WO2006079766A1

WO2006079766A1 - Method of manufacturing hypodermic needle and safety assembly incorporating such needle

Info

Publication number: WO2006079766A1
Application number: PCT/GB2005/000293
Authority: WO
Inventors: Phillip Owen Byrne; Harry Raymond Ingham; Penelolpe Rosemary Attridge
Original assignee: Id-Tech Limited
Priority date: 2005-01-27
Filing date: 2005-01-27
Publication date: 2006-08-03

Abstract

A safety assembly for a hypodermic needle is disclosed. A hypodermic needle has a needle blade (4) which is splayed such that the needle blade (4) extends beyond the outer circumference of a needle shaft. A capping device (6) allows access to the needle blade in a first position and prevents access to the needle blade in the second position. The portion of the needle blade (4) extending beyond the outer circumference of the needle shaft (2) prevents the capping device from being removed from the needle.

Description

METHOD OF MANUFACTURING HYPODERMIC NEEDLE AND SAFETY ASSEMBLY

INCORPORATING SUCH NEEDLE

The present invention relates to a method of manufacturing a hypodermic needle assembly for use with a capping device . The method also relates to a safety assembly incorporating such a needle .

Medical staff, patients and members of the general public are at risk from needle stick injuries in which a person is inadvertently pricked by a contaminated hypodermic needle . Such inj uries can result in the victim being infected with diseases such as AIDs or hepatitis .

An attempted solution to this problem is disclosed in US6663592 which describes an intravenous catheter introducer assembly having a safety device . The catheter introducer assembly comprises a catheter with a hypodermic needle inserted through the longitudinal axis of the catheter with the needle tip proj ecting from the end of the assembly . A protector sleeve is stored in a chamber in the catheter hub . The protector sleeve is substantially cylindrical and mounted coaxially on the needle shaft . The protector sleeve has a resilient flange which proj ects inwardly of the sleeve and engages the surface of the needle shaft . A circumferential groove is formed in the needle shaft near the needle tip such that when the catheter is inserted into the patient, the needle hub can be pulled away from the catheter which slides the needle rearwardly through the catheter . When the circumferential groove in the needle shaft encounters the resilient flange of the protector sleeve, the resilient flange locks into the circumferential groove of the needle thus covering the needle tip with the protector sleeve . Further withdrawal of the needle from the catheter pulls the needle and protector sleeve through a flexible retainer to completely remove the needle with protected needle tip from the catheter .

This assembly suffers from the drawback that a circumferential groove must be machined in the shaft of the needle . It is difficult and relatively costly to accurately machine a circumferential groove in a needle of small diameter, making an assembly of this type unsuitable for a low cost product such as a disposable hypodermic needle .

Another safety device for a catheter introducer assembly is described in WO03011381. This device comprises a cannula needle which is inserted coaxially along the longitudinal axis of a cannula . The needle tip proj ects from the end of the cannula to enable the needle to be injected into a patient to insert the cannula . A protective device for the tip of the cannula needle is mounted onto the back of the cannula . The protective device comprises a generally cylindrical hollow body supporting a plurality of fins which are inclined forwardly towards the needle tip . When the needle is withdrawn from the cannula, an annular groove machined in the needle shaft near to the tip of the needle is moved into alignment with the fins, until the fins engage the annular groove and lock the protective device over the needle tip . Further withdrawal of the needle entirely removes the needle and protector device from the cannula .

A second embodiment of WO03011381 replaces the annular groove and fins with an annular ridge formed in the needle shaft near the tip, and a blocking ring disposed in the protector device that engages the annular ridge to have the same effect on withdrawal of the needle as the first embodiment .

Both embodiments of WO03011381 suffer from the drawback that it difficult to either machine an annular groove in the shaft of a needle, or form an annular ridge on the needle shaft remote from the blade, especially for small diameter needles . Furthermore, as the annular groove or ridge is formed remote from the blade of the needle, this tends to increase the length of the protector assembly leading to an associated increase in cost . Moreover, the devices of WO03011381 comprise several moving parts which further increases cost and increases the possibility that one of the parts may malfunction, thus rendering the assembly unusable . These disadvantages make the devices of WO03011381 particularly unsuitable for use with cheap devices such as disposable syringes .

