This invention relates to a safety device for a medical needle having a sharp tip and mounted in a hub spaced from the tip, the needle being intended for penetration of a human or animal body, or for other medical uses such as the penetration of a pierceable membrane of an intravenous medication system. For convenience, in the following all medical uses of the needle will be described simply as the penetration of a body, even though specific embodiments may be intended for other medical uses. The invention further relates to the combination of a safety device as aforesaid and a medical needle associated with the housing of the safety device to project forwardly from the housing, for exposure beyond a sleeve slidable telescopically with respect to the housing. Yet further, the invention relates to the combination of a medical needle safety device as aforesaid and a container for the safety device to serve as a package for that device until the device is required for use.

Throughout this specification the terms forward and forwardly used in relation to the safety device and a syringe refer to the end thereof which is approached to a body when a procedure is to be performed, and the direction towards that end. Conversely, the terms rearward and rearwardly refer to the end of the safety device opposed to the forward end and the direction away from that forward end.

Fluids of various kinds may be administered to a human or animal body by means of a hollow needle in conjunction with a source of the required fluid. For example, such a needle may be used in conjunction with a syringe holding a liquid drug which may be contained directly in the syringe barrel or in a cartridge located within the syringe, the needle being used to penetrate the body at the site at which the drug is to be received. Equally, body fluids may be withdrawn by using a hollow needle which is used to penetrate the body until the tip is located at the site from which fluid is to be withdrawn.

A recognised hazard for clinicians and other persons using medical needles for the above described purposes, as well as people who may be exposed to used needles in the course of the disposal of those needles, is the risk of a so-called needle-stick injury - that is to say the accidental penetration of a person's skin by the needle. Prior to the use of the needle to supply a fluid to or to withdraw fluid from a body, this rarely presents much of a problem, though once the needle has been used on a body, there is a very much higher risk of a serious consequence for a person suffering a needle-stick injury. During use of the needle to penetrate the body tissues of a patient, the needle is likely to become contaminated with various organisms; should a person subsequently suffer a needle-stick injury, infection could occur.

There have been numerous proposals for protecting the sharp tip of a used needle, in order to reduce the risk of a needle-stick injury following use of the needle. Some proposals have actually increased the likelihood of such an injury by virtue of the action which must be performed to protect the tip, even if the risk thereafter is lessened. Despite all of the proposals which have previously been made, very few have achieved commercial success, nor has there been wide acceptance by the medical industry. Many proposals are somewhat complex and involve a significantly greater manufacturing cost, and so are unacceptable on economic grounds. Others are much more difficult to use as compared to an unprotected needle, and so are rejected by clinicians. Yet further proposals do not allow compliance with best practice protocols.

A device which protects a needle tip after use without an operator having to perform any extra step on withdrawing the needle from a body is usually referred to as a passive protection device. This may be contrasted with an active protection device, where an operator is required to perform an extra step in order to protect a needle, following the withdrawal of the needle from a body. One known form of such a device requires the operator to apply extra pressure to the syringe plunger following completion of the injection and the withdrawal of the needle from the patient but the requirement to apply extra pressure often means that the operator merely throws the used syringe into a sharps container, without giving protection to the needle tip. Another device requires the operator to apply lateral pressure to the needle to bend the needle into engagement with a cap supported adjacent the unbent needle tip. This carries significant risks for the operator, who has to apply pressure very close to the needle tip and thus there is a likelihood of the operator accidentally contacting the needle tip.

Health and safety legislation has led to a significant demand for protection devices for use with medical needles and which allow a clinician or perhaps others to use the needle in much the same way as is done with an unprotected needle, but which can be manufactured economically and which provide a high degree of protection against needle-stick injury. Passive protection devices tend to be somewhat larger than active devices in view of the greater complication required, and also are significantly more expensive to manufacture. There is thus a need for an active device which is simple, cheap to manufacture, unobtrusive but easy to operate with minimal risk to the operator. So far, no widely accepted active protection device is available and which meets these requirements.

