GB2528269A

GB2528269A - Single use safety syringe with automatic retractable needle

Info

Publication number: GB2528269A
Application number: GB1412531.4A
Authority: GB
Inventors: Ebrahim Karolia; Martin John Heywood
Original assignee: COMMODIOUS LLP
Current assignee: COMMODIOUS LLP
Priority date: 2014-07-15
Filing date: 2014-07-15
Publication date: 2016-01-20
Also published as: GB201412531D0; WO2016009165A1

Abstract

A single use safety syringe comprising a fluid chamber 2, a needle assembly 14 and a separate storage chamber 4 attached laterally to the fluid chamber such that after use the needle assembly is automatically withdrawn into the storage chamber preventing accidental needle pricks. The syringe may have two plungers 6 8 which are both retracted by the same slider 10. The safety plunger 8 is then held in position via a ratchet system 16. When the syringe is used, slider 10 is compressed and due to its construction only moves fluid plunger 6 down. A bar of the slider 10 engages with a retaining clip 12 (normally engaged with clip housing 28), which is released and thus releases the needle assembly 14. Due to a vacuum created by plunger 8 when it is withdrawn, a spring and/or elastic material, the needle assembly is retracted into the storage chamber. Seals 22 prevent fluid or air entering the storage chamber.

Description

Single use safety syringe with retractable needle This invention relates generally to a safety syringe of the type for use with a hollow needle.

After use of the syringe the needle and assembly are retracted into a separate storage chamber, specifically not the syringe fluid chamber and not the fluid plunger, thereby preventing accidental pricking after use and making the syringe so it cannot be re-used. The retraction of the needle and assembly is effected by the creation of a vacuum and/or applying torsion to a spring or elastic material during the normal operation of the syringe. A syringe of this general type is sometimes referred to as a "retractable syringe"; what is meant by this term is that the needle retracts within the body of the syringe.

It is well known that many dangerous communicable diseases are spread through contacting the body fluids of an infected person. After use of a syringe, residual body fluids are likely to remain on or within the syringe needle. For this reason, syringes are typically intended for a single use only. In order to be handled safely after use, the needle of a syringe must be covered to prevent it from accidentally pricking a person who is, for example, collecting the syringe for disposal, thereby releasing residual body fluids into such person. Typically, a protective cap is provided with the syringe, which after use of the syringe, can be used to cover the tip of the needle. However, it sometimes happens that persons attempting to cap a used needle miss the cap and accidentally stab themselves, resulting in potential exposure to communicable diseases. Further, spread of communicable and dangerous diseases is effected by drug-addicted individuals sharing and re-using needles and syringes intended for single use. There have been several attempts to address this problem by incorporating into syringes, mechanisms for retracting the needle into the syringe following use and thereby preventing re-use.

U.S. Patent No. 5,334,155 (Sobel, 2 August 1994) discloses a needle guard comprising an evacuated double walled protective sheath. Before use, the partial vacuum within the protective sheath causes the sheath to fold inwardly upon itself so that the needle extends beyond the protective sheath and may be used for injections. Subsequent to injection, the double wall of the protective sheath can be breached in one place so that the inside of the protective sheath reaches atmospheric pressure. The protective sheath then extends to cover the projecting needle. However, the protective sheath may interfere with use of the syringe as it may obstruct the view of the point the needle is to be inserted into the patient. In addition, it is inconvenient to use; after injection, the user must change the user's hand position on the syringe in order to breach the double wall and activate the sheath. In this manner activation of the safety mechanism is not automatic following injection of the medicament.

The protective safety device shown in U.S. Patent No. 5,188,614 (Hart, 23 February 1993) is a hollow cylindrical casing that encompasses the syringe. A dual component foaming agent is disposed at the downstream end of the casing. Following injection, the two components of the dual component foaming agent are mixed, creating an expanding foam mixture that forces the syringe back within the casing and encompasses the needle. However, this device suffers from the disadvantages that the casing may interfere with the use of the syringe in making injections as it is designed to fit over a conventional syringe thereby changing the size and feel of the device as compared to a conventional syringe. In addition, a considerable amount of material is necessary in order to make the protective sheath, increasing the expense of both making and disposing of the device.

U.S. Patent No. 6,193,695 (Rippstein, 27 February 2001) discloses a safety syringe comprising a vacuum chamber on the upstream side of the plunger head. Following injection of medicament, the plunger head engages the needle head, the ambient atmospheric pressure external to the needle head acts on the needle head, forcing the needle and plunger back against the vacuum into the syringe body. The plunger arm may then be snapped off by the user to prohibit further use of the needle. This device suffers from the disadvantage that accidental re-extension of the needle is possible if the plunger arm is not snapped off by the user. A further disadvantage of this device is that if the user does not apply a constant injection force, there is the possibility that the plunger will retract under the vacuum before the medicament is completely injected, thereby causing the syringe to work in reverse especially when clearing an air bubble in the fluid.