US6623458 describes a safety device for a hypodermic needle . The device comprises a spring loaded safety clip assembly which is mounted in the needle hub of a syringe . When the syringe has been used, further pressure applied to the needle plunger releases the spring loaded safety clip which slides along the needle until a restraining opening in the rear wall of the safety clip encounters a crimped needle stop formed on the shaft of the needle . This prevents the safety clip from being pushed off the end of the needle . The safety clip locks over the tip of the needle thus preventing access to the used needle tip .

This device suffers from the drawback that it is difficult to form a crimped needle stop on the shaft of a small diameter needle . Also, the crimped needle stop is disposed some distance from the needle tip which tends to increase both the length of the needle and the length of the safety clip . Spring loaded needle safety devices of this type are expensive as they have several moving parts , making a safety device of this type unsuitable for a disposable hypodermic syringe . Japanese patent application no . 2001-006446 describes a protector device for mounting on a hypodermic needle . The protector device comprises a protector body formed in a substantially S-shape from an elastic material . The S-shaped protector has three holes which are aligned when the protector device is mounted on the shaft of the needle . When the needle has been used, the protector device is slid along the shaft of the needle until the foremost hole moves past the tip of the needle . This causes the elastic protector to spring upwardly, thus covering the tip of the needle with the leading edge of the protector . In this condition, the middle hole of the protector resiliently engages the shaft of the needle to prevent further forward movement of the protector along the needle .

This device suffers from the drawback that as only resilient contact prevents further forward motion of the protector on the needle , a relatively small force is needed to overcome this frictional engagement making it relatively easy for the protector to be pulled completely from the needle . Also, the user is able to realign the holes on the protector with the needle to allow the protector to be pushed back along the needle .

Japanese patent application no . 2000-284157 describes a safety device for a needle comprising a capping device having two j aws that can be resiliently closed over the tip of the needle when the capping device is slid forwardly along the needle . A bulge in the shaft of the needle prevents the capping device being pulled away from the needle .

This device suffers from the drawback that it is relatively difficult and expensive to form a bulge in the shaft of a needle, especially a small diameter needle . Also, as the bulge is located remote from the tip, this tends to increase the length of the needle and also the length of the capping device making the capping device more costly to manufacture .

Japanese patent application no . 07-174456 describes a safety- device for a cannula insertion assembly. A hypodermic needle is inserted coaxially in the cannula and comprises an annular groove formed in the shaft of the needle near the tip . The protector device comprises a stopper which elastically engages the locking groove as the needle is pulled away from the cannula to cover the needle tip with the protector device .

This device suffers from the drawback that it is difficult to accurately machine a groove in a small diameter needle . Also, as the groove is located remote from the tip, this tends to increase the length of the needle and also the length of the capping device , making the capping device more costly to manufacture . Finally, as this device comprises several moving parts , the device is relatively expensive to manufacture and more prone to malfunction .

Preferred embodiments of the present invention seek to overcome the disadvantages of the above prior art .

According to an aspect of the present invention, there is provided a method of manufacturing a hypodermic needle for use with a capping device, the capping device having a first position allowing access to a blade of the needle and a second position preventing access to the blade of the needle, the method comprising adjusting the profile of said needle such that a portion of sa'id needle blade extends a greater radial distance from a longitudinal axis of the needle than, the adj acent portion of the unadjusted needle, and is adapted to cooperate with the capping device to prevent access to the blade of the needle . This provides the advantage of a relatively inexpensive and simple method for providing a means of retaining a needle capping device in a position in which the needle blade is capped. By adjusting the profile of the needle at the needle blade, this also provides the advantage that the length of the capping device can be reduced compared with known devices , since the capping device will not need to engage either a recess or protrusion formed on the surface of. the needle at a location remote from the needle blade . This reduces the cost of manufacture of the needle and capping device .

In a preferred embodiment , the method further comprises the step of providing a capping device mounted on said needle .

The unadj usted needle may have a substantially circular cross section and said needle blade may be adjusted as to have a non circular cross section .

This provides the advantage that a standard cylindrical hypodermic needle can be pressed to provide an elliptical section providing a relatively inexpensive and simple method of deforming the needle blade .

The needle blade may be adjusted by bonding additional material to said needle blade or shaft .

Said additional material may include at least one ceramic material .

The portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of the unadj usted needle may be adapted to cooperate with the capping device to prevent said capping device being moved from the second said position to the first said position .

The portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of the unadjusted needle may be adapted to cooperate with the capping device to prevent removal of said capping device from said needle .

