profile and to trigger the moving elements upon detection.

[0010] The invention relates to a protective cover assembly for a syringe, medical chamber or similar system as used in connection with the attached assembly operating as a syringe. According to the proposed solution of the system, the user can use the filled syringe in a similar way as in the case of simple filled syringes. The user can observe the drug, remove air, titrate the desired dose, hold the syringe according to training, penetrate through the skin and inject. The needle will be shielded automatically without any user action. The casing will be synchronized with the end of delivery or emptying of the chamber.

[0011] According to the object of the invention, a medical device is provided comprising an automatically operated shield system attached to the syringe barrel. The system includes a sleeve housing defining the housing assembly. The sleeve needle shield is slidably mounted in the housing and preferably telescopically held. The syringe barrel is held inside the housing and covers the assembly, partly inside the sleeve cover. The shield is retracted from the retracted position and covers the needle cannula until the end of injection.

[0012] In the present solution, the sheath comprises a locking element adjacent its proximal end and the housing comprises a locking element adjacent its distal end, which loosely holds the shield in its retracted position. In the preferred solution, the shield locking elements consist of two sliders adjacent to the housing slots. Locking means prevent forward movement of the shield before reaching the end of delivery. The strength of this connection should be sufficient to resist the weight of the shield only for the effects of collision. No force is applied to the locking elements. The force required by the spring to separate the cover from the housing is minimal.

[0013] The compressed spring is enclosed in a pusher assembly. During injection, the pusher is moved forward by the user to move the drug from the glass cylinder to the user's tissue. The cover is loosely held in the housing. The spring is released from the pusher and axially aligns the shield along the extended position during injection. When the force is applied by the spring, the sheath is loosened from the retracted position and covers the needle.

[0014] The pusher comprises a central rod acting as a typical rod and two side arms acting as sensor elements. The sensor elements are deformable arms that trap the spring. The sensor arms act as a cam that detects the external profile of the syringe under spring loading. When the cams reach the distal part of the cylinder, the arms deform and the spring is released from the pusher. The spring bypasses the pusher, acts on the cover and releases the latch. When the cover is released, the spring moves it to its extended position, in which it locks.

[0015] The proximal end of the housing is preferably adapted to engage and holds the syringe flange at the entrance of the syringe barrel through the proximal end of the housing. When the syringe is closed in the housing, it remains stationary.

[0016] Filled syringes are sometimes used to withdraw a drug, for example to mix a second pharmaceutical inside a filled cylinder. For this purpose, the possibility of axial connection between the pusher and the eye of the syringe is important. Axial fastening is achieved by a latch or thread; the inner part being in the rubber piston and the outer connecting part at the distal end of the pusher stem. The presented solution presents a snap connection between the stem and the piston, which will be explained later, the threaded connection is also possible to use.

[0017] Compared with other techniques, the present invention is unique in that it is closest to regular manual injection. Shorter training time is anticipated for obtaining confidence in using the system. The described solution does not require any additional actions from the user and is automatically triggered by the internal operating conditions of the system. Activation of automatic safety elements is conditioned by a minimum dimension chain and requires only a single part in addition to the syringe.

Brief description of the drawings [0018]

FIG. 1 is a one-dimensional isometric view of a preferred embodiment according to the invention;

FIG. 1A defines the cross-sectional planes AA, BB and CC of the device, where AA the cross-section of the pusher side arms providing a view of the observation window, BB cross-section through the plane of the locking sliders and CC cross-section through the plane of the stops;

FIG. 2 external view of the device in the inflated position from the observation window;

FIG. 3 an external view of the device in the fill position in a plane perpendicular to the plane of FIG. 2

FIG. 4 a view of the device as in FIG. 2 in the blocking position;

FIG. 5 a view of the device as in FIG. 3 in the blocking position;

FIG. 6 a cross-section of the device in the AA plane according to FIG. 1A in the fill position;