According to this invention, there is provided a safety device for shielding a medical needle having a sharp tip, which device comprises:

- a needle mount for directly or indirectly supporting a medical needle;

- a needle cover for covering a mounted needle;

- a needle shielding sleeve for surrounding a supported needle and cover and arranged coaxially with the mount for sliding rearward movement relative to the mount from a shielding position whereat the sleeve substantially fully surrounds the needle cover towards a non-shielding position whereat a substantial part of the cover is exposed beyond the forward end of the sleeve;

- a sliding surface provided on one of the sleeve and mount;

- at least one elongate resiliently flexible finger provided on the other of the sleeve and mount, the finger having an inner surface for sliding on the sliding surface on rearward movement of the sleeve, said rearward movement thereby resiliently deforming the finger to store energy therein to assist the return of the sleeve to a needle shielding position; whereby rearward movement of the sleeve to the non-shielding position exposes the cover for removal.

It will be appreciated that the safety device of this invention is relatively simple and yet provides safety to a medical needle having a sharp tip. The arrangement is such that the needle cover cannot be easily accessed for removal until the needle shielding sleeve has been moved towards a non- shielding position but when in that position, the cover can be removed by grasping the part of the cover exposed beyond the sleeve and then pulling the cover away from the needle. In an alternative arrangement, movement of the sleeve towards the non-shielding position allows the cover to fall away from the device under gravity, by appropriate downward tilting or pointing of the device.

Preferably, there is a latching mechanism arranged to latch the sleeve at the non-shielding position until unlatched for return of the sleeve to the shielding position, whereby the sleeve remains in the non-shielding position following the removal of the needle cover. Such a latching mechanism may comprise a lug formed on said one of the sleeve and mount and a camming surface provided on the inner surface of the finger for interacting with the lug to hold the sleeve at the non-shielding position. In an alternative embodiment, the latching mechanism is arranged to hold the sleeve in the non-shielding position by friction between overlying parts of the sleeve and the mount. In one embodiment, the mount may comprise the combination of a needle hub and a syringe, and in this case the friction may occur between the sleeve and the syringe, or perhaps a label carried by the syringe, such as a self-adhesive label adhered to the syringe.

Further, the safety device preferably has a blocking mechanism arranged to block rearward movement of the sleeve from the shielding position, unless rendered inactive. Thus the blocking mechanism my perform a blocking action when the sleeve is returned to a shielding position from the non-shielding position, but the blocking mechanism being rendered inactive on initial movement of the sleeve from a needle shielding position towards a non- shielding position. Such a blocking mechanism may comprise an abutment surface provided on said one of the sleeve and mount, and the finger has a part in radial alignment with the abutment surface when the finger is undeformed to block movement of the sleeve from its needle shielding position. Conveniently, that part of the finger in radial alignment with the abutment surface when the finger is undeformed comprises the free end of the finger.

In order to allow said initial movement of the sleeve from its shielding position towards its non-shielding position without the blocking mechanism serving to block that movement, advantageously there is provided a control member having an initial position for interaction with the blocking mechanism to render the blocking mechanism inactive and so allow movement of the sleeve from the needle shielding position towards the non-shielding position, and when the control member is displaced from its initial position the blocking mechanism is active and so operates to block rearward movement of the sleeve. Further, the control member when in its initial position may serve to deliver the finger on to the sliding surface such that relative movement between the sleeve and mount deforms the finger to store energy therein. In one embodiment, the control member is arranged for displacement from said initial position thereof by the movement of the sleeve from the non-shielding position to the shielding position. For example, the control member may be mounted within the sleeve for axial sliding movement with respect thereto, the control member being displaced from its initial position by the movement of the sleeve from its non- shielding position to its shielding position. In the alternative, the control member may comprise a part of the needle cover and the removal of the needle cover displaces the control member (being a part of the needle cover) from its initial position.

In the case of a device having a latching mechanism which includes a lug formed on one of the sleeve and mount, and which also includes a blocking mechanism having an abutment surface for interaction with a part of the finger, that lug may provide both the sliding surface for the latching mechanism and the abutment surface for the blocking mechanism.

Preferably, the sliding surface is provided on the mount and the resiliently flexible finger is provided on the sleeve.

In one embodiment, the sleeve when in the shielding position interacts with the needle cover to resist movement of the needle cover in the forward direction, off the needle. Further, the sleeve when in the shielding position may hold the rearward end of the needle cover in contact with the needle mount.

This invention extends to the combination of a safety device of this invention as described above and a needle supported by the needle mount and provided with a removable needle cover. The needle mount may comprise a syringe having a needle permanently affixed thereto, or may comprise a support for a needle hub having a needle projecting forwardly therefrom, the needle mount being configured for mounting on an injection device, such as a syringe.