According to another aspect of the present invention, there is provided a safety assembly for a hypodermic needle comprising :

a needle having a shaft and a needle blade , a portion of the needle blade extending a greater radial distance from a longitudinal axis of the needle than an adj acent portion of said shaft; and

a capping device having a first position allowing access to the blade of the needle and a second position preventing access to the blade of the needle , wherein said portion of the needle blade extending a greater radial distance from a longitudinal axis of the needle than said adj acent portion of said shaft is adapted to cooperate with the capping device to prevent access to the blade of the needle .

This provides the advantage that as the portion of the needle that retains the capping device in the second said position is formed at the blade of the needle or very close to the blade or incorporates both blade and shaft rather than at a location remote from the needle blade , the length of the capping device can be reduced- in order to reduce the cost of the safety assembly. This also provides the advantage that a circumferential groove or ridge does not have to be machined in the needle shaft , further decreasing the cost of the assembly .

The needle shaft may have a substantially circular cross section and said needle blade may have a non-circular cross section with a dimension greater than the diameter of needle shaft .

This provides the advantage that the only modification needed to a standard cylindrical needle is to press a portion of the needle at the blade thus altering the cross section. This is a relatively inexpensive and simple method of altering the profile of the needle blade for retaining a capping device .

The portion of the needle blade extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of the needle shaft may be formed by bonding additional material to the needle blade .

In a preferred embodiment, the additional material includes at least one ceramic material .

The portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of said shaft may be adapted to cooperate with the capping device to prevent said capping device being moved from the second said position to the first said position .

The portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of said shaft may be adapted to cooperate with the capping device to prevent said capping device from being removed from the needle . According to a further aspect of the present invention, there is provided a needle comprising a safety assembly as defined above .

Preferred embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings in which : -

Figure 1 is a cross sectional view of a hypodermic needle safety assembly of a first embodiment of the present invention, with a capping device thereof in a retracted condition;

Figure 2 shows the needle of Figure 1 with the capping device moved towards the needle blade;

Figure 3 shows the needle of Figure 1 with the capping device locked into position over the needle blade;

Figure 4 is a cross sectional view of a safety assembly of a second embodiment of the present invention with a capping device thereof in a retracted condition;

Figure 5 shows the needle of Figure 4 with the capping device moved along the needle towards the needle blade;

Figure 6 shows the needle of Figure 4 with the capping device locked into position over the needle blade;

Figure 7 is a top view of a standard needle tip having a needle blade ; Figure 8 is a top view of a first embodiment of a needle having splayed blade formed by means of a method embodying the present invention;

Figure 9 is a side view of the needle of Figure 8 ;

Figure 10 is a top view of a second embodiment of a needle having a splayed blade;

Figure 11 is a top view of a third embodiment of a needle having a splayed blade ;

Figure 12 is a cross sectional view of a fourth embodiment of a needle in which additional material is bonded to the blade of the needle ;

Figure 13 is a cross sectional view of the needle of Figure 12 in which the needle blade is held in a capping device;

Figure 14 is a cross sectional representation of a circular needle shaft before the blade is formed; and

Figure 15 is a cross sectional representation of an elliptical needle shaft end before the blade is formed.

Referring to Figure 1 , a hypodermic needle comprises a sharp needle blade 4 for penetrating the skin and/or tissue of a patient . It can be seen that the needle blade 4 is splayed such that the needle blade 4 extends beyond the outer circumference of the needle shaft 2. A capping device 6 is formed from a plastic material and comprises an aperture 8 which slidably engages the needle shaft 2 in order to allow the capping device 6 to slide along the needle shaft 2. The capping device comprises a support arm - 10 which guides the capping device on the underside of the needle shaft 2 and a resilient flap 12 which is resiliently biased against the needle shaft 2 in the position shown in Figure 1. A gripping portion 14 allows the user to grip the capping device remote from the front end of the capping device and therefore remote from the needle blade 4.

Referring to Figure 2 , when the hypodermic needle has been used, for example with a syringe in order to either inj ect a patient with drugs or to take a sample of bodily fluid such as blood from a patient , it is desirable that the used needle blade 4 does not come into contact with other persons such as medical staff in order to prevent the spread of infection and diseases such as AIDs or hepatitis . The capping device 6 can be slid along needle shaft 2 such that the resilient flap 12 rides up along needle blade 4.