U.S. Patent No. 6,413,236 (Van Dyke, 2 July2002) discloses a safety syringe comprising a vacuum chamber on the upstream side of the plunger head. Following injection of medicament, the plunger head engages the needle head, and the ambient atmospheric pressure external to the needle head acts on the needle head, forcing the needle and plunger back against the vacuum into the syringe body. In this patent, in contrast to U.S. Patent No. 6,193,695, the needle is lodged in the syringe body at an angle so that the piercing tip end of the needle is pressed against the inner surface of the syringe prohibiting re-extension of the needle even though the plunger arm is fully extended outside the syringe body. However, this device still has the disadvantage that if the user does not apply a constant injection force, there is the possibility that the plunger will retract under the vacuum before the medicament is completely injected, thereby causing the syringe to work in reverse especially when clearing an air bubble in the fluid.

There are other designs where a vacuum is pre-formed at manufacturing stage in the plunger body. However this adds a manufacturing cost and there is a loss of vacuum over time which means the product has a shelf life and therefore cannot be described as totally reliable.

A syringe designed to provide an optimal solution to the problem of prevention of accidental needle pricking after the use of the syringe for injection would include the following characteristics: 1. The syringe mechanism should be relatively simple, in that it should be made from as few parts as possible, consistent with its design objectives, and should be simple to operate with no training required for use.

2. The syringe mechanism should reliably retract the needle so that accidental pricking is prevented.

3. The syringe should be as inexpensive to manufacture as possible.

4. There should be as little waste as possible from plastics and other materials on disposal of the redundant syringe.

5. Safety-related means should not appreciably interfere with the feel of the syringe in the users hand.

6. Once the needle has been retracted, a reliable safety device should prevent the needle from becoming once again exposed.

7. The syringe should be ergonomically designed to give easier use and thus less suffering to the patient.

It is an object of the present invention to provide an improved vacuum-operated safety syringe with a retractable-needle that also achieves the objectives stated 1. toY. The present invention proposes a syringe fitted with a conventional fluid chamber and separate needle assembly storage chamber, after use the whole needle assembly will be drawn into the storage chamber such that the needle cannot prick anybody and the syringe cannot be re-used.

The withdrawal of the needle assembly into the safety storage chamber is preferably provided by a vacuum although the withdrawal could also be provided by other means, such as a spring or elastic material.

The needle assembly may have different size needles, so that the user can select the correct needle size for the job in hand.

The invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows a syringe assembly (section view) prior to fitting the needle assembly.

Figure 2 shows a syringe assembly (section view) with the needle assembly fitted and the fluid chamber full and ready to be dispensed.

Figure 3 shows a syringe assembly (section view) with the fluid dispensed and the needle assembly safely withdrawn into the safety storage chamber.

Figure 4 shows front, side, top and bottom views of a typical arrangement of the fluid chamber and safety storage chamber.

Figure 5 Shows an exploded view of a typical arrangement of the syringe assembly components.

Figure 6 Shows a detailed 3D style view of a needle and the complete needle assembly.

In Figure 1, a syringe assembly is shown prior to fitting the needle assembly, a fluid plunger 6 is shown prior to use attached to an externally fitted slider plate 10. The fluid chamber 2 is conventional but the filling/dispensing hole or port 18 is arranged at the bottom to one side.

The safety storage chamber 4 has the safety plunger 8 in a forward position and this is also attached to the external slider plate 10. In this arrangement the safety plunger 8 is shown with no spring or elastic material attached but in some arrangements a spring or elastic material may be attached. The ratchet system 16 that only allows upwards movement of the safety plunger 8 is shown as is the needle assembly retaining clip 12, the clip is shown ready to receive the needle assembly as it is protruding into the safety chamber 4. The slider 10, has a bar with a chamfered tip that in the position shown in Figure 1 just contacts the top of the retaining clip 12.