FIG. 7 a cross section of the device in the BB plane according to FIG. 1A in the fill position;

FIG. 8 a cross section of the device in the CC plane according to FIG. 1A in the fill position;

FIG. 9 a close-up view of the cross-section of the collar and housing connection;

FIG. 10 cross section 6 after delivery and before removal from the injection site;

FIG. 11 cross section FIG. 7 after delivery and before removal from the injection site;

FIG. 12 cross section FIG. 6 devices in the blocking position after removal from the injection site;

FIG. 13 cross section FIG. 7 devices in the blocking position after removal from the injection site;

FIG. 14 cross section FIG. 8 devices in the blocking position after removal from the injection site;

FIG. One-dimensional axonometric view of the housing;

FIG. 16 one-dimensional axonometric projection of the pusher;

FIG. 17 one-dimensional axonometric view of the cover;

FIG. 18 one-dimensional axonometric view of the front cover window

FIG. 19 cross section of the filled cylinder;

FIG. 20 view of the dismantled safety syringe.

Detailed description of the invention [0019] A safety system is used in glass or plastic pre-filled syringes to protect users against accidental needle puncture after injection and / or to prevent reuse of a previously used device. The attached figures illustrate three plastic parts that, together, form a solution and subassembly of the filled chamber.

[0020] The following description includes three steps for using the proposed solution: storage conditions for the complex system; termination of administration before removing the injection device from the tissue; and the syndrome after removal from the injection site with an automatically shielded and protected needle.

[0021] The operation of the device described in the proposed solution is in accordance with the conventional method of using a simple, standard filled syringe. The syringe assembly (including the filled syringe) is packaged to protect its contents. When the syringe is removed from the packaging, it is necessary to follow the manufacturer's instructions: check the drug and its designation, identify the specific details of the device. If possible, the security device is made of transparent polymers such as acrylic, polycarbonate or polystyrene. Selected materials do not require sterilization. The user should be able to remove air bubbles, measure the required dose using the syringe scale, just like using similar market products. In special cases, the user will need to take extra medicine or thinner. The solution should take this need into account allowing the piston to move both in the proximal and distal direction through a stable connection between the stem and the piston. These operations will occur after the needle cover assembly has been removed. Safety features should allow the user to interact with the assembly as with simple, filled syringes.

[0022] The injection process follows a generally known methodology. The device should create the minimum level of visual interference with the device that the user may need. In the diameter of a typical device there will be some increase in diameter as a result of using additional partitions in the chamber. However, this increase does not cause differences during use.

[0023] Unlike other solutions described in the prior art, the invention does not require any additional action from the user. The injection process is carried out as usual. As soon as the injection is completed, the screening assembly is automatically activated, providing the user with an additional tactile indication of the end of delivery beyond the usual visual indication. While the user removes the device from the injection site, the sheath is moved by a spring in the distal direction thereby shielding the needle. The cover is closed in a housing. The protrusion by the spring does not require an increase in the force applied by the user during the injection. The needle of the device is secured together with the readiness of the device for its safe removal.

[0024] The basis of the operation used in the described solution are sensor elements moving over the outer part of the chamber detecting reaching the end of the cylinder during the automatic extension of the shielding assembly.

[0025] FIG. 1-3 show different views of the present invention in its initial state prior to use. These and other figures do not take into account the transparency of plastic components. The safety syringe has a housing 100, a cover 200 and a syringe plunger pusher 300. The spring 400 is located inside the assembly. It is important to position the spring so that the coils do not interfere with the observation of the scale and / or the drug. The observation window 110 (or transparent housing) reveals the chamber scale 502 and drug 560. The user holds the housing 100 in the clamp 112 and applies force, typically with the thumb, to the portion 352 of the plunger pusher 300. The needle shielding assembly 570 exposed to the user is part rigid plastic 550 closing sterile 540 elastomeric cover or 540 sterile self elastomeric cover.

