WO1988002640A2

WO1988002640A2 - Improvements in or relating to syringes

Info

Publication number: WO1988002640A2
Application number: PCT/GB1987/000728
Authority: WO
Inventors: John Stewart Parry
Original assignee: Sterimatic Holdings Limited
Priority date: 1986-10-17
Filing date: 1987-10-16
Publication date: 1988-04-21
Also published as: WO1988002640A3; AU8076387A

Abstract

A syringe (1) comprises a hollow cylindrical barrel (2), a plunger (9) which delimits a chamber within the barrel (2) and which is longitudinally reciprocable within the barrel (2) to draw liquid into, and expel liquid from, the chamber by way of an outlet (3), and a deactivating arrangement which, after the plunger (9) has been moved to a position to expel the liquid from the chamber, prevents further liquid from being drawn into the chamber. Such an arrangement renders the syringe (1) non-reusable.

Description

"Improvements in or Relating to Syringes"

This invention relates to syringes for delivery of a dose of injectate or other substan preferably through a hollow needle or tube.

The use of cheap, disposable plastics syrin is well established for the injection of patients and various laboratory applications. Such syringes intended to be used only once prior to disposal. Eith the syringe may be supplied with a needle integral attached thereto, or alternatively the needle may supplied separately from the syringe in which case t needle is fitted to the syringe immediately prior to us In either case the needle is intended to be thrown aw after a single use together with the body of the syringe

However, it is found that in practice su syringes are often used more than once prior to disposa most notably by unsupervised drug users. This can highly dangerous not only because of the risk of infecti due to contamination of the needle but also due to t danger of transfer from one user to another of bloo related diseases, such as AIDS (acquired immune deficien syndrome) .

It is an object of the invention to provide syringe of a novel form which makes it difficult impossible to use the syringe more than once.

According to the present invention, there provided a syringe in accordance with claim 1.

Claims 2 to 5 set out four alternati embodiments in accordance with the invention.

In the case of the embodiment of claim 3, th releasable coupling means may be adapted to operativel couple the two parts of the plunger together during a least one stroke of the operating part in the direction t increase the size of the chamber, for example so as t draw liquid into the barrel, and to enable the piston par to be subsequently moved to decrease the size of th chamber by means of the operating part, for example so a to expel liquid from the barrel.

However, the coupling means should be such that subsequent to the delivery of the liquid, movement of th operating part in the direction to increase the size o the chamber will cause the operating part to b operatively decoupled from the piston part, so that th syringe will be rendered non-reusable.

In order that the invention may be more full understood, preferred forms of syringe in accordance wit the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a longitudinal section through tw ends of a first syringe;

Figure 2 is an explanatory cross-section throug a piston part of the syringe taken along the line II-II i Figure 1;

Figures 3 and 4 are developed views of tw diametrically opposite portions of the outside surface o the piston part; Figure 5 is a longitudinal section through t end of the syringe and a needle to be connected to t syringe;

Figure 6 is a longitudinal section through second syringe;

Figure 7 shows part of a third syringe;

Figures 8A - C show sections through the part Figure 7 in three successive phases of operation;

Figures 9A - C show sections through modification of the part of Figure 7; and

Figures 10A - C show sections through part of fourth syringe in three successive phases of operation.

Referring to Figure 1, the syringe 1 comprises transparent hollow cylindrical barrel 2 having an outlet at one end surrounded by an integral connector 3a f attachment of a hollow needle (not shown), and a plunger displaceable within the barrel 2.

The plunger 4 is formed in two parts, namely piston part 5 incorporating a resilient piston element in fluid-tight engagement with the inside surface of t barrel 2, and a transparent tubular operating part 9. T parts 5 and 9 are operatively coupled together by releasable coupling arrangement comprising two projectio 10 and 11 projecting inwardly of the inside surface of t operating part 9 at diametrically opposite locations, a two guide tracks 12 and 13 in the outside surface of t piston part 5 within which the projections 10 and 1 respectively are engaged. Figure 2 is a diagrammatic cross-section throug the piston part 5 showing the circumferential extent of the guide tracks 12 and 13. Furthermore Figures 3 and 4 are developed views of portions of the outside surface o the piston part 5 showing the form of the guide tracks 13 and 12 respectively.