By way of example only, two specific embodiments of active protection device of this invention will now be described in detail, reference being made to the accompanying drawings in which:-

Figure 1 is an exploded isometric view of the first embodiment of an active needle protection device, together with a syringe having a permanently attached staked-in needle, which syringe is typically pre-filled with a liquid medicament;

Figure 2 shows the device and syringe of Figure 1 , assembled together;

Figure 3 shows the device prepared for performing an injection;

Figure 4 shows the prepared device following removal of the needle cover;

Figure 5 shows the device following the performance of an injection and with the needle protected by the sleeve of the device;

Figure 6 is an axial cross-section on an enlarged scale of the device of Figure 2, when fitted to a syringe;

Figure 7 is a view similar to that of Figure 6 but showing the start of preparing the device for the performance of an injection; Figure 8 is a view similar to that of Figure 7 but showing the device partly prepared for the performance of an injection;

Figure 9 is a view similar to that of Figure 8 but with the device fully prepared and the needle cover removed;

Figure 10 is a view similar to that of Figure 6 but at the completion of a medical procedure and with the sleeve blocked in a needle shielding position;

Figure 1 1 illustrates an operator activating the device to give protection to the needle, following the performance of a procedure;

Figure 12 shows the second embodiment of device together with a syringe barrel having a permanently attached staked-in needle but before filling of the syringe with a liquid medicament;

Figure 13 shows the device and syringe barrel of Figure 12, assembled together;

Figure 14 shows the assembly of Figure 13 but following filling of the syringe barrel with a liquid medicament and then the stoppering of the barrel and the attachment of a plunger to the stopper;

Figure 15 shows the device prepared for performing an injection;

Figure 16 shows the device following removal of the needle cover;

Figure 17 shows the device following the performance of an injection and with the needle protected by the sleeve of the device;

Figure 18 is an exploded view on the device and the syringe barrel of Figure 13;

Figures 19A and 19B are respectively isometric and side views with the device having part of the cover cut away for clarity; and

Figures 20 to 24 show the successive steps of preparing the second embodiment of device through to completion of a medical procedure with the sleeve blocked in a protecting position, generally corresponding to Figures 7 to 10 for the first embodiment.

The first embodiment of active needle protection device of this invention is shown in Figures 1 to 1 1 . As shown in Figure 1 , the device 10 comprises a mount 1 1 , a ring-shaped control member 12, a resilient needle cover 13 and a protection sleeve 14. The syringe 15 is entirely conventional and as shown is in a ready-to-fill format, typically by location in an apertured tray along with a plurality of similar syringes all having a respective safety device attached thereto. The syringe comprises a barrel 16, typically of glass, having a staked-in needle 17 held in the syringe nose 18 by an adhesive 19, and a plunger 20 having an enlarged head 21 . The syringe may be pre-filled with a liquid medicament in an automatic machine pre-filling a plurality of the syringes held in a tray, the medicament being driven out of the syringe barrel 16 through the needle 17 by a stopper (not shown) acting as a piston and mounted on the forward end of the plunger 20. Alternatively, immediately before use the syringe may be filled with a medicament drawn up from a vial through the needle 17.

The forward end of the barrel 16 merges into the nose 18 which tapers towards the forward end of the nose, whereat there is an annular rib 24. This profile is also conventional and has been developed to allow the use of a resilient needle cover which may be snap-fitted to the nose of the syringe to resist so-called pop-off when the syringe and cover are subjected to pressure changes such as may occur during filling of the syringe barrel, sterilisation or storage, and also to retain the cover in position before use. The resilient needle cover may have a rigid plastic outer sheath, and so take the form of a rigid needle shield (RNS).

The mount 1 1 has an internal profile best seen in Figures 6 to 10 which enables the mount to be snap-fitted on to the tapered part of the nose 18, the forward radial face 25 of the mount engaging rearwardly of the rib 24. The mount is mostly frusto-conical in external shape but can include a pair of diametrically opposed regions each of which includes a first surface 26 extending rearwardly from the forward end of the mount and a lug 27 at the rearward end of that first surface. The lug defines a forward-facing abutment surface 28 and a sliding surface 29 (see particularly Figures 6 to 10) and a rearward-facing shoulder 30. The control member 12 comprises a simple cylindrical annulus the inner diameter of which fits over the rib 24 of the syringe nose and, in the initial setting of the device, lies closely adjacent the radial face 25 of the mount. The purpose of the control member will be described in further detail below.

