WO2008132518A1

WO2008132518A1 - Piercing needle assembly irreversibly locked with a reversible latching mechanism

Info

Publication number: WO2008132518A1
Application number: PCT/GB2008/050315
Authority: WO
Inventors: Iden Shams
Original assignee: Iden Shams
Priority date: 2007-05-01
Filing date: 2008-05-01
Publication date: 2008-11-06
Also published as: GB0708366D0; GB2448885A

Abstract

A medical piercing needle assembly comprising: a piercing needle slidably attached to a sheath; wherein the piercing needle is moveable between two positions such that: in its first position, the piercing needle is reversibly lockable such that its piercing end projects from said sheath to an extent to allow it, in use, to pierce an object; and such that: in its second position, the piercing needle is irreversibly locked such that its piercing end is contained within said sheath. In particularly preferred embodiments, the sheath comprises telescopic portions.

Description

PIERCING NEEDLE ASSEMBLY IRREVERSIBLY LOCKED WITH A REVERSIBLE LATCHING MECHANISM

Field of the Invention

The invention relates to medical piercing needles such as hypodermic syringes, cannula introducers and needles for body piercing that are adapted to prevent needle-stick injuries.

Background and Prior Art Known to the Applicant

The problem of cross-infection in hospitals and other quasi-medical settings is well known, and of particular concern is the protection of medical staff and other personnel within the vicinity from so-called "needle-stick" injuries whereby a needle that has been in contact with e.g. a patient's blood may accidentally puncture the skin of another and cause cross- infection. Situations where there is a potential risk from this kind of injury include not only medical environments such as hospitals and doctors' surgeries, but also the increasingly popular body piercing salons where piercing needles may be used for the introduction of body jewellery.

In the medical context, one particular procedure of concern is the fitting of intravenous cannulae. In this procedure, a flexible cannula is located over a piercing needle, in the form of a hypodermic needle; the needle and surrounding cannula is introduced into a vein until blood is seen to emerge from the end of the needle. The needle is then withdrawn, leaving the cannula located within a vein, thus providing convenient access for an attending clinician to take blood samples, administer intravenous medication and the like. When the needle is withdrawn from the cannula, it is clearly contaminated with blood and poses a risk for needle-stick injury to the clinician and others who may come into contact with the used device.

In some existing "safety cannulae", a sheath is provided into which a needle is automatically withdrawn (upon user-activation of a spring-driven mechanism) to encapsulate the sharp end of the needle. One drawback that arises from this device is that the sheath itself needs to be at least as long as the needle, leading to an overall excessively long device. Another drawback is the fear that activation of the spring-driven mechanism can cause the needle to be withdraw very rapidly into the sheath with the possibility that body fluids might be ejected as an aerosol from the end of the needle and the possible cross-infection that could ensue were this to occur. Thirdly, if a spring-actuated mechanism were to fail before the needle was full retracted into the sheath, there would be nothing that an operator could do to safely ensure the sheathing of the needle.

It is therefore among the objects of the present invention to provide improved sheathing mechanisms for such needles.

Summary of the Invention

Accordingly, the invention provides a medical piercing needle assembly comprising: a piercing needle slidably attached to a sheath; wherein said piercing needle is moveable between two positions such that: in its first position, the piercing needle is reversibly lockable such that its piercing end projects from said sheath to an extent to allow it, in use, to pierce an object; and such that: in its second position, the piercing needle is irreversibly locked such that its piercing end is contained within said sheath, wherein the locking mechanism is a manual reversible latching mechanism comprising a hook member and having an actuation portion. Preferably, said sheath comprises a plurality of telescopic portions.

In any aspect of the invention it is further preferred that said piercing needle is hollow. In this way, the emergence of e.g. blood from the distal end of the needle provides an indication that the needle has entered the desired body cavity. Preferably, said hollow piercing needle is in fluid communication with a transparent chamber, whereby, in use, a user can observe fluid entering said chamber.

Also in any aspect of the invention it is further preferred that movement of the needle between the two said position is effected solely by manual intervention of a user, in use. This prevents any possibility of aerosol formation that could potentially arise from e.g. a spring-driven system described above. Also, by allowing (or indeed requiring) that the needle is withdrawn by the manual intervention of the user, this allows the needle to be withdrawn in an entirely controlled fashion by an attending clinician.

Included within the scope of the invention is a medical cannula set comprising a cannula introducer being an assembly according to any preceding claim and a cannula.

Also included within the scope of the invention is a medical piercing needle assembly substantially as described herein with reference to and/or as illustrated by any appropriate combination of the drawings.

Also included within the scope of the invention is a medical cannula set substantially as described herein with reference to and/or as illustrated by any appropriate combination of the drawings.