In Figure 2 the needle assembly 14 has been fitted and is held in position by the retaining clip 12 which is located into the groove 28 of the needle assembly. During fitting of the complete needle assembly 14 the chamfered edges of the vacuum seals 22 push the corresponding chamfer on the retaining clip 12 thus allowing the needle assembly 14 to push the retaining clip 12 out of the way during fitting the assembly 14 into the safety storage chamber 4. The groove 28 has parallel square edges that do not allow the clip 12 to be moved irrespective of whether the assembly 14 is pulled or pushed. Thus when the clip 12 is located in the groove 28 the assembly 14 cannot be moved upwards or downwards. The slider 10 is shown in the upwards position and has caused the fluid plunger 6 to move upwards drawing fluid in through the needle assembly 14 via the assembly port/hole 26 and the filling/dispensing hole or port 18. In Figure 2 the assembly po Whole 26 is shown as a hole made on one side of the assembly 14 and located directly opposite the filling/dispensing hole or port 18, this is for ease of drawing only. The port/hole 26 can be in any orientation and fluid can still pass in both directions during filling and dispensing because of the groove around the assembly created between the two seals 24. Also in some designs the port/hole 26 is made right through the assembly 14 and this is shown more specifically in Figure 6. In this arrangement shown in Figure 2 the movement of slider 10 has also caused the safety plunger 8 to move upwards forming a vacuum in the safety chamber 4, the double seals 22 on the needle assembly prevent the loss of vacuum. In other arrangements the movement of slider 10 upwards may torsion a spring or elastic material attached to the top of the assembly 14 and the safety plunger 8. It should be noted that air bubbles in the fluid chamber 2 are easily cleared by inverting the syringe and pushing the slider 10, towards the needle, the ratchet 16 prevents the safety plunger from moving thus holding the vacuum created as shown in this arrangement Figure 2. In other arrangements using springs or elastic material the torsion or tension is also maintained by the ratchet system 16 that prevents loss of torsion or tension even though the slider is moved downwards. The design of the slider 10 means it can push or pull the fluid plunger 6 but only pull the safety plunger 8. The seals 24 prevent fluid escaping into the safety chamber 4 or past the clip 12 or outside the main body of the device. There are two air escape holes 20 in the top of the device that prevent pressure build up, be that positive or negative, during operation of the syringe.

In Figure 3, the fluid has all been dispensed and the fluid plunger 6 has been pushed by means of the slider 10 to the bottom of the fluid chamber 2 dispensing all the fluid out of the hole/port 18. The bar with the chamfered tip that runs down the underside of the slider plate 10 has engaged with the top of the retaining clip 12, this has been forced back into the central groove thus the vacuum created in the safety storage chamber 4 has acted upon the needle assembly 14 and drawn the whole assembly 14 upwards into the storage chamber as shown. In other arrangements using springs or elastic material as the action of the slider plate 10 on the retaining clip 12 forcing this back into the central groove allows the torsion or tension created to act upon the needle assembly and draw the assembly 14 upwards into the storage chamber.

The whole syringe assembly can now be disposed of safely without danger of the needle pricking somebody or the syringe being re-used.

In Figure 4 there are different views of the arrangement of the components as described and referred to in figures 1,2 and 3. The groove or slot in which the slider plate 10 runs up and down is shown clearly in this drawing on the C -C and B -B end views.

In Figure 5 the exploded view of the components used in this particular syringe assembly are shown for clarity. The slider plate 10 is shown and the means of attaching the fluid plunger 6 and the safety vacuum plunger 8 is shown more graphically. The holes 20 in the top cover plate are shown that allow air to pass in or out to prevent pressure build up during operation of the syringe are shown more clearly.

In Figure 6 the needle assembly 14 is shown in a 3D view to more clearly show the arrangement of the two vacuum retaining seals 22, the retaining clip housing 28 and the fluid filling and dispensing port 26 with the associated seals 24 that prevent fluid escaping when it is being drawn in or dispensed. In this case the fluid filling and dispensing port 26 is shown as a hole right through the body of the needle assembly

Claims

Claims 1) A single use safety syringe comprising a normally operated syringe with laterally attached separate storage chamber such that after use the needle and assembly are automatically withdrawn into the storage chamber so that the syringe cannot be re-used.
2) A single use safety syringe according to claim 1), in which the storage chamber is sized to accommodate the full length of any needle used so that it does not protrude from the storage chamber after use.
3) A single use safety syringe according to claim 1) in which the needle assembly is so constructed to have a lateral hole above any hollow needle fitted which allows the needle assembly to be fitted laterally to the syringe fluid chamber.
4) A single use safety syringe according to claim 3) in which the needle assembly has an arrangement of seals which allows the needle assembly to be fitted laterally to the syringe fluid chamber.
5) A single use safety syringe according to claim 1) in which there is a mechanism to allow simultaneous withdrawal of two plungers in separate chambers.
6) A single use safety syringe according to claim 5) in which the mechanism can only depress one plunger and not act upon any other plunger.
7) A single use safety syringe according to all preceding claims in which a vacuum is formed in a storage chamber simultaneous to the filling of a fluid chamber.
8) A single use safety syringe according to claim 7) in which a spring is tensioned instead of or as well as a vacuum.
9) A single use safety syringe according to claim 7) in which an elastic material is tensioned instead of or as well as a vacuum.