Referring to Figure 3, the guide track 13 has a profiled forward edge 14 with which the projection 11 engages when the plunger 4 is moved forwardly in the direction of the outlet 3, and two parallel side edges 15 and 16, the guide track 13 opening opposite the profile edge 14 on the side of the piston part 5 remote from the outlet 3, as shown in Figure 1.

Referring to Figure 4, the guide track 12 has a straight forward edge 17 and a profiled rearward edg 18 with which the projection 10 engages when the plunger 4 is moved rearwardly in the direction away from the outle 3. The guide track 12 also has two parallel side edges 19 and 20 which, together with the edges 17 and 18, define circumferentially-extending slot portion 21. In additio the guide track 12 includes a longitudinally-extendin slot portion 22 communicating with the end of th circumferentially-extending slot portion 21 adjacent th edge 19 and opening at the side of the piston part 5 remote from the outlet 3.

The profiled edge 14 of the guide track 13 ha three saw teeth 23, 24 and 25 defining ramp surfaces an four successive forward engagement positions for th projection 11, as indicated by the letters A, C, E and G The profiled edge 18 of the guide track 12 has a ram surface 26 and three saw teeth 27, 28 and 29 defining ram surfaces and three successive rearward engagemen positions for the projection 10, as indicated by th letters B, D and F.

The operation of the syringe, and the functio of the profiled edges 14 and 18 of the guide tracks 13 an 12, will now be described with reference to the letters A, B, C, D, E, F and G denoting successive forward an rearward engagement positions of the projections 11 and 1 in the guide tracks 13 and 12.

A. When the syringe is initially assembled the tw parts 5 and 9 of the plunger 4 are fitted together so tha the projections 11 and 10 are accommodated within the guide tracks 13 and 12 with the projection 11 in the position A engaging the forward edge 14 and the projection 10 engaging the ramp surface 26 of the rearward edge 18. With the two parts 5 and 9 coupled together in this manner the plunger 4 is introduced into the barrel 2 and pushed forwardly until the piston element 6 is adjacent the outlet 3.

B. As an additional test step during assembly the plunger 4 is moved rearwardly away from the outlet 3 by manually grasping the operating part 9, in order to ensure that the piston element 6 is properly connected to the plunger 9. This movement causes the projection 10 to move along the ramp surface 26, thus causing relative rotation between the parts 5 and 9, and to enter the rearward engagement position B. Simultaneously the projection 11 is brought to a position 11' clear of the tooth 23. The syringe is supplied to the user in this state.

C. In use of the syringe to perform an injection the user initially moves the plunger 4 to its fully forward position in order to expel air from the barrel 2 through the outlet 3. This causes the projection 11 to move along the ramp surface of the tooth 23, thus causing further relative rotation of the parts 5 and 9, and to enter the forward engagement position C. Simultaneously the projection 10 is moved to a position clear of the tooth 27.

D. The user then moves the plunger 9 in the direction away from the- outlet 3 to draw up injectate into the barrel 2 from an injectate container through a hollow needle attached to the connector 3a. This causes the projection 10 to move along the ramp surface of the tooth 27 to the rearward engagement position D, with consequent further relative rotation of the parts 5 and 9. Simultaneously the projection 11 is moved to a position clear of the tooth 24.

E. The user then moves the plunger 4 forwardly by a short distance towards the outlet 3 in order to expel any entrained air from the barrel 2. This causes movement of the projection 11 along the ramp surface of the tooth 24 to the forward engagement position E, with consequent further relative rotation of the parts 5 and 9. Si ultaneously the projection 10 is moved to a positio clear of the tooth 28.