[0026] FIG. 4 and FIG. 5 illustrate the use of the device, in particular activation of the cover. The skirt bumper 212 has been moved from the upper position of the guide track 106 in Fig. 2 to the bottom position of the same track in FIG. 4 preventing subsequent distal movement of the guard. Furthermore, the locking pawl has been pivoted externally and prevents backward movement of the cover 200 as illustrated in FIG. 4 and FIG. 5. The locking pawl is initially positioned in the upper position of the guide track 105.

[0027] Figures from FIG. 6 to FIG. 14 depicts cross-sectional views of the device displaying 3 positions in 3 different perspectives. The AA plane is parallel to the viewing window 110 enabling an accurate view of the pusher 300 at various stages of operation. FIG. 6, 10 and 12 are cross-sections in the AA plane. The cross-section BB is the plane of the locking pawl 210, enabling an accurate view of the latch 210 in the slot 105 at various stages of operation. 7, 11 and 13 are cross sections in the BB plane. Cross section CC in the plane of the stop 212 in the slot 106 at various stages of operation. FIG. 8 and 14 are cross-sections in the CC plane.

[0028] FIG. 6, FIG. 7 and FIG. 8 illustrate the different cross-sectional perspectives of the solution before using it. The follower cannot perform a sliding distal movement along the cylinder until the cannula 530 is shorted by 540. The movement of the follower in the proximal direction is prevented by the same elements.

[0029] FIG. 9 is a close-up view showing the flange 520 attached to the housing 100 by means of latches 111. The latches 111 prevent axial movement of the chamber while the slots of the housing 114 connected to the arms 320 prevent rotation of the pusher. The chamber 500 is latched into the housing by 111 and is supported in the radial plane by cams 340 pressing the cylinder 501 with the reaction of a spring 400. The displacement of the sterile cover assembly 570 can be triggered by pressure on 570. The chamber is assisted by a housing flange 116 when the needle covering assembly 570 is removed.

[0030] The use of the device begins when the needle covering assembly 570 is removed. After removal of the air bubbles, titration and other operations, the user begins the injection process by holding the device in the housing handle 112 with two fingers and a thumb on the base 350.

The needle is inserted in a conventional manner. The pusher is then pushed with the thumb, while the safety syringe is held in place with two other fingers. The tappet 300 slides longitudinally during guidance preloaded with spring 400. Except for the axial displacement of the pusher and piston, there are no other changes in the relative positioning of the other components of the solution. [0031] The delivery completion is detailed in FIG. 10 and FIG. 11.

FIG. 10 presents the pusher after the cams 340 have reached the end of the cylinder 503. The distal arm 322 of the pusher 300 deflects under the influence of spring 400 into its structural shape. Spring 400 will continue to slide along cam cone 342 until it bypasses. The proximal side of the spring continues to push the pusher through the abutment of the spring 323, while its distal end exerts pressure on the surface 205 of the skirt flange 204. The user is not expected to perform any additional external activities with respect to customary injection techniques. The spring pressure additionally provides the user with both tactile and auditory indication of the end of delivery signaling the moment of removal of the device from the injection site.

[0032] FIGS. 12, 13 and 14 show a preferred solution after the syringe assembly has been removed from the injection site and is ready for disposal. Under the influence of the axial force of the spring 400, the cover 200 moves to the distal side and is locked. The front movement of the cover 200 allows the pawls 210 to deflect until engaged with the front edge 102 of the housing 100. During the frontal movement of the cover 200, the proximal end of the spring is supported by the support of the spring 323 of the pusher 300. The potential backward movement of the pusher 300 is prevented by the provided cam support 340 at the end 503 of cylinder 501. Limiter 212 (FIGS. 8 and 14) slides in the slots 106 from its proximal end to the distal side and prevents the shield 200 from being removed from the device. Injection is completed and the device secured for disposal.