Brief Description of the Drawings

The invention will be described with reference to the accompanying drawings in which:

Figure 1 is an exploded perspective drawing of a device according to the present invention;

Figure 2 is a cross-section of a needle-receiving portion of the device;

Figure 3 is a perspective view of a needle-receiving portion of the device;

Figures 4 and 5 are perspective views of a needle-actuating portion of an embodiment of the invention;

Figures 6 and 7 are perspective views of a first telescopic portion of an embodiment of the invention;

Figures 8 and 9 are perspective views of a second telescopic portion of a device according to the invention; Figures 10 and 11 are perspective views of a housing forming part of an embodiment of the invention;

Figure 12 is a cross-sectional view through an embodiment of the invention, in its non- extended configuration; Figure 13 is a cross-section through an embodiment of the invention, in its extended configuration.

Description of Preferred Embodiments

Figure 1 shows an exploded perspective view of a medical piercing assembly, generally indicated by 1, according to the present invention. The component parts of the assembly comprise, at a proximal end, a piercing needle 2, a housing 3, a needle-receiving portion 4, a needle-actuating portion 5, a first telescopic portion 6 and a second telescopic portion 7. Together, the housing 3 and first and second telescopic portions 6, 7 form the sheath of the assembly. Details of each component part will be described below.

In this embodiment, the needle 2 comprises a hollow hypodermic needle of the type used for injections, or the introduction of a cannula into a body cavity (such as a vein) of a patient. Figures 2 and 3 illustrate respectively a cross-section and a perspective view of the needle-receiving portion 4. The needle-receiving portion 4 is of generally cylindrical form and has, at its proximal end, a needle-receiving cavity 8 in fluid communication with a chamber 9 via a fluid channel 10. At least a portion of the wall 11 of the chamber 9 is constructed from a transparent material such as plastics to enable any fluid entering the chamber 9 to be viewed by a user, in use. When the device is assembled, the distal end of the needle 2 is inserted into the needle-receiving cavity 8 and secured there by e.g. an interference fit, or by a suitable adhesive.

Figures 4 and 5 illustrate, in perspective view, the needle-actuating portion 5. In this embodiment, the needle-actuating portion 5 has a number of functions: the needle- actuating portion 5 has a cap 12 that serves to close the open end of the chamber 9 illustrated in figure 2. The cap 12 is provided with a small hole 13 to allow air to escape from the chamber 9 when fluid, such as blood, passes up the needle to and into the chamber 9, in use. The needle-actuating portion 5 also comprises one part of a proximally-located needle latching mechanism in the form of a resiliently-deformable hook member 14 a ridged actuating portion 15. The needle-actuating portion also comprises a pair of clips 16 that form part of an irreversible needle locking mechanism. Details of the method of operation of the needle latching mechanism and needle locking mechanism will be described more fully below.

Figures 6 and 7 illustrate, in perspective view the first telescopic portion 6 of the assembly. The first telescopic portion 6 is generally of the form of a hollow cylinder, open at both ends. Along the length of the telescopic portion is located a slot 17 through which the arm portion 18 of the needle-actuating portion 5 extends when the device is assembled. At the proximal end 19 of the first telescopic portion 6 are three reversibly deformable tab members 20 having inwardly-facing projecting portions that, once assembled, engage with corresponding channels on the housing 3 to be described in more detail below. At the distal end 21 of the first telescopic portion 6 there are four slots 22 that, once assembled can receive corresponding tab portions 23 located on the second telescopic portion 7. Located on the outer surface of the first telescopic portion 6 are four operating channels 24 recessed into the surface of the first telescopic portion 6 and disposed longitudinally thereon. These operating channels 24 serve to receive corresponding tab portions 23 from the second telescopic portion 7 to guide the sliding of the two telescopic portions 6, 7 to enable the telescopic sheath to be extended and collapsed, in use. The slots 22 are located at an end region of the operating channels 24 and serve to receive the inwardly projecting portions of the tabs 23 of the second telescopic portion 7 to lock the two telescopic portions in an extended configuration upon retraction of the needle into the sheath.

Also located on the outer surface of the first telescopic portion 6 are three assembly channels 25 recessed into the outer surface of the first telescopic portion 6 and running longitudinally thereon. The assembly channels 25 are located adjacent the operating channels 24 and serve to aid assembly of the two telescopic portions.

