GB2552798A

GB2552798A - Medical device

Info

Publication number: GB2552798A
Application number: GB1613659.0A
Authority: GB
Inventors: Fauerby Larsen Bent
Original assignee: Danish Medical Innovatoin Aps
Current assignee: Danish Medical Innovatoin Aps
Priority date: 2016-08-09
Filing date: 2016-08-09
Publication date: 2018-02-14
Anticipated expiration: 2036-08-09
Also published as: GB2552798B

Abstract

A medical device e.g. syringe comprising a barrel 12, a needle holder 16, the needle holder 16 comprising an outer portion 30 connected to the barrel 12, an inner portion 32 comprising a needle 18, a breaking portion 34 connecting the inner portion 32 to the outer portion 34, and a spring 28 for retracting the needle 18 into the barrel 12. A plunger 22 movable within the barrel 12 towards the needle holder 16, a cutting element 26 projecting from the plunger 22, the cutting element 26 arranged to contact and break the breaking portion 34 of the needle holder 16 to allow the spring 28 to retract the needle 18 into the barrel 12 as the plunger 22 is retracted.

Description

(54) Title ofthe Invention: Medical device

Abstract Title: Medical device with retractable needle (57) A medical device e.g. syringe comprising a barrel 12, a needle holder 16, the needle holder 16 comprising an outer portion 30 connected to the barrel 12, an inner portion 32 comprising a needle 18, a breaking portion 34 connecting the inner portion 32 to the outer portion 34, and a spring 28 for retracting the needle 18 into the barrel 12. A plunger 22 movable within the barrel 12 towards the needle holder 16, a cutting element 26 projecting from the plunger 22, the cutting element 26 arranged to contact and break the breaking portion 34 ofthe needle holder 16 to allow the spring 28 to retract the needle 18 into the barrel 12 as the plunger 22 is retracted.

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MEDICAL DEVICE Field of the Invention

The present invention relates to a medical device, such as a syringe, which has a retractable needle.

Background of the Invention

Many forms of medical device have a needle for the delivery of fluids of various sorts into the body of an animal or human, or for aspirating fluids from the body of an animal or human. The danger of injuries from such needles is well known, and are often referred to as needlestick injuries. Such injuries carry the risk of contamination and infection to the user of a medical device from bodily fluids which may be present on the needle.

There have been attempts to provide medical devices which are safer to use and which address the problem of such needlestick injuries. Some of these devices, such as safety syringes, have retractable needles such that, after use, the needle is withdrawn within the body of the device thus intending to prevent any inadvertent injury. However, known devices can suffer from a number of disadvantages.

The mechanism for activating the movement of the needle into the body of the device can be quite difficult to perform by hand, and can often require considerable force. In some cases the mechanism is not completely reliable, and so the needle can be prevented from moving into the body of the device in some situations. Furthermore, the uncontrolled rapid withdrawal of the needle into the body of the device can cause further problems, such as the unwanted splashing of fluid from the needle during a sudden movement.

The present invention seeks to provide a medical device which is safer to use.

US2012/004621 discloses a medical device having a barrel, a retractable needle, a needle retraction assembly and a plunger, the needle retraction assembly including and being held inside the barrel prior to retraction at least in part by a retainer member contacting the barrel, the plunger comprising seal with a body having at least a portion that is rearwardly moveable relative to the plunger and an elastomeric web that seals a retraction cavity inside the plunger prior to retraction of the needle, the retainer member and the plunger seal each cooperating with an inside wall of the barrel to provide a sealed liquid containment chamber inside the device.

The present invention seeks to provide a medical device which can retract a needle of the medical device into the inner volume of the device to prevent re-use of the device and for storing the needle in order to protect healthcare personnel against any contact to a used needle. The present invention also seeks to provide a medical device which can achieve a controlled retraction of the needle.

Description of the Invention

The present invention will now be described by way of example, with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a medical device in the form of a safety syringe of the invention;

Figure 2 is a cross-sectional view of a syringe of the invention;

Figure 3 is an enlarged partial cross-sectional view of a safety syringe;

Figure 4 is an enlarged partial cross-sectional view showing a cutting element in contact with the breaking portion of a syringe;

Figure 5 shows a cutting element after breaking the breaking portion of the syringe;

Figure 6 shows the needle partially retracted into the syringe; and

Figure 7 shows the needle fully retracted within the syringe.