F. After insertion of the needle into the site o injection, the user then moves the plunger 4 backwar again to aspirate the needle ensuring the needle is not in a vein . This causes movement of the projection 10 along the ramp surface of the tooth 28 to the rearward engagement position F, with consequent further relative rotation of the parts 5 and 9. Simultaneously the projection 11 is moved to a position clear of the tooth 25.

G. The plunger 4 is then moved forwardly to deliver the dose of injectate through the needle. This causes movement of the projection 11 along the ramp surface of the tooth 25 into the forward engagement position G, with consequent further relative rotation of the parts 5 and 9. Simultaneously the projection 10 is moved to a position clear of the tooth 29.

With the two parts 5 and 9 of the plunger 4 in these final relative positions, further movement of the plunger 4 in the direction away from the outlet 3 will cause the operative coupling between the two parts 5 and 9 to be released, thus rendering the syringe non-reusable. More particularly, such movement will cause the projection 10 to move along the ramp surface of the tooth 29 and to enter the longitudinally-extending slot portion 22 along which it will be drawn by further outward movement of the operating part 9. Thus the operating part 9 will be decoupled from the piston part 5, and the piston part 5 will remain within the barrel 2 when the operating part 9 is removed from the barrel 2.

It should be understood that various modifications of the above-described syringe are contemplated within the scope of the invention. For example, the number of saw teeth provided along the profiled edges of the guide tracks may be increased or decreased depending on the intended use and mode of operation of the syringe (such as where the syringe is to be used for taking a blood sample in conventional manner). Also the saw teeth may be provided in a single guide track to be engaged by a single projection. The guide track may take a variety of forms, and may be located either on the piston part or the operating part, either internally or externally of the part bearing the projections.

Figure 5 shows a possible modification to the syringe described above enabling a needle 120 to be fitted to the connector 3a on the barrel 2 in such a manner as to prevent the needle 120 from being detached from the syringe after use. The needle 120 has a metal needle part 121 permanently connected to a plastics connector 122 by way of a metal bush 123 on the end of the needle part 121. The connector 122 has a flange 124, and the inside surface of the connector 122 has an annular recess 125 therein for receiving an annular rib 114 on the outside surface of the connector 3a. In order to prevent the needle 120 from being subsequently detached from the connector 3a after fitting, the annular rib 114 has a shoulder 115 which engages a shoulder 126 of the annular recess 125. For ease of fitting of the connector 122 over the connector 3a, the annular rib 114 has a ramp surface 116 which engages a corresponding ramp surface 127 of the recess 125. Furthermore, in order to guard against the needle 120 being forcibly removed from the connector 3a, either or both of connectors 3a and 122 may be formed with an annular weakened region such as 119 which will tend to fracture if an attempt is made to detach the needle 120.

In a further modification of the syringe of Figures 1 to 4 releasable sealing means are provided comprising one or more through bores, and preferably four through bores, extending through the piston part 5, and a corresponding number of pegs projecting from the operating part 9 and sealingly engaged in the through bores when the piston part 5 and the operating part 9 are coupled together in use. Thus, during each of the operating steps A to G of the syringe described above, the sealing of the through bores by the pegs ensures that there is no fluid communication across the piston part 5. However, when the coupling between the two parts 5 and 9 is released after the injection has been effected, the pegs are drawn out of the through bores as the parts 5 and 9 move apart and fluid communication is thereby established across the piston part 5 by way of the through bores. Such releasable sealing means acts as a further measure to prevent the syringe being reused, for example by forcing injectate through the outlet 3 under pressure into the barrel 2.

Figure 6 shows a second form of syringe 31 in accordance with the invention. The syringe 31 comprises a hollow cylindrical barrel 32 made of transparent plastics material having an integral connector 33 at one end for attachment of a hollow needle (not shown), and a plunger 34 displaceable within the barrel 32. The barrel 32 has a tabulated scale (not shown) marked on its outer surface for measuring the dose to be delivered by the syringe. In addition a flange 35 is provided on the end of the barrel 32 remote from the connector 33.