At the distal end 21 of the first telescopic portion 6 are outwardly-projecting portions 26 located adjacent the end of the operating channels 24. These outwardly projecting portions 26 co-operate, in use, with the corresponding inwardly-projecting tab members 23 of the second telescopic portion 7. Figures 8 and 9 illustrate, in perspective view, the second telescopic portion 7 of the assembly. The portion is of the form of a generally hollow cylinder, closed at its distal end 27. The second telescopic portion 7 also has a slot 28 running along the length of the portion, and through which, the arm member 18 of the needle-actuating portion 5 projects, in use.

On the closed face 29 of the second telescopic portion are located two rectangular holes 30 that form a second part of the irreversible locking mechanism and receive the clip members 16 of the needle-actuating portion 5 to lock the needle within the sheath when the device is in its extended configuration.

Figures 10 and 11 illustrate, in perspective view, the housing 3. At its proximal end 31 the housing 3 has a hollow, and generally cylindrical projection 32. The hollow interior of this projection 32 serves to receive the needle 2 when the device is assembled and thus serves to provide a proximal needle guide to ensure that the needle 2 remains substantially coaxial with the sheath when in use, or being withdrawn into the sheath. The outer surface of the projection 32 also serves as a cannula mating surface to receive a cannula (not illustrated) when the device is serving as a cannula introducer. Projecting from the outer surface of the housing 3 is a plate 33 through which is a slot 34. This slot 34 acts as the second part of the reversible latching mechanism and, when assembled, receives the hook member 14 of the needle-actuating portion 5. A generally cylindrical portion 35 of the housing 3 functions as part of the sheath of the device. Recessed into the counter surface of the cylindrical portion 35 are three operating channels 36 that serve, when assembled to receive the corresponding tab portions 20 of the first telescopic portion 6 located at the distal end of each of the operating channels 36 is a slot 37 communicating with the interior cavity of the cylindrical portion 35. The slots 37 serve to receive the corresponding inwardly projecting tab portions 20 of the first telescopic portion 6 when the device is in its extended configuration, and to lock the two pieces 3, 6 together in that extended configuration to ensure that the needle 2 is irreversibly retained within the sheath. Also located on the outer surface of the cylindrical portion 35, are three assembly channels 38 located adjacent the operating channels 36.

To further illustrate the various features of each component, a method of assembly of the device will now be described: The proximal end 19 of the first telescopic portion 6 is aligned with the distal end of the housing 3 such that the three projecting tabs 20 of the first telescopic portion are aligned with the open ends of the assembly channels 38 of the housing 3. In this configuration, it will be seen to be slot 17 on the first telescopic portion 6 is 90D out of alignment with the slot 39 of the housing 3. The two pieces are pushed together so that the projecting tabs 20 slide along the assembly channels 38 of the housing 3. When the tabs 20 reach the ends of the assembly channels 38, the two portions are rotated relative to each other such that the tabs 20 move into the operating channels 36. The inwardly-projecting portions of the tabs 20 have a chamfered end 40 to facilitate resilient deformation of the tabs 20 to enable them to pass over the surface of the cylindrical portion 35 of the housing 3 and into the operating channels 36. The two slots 39, 17 would now be aligned. At the proximal end of the operating channels 36 of the housing 3 are located small steps 41 (illustrated in figure 11) such that the proximal portion 36a of the operating channels 36 is recessed slightly deeper into the cylindrical portion and the rest of the channel. In this way, the tabs 26 are held within this further recessed portion 36a and abut the edge of the step feature 41. The first telescopic portion 6 is thus held in its unextended configuration.

Next, the distal end of the needle 2 may be affixed into the needle-receiving cavity 8 of the needle-receiving portion 4 as described above. The cap portion 12 of the needle- actuating portion 5 may then be inserted into the open end of the chamber 9 of the needle-receiving portion 4. The sharp, proximal end of the needle 2 may then be passed through the first telescopic portion 6, the housing 3, and exit through the hole in the projecting portion 32. The arm member 18 of the needle-actuating portion 5 passes along the slots 17, 39 of the housing and first telescopic portion. The hook member 14 of the needle-actuating portion 5 then passes into the slot 34 located in the plate 33 of the housing 3. The proximal end 42 of the hook portion 14 is angled such that it engages with the end of the slot 34 and deforms the hook member so that it can pass through the slot. Once the hook portion 14 is clear of the slot the resiliently-deformable material springs back to engage the hook portion with the plate 33.

In use, when the needle is retracted into the sheath, the needle-receiving portion 4 also acts as a distal needle guide; the diameter of the needle-receiving portion 4 is slightly smaller than the bore of the telescopic portions, and so - in combination with the proximal needle guide (the bore of the projecting portion 32 of the housing 3) - keeps the distal end of the needle aligned along approximately the axis of the device.

