Protective device for a needle assembly

The invention provides a protective device (10) for a needle assembly (12) having a needle hub (14) and a needle (16) projecting from the hub. The protective device includes an end cap (20) which has an opening (36) through which the needle (16) may pass, and a resilient member (22) extending about the needle (16) between the needle hub (14) and the end cap (20). The resilient member (22) is deformable between a first condition in which it holds the end cap (20) over a sharpened end (18) of the needle (16) and a second condition in which the end cap (20) is withdrawn from the sharpened end of the needle (16). Furthermore, the resilient member (22) is biased towards the first condition and is arranged to bias the end cap (20) into a safety position in which the sharpened end of the needle (16) is offset relative to the opening (36) in the end cap (20). The protective device (10) also includes a sheath (24) covering at least the sharpened end (18) of the needle (16). The sheath (24) extends into the opening (36) in the end cap (20) so as to hold the sharpened end of the needle (16) in alignment with the opening (36), against the bias of the end cap (20). The sheath (24) is also removable from the needle (16) to expose the sharpened end (18) for use, and after use, to allow the resilient member (22), upon return to the first condition, to automatically displace the end cap (20) into the safety position.

BACKGROUND OF THE INVENTION

THIS invention relates to medical equipment, and more specifically to a protective device for a needle assembly having a hub for attachment to a syringe, a catheter or a blood-drawing holder, and a hypodermic needle extending from the hub.

Protective devices for needle assemblies are known. For example, U.S. Pat. No. 5,538,508 discloses a protective device which includes an end cap and a resilient, generally tubular member for holding the end cap over a sharpened end of a hypodermic needle. The end cap includes a blocking surface for containing the sharpened end of the needle, and an off-centre opening adjacent the blocking surface for allowing the needle to pass through the end cap for use. The generally tubular member is arranged to bias the end cap into a safe position in which the sharpened end of the needle is aligned with the blocking surface. To expose the needle for use, it is necessary to manipulate the end cap by aligning the sharpened end of the needle with the opening in the end cap and then withdrawing the end cap over the needle against the resilience of the generally tubular member.

Although this device is effective in containing the sharpened end of the needle before and after use, aligning the needle with the opening in the end cap and also then overcoming the resiliency of the generally tubular member can be awkward in certain medical applications.

It is an object of the present invention to provide a protective device for a needle assembly which is effective in containing the sharpened end of a needle before and after use, and which allows the needle to be exposed for use relatively easily.

SUMMARY OF THE INVENTION

According to the invention there is provided a protective device for a needle assembly having a needle hub and a needle projecting from the hub, the protective device comprising:an end cap which includes an opening through which the needle may pass;a resilient member extending about the needle between the needle hub and the end cap, the resilient member being deformable between a first condition in which it holds the end cap over a sharpened end of the needle and a second condition in which the end cap is withdrawn from the sharpened end of the needle, the resilient member being biased towards the first condition and being arranged to bias the end cap into a safety position in which the sharpened end of the needle is offset relative to the opening in the end cap; anda sheath covering at least the sharpened end of the needle, the sheath extending into or through the opening in the end cap so as to hold the sharpened end of the needle in alignment with the opening, against the bias of the end cap, and the sheath being removable from the needle to expose the sharpened end for use, and after use, to allow the resilient member, upon return to the first condition, to automatically displace the end cap into the safety position.

Preferably, the sheath is formed from a rigid material which extends over the sharpened end of the needle.

In one arrangement, the sheath comprises a sleeve which extends over the sharpened end of the needle. The sleeve may be open-ended, in which case it may extend from the needle hub over the sharpened end of the needle. Alternatively, the sleeve may be closed at one end, in which case it may cover only a portion of the needle.

Preferably, in the first condition of the resilient member with the sheath covering the needle, the sharpened end of the needle is spaced at least 1 mm from the opening in the end cap and the sheath extends at least 2 mm beyond the sharpened end of the needle.

In a particularly preferred arrangement, in the first condition of the resilient member with the sheath covering the needle, the sharpened end of the needle is spaced at least 2 mm from the opening in the end cap and the sheath extends at least 5 mm beyond the sharpened end of the needle.

The end cap may include a rigid blocking surface adjacent the opening through which the needle may pass, the blocking surface serving to contain the needle within the end cap.

In one arrangement, the end cap defines a recess for receiving the sharpened end of the needle and the opening comprises a passage extending from a leading end of the end cap into the recess adjacent the blocking surface.

Typically, the length of the passage is greater than the length of the portion of the sheath extending beyond the sharpened end of the needle. In this way, the sheath may be positioned entirely within the protective device.

In one arrangement, the opening in the end cap is located on one side of the cap, and the leading end of the end cap is inclined so as to extend backwards and away from the opening. In this way, with the resilient member in the first condition and the sheath removed from the needle, accidental contact with the inclined leading end of the end cap urges the sharpened end of the needle away from the opening in the end cap.

The resilient member may comprise a generally tubular member which defines at least one cut-out along its length for allowing the resilient member to deform between the first condition and the second condition.

Preferably, the at least one cut-out comprises a pair of opposed slits or slots which extend along a portion of the length of the resilient member to define two opposed limbs. The slits or slots may each include notches along their length which predispose the limbs to bow outwardly when the resilient member is deformed from the first condition to the second condition.

The resilient member may be mounted skew on the needle hub to provide the biasing of the end cap into the safety position.

The invention extends to a protective device of the type describe above attached to a needle assembly.

DETAILED DESCRIPTION OF THE INVENTION

The present invention has application in the medical field, and more specifically in protective devices for hypodermic needles. The invention is embodied in a protective device for a needle assembly of the type generally used with syringes, catheters or blood-drawing holders. Such assemblies typically include a needle hub for attachment to the syringe, catheter or blood-drawing holder, and a hypodermic needle extending from the hub.