According to an aspect of the invention there is provided a medical device comprising a barrel, a needle holder, the needle holder comprising an outer portion connected to the barrel, an inner portion comprising a needle, a breaking portion connecting the inner portion to the outer portion, and a spring for retracting the needle into the barrel, a plunger movable within the barrel towards the needle holder, a cutting element projecting from the plunger, the cutting element arranged to contact and break the breaking portion of the needle holder to allow the spring to retract the needle into the barrel as the plunger is retracted.

Preferably, the medical device is a syringe.

Conveniently, the inner portion and the outer portion of the needle holder are substantially cylindrical.

Advantageously, the breaking portion is substantially annular.

Preferably, the cutting element is substantially circular.

Conveniently, the plunger has a substantially convex face and the needle holder has a substantially concave face.

Advantageously, the plunger is not hollow.

Preferably, the spring is substantially conical.

Conveniently, the springs acts to angle the needle away from the axis of the barrel upon retraction.

Advantageously, the retraction of the needle into the barrel is limited by the retraction of the plunger into the barrel.

Preferably, the barrel and/or plunger comprise a thermoplastic polyolefin, preferably a homo- or co-polymer of polyethylene or propylene or mixtures thereof.

Conveniently, the needle holder comprises a styrene acrylonitrile copolymer, unplasticised polyvinyl chloride (PVC), or acrylonitrile butadiene styrene (ABS).

According to another aspect of the invention, there is provided a method of operating a medical device as defined above, comprising moving the plunger towards the needle holder to expel material from the barrel through the needle; contacting and breaking the breaking portion of the needle holder with the cutting element of the plunger; and allowing the spring to retract the needle into the barrel as the plunger is retracted.

The present invention will now be described in more detail.

Figure 1 is a perspective view of a medical device of the present invention, in the form of a syringe 10. The syringe 10 comprises a barrel 12 having a pair of perpendicularly extending projections 14 at its proximal end. The projections 14 facilitate the manual handling and use of the device. At the distal end of the barrel 12 there is located a needle holder 16 from which projects a needle 18. Figure 1 shows a removable safety cap 20 fitted at the distal end of the barrel 12, covering the needle 18. Within the barrel 12 there is located a plunger 22 connected to a piston 24 having a handle portion 26 at its proximal end. In use, a user may grasp the projection 14 with their fingers whilst depressing the handle portion 25 with their thumb in order to move the plunger 22 within the barrel 12 towards the needle holder 16.

Figure 2 shows a cross-sectional view of the syringe 10 described above. Figure 2 shows the syringe 10 in a little more detail, with the plunger 22 located towards the proximal end of the barrel 12, being connected to the handle portion 25 by the piston 24. On the face of the plunger 22 that faces towards the distal end of the barrel, there is located a breaking element 26. In the embodiment shown the breaking element 26 is a circular or ring-like projection on the external surface of a plunger 22. The function of the breaking element 26 will be described in more detail below. The needle holder 16 serves to hold the needle 18 in position for use. It also facilitates the retraction of the needle 18 after use. As shown there is a spring 28 within the needle holder 16, the function of which will be described in more detail below.

Figure 3 is a partial enlarged view of the syringe 10. Figure 3 shows the position where the plunger 22 has been moved within the barrel towards the distal end of the barrel 12. In moving within the barrel towards the distal end as shown, the plunger 22 has ejected material from within the plunger 12 out through the bore of the needle 18.

As shown, the needle holder 16 comprises an outer portion 30 adjacent to the internal surface of the barrel 12, and an inner portion 32 which holds or carries the needle 18. In the embodiment shown, both the outer portion 30 and the inner portion 32 of the needle holder 16 are substantially cylindrical. The inner portion 32 is located substantially concentrically within the outer portion 30. The outer portion 30 and the inner portion 32 of the needle holder 16 are connected by a relatively thin and mechanically weak area, identified as the breaking portion 34.