The second telescopic portion 7 of the device then completes the assembly. The proximal end of the second telescopic portion 7 is aligned with the distal end 21 of the first telescopic portion 6 such that the inwardly projecting tabs 23 are aligned with the assembly channels 25 of the first telescopic portion. The two pieces are pushed together such that the tabs 23 slide along the assembly channels 25. In this configuration, the slot 28 of the second telescopic portion 7 is 90D out of alignment with the slot 17 of the first telescopic portion. The pieces are then rotated relative to each other such that the inwardly projecting tabs 23 of the second telescopic portion resiliency deform, ride over the outer surface of the first telescopic portion and click into place in the operating channels 24 of the first telescopic portion 6. Again, a step feature 42 is provided in the operating channels 24 (corresponding in structure to the step feature 41 on the operating channel 36 of the housing 3) to temporarily hold the two pieces in their non-extended configuration. Assembly of the device is now complete.

Figure 12 is a cross-section of the assembled device in its non-extended configuration. Figure 12 illustrates how the hook portion 14 of the needle-actuating portion 5 engages with the plate 33 of the housing 3. If the piercing assembly 1 is to be used as a cannula introducer, a cannula is slipped over the needle 2 to engage with the outer face of the projecting portion 32. The whole device would then be packaged and sterilised (e.g. by the use of gamma radiation) ready for use.

Use of the device will now be described to further illustrate and clarify the features of the invention. After removal from its sterile packaging the needle 2 and its surrounding cannula (not illustrated) may be inserted into a body cavity of a patient, e.g. into a patient's vein. Again using the example of an intravenous cannula introducer, blood will flow through the lumen of the needle 3 and into the chamber 9. The blood within the chamber 9 will be visible to an attending clinician due to the transparent nature of at least a portion of the chamber walls 11. The chamber 9 may be viewed through the slots 17, 28, 39 of the various components or alternatively each component can itself be made transparent to further improve the visibility. To withdraw the needle 2 the attending clinician depresses the actuating surface 15 of the needle-actuating portion 5 to release the hook member 14 from the slot 34 the needle 2 may then be drawn back into the sheath by pulling the actuating surface 15 towards the distal end of the device. The projecting tabs 20, 23 will slide along the operating channels 36, 24, forming slightly to ride over the step features 41, 42. When they reach the end of the operating channels the inwardly-projecting tabs 20 of the first telescopic portion 6 will click into the corresponding slots 37 in the housing; similarly the inwardly projecting tabs 23 of the second telescopic portion will click into the corresponding slots 22 on the first telescopic portion thus locking the telescopic portions into their extended configuration. Finally, the clip member 16 of the needle-actuating portion engages with the holes 30 in the distal face 29 of the second telescopic portion and lock, effectively irreversibly, into place. The inwardly-facing ends of the clip members 16 (illustrated in figure 4) are chamfered to engage with a corresponding chamfer edge of the holes 30 to enable the clip member 16 to deform slightly and then snap into place locking the two elements together.

Figure 13 is a cross-section of the device in its extended configuration illustrating how the needle 2 is safely contained within the sheath formed by the housing 3 the first telescopic portion 6 and the second telescopic portion 7.

Claims

1. A medical piercing needle assembly comprising: a piercing needle slidably attached to a sheath; wherein said piercing needle is moveable between two positions such that: in its first position, the piercing needle is reversibly lockable such that its piercing end projects from said sheath to an extent to allow it, in use, to pierce an object; and such that: in its second position, the piercing needle is irreversibly locked such that its piercing end is contained within said sheath, wherein, the locking mechanism is a manual reversible latching mechanism comprising a hook member and having an actuation portion.

2. An assembly according to claim 1 wherein said sheath comprises a plurality of telescopic portions.

3. An assembly according to any preceding claim wherein said piercing needle is hollow.

4. An assembly according to claim 3 wherein said hollow piercing needle is in fluid communication with a transparent chamber, whereby, in use, a user can observe fluid entering said chamber.

5. An assembly according to any preceding claim wherein movement of the needle between the two said position is effected solely by manual intervention of a user, in use.

6. A medical cannula set comprising a cannula introducer being an assembly according to any preceding claim and a cannula.

7. A medical piercing needle assembly substantially as described herein with reference to and/or as illustrated by any appropriate combination of the drawings.

8. A medical cannula set substantially as described herein with reference to and/or as illustrated by any appropriate combination of the drawings. A medical piercing needle assembly comprising: a piercing needle slidably attached to a sheath; wherein said piercing needle is moveable between two positions such that: in its first position, the piercing needle is reversibly lockable such that its piercing end projects from said sheath to an extent to allow it, in use, to pierce an object; and such that: in its second position, the piercing needle is irreversibly locked such that its piercing end is contained within said sheath.