[0033] Once the device has been used and the sheath has been extended by the spring, its re-use is very difficult, this is due to the position of the spring 400 acting as a support sleeve inside the cylindrical body 203.

Description of individual elements:

[0034] Housing 100 is shown in FIG. 1-5. The housing 100 has a cylindrical portion 103 and a flange 116 on its proximal side 101. The distal side 112 of the flange 116 is adapted to be gripped by fingers. Various shapes of gripping surfaces can be used in the proposed safe syringe solution.

[0035] The proximal surface 113 of the housing flange 116 includes latch members 111 for permanently securing the flanges of the chamber 520 (the chamber is described in FIG. 19) to the housing 100 during assembly of the assembly. The latches 111 are sized to cover the wider portion of the chamber flange. During use, the chamber 500 is stationary relative to the housing.

[0036] The housing 100 in its cylindrical portion 103 has an additional three sets of elongated holes, including an observation window 110 on both sides 103, a slide gate slide path 105 and a stop fence 106 paths. Paths 105 and 106 may be arranged along the diameter of part 103. Tracks 105 and 106 and observation windows 110 are coaxial with the housing axis. Side walls 110, 105 and 106 may be parallel as shown in FIG. 15, to simplify injection molding production. Furthermore, the observation window 110 is not mandatory for transparent plastic materials.

[0037] The flange 113 has a round central opening 115. The diameter 115 is larger than the outside diameter of the spring 400 and is smaller than the diameter of the chamber flange 520. The latches 111 for blocking the chamber are arranged on its larger side 520 adjacent to the proximal surface 113 of the housing flange 116 Flange 116 includes two slots 114 adapted to lateral pusher arms.

[0038] The pusher 300 is shown in FIG. 16. The push rod has a 305 pin similar to a typical syringe pin. At the end of the stem 305 there is a button 345 with a groove 344 and a plate 312 for gripping the piston. Alternatively, button 345 may have a thread for connecting the chamber piston.

[0039] On the proximal side, the pusher 300 has a base 350 acting as a typical push-pull piston. The base 350 also acts as a bridge connecting the pin 305 attached to it and the side arms 320. Each side arm 320 has a front portion 322 and a rear portion 321. The midpoint at which 321 becomes 322 has a projection 330. The projection 330 contacts and moves along cylinder chamber surface.

[0040] The front portion of the arm 322 is constructed to lock and retain the preloaded spring while the device is being stored. The proximal end of the spring rests on the spring support 323. The distal end of the spring loosely rests on the cam cone 342. The distal end of the front part of the arm 322 has a cam 340 resting on the cylinder chamber and the front cone 343 for support in the assembly. 342 allows the spring to be bypassed when a delivery end is detected. Cam 340 follows the outer shape of the chamber and acts as a sensor system. The front arm 322 at the proximal end may have a reduced thickness 335 as an axis.

[0041] The cover 200 is shown in FIG. 17 and FIG. 18. Shield 200 has a cylindrical body 203. Shield 200 has a proximal end 201 and a distal end

202. Additionally, it has a flange 204 at the distal end 202 of the cylindrical body

203. The outer diameter 203 is in sliding contact with the inner diameter of the cylindrical portion 103 of the housing. The collar 204 has a needle hole 206 with a diameter large enough to allow removal of the needle covering assembly 570. The proximal portion 205 of the collar 204 is flat, while the outer portion 207 of the collar 204 can be shaped like a cone for better needle visibility. The cylindrical body 203 may include two holes 213 located along the diameter and connecting the windows of the housing 110 to form an observation window of the safety syringe. The longitudinal slots 214 act as guide paths for the side arms of the pusher. Undercuts 215 are provided to facilitate modeling of locking pawls 210. Locking latches 210 provide two functions: one to keep the shield in its axial position prior to shielding and the second to prevent needle exposure after use. In the absence of forces applied to the shield, it essentially maintains its position before shielding. The distal side of the latch 211 interacts with the slot of the housing 105 to prevent any displacement until an axial force is applied when the shield is lowered.