In normal use, the inner portion 32 and the outer portion 30 of the needle holder 16 are securely connected together, and allow the use of the syringe to inject fluid into an animal or human, or to aspirate fluids from an animal or human. Figure 3 also shows the spring 28 in a compressed position, located between the distal end of the barrel 12 and the inner portion 32 of the needle holder 16. Although the spring 28 exerts a force on the inner portion 32 of the needle holder 16 towards the proximal end of the barrel 12, the integrity of the breaking portion 34 ensures that the inner portion 32 and needle 18 remain where they are during use.

Once all of the fluid has been expelled from the chamber 12 into the body of the patient, or if a sufficient amount has been injected has been injected or aspirated, the user can decide to activate a retraction mechanism to withdraw the needle 18 into the barrel 12 of the syringe 10. This serves to prevent unwanted needlestick injuries, and also prevents potentially dangerous reuse of the syringe. Figure 4 shows the position following on from that shown in Figure 3, with the plunger 22 being moved very near to the distal end of the barrel 12. The cutting element 26 is in contact with the breaking portion 34 of the needle holder 16. In the position shown in Figure 4, the cutting element 26 is in contact with the breaking portion 34, but has not actually broken the breaking portion 34. In use the user would be able to feel the physical resistance at this stage so they know that further pressure exerted onto the plunger 22 will cause the cutting element 26 to break the needle holder 16 at the breaking portion 34.

Figure 5 shows the position following on from that in Figure 4, where the user has exerted more pressure to force the plunger 22 further towards the distal end of the barrel 12. In this position the cutting element 26 has broken through the breaking portion 34 of the needle holder 16, thus physically separating the outer portion 30 of the needle holder 16 from the inner portion 32. The figures show a preferred embodiment in which the interior face of the needle holder 16 is concave. In other words, the face of the needle holder which faces into the barrel is not concave or planar, it is either conical or concave. It is has been found that such a shape ensures a more accurate breaking of the breaking portion by the cutting element.

Another advantage of the present invention is that the cutting element is provided on the exterior of the plunger. This allows for a simple and inexpensive construction of the plunger and device and also provides advantages in use. The cutting element is simply brought into contact with the breaking portion 34 as the user moves the plunger towards the distal end of the barrel 12. The user will then be able to feel that the cutting element has contacted the breaking portion 34. They can then exert slightly more pressure in order to break the breaking portion 34 of the needle holder 16. As no other elements or parts of the device need to be broken or moved at this stage, the force required to activate the retraction method is kept to a minimum. This ensures that the syringe is easy to use by the user without needing to exert unnecessarily large forces, which can cause problems and injury both to the user and the patient.

So, in the position shown in Figure 5 the cutting element 26 has broken through the breaking portion 34, thus physically separating the inner portion 32 with the attached needle 18, from the outer portion 30 of the needle holder 16. The spring 28, as mentioned above, inserts a force on the inner portion 32 of a needle holder 16 to push it into the interior of the barrel 12. However, as shown the plunger 22 is in position in contact with the needle holder 16. As such, the inner portion 32 and needle 18 can only be retracted into the barrel 12 as the plunger 22 is also retracted into the barrel 12. In some embodiments the spring 28 exerts a sufficient force to push the plunger 22 towards the proximal end of the barrel 12, ensuring a controlled retraction of the needle 18 into the barrel 12. In other embodiments the user is required to manually withdraw the plunger 22 towards the proximal end of the barrel 12 to allow the spring 28 to push the inner portion 32 and needle 18 into the interior of the barrel.

These features of the device are advantageous as it allows for the controlled retraction of the needle 18 into the barrel 12. This ensures that the needle does not rapidly and uncontrollably withdraw into the barrel, which can cause unwanted splattering or spillage of fluids from the needle 18. This is advantageous as the unwanted scattering of the fluids such as blood is an infection risk and should be avoided.