The sleeve 14 of the device is mostly cylindrical and is a sliding fit over the barrel 16 of the syringe but the sleeve includes a pair of diametrically opposed slots 31 formed therein to extend parallel to the sleeve axis. In each slot there is provided a resiliently deformable finger 32, the forward end 33 of the finger being conjoined to the sleeve at the forward end of the slot. The rearward end 34 of the finger is free and normally lies generally within the slot but the finger may be resiliently flexed outwardly, as shown for example in Figures 7 to 9. Each finger has a camming surface 35 on its inner face, for interacting with the respective lug 27 of the mount 1 1 and the rearward end 34 of the finger is profiled for interacting with the abutment surface 28 of the lug, as will be described hereinbelow.

At its forward end, the sleeve 14 has an in-turned flange 36 with a central hole 37 through which the needle 17 of a connected syringe may project, when the sleeve has been moved rearwardly. The needle cover 13 is of a resilient elastomeric material and defines an axial opening 38 from its rear end within which the needle 17 is accommodated, the sharp tip of the needle penetrating the material of the cover so as to be stoppered thereby and prevent medicament pre-filled in the syringe barrel from dribbling out of the needle. As the mount 1 1 is positioned on the syringe nose 18, the needle cover 13 cannot locate thereon in the conventional manner. Instead, the rear end of the cover is profiled to engage and effect a seal against the front of the nose 18. The cover is held in that sealing engagement by virtue of an annular rib 39 provided at the forward end of the cover, engaged with the inner radial face of the sleeve flange 36, the relaxed length of the cover being slightly larger than the distance between said inner radial face and said front of the nose 18. Figure 6 shows the device in its initial setting where the fingers 32 are lying in their respective slots 31 and the needle cover 13 is inaccessible and so cannot be removed from within the sleeve 14, to give access to the needle 17. When the device, as mounted on a syringe, is to be used to perform an injection, the device must be prepared for use by manually moving the sleeve 14 rearwardly with respect to the syringe 15. In the first stage of this rearward movement, the rearward ends of the camming surfaces 35 on the fingers 32 engage and move on to the outer surface of the control member 12 (Figure 7) so moving the forward ends 33 of the fingers outwardly such that those rearward ends no longer are aligned with the abutment surfaces 28. In this initial movement of the sleeve, the cover 13 is slightly compressed axially.

Continued rearward movement of the sleeve brings the camming surfaces 35 on to the sliding surfaces 29 of the lugs 27 (Figure 8), so flexing the fingers resiliently outwardly. Also, the rib 39 of the needle cover is deformed resiliently inwardly to allow the forward end of the needle cover to emerge through the central hole 37 of the sleeve.

Yet further rearward movement of the sleeve 14 flexes the fingers 32 outwardly until the setting of Figure 9 is reached where the forward ends of the camming surfaces 35 are disposed immediately rearwardly of the shoulders 30 of the lugs 27. That interengagement between the forward ends of the camming surfaces and the shoulders serves to hold the sleeve in that position notwithstanding the resilient flexing of the fingers. In this position, the cover may be grasped and pulled away from the needle, as shown in Figure 9, so preparing the syringe and device ready for performing an injection. In an alternative arrangement, the cover may fall away from the device if appropriately pointed downwardly.

At the completion of the injection, the syringe and device is pulled away from a patient and then the sleeve 14 is pushed forwardly by the operator, typically using a forefinger of the hand used to perform the injection and depress the plunger 20. This action is shown in Figure 1 1 . At the start of this action, the forward ends of the camming surfaces 35 move on to the sliding surfaces 29 of the lugs 27 whereafter further forward movement of the sleeve is assisted by those fingers 32 attempting to move to their initial positions disposed within the slots 31 , and so urging the sleeve forwardly. As the sleeve moves forwardly, the camming surfaces contact the control member 12 and then pull that control member forwardly off the nose of the syringe, so that the control member is located in a forward part of the sleeve. Another possibility (not shown) is for there to be friction between the sleeve and the control member which serves to retain the control member in a forward part of the sleeve.