The plunger -34 includes a piston part 36 which sealingly engages the inside surface of the barrel 32 by means of an O-ring 37. Integrally formed with the piston part 6 is an operating part 38 of generally cruciform cross-section having a flange 39 at its end remote from the piston part 6.

In addition a locking formation in the form of an annular rib 40, which is barbed in section, is provided on the inside surface of the barrel 32 close to the connector 33. The rib 40 has a ramp surface 41 to assist movement of a locking portion 43 of the piston part 36 of the plunger 34 over the rib 40 in the direction of movement indicated by the arrow 41A, and a shoulder 42 for engaging behind an annular rib 44, which is also barbed in section, on the locking portion 43 to prevent the plun 34 from being drawn back for further use once the lock portion 43 has been moved beyond the rib 40. The plun 34 includes a necked portion 47 which is adapted fracture if an attempt is made to draw the plunger 34 b when the locking portion 43 is in locking engagement w the rib 40.

Various modifications of the above-descri embodiment are contemplated within the scope of invention. The annular rib 40 may be replaced b plurality of projections equiangularly spaced around periphery of the inside surface of the barrel 3 Alternatively the annular rib 40 may be replaced by annular recess, and a flexible skirt may be provided the piston part 36 which is adapted to enter the rece and to be locked behind a shoulder in the recess when is moved over the recess. The flexible skirt may be continuous annular skirt extending around the periphery the piston part 36 or alternatively may be constituted a plurality of flexible projections equiangularly spac around the periphery of the piston part 36.

In another variant, a locking portion on t front of the piston part is adapted to enter an extensi part on the end of the barrel 32, possibly within t connector 33, in order to lockingly engage an annular r or recess on the inside wall of the extension part in manner similar to that described with reference to t engagement with the annular rib 40 or recess on the insi wall of the barrel.

In a further variant, the necessary locking i provided by a projection provided on the end wall of th barrel 32 and adapted to engage within a recess in th piston part 36 and to be locked therein by virtue o interengaging locking formations thereon. Alternativel the projection may be adapted to puncture a weakene region of the piston part and to be locked within th recess so formed by engagement of a shoulder on th projection behind the part of the piston part immediatel surrounding the punctured portion. For example th projection may be of pointed conical form having a annular recess at its base adjacent the end wall definin the shoulder. The hole formed by puncturing of th weakened region preferably places the two sides of th piston part in fluid communication so that there is n possibility of the piston part being subsequently reused.

Although it is preferred that such destructio of the piston sealing is accompanied by locking of th projection within the recess so formed, a simila arrangement in which the projection merely punctures th weakened region, but does not thereby become locked in th recess, is also within the scope of the invention.

In a further variant the piston part is attache to the operating part of the plunger in such a manner a to allow limited movement between the two parts. Furthermore the projection is provided on the operatin part, rather than on the inside surface of the barrel, an the piston part is adapted to be displaceable with resp to the projection when it contacts a projecting portion the inside surface of the barrel so as to cause weakened region of the piston part to be punctured by projection ori the operating part.

In the above described locking arrangements is not essential that the locking is such as to prev all further movement of the piston part. It may sufficient in certain circumstances for the lock formations to limit further movement of the piston p over a substantial distance in the locked state, example over a distance defined between the end of barrel and a locking formation on the inside of barrel.

Figure 7 shows a flap valve arrangement wh may be positioned either within a syringe barrel or wit the outlet of the barrel, in accordance with a furt embodiment of the invention, in order to render syringe non-reusable. Liquid drawn into or expelled fr the barrel must pass through this flap valve arrangemen The flap valve arrangement comprises more particularly circular wall 50 incorporating a flap 51 integr therewith and pivotable along a line of weakness 52 open an aperture in the wall 50.