The design of the present invention provides a number of other advantages. In particular, the present device does not require a hollow inner cylinder or plunger/piston. Some prior art safety syringes withdraw the needle into a hollow region within the device, particularly within the plunger/piston. The present invention has an advantage over those designs in that the sudden and uncontrolled retraction of the needle into the device is avoided. In the present invention, the fact that the retraction of the needle is limited by the retraction of the plunger serves to provide a smooth and controlled withdrawal of the needle into the device. Furthermore, the present invention does not require a hollow region or inner cylinder, particularly a hollow plunger/piston arrangement. This results in a simpler manufacturing construction of the device, which is lighter and simpler to use. Also keeps costs down compared to more complicated designs.

Figure 6 shows the situation following on from Figure 5, where the plunger 22 has been withdrawn further towards the proximal end of the barrel 12. This allows the spring 28 to push the inner portion 32 of the needle holder 16 towards the proximal end of the barrel

12. As shown the outer portion 30 of the needle holder 16 remains in place at the distal end of the barrel 12. However, the inner portion 32 of the needle holder 16 along with the needle 18 are partially retracted towards the interior of the barrel 12.

As this process is continued, it leads to the situation shown in Figure 7. In Figure 7 the plunger 22 has been retracted further towards the proximal end of the barrel 12. The spring 28 has fully extended, serving to completely retract the inner portion 32 and needle 18 into the interior of the barrel 12. In the embodiment shown the spring 28 is a conical spring. In other words the spring 28 is tapered such that the end of the spring towards the distal end of the barrel 12 is wider than the end of the spring towards the proximal end of the barrel 12. The spring causes the needle 18 to be tilted at an angle to the longitudinal axis of the barrel 12. As shown, this means that, as the needle 18 withdrawn into the interior of the barrel 12, the needle is tilted such that the tip 35 of the needle 18 is at an angle relative to the longitudinal axis of the barrel. So if the user did try to reuse the syringe by exerting pressure on the plunger 22, the needle 18 will simply abut the interior of the distal end of the barrel 12, rather than be pushed back out of the aperture 36 through which the needle 18 was initially retracted.

Hereby it can be achieved that the syringe can be operated in the same way as traditional syringes during preparation and filling with liquid. Also, in normal use for injection, the use of the syringe is the same as that of traditional syringes. This new invention is activated when the operation of injection is completed because by pressing down the piston in order to empty the inner volume of the syringe, the cutting device will automatically come into contact with the breaking area between the inner and the outer cylinder. By a slightly increasing pressure upon the piston, the cutting device will penetrate the breaking area and in that way release the inner cylinder. Pulling back the piston will release the spring which spring now forces the inner cylinder and the needle in an upwards direction. The speed of the retraction of the needle is controlled either by the friction between piston and barrel or by ventilation openings into the inner volume of the syringe when the breaking area is penetrated. Hereby a slow and gentle retraction of the needle is achieved which is almost fully independent of the speed of retraction of the piston. The spring continues pulling back the needle up to a position where the needle is fully integrated in the syringe. If the piston is reactivated and pressed downwards, the spring is acting upon the forces at the needle and the inner cylinder in a not totally axial direction whereby the needle is forced in a sideward direction and the needle will not hit the opening in the syringe, so the needle is totally protected inside the syringe. In this way it is achieved that no medical personnel or any personnel handling waste will come in contact with a used needle. In hospitals, often personnel are injured by using needles which today starts a huge programme to protect the medical personnel against the consequences of the used needle. Therefore, the pending application has a large potential in protecting health care personnel and waste-handling personnel because the risk of being injured by needles is totally eliminated.

In a preferred embodiment of the invention the breaking area of the connection between outer and inner cylinders can be circular. Hereby it can be achieved that the breaking area operates as a liquid-tight diaphragm in operation until the breaking area is activated by the cutting device fastened to the piston. As soon as the circular breaking area is penetrated, the spring force will break the rest of the circular breaking area, and the spring will start pushing the inner cylinder and the needle upwards in the volume beneath the piston. The speed of retention has already been described above.