Referring to Figure 3 , as the resilient flap 12 is pushed past the needle blade 4 the resilient flap 12 snaps forwardly into the position shown in Figure 3 against stop 16 such that the capping device 6 completely encloses the needle blade 4 to prevent access to needle blade 4. It can be seen that the radial extent of the needle blade 4 from the longitudinal axis X of the needle shown by arrow A is greater than the radial distance from the needle axis X to the edge of aperture 8 shown by arrow B . Consequently, aperture 8 prevents the needle blade 4 from being pulled rearwardly out of the capping device 6. Resilient flap 12 prevents the needle blade 4 being pushed forwardly to expose the used needle blade 4. The used needle blade 4 is therefore safely enclosed by capping device 6, and the used needle can then be disposed of in the conventional manner .

A second embodiment of a needle and capping device is shown in Figures 4 to 6. Parts common to the embodiment of Figures 1 to 3 are shown with like reference numerals but increased by 100.

A hypodermic needle having a shaft 102 is attached to a hub 120 which may form part of a hypodermic syringe . The needle has a blade 104 on which additional tubing 122 is bonded. The additional tubing may be a ceramic material which is either bonded or heat shrunk onto the needle either before or after formation of the needle blade by grinding . The additional tubing 122 serves to increase the radius of the needle at the needle blade compared with the needle shaft 102.

The capping device 106 comprises a resilient locking j aw 112 which is resiliently biased against the underside of needle shaft 102 when the j aw is displaced by the needle shaft 102. An aperture 108 serves to hold the capping device 106 on the needle shaft 102 and also guide the capping device 106 along the needle 102. A gripping portion 114 is provided to enable the needle user to grip the capping device remote from the forward end of the capping device and therefore remote from the blade 104. It can be seen that as the capping device 106 is slid forwardly along the needle shaft 102 , the locking j aw 112 first comes into contact with the additional tubing 122 formed around the blade 104 and then snaps shut once it has moved past the additional tubing 122 into the locked position shown in Figure 6. The locking j aw 112 has an inclined forward edge 113 to enable it to slide over additional tubing 122.

Referring to Figure 6, it can be seen that the radial extent of the additional tubing 122 is greater than the radial extent of aperture 108 , thus preventing the needle blade 104 from ^■ being pulled rearwardly out of the capping device 106. Locking j aw 112 prevents the needle blade 104 being pushed forwardly out of the capping device 106. The used needle blade 104 is therefore safely enclosed by capping device 106, and the used needle can then be disposed of in the conventional manner .

Figure 7 shows standard hypodermic needle 230 comprising a needle shaft 232 having a circular cross section and a sharpened needle blade 234 for inj ecting a patient . The needle blade is generally formed by grinding a section of cylindrical hypodermic tubing to produce a sharp edge . The needle tube 236 is generally circular in cross section .

Referring to Figures 8 and 9, a first embodiment of a needle 330 having a splayed blade 334 and formed by means of a method embodying the present invention is shown . The needle has a standard shaft 332 having circular cross section. However, the needle blade 334 is pressed to change the cross section of the blade 334 from a circular cross section to an elliptical cross section and splay the edge 336 outwardly . This means that the radial extent of the edge 336 of the blade 334 extends beyond that of the shaft 332 in order to form a needle blade 334 that cannot be removed from a capping device such as that shown in the embodiments of Figures 1 to 3 and Figures 4 to 6.

It will be understood by persons skilled in the art that even though the needle blade 334 of Figure 8 has been pressed into an elliptical cross section and also splayed outwardly, only one of these features is actually required in order to form a portion of the blade edge 336 that extends a further radial extent than the needle shaft 332. It will also be understood by persons skilled in the art that the needle blade can either be pressed either before or after the blade is actually ground into the needle shaft . Referring to Figure 14 and 15 , cross sectional representations of a circular needle blade and an elliptical needle blade are shown . The cross sectional area of a circular needle blade having a radius of 2 units is approximately 12.57 square units . The cross sectional area of an elliptical needle blade having a maj or axis of 2.2 units and a minor axis of 1.8 units is approximately 12.43 square units . It can therefore be seen that by selecting appropriate dimensions to deform a needle of circular cross section into an elliptical cross section, the cross sectional area of the needle blade does not decrease by a large amount in order to form an elliptical blade . This means that there is only a small loss in the flow-rate of material through the needle blade when comparing a needle blade of circular cross section to a needle blade of elliptical cross section with appropriately chosen dimensions .