Figures 8A to C show sections through the wa 50 along the line VIII-VIII in Figure 7 in thr successive phases of operation. In the initial positi of the valve arrangement prior to use of the syringe, t flap 51 will lie in the plane of the wall 50 with th chamfered edge 53 of the flap 51 being engaged with correspondingly chamfered seating 54. When injectate i to be drawn into the barrel by drawing back the plunger o the syringe, the flap 51 is caused to open as shown i Figure 8A and injectate may flow into the barrel in th direction of the arrow 55.

Subsequently, when injectate is to be delivere to the site of injection along the hollow needle by movin the plunger towards the outlet of the barrel, the pressur of injectate on the flap 51 causes the flap 51 to b forced through the seating 54 by a snap action, thereb opening the valve arrangement in the opposite direction a shown in Figure 8B and allowing flow in the direction o the arrow 56. If an attempt is then made to draw furthe injectate into the syringe barrel, the flap 51 will b brought back to a position as shown in Figure 8C in whic the flap 51 substantially closes off the aperture but i prevented from moving back through the aperture by virtu of the shapes of the edge 53 of the flap 51 and th seating 54.

Figures 9A to 9C show a modification of the fla valve arrangement of Figures 7 and 8 in three successiv phases of operation corresponding to the phases o operation shown in Figure 8. In this case the flap 51 i initially retained open by means of a resilient pin 57 o the flap 51 being engaged within a recess 58 in th peripheral portion of the wall 50 at a positio dia etrically opposite to the line of weakness 52, shown in Figure 9A.

A still further arrangement for preventing t syringe from being used more than once is illustra diagrammatically in Figure 10 which shows a secti through a piston part 61 of a plunger 74 and through t barrel 73 in the vicinity of the piston part 61, in thr successive phases of operation. The piston part comprises a seating part 62 of relatively rigid materi and an annular sealing member 63 of relatively resilie material which engages an annular seating 64 on t seating part 62. The sealing member 63 has a deformab annular flange 65 which sealingly engages the insi surface of the barrel 73 and which is movable between t annular positions by a snap action.

The annular flange 65 on the sealing member is initially in a first angular position as shown Figure 10A and remains in this position, whilst providi sealing of the piston part with respect to the insi surface of the barrel 73, as the piston part 61 is dra along the barrel to draw injectate into the barrel. Wh the direction of movement of the piston part 61 subsequently reversed to expel injectate or air from t barrel, this causes the annular flange 65 on the seali member 63 to be snapped over into a second annul position as shown in Figure 10B. In this position t sealing member 63 as a whole is caused to take up position in which its angle of inclination relative to t seating 64 is decreased with the result that the interna diameter of the sealing member 63 is slightly increased. Thus the sealing member 63 becomes a looser fit on th seating 64, although it continues to provide sealin between the piston part 61 and the inside surface of th barrel 73 during movement of the piston part 61 toward the outlet since such movement tends to press the annular flange 65 firmly against the inside surface of the barrel 3.

However, if the direction of movement of th piston part 61 is again reversed, for example in a attempt to draw up further injectate, the engagement o the sealing member 63 with the inside surface of th barrel 73 will overcome the engagement of the sealin member 63 with respect to the seating 64 with the resul that the sealing member ^'63 will become disengaged from th seating 64 and will remain in its end position within th barrel 73 as the seating part 62 is drawn back (Figur IOC) .

In a variant of this embodiment, instead of th sealing member 63 being a loose fit on the seating 64 i its second position, the sealing member 63 adopts a for in its second position which provides considerabl resistance to movement of the piston part 61 in th direction away from the outlet.

In a further variant the complete piston part i made of resilient material and is a force fit within tubular operating part. Furthermore the piston part i provided with one or more annular flanges generally described with reference to Figure 10 except that the each annular flange is integral with the remainder of piston part. In this case the snapping over of the each annular flange into its second position increases frictional engagement of the piston part with the ins surface of the barrel to such an extent that, when operating part is subsequently drawn in a direction a from the outlet, the operating part becomes disenga from the piston part and the piston part is left in barrel in the vicinity of the outlet.