In a further preferred embodiment of the invention the cutting device can comprise at least one sharp edge for partly penetrating the breaking area. Depending on the design of the cutting device, which could be a type of double-edged knife cutting partly the breaking area, the spring is allowed to perform breaking of the rest of the breaking area. Depending on the force of the spring, this force is sufficient for pushing back the piston so that if the person using the syringe simply removes his/her thumb from the handle, the retention of the needle and the movement backwards of the piston will be performed automatically by the spring. Hereby a very slow retention of the needle is further achieved.

In a further preferred embodiment of the invention the cutting device can comprise a plurality of edges for partly penetrating the breaking area. Hereby it can be achieved that the breaking area will be penetrated at several points when pushing down the piston through its end position. Hereby the cutting area is weakened in such a way that the force of the spring will automatically break the rest of the material, and if the spring is sufficiently strong, the inner part of the cylinder carrying the needle together with the piston will be moved slowly upwards.

In a further preferred embodiment of the invention the cutting device can comprise a circular edge for penetrating the circular breaking area. Hereby it can be achieved that the whole circle of the breaking area will be penetrated more or less by the downwards end movement of the piston. Hereby the spring is released, and the inner part of the cylinder together with the needle starts moving upwards pressing the piston in an upwards direction until the piston ends in its top position. Hereby the needle is fully protected inside the syringe.

In yet another embodiment, the needle holder is made of styrene acrylonitrile copolymer, unplasticized, i.e. rigid, polyvinyl chloride (PVC) or acrylonitrile butadiene styrene (ABS) or mixtures thereof. These polymers are particularly preferred as they provide a clean break without tendency to break in a hinged break when the cutting device penetrates the breaking area. In addition these materials can be provided in medical grade quality, and can be subjected to sterilisation without altering the physical or chemical properties of the resin, preferably by gamma radiation or by chemical sterilisation using ethylene oxide gas. In addition, the above-mentioned polymeric materials are compatible with the other resins used in the syringe, in particular the resin used in the piston or the polyolefin material used in the barrel and/or the plunger. The needle holder is preferably cast by injection moulding or similar well-known techniques, and the above-mentioned polymers are particularly suitable for injection moulding as they will not need a slip agent and they are less likely to leave any welding lines and/or air traps in the moulded needle holder.

A non-limiting example of a suitable styrene acrylonitrile copolymer is e.g. Kostil® provided by Versalis SpA and having a density of 1,07g/m³ or similar commercially available medical grade styrene acrylonitrile copolymers.

A non-limiting example of a suitable unplasticized, i.e. rigid, polyvinyl chloride (PVC) is e.g. Hy-Vin® provided by Ineos compounds and having a density of 1.35 g/m³ or similar commercially available medical grade unplasticized PVC.

A non-limiting example of a suitable acrylonitrile butadiene styrene (ABS) is e.g. Cyclolac® provided by Versalis SpA having a density of 1,04-1,06 g/m³ or similar commercially available medical grade ABS polymers.

In another preferred embodiment, the barrel and/or the plunger are likewise made of a commercially available medical grade resin, in particular a thermoplastic poyolefin, especially a homo- or copolymer of polyethylene (PE) or polypropylene or mixtures thereof because they provide a syringe of high quality, which can be sterilized by gamma radiation, or chemically sterilized using ethylene oxide gas. In particular, a high density PE is preferred for producing the barrel and a polypropylene copolymer is used for producing the plunger.

In order to be able to cut the inner cylinder from the outer cylinder of the needle holder, the cutting device is made of a material having a hardness which is equal to or higher than the material used for the needle holder. The cutting device is e.g. made of the same material as the needle holder, i.e. as indicated above or a medical applicable polymeric or metallic material having a hardness equal to or higher than the material used for the needle holder as indicated above.

In the following the invention is disclosed as a method for operating a syringe, which method comprises at least the following sequence of steps:

a. prepare the syringe and fill the inner volume of the syringe with a defined liquid,

b. perform injection by pressing the piston downwards and forcing the liquid to flow through the needle,

c. let the edges of the cutting device penetrate the breaking area of the needle holder,

d. automatically move the piston upwards,

e. release the spring and let the spring move the inner cylinder of the needle holder upwards and retract the needle into the barrel.