Figure 10 shows a second embodiment of a needle 430 having a splayed blade 434. Again, the needle has a shaft 432 of circular cross section and the needle blade 434 has been firstly pressed into an elliptical shape and then splayed outwardly in order to provide a portion of the needle blade 434 that extends a further distance from the longitudinal axis of the needle than a portion on the needle shaft 432. The difference between the embodiment of Figure 10 and that of Figures 8 and 9 is that the embodiment of Figure 10 is both pressed into an elliptical shape and splayed outwardly a further distance along the needle shaft 432 than the embodiment of Figures 8 and 9.

Figure 11 shows a third embodiment of a hypodermic needle 530 having a splayed blade 534. Again, the needle has a shaft 532 of circular cross section. The needle blade 534 has been formed into a flattened spear shaped tip 536. This both increases the radial extent of the blade 534 and also facilitates the injection of a patient by making the needle blade 534 sharper .

Figure 12 shows a fourth embodiment of a needle 630. The needle has a shaft 632 of circular cross section and a blade 634 which has been ground into the shaft . Additional tubing 636 is disposed on the needle shaft 632. The additional tubing 636 can either be bonded or heat shrunk onto the blade 634. The additional tubing 636 may be a ceramic material .

The additional tubing 636 serves to increase to radial extent of the needle blade 634 in order to prevent the needle blade being pulled from a capping device as shown in Figures 4 to 6. The rear edges 638 of the additional tubing 636 may be chamfered in order to facilitate easy withdrawal of the needle from a patient .

Referring to Figure 13, the needle 630 of Figure 12 is shown disposed in a capping device 640. The capping device 640 comprises a flap 642 that is actuated by a spring 644 when the flap 642 passes over the needle blade 634. The capping device 640 works in substantially the same way as the capping device shown in Figures 1 to 3.

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims .

Claims

1. A method of manufacturing a hypodermic needle for use with a capping device, the capping device having a first position allowing access to a blade of the needle and a second position preventing access to the blade of the needle , the method comprising adjusting the profile of said needle such that a portion of said needle blade extends a greater radial distance from a longitudinal axis of the needle than the adj acent portion of the unadj usted needle, and is adapted to cooperate with the capping device to prevent access to the blade of the needle .

2. A method according to claim 1, further comprising the step of providing a capping device mounted on said needle .

3. A method according to claim 1 or 2 , wherein the unadjusted needle has a substantially circular cross section and said needle blade is adj usted so as to have a non- circular cross section .

4. A method according to claim 1 or 2 , wherein the needle blade is adjusted by bonding additional material to said needle blade .

5. A method according to claim 4 , wherein said additional material includes at least one ceramic material .

6. A method according to any one of the preceding claims , wherein said portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of the unadjusted needle is adapted to cooperate with the capping device to prevent said capping device being moved from the second said position to the first said position .

7. A method according to any one of the preceding claims , wherein said portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of the unadj usted needle is adapted to cooperate with the capping device to prevent removal of said capping device from said needle .

8. A safety assembly for a hypodermic needle comprising :

a capping device having a first position allowing access to the blade of the needle and a second position preventing access to the blade of the needle, wherein said portion of the needle blade extending a greater radial distance from a longitudinal axis of the needle than said adj acent portion of said shaft is adapted to cooperate with the capping device to prevent access to the blade of the needle .

9. An assembly according to claim 8 , wherein the needle shaft has a substantially circular cross section and said needle blade has a non-circular cross section with a dimension greater than the diameter of needle shaft .

10. An assembly according to claim 8 , wherein the portion of the needle blade extending a greater radial distance from the longitudinal - axis of the needle than the adj acent portion of the needle shaft is formed by bonding additional material to the needle blade or shaft .

11. An assembly according to claim 10 , wherein said additional material includes at least one ceramic material .

12. An assembly according to any one of claims 8 to 11 , wherein said portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of said shaft is adapted to cooperate with the capping device to prevent said capping device being moved from the second said position to the first said position .

13. An assembly according to any one of claims 8 to 12 , wherein said portion of said needle extending a greater radial distance from the longitudinal axis of the needle than the adj acent portion of said shaft is adapted to cooperate with the capping device to prevent said capping device from being removed from the needle .

14. A safety assembly for a hypodermic needle, the assembly substantially as hereinbefore described with reference to the accompanying drawings .

15. A needle comprising a safety assembly according to any one of claims 8 to 14.