[0042] The second function of the sheath is to prevent needle exposure after use. The locking pawl 210 is shaped to be relatively flexible for radial deflection and at the same time rigid for the applied axial force. When the cover 200 is moved to the cover position, the pawl 210 rests on the housing 102 and prevents the cover from retracting. Cover 200 also includes stops 212 to prevent relative rotation of the cover and housing and to prevent dismantling of the cover.

[0043] Shield 200 is designed for injection molding. In particular, side walls 210 and 212 may be parallel to the side walls of the observation window 213. Elements 213, 210 and 212 are designed to be connected to 110, 105 and 106. The flange 204 includes top local slots 216 on its inner side. They are introduced to minimize the shield weight.

[0044] The chamber assembly 500 is shown in FIG. 19. The chamber assembly includes a cylinder 501 usually made of glass, a needle 530 attached to its distal end, and a collar 520 at its proximal end. Cylinder 501 contains drug 560 that is retained inside cylinder 501 by a stop 510. The piston is also used to push the drug through the cannula 530. The cannula 530 is covered with a sterile 540 elastomer covering. The elastomer cover can also be covered with a sterile plastic cover 550. Elements 530 and 540 form a sterile cover set 570. The components described are common to conventional chambers. The preferred solution of the invention is designed to integrate standard components without any changes. Cylinder 501 is sometimes covered with laminate with printed 502 scale. The cylinder 501 is a sleeve element having a constant outer diameter with a distal end 503 with a tapered diameter along the cannula. The 400 spring is a standard coil spring.

[0045] Description of the assembly process [0046] The assembly process of the safety syringe assembly with filled chambers takes place under conditions with special requirements for purity leading to the final assembly of closed components with sterile contents. In addition, the aspect of material selection will be discussed.

[0047] One of the assembly options for the assembly is described below. An exploded view of the solution is shown in FIG. 20. Folding begins by attaching the pusher 300 to the chamber 500 by snapping or screwing member 345 into the piston 530. The position of the pusher 300 relative to the flange 520 of the chamber 500 should be controlled for a chamber with a threaded locking element. Limited unscrewing may be required for the correct orientation of the elements. The next step is to position the spring 400 on the front of the arm 322. The spring 400 is placed on the pusher and in the chamber assembly by applying axial force. The frontal cone 343 at the distal end 320 supports spring fastening. Under the influence of radial force, the spring 400 may be slightly deformed to an oval shape to interact in the assembly.

[0048] The chamber 500, the pusher 300 and the tensioned spring 400 form a subassembly.

This subassembly is introduced into the proximal opening 115 of the housing 100. The rotational position is dictated by the slots 114 leading the side arms 320.

The outside diameter of the spring 400 is smaller than the opening 115. The subassembly is moved forward until the chamber flange 520 is attached via latches 111 to the housing 100. The connection is permanent, no relative, axial or rotational movement between the housing 100 and the chamber 500 is possible.

[0049] The final assembly stage requires a cover 200. The slots 214 are located to connect with the arms 320. The outer diameter 203 fits into the insertion into the inner diameter 103. The inner diameter 203 is larger than the outer diameter of the spring 400. The shield 200 is inserted into the distal assembly end until the stop 212 contacts the distal edge 102 of the housing 100. The proximal edge 212 is tapered. The axial force applied to the sheath 200 will deflect portions of the sleeve body 203 separated by the cam guide paths 214. This will return to its original position when the stops 212 reach the slots 106. This stage completes assembly of the assembly.

[0050] The invention described above relates to an injection device in which the needle insertion steps and injections are carried out manually, which invention can also be used in automatic injection devices in which one or both of these operations are carried out automatically. In particular, the shield driving means may additionally provide the driving force of said pusher and a spring release mechanism securing the spring to the pusher at its distal end.

Aleksandra Twardowska, PhD

Patent Attorney