The invention also contemplates within its sc an arrangement in which a projection is provided on inside wall of the barrel or the end wall in the vicini of the outlet, and the piston part, or a sealing pa thereof, is adapted to be decoupled from the operati part when the piston part contacts the projection movement of the plunger towards the outlet.

Claims

1. A syringe comprising a hollow cylindrica barrel, a plunger which delimits a chamber within th barrel and which is longitudinally reciprocable within th barrel to draw liquid into, and expel liquid from, th chamber by way of an outlet, and deactivating means which after the plunger has been moved to a position to expe the liquid from the chamber, prevents further liquid fro being drawn into the chamber.

2. A syringe according to claim 1, wherein th deactivating means comprises interengaging lockin

' formations attached to the barrel and the plunger an adapted to engage one another when the plunger is moved t said position so as to prevent the plunger fro subsequently being moved back to draw further liquid int the chamber.

3. A syringe according to claim 1, wherein th plunger comprises a piston part in fluid-tight engagemen with the interior surface of the barrel and an operatin part, and the deactivating means comprises a releasabl coupling device which couples together the piston part an the operating part, the coupling device being releasabl by movement of the plunger to said position by means o the operating part and being incapable of subsequent re engagement solely by moving the operating par longitudinally of the barrel.

4. A syringe according to claim 1, wherein th deactivating means comprises a valve device through whic liquid is drawn into, and expelled from, the chamber, valve device being initially in a first state in wh liquid may be drawn into the chamber through the va device and being caused, by the action of liquid be expelled from the chamber through the valve device, change to a second state in which the valve dev prevents further liquid from being drawn into the cham to any substantial extent.

5. A syringe according to claim 1, wherein plunger comprises a piston part in fluid-tight engageme with the interior surface of the barrel and an operati part, and wherein the deactivating means comprises portion of the piston part which, by being punctured otherwise, places the chamber in fluid communication wi the atmosphere when the plunger is moved to said positio

6. A syringe according to Claim 2, wherein t plunger comprises a piston part in fluid-tight engageme with the interior surface of the barrel and an operati part, and wherein the interengaging locking formatio comprise recessed or projecting formations on an insi surface of the barrel, or an extension thereof, over whi a portion of the piston part is movable during expulsi of liquid but which subsequently prevents said porti being moved back over the formations in the opposi direction.

7. A syringe according to claim 3, wherein t releasable coupling device includes interengageab coupling elements on the two parts respectively of t plunger, one of the elements comprising a guide track an the other element comprising a projection engageable i the guide track.

8. A syringe according to claim 3 or 7, wherein th operating part includes a tubular portion surrounding cylindrical portion of the piston part, and the releasabl coupling device includes interengageable coupling element on the two portions respectively.

9. A syringe according to claim 3, 7 or 8, wherei releasable sealing means is provided for sealing th piston part, said sealing means being released by releas of the coupling means to place the chamber in flui communication with the atmosphere.

10. A syringe according to claim 5, wherein th deactivating means comprises a deformable annular flang for maintaining the piston part in fluid-tight engagemen with the interior surface of the barrel, the annula flange being initially in a first state permitting th plunger, with the annular flange thereon, to be moved t draw liquid into the chamber, and being caused, by th action of moving the plunger to expel liquid from th chamber, to change to a second state in which the annula flange is prevented from being moved by means of th operating part to draw further liquid into the chamber.

11. A syringe comprising a hollow cylindrica barrel, a plunger which delimits a chamber within th barrel and which is longitudinally reciprocable within th barrel to expel liquid from the barrel by way of a outlet, and a connector for attachment of a hollow nee or tube to the outlet, wherein the connector incorpora locking means for locking the hollow needle or tube on connector and preventing subsequent detachment of hollow needle or tube from the connector.