Eventually, the position of Figure 10 is reached where the sleeve is fully forwardly and so surrounds and protects the sharp tip of the needle and the rearward ends 34 of the fingers 32 are adjacent the abutment surfaces 28. If an attempt is made to move the sleeve rearwardly once more, the rearward ends 34 of the fingers 32 will engage the abutment surfaces 28 and so prevent further rearward movement, those rearward ends 34 and the abutment surfaces 28 being profiled to resist outward springing movement of the fingers. As the control member is in the forward part of the sleeve, moved from its initial position, it cannot perform the function of flexing the fingers outwardly as has been described above with reference to Figure 6, for initialising the device.

The second embodiment of active needle protection device of this invention is shown in Figures 12 to 24, and differs from the first embodiment in that no separate control member is provided; rather, the function of the control member is provided by the needle cover itself. In view of this, like parts having the same function in the two embodiments will be given the same reference numbers and will not be described again in detail here.

Figure 12 shows the syringe barrel 16 and needle 17 before the filling of the syringe with a liquid medicament and the fitting of the plunger 20 to the barrel. The mount 44 is essentially the same as that of the first embodiment but has a slightly greater rearward extent beyond the lugs 27. The sleeve 14 is the same as that of the first embodiment and the device is fitted to the syringe nose 18 in the same manner as described above with reference to the first embodiment, but before the filling of the syringe with medicament, typically by being located in an aperture of a tray carried by a tub along with a plurality of like syringes for filling by an automated machine. As the device includes a needle cover 45, that cover is fitted to the syringe and needle prior to filling, to stopper the sharp tip of the needle, to complete the assembly of Figure 13. The syringe barrel is then filled with a medicament in a conventional manner and the plunger 20 together with the stopper is inserted into the barrel 16 (Figure 14).

The device is initialised by sliding the sleeve rearwardly, so flexing the fingers 32 outwardly (Figure 15) this exposing the needle cover 45 so that the needle cover may be grasped and pulled away from the device to expose the needle (Figure 16), or being allowed to fall away. After performance of the injection, the sleeve 14 is pushed forwardly as described with reference to the first embodiment, with the fingers assisting the movement of the sleeve forwardly. This is continued until the rearward ends 34 of the fingers are wholly disposed in the slots 31 , adjacent the abutment surfaces 28 (Figure 17), so blocking the sleeve against subsequent rearward movement, to confer protection to the sharp tip of the needle.

As mentioned above, the functionality of the control member 12 of the first embodiment is provided by the needle cover 45 itself. For this purpose, the needle cover is furnished with a control ring 46 near to, but displaced rearwardly from, the forward end of the cover. The control ring could be an integral part of the control member, or could be a separate component fitted thereto. In order to allow that control ring to co-operate with the fingers 32, the inwardly-directed surface of each finger 32 is somewhat differently profiled as compared to the first embodiment. Thus, the internal surface of each finger has a relatively short camming surface 47 near the forward end thereof, which bears on the control ring 46 when the sleeve 14 is in its initial position (Figures 19A and 19B). In this way, the part of the cover between the control ring and its rearward end is compressed slightly so as to maintain the cover in sealing contact with the forward end of the syringe nose 18; with this second embodiment, there is need not be an interaction between the flange 36 of the sleeve and the forward end of the cover.

On initial rearward movement of the sleeve from the setting of Figure 19, there is interaction between the rearwardly-directed end of the camming surface 47 and the ring 46 (Figure 20) in order to flex resiliently the fingers outwardly and move the rearward ends of the fingers clear of the abutment surfaces 28 of the mount 44. This brings the inner surface of each finger on to the corresponding sliding surface 29 of the respective lug 27 (Figure 21 ) and from this point the operation of the device continues as has been described above in relation to the first embodiment (Figures 22, 23 and 24). Once the cover 45 has been exposed (Figures 21 and 22) it may be grasped and pulled away from the syringe so making the device ready for performing an injection (Figure 23), or the device may be pointed downwardly so allowing the cover to fall away under gravity. At completion of the injection, the sleeve is pushed forwardly as has been described above (Figure 1 1 ) with the fingers urging the sleeve forwardly until the sleeve reaches its protecting position fully surrounding the sharp tip of the needle (Figure 24). The resilient fingers will assist the forward movement of the sleeve, but it may be necessary to push the sleeve only a small distance, the sleeve then moving fully forwardly to the protecting position solely by the action of the fingers. Subsequent rearward movement of the sleeve is blocked by interaction between the rearward ends of the fingers and the abutment surfaces 28 of the mount 44, as with the first embodiment.