Hereby it is achieved that the syringe can be used as traditional syringes by filling a liquid into the syringe and performing normal operation. This invention is not activated until the piston reaches its lower position and the breaking area is broken by the cutting tool. The spring is hereby released, and the spring starts pressing the inner cylinder upwards, and forces generated by the spring are acting upon the piston. Hereby the piston will be forced to move upwards in a very slow manner because the friction between piston and barrel limits the speed of the upwards movement. Hereby a very soft and gentle retraction of the needle is performed which in some situations can avoid complications to a patient. In this way, the needle is retracted directly from the patient and into the inner of the syringe. Hereby any possible contact with the needle is avoided. Because of the spring acting in a non-axial direction, pressing the piston downwards will move the needle in a sideward direction so the needle will be fixed into the syringe. Hereby full protection of the needle in the inner of the syringe is achieved. By using this syringe no healthcare personnel will be injured by contact with needles having been used for sick persons.

The present invention relates to medical devices in general which comprise a needle. A preferred embodiment is a syringe, although the invention is not limited just to syringes.

One aspect of the invention relates to the cutting element on the plunger. In the present invention the cutting element projects from the plunger. In other words, the cutting element is on the external face of the plunger, which faces towards the needle holder. In use, the user can exert pressure to move the plunger within the barrel towards the needle holder. In doing so material contained within the plunger, such as a solution of a drug, will be forced of the barrel through the needle and out of the device. Once the desired amount of material has been expelled from the barrel, or all of the material has been expelled from the barrel, the needle can be retracted for safety. If all of the material has been injected into the patient, then the withdrawal of the needle can occur without having to remove the needle from the body of the patient. It is also an option for the user to withdraw the needle from the body of the patient before activating the mechanism to withdraw the needle itself.

In order to withdraw the needle into the body of the device, the plunger is moved into contact with the needle holder. The cutting element projecting from the plunger will contact the breaking portion of the needle holder. As pressure is exerted on the plunger, the breaking element of the plunger will break the breaking portion of the needle holder. This will separate the outer portion of the needle holder (which is attached to the barrel) from the inner portion of the needle holder (which carries the needle). As mentioned above, the medical device comprises a spring for retracting the needle into the barrel. The spring is compressed such that it exerts a force acting to move the inner portion of the needle holder and the needle into the barrel. Once the breaking portion has been broken, the inner portion is separate from the outer portion of the needle holder. The spring will exert a force acting to retract the needle. However, this cannot happen unless the plunger is retracted into the barrel. This allows for a controlled retraction of the needle. This is particularly advantageous over syringes where no such control is provided. In many prior art syringes, once the retraction mechanism is activated, the force rapidly and uncontrollably withdraws the needle into the device, often into a hollow plunger. This rapid withdrawal of the needle is unwanted for several reasons. Firstly, if the syringe is within the body of the patient when retraction is initiated, the rapid withdrawal can cause pain and additional injury. Furthermore, the rapid withdrawal can cause splashing or splatter of material from the needle, including bodily fluids. This is clearly raising the risk of infection and injury for both the patient and the user of the medical device. Instead the present invention allows for the controlled retraction of the needle once the retraction mechanism has been initiated.

As mentioned above, the retraction of the needle into the barrel of the medical device is limited by the retraction of the plunger within the barrel. In a further embodiment, the user can press the plunger against the needle carrier to break the breaking portion and then release the plunger. The force of the spring will then, controllably, retract the needle whilst also pushing against and retracting the plunger into the barrel at the same time. In other embodiments the user may control the retraction of the needle by moving or helping to move the plunger into the barrel.

Advantageously, the force of the spring acts to angle the needle in such a way such that it prevents the needle from being moved to subsequently project from the medical device. In other words, as the spring acts to withdraw the needle into the barrel, it also acts to tilt the needle away from the longitudinal axis of the barrel. As such, if a user attempts to push the needle back out of the medical device, this cannot happen because the needle tip is located away from the aperture leading out of the barrel. So exerting force on the plunger to move the needle would not cause the needle to be forced back out of the barrel. This is particularly the case when a conical spring is used. By conical spring we mean a spring which is tapered such that the end of the spring located near the end of the barrel is wider than the end of the spring which extends into the barrel.