FIG. 1of the accompanying drawings illustrates a protective device according to one embodiment of the present invention. The protective device is designated generally with the reference numeral10and is shown attached to a needle assembly12which includes a needle hub14and a hypodermic needle16extending from the hub to a sharpened end18.

The needle protective device10includes an end cap20, a resilient member22and a sheath24. To protect users from the sharpened end of the needle16, the end cap20is formed from a relatively rigid material. For example, the end cap may be injection moulded from a medical grade, clear polystyrene. As can be seen, the end cap20has a leading end26, a trailing end28and a sidewall30extending between the leading end and the trailing end. The trailing end28defines a beveled entrance32feeding into a recess34for receiving the sharpened end18of the hypodermic needle. As representatively illustrated inFIG. 1, the end cap20defines an opening36adjacent a blocking surface38. The opening36allows the needle16to pass through the end cap20for use, and the blocking surface38retains the sharpened end of the needle within the recess34after use, as will be described in more detail below.

With reference now toFIG. 5of the drawings, the resilient member22may comprise a generally tubular member42which includes a pair of slits44(only one of which is visible) extending along a portion of the length of this member on opposite sides thereof to define a pair of resilient limbs46. Each slit44may include a notch48on each side of the slit approximately midway along its length, and a generally circular opening50at each end of the slit, as shown. The notches48predispose the limbs46to bow outwardly in a manner which is described in more detail below, while the openings50prevent tearing at the ends of the slits44in use. As representatively illustrated inFIG. 5, the tubular member42may carry four, equally spaced apart fins43which extend along the length of this member for increased resiliency. The tubular member42may be formed in an injection moulding or extrusion process from a medical grade liquid or standard silicone rubber having a Shore hardness of 30 to 80.

With reference toFIGS. 1 and 2of the drawings, the resilient member22may be attached to the needle hub14and to the end cap20by simply stretching the ends of the resilient member over the needle hub and the end cap. Alternatively, in addition to stretching, a suitable adhesive may be used to bond the resilient member22to the needle hub14and the end cap20. A flange40on the end cap20and a flange52on the needle hub14serve as end stops during attachment of the resilient member to the needle hub and to the end cap, and the end of the resilient member22connected to the needle hub14is mounted skew, as shown most clearly inFIG. 1, so as to bias the end cap20in the direction of the arrow A.

The resilient member22is seen to extend about the needle16between the needle hub14and the end cap20, and is deformable between a first condition in which it holds the end cap20over a sharpened end of the needle16, as illustrated inFIG. 1, and a second condition in which the end cap20is withdrawn from the sharpened end of the needle16, as illustrated inFIG. 2. This deformation is permitted by the resiliency of the limbs46which, under sufficient axial compressive loading, bow outwardly allowing the end cap20to be drawn back against the needle hub14into theFIG. 2condition, and which, when released, have sufficient resiliency to return to the extended,FIG. 1condition, snapping the end cap20over the sharpened end of the needle16.

As representatively illustrated inFIG. 1of the drawings, the sheath24may be formed as an open-ended sleeve which extends from the needle hub14beyond the sharpened end18of the needle. To protect users from the sharpened end of the needle prior to use, the open-ended sleeve may be formed from a relatively rigid material, such as, for example, a medical grade polypropylene, polystyrene or polyurethane.

The resilient member22is arranged to hold the end cap20over the sharpened end of the needle16so that the tip of the sharpened end falls short of the entrance to a passage54defining the opening36(seeFIG. 1). Typically, the distance between the tip of the sharpened end18and the entrance to the passage54is at least 1 mm, and preferably is between 2 mm and 4 mm. The extent to which the sheath24extends beyond the tip of the sharpened end18depends on the nature and extent of the opening36, but typically is at least 2 mm, and preferably is between 3 mm and 10 mm. InFIG. 1, it can be seen that the leading end of the sheath24extends into the passage54a sufficient distance to hold the sharpened end of the needle16in alignment with the opening36, but not so far as to extend beyond the leading end26of the end cap20.

In practice, the needle hub14of the protective device10is connected to a syringe, a catheter or a blood-drawing holder (not shown) with the device in theFIG. 1condition in which the sheath24aligns the needle16with the opening36in the end cap20. In this condition, the sheath24is held in position by the biasing of the end cap20in the direction of the arrow A, and the rigidity of the sheath24prevents an accidental needle stick injury. To expose the needle16for use, the end cap20is simply withdrawn from the sharpened end of the needle16towards the needle hub14into theFIG. 2condition, and the sheath24is removed, as illustrated inFIG. 3. With the end cap20withdrawn, the sheath24may be dropped off the needle16or alternatively removed by hand to expose the needle for use.

After use, the end cap20is simply released, and the resiliency of the limbs46automatically drive the end cap20away from the needle hub14so that it snaps over the sharpened end of the needle16, and the biasing of the end cap20by the resilient member22automatically moves the end cap into a safety position (illustrated inFIG. 4) in which the sharpened end of the needle16is located within the recess34, offset relative to the opening36and aligned with the blocking surface38. In this condition, the sharpened end of the needle16is safely retained within the end cap20during disposal of the needle arrangement, thereby reducing the likelihood of a needle stick injury. It will also be appreciated that in the event of accidental contact with the leading end of the end cap20after use, the inclined surface26serves to urge the sharpened end of the needle16away from the opening36, thereby further reducing the likelihood of a needle stick injury.

Thus, the protective device10automatically retains the sharpened end of the needle16in a safe condition when the needle is not required, and yet allows the sharpened end to be exposed for use relatively easily.