It is also advantageous for the face of the needle holder to be concave. By this we mean that the face of the needle holder which faces the barrel is concave. This helps to ensure a clean and accurate break of the breaking portion by the cutting member of the plunger. In a preferred embodiment the face of the plunger facing the needle holder is convex. By convex mean both shapes which are curved and/or conical.

An advantage of the medical device is that it can be provided in the form of a familiar product design. For example, the medical device can be in the form of a syringe, familiar to users. This helps to ensure correct use and minimises any additional training of health/clinical staff.

Claims

1. A medical device comprising a barrel, a needle holder, the needle holder comprising an outer portion connected to the barrel, an inner portion comprising a needle, a breaking portion connecting the inner portion to the outer portion, and a spring for retracting the needle into the barrel, a plunger movable within the barrel towards the needle holder, a cutting element projecting from the plunger, the cutting element arranged to contact and break the breaking portion of the needle holder to allow the spring to retract the needle into the barrel as the plunger is retracted.

2. The medical device according to Claim 1 which is a syringe.

3. The medical device according to Claim 1 wherein the inner portion and the outer portion of the needle holder are substantially cylindrical.

4. A medical device according to any preceding claim wherein the breaking portion is substantially annular.

5. A medical device according to any preceding claim wherein the cutting element is substantially circular.

6. A medical device according to any preceding claim wherein the plunger has a substantially convex face and the needle holder has a substantially concave face.

7. A medical device according to any preceding claim wherein the plunger is not hollow.

8. A medical device according to any preceding claim wherein the spring is substantially conical.

9. A medical device according to any preceding claim wherein the springs acts to angle the needle away from the axis of the barrel upon retraction.

10. A medical device according to any preceding claim wherein the retraction of the needle into the barrel is limited by the retraction of the plunger into the barrel.

11. A method of operating a medical device as defined in any preceding claim, comprising moving the plunger towards the needle holder to expel material from the barrel through the needle; contacting and breaking the breaking portion of the needle holder with the cutting element of the plunger; and allowing the spring to retract the needle into the

10 barrel as the plunger is retracted.

25 10 17

Intellectual

Property

Office

Application No: GB1613659.0 Examiner: Dr Matthew Parker

11. A medical device according to any preceding claim wherein the barrel and/or plunger comprise a thermoplastic polyolefin, preferably a homo- or co-polymer of polyethylene or propylene or mixtures thereof.

12. A medical device according to any preceding claim wherein the needle holder comprises a styrene acrylonitrile copolymer, unplasticised polyvinyl chloride (PVC), or acrylonitrile butadiene styrene (ABS).

10 13. A method of operating a medical device as defined in any preceding claim, comprising moving the plunger towards the needle holder to expel material from the barrel through the needle; contacting and breaking the breaking portion of the needle holder with the cutting element of the plunger; and allowing the spring to retract the needle into the barrel as the plunger is retracted.

AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS

1. A medical device comprising a barrel,

5 a needle holder, the needle holder comprising an outer portion connected to the barrel, an inner portion comprising a needle, a breaking portion connecting the inner portion to the outer portion, and a spring for retracting the needle into the barrel, a plunger movable within the barrel towards the needle holder, a cutting element projecting from the plunger, the cutting element arranged to

10 contact and break the breaking portion of the needle holder to allow the spring to retract the needle into the barrel as the plunger is retracted;

wherein the retraction of the needle into the barrel is limited by the retraction of the plunger into the barrel.

15 2. The medical device according to Claim 1 which is a syringe.

20 4. A medical device according to any preceding claim wherein the breaking portion is

LO substantially annular.

CM

7. A medical device according to any preceding claim wherein the plunger is not 30 hollow.

35 9. A medical device according to any preceding claim wherein the barrel and/or plunger comprise a thermoplastic polyolefin, preferably a homo- or co-polymer of polyethylene or propylene or mixtures thereof.

10. A medical device according to any preceding claim wherein the needle holder comprises a styrene acrylonitrile copolymer, unplasticised polyvinyl chloride (PVC), or acrylonitrile butadiene styrene (ABS).