WO1999008735A2

WO1999008735A2 - Hand-held manual injector

Info

Publication number: WO1999008735A2
Application number: PCT/GB1998/002433
Authority: WO
Inventors: Douglas Whitfield; Joel Kurt Hinebaugh; Otto Heinrich Heimes
Original assignee: Nycomed Imaging As; Piesold, Alexander, James
Priority date: 1997-08-14
Filing date: 1998-08-13
Publication date: 1999-02-25
Also published as: WO1999008735A3; AU8740798A

Abstract

A hand-held manual injector (10, 110) comprises a support portion (60, 160) for receiving a barrel (72) of a syringe (70) or cartridge and a body (12, 112) with a pusher rod (16, 116). The pusher rod (16, 116) can be advanced through the body (12, 112) towards the syringe support portion (60, 160) by manual actuation of a lever (26, 126), which activates a friction drive mechanism (14, 114). The syringe support portion (60, 160) is adapted to retain the syringe barrel (72) and prevent it from moving longitudinally during an injection. This is done by having flanges (74) on the syringe barrel (72) fit into a slot (66, 166a, 166b, 166c) on the support portion (60, 160).

Description

■HAND -HELD MANUAL INJECTOR

FTKT.D OF THE INVENTION

The present invention relates to a hand-held injector for use with a syringe or cartridge comprising a barrel having a front end with a nozzle and a rear end with a flange, and a plunger.

DESCRIPTION OF THE PRIOR ART

In the medical field, it is frequently necessary to dispense fluid from a syringe, cartridge or the like, for injection into a patient, either directly through a hypodermic needle or through a catheter attached to the needle. This can be done manually, and manual injection is common for injections of small volumes of relatively low viscosity fluids, such as drugs administered intravenously or the like, as the force needed to inject the fluid is not particularly large and can easily be generated by hand.

However, for injections of larger volumes of more viscous materials, such as contrast agents for X-ray or similar imaging, the force needed to inject the fluid is considerably greater. In addition, for the comfort of the patient, it is preferred that a narrow needle be used, which in turn further increases the force required to inject the material. As a result, considerable effort is required to force the liquid from the barrel of the syringe or cartridge.

It is known to provide powered injectors for injections of such fluids, where the injection force is generated by an electric motor . Examples of such injectors are disclosed in US 5269762 and US 5322511. However, this type of injector requires an electrical power source to operate. If the source is mains electricity, then this limits the areas where the injector can be used, and the use of batteries (which are housed inside the injector) increases the weight of the injector. Further, the drive system for converting the high speed rotational motion of the electric motor into the low speed longitudinal motion required to carry out an injection can be complex and expensive to manufacture .

Manually powered injectors using leverage to assist the user to inject the fluid have also been proposed. Examples are described in US 3141583, US 3517668, US 3905365 and US 4923096. However, this type of known injector is generally inconvenient to use because of the need to unscrew or otherwise detach a cap, sleeve, nut or the like when it is desired to remove and replace the cartridge or syringe. Thus, loading and unloading the injector can be a time consuming operation. Moreover, the tooth drive systems of some of these known injectors may adversely affect the smoothness of operation during the injection procedure.

STTMMAKY OF THE INVENTION

Accordingly, it is an object of the invention to provide a hand-held injector which can be operated by hand without requiring any additional power sources.

It is a further object of the invention to provide a hand-held injector which is mechanically simple and robust .

It is another object of the invention to provide a hand-held injector which is easy to load and unload with a syringe or cartridge.

Accordingly, the invention provides a hand-held injector for use with a syringe or cartridge comprising a barrel having a front end with a nozzle and a rear end with a flange, and a plunger, the injector comprising a body, a support portion in fixed relationship to said body and having a slot for receiving the flange of the barrel so as to prevent forward and rearward longitudinal movement thereof, a pusher member supported on said body and longitudinally movable relative thereto, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly, and a manually-operated drive mechanism comprising a manually-actuatable lever operatively connected to said pusher member whereby, in use, actuation of said lever moves the pusher member forwardly. The slot is preferably a drop-in slot into which the flange of the syringe or cartridge may be inserted from above .

In one form of the invention, the support portion extends forwardly of said body and said slot is provided at a front end of the support portion. Such an arrangement is suitable for use with a syringe having a plunger provided with a plunger rod. In use, the pusher contact of the pusher member engages with the rear end of the plunger rod so as to push the plunger rod and thus cause the plunger of the syringe to move forwardly. The forwardly extending support portion may comprise a plurality of rods, bars or the like, but in a preferred embodiment it comprises a part-cylindrical member.

In an alternative form of the invention, the slot of the support portion is provided adjacent said body.

Such an arrangement is suitable for use with a cartridge which has a plunger but no plunger rod. In use, the pusher of the pusher member engages the plunger directly. However, in both of these arrangements, the syringe or cartridge projects forwardly from the front of the body. This can lead to the combination of the injector and the syringe or cartridge being cumbersome as a result of its length. In addition, if the body is supported by means of a grip or a handle or similar, which is held by a user, then the mass of the syringe or cartridge, and more particularly any contents thereof, will be disposed some distance away from the point of support, resulting in a considerable moment which must be resisted by the user's muscles.

Accordingly, in a further alternative preferred form of the invention, the pusher contact is offset from the axis of the longitudinally moveable pusher member. By having the pusher contact offset from the axis of the pusher member, there is increased flexibility as to the position of the slot for receiving the syringe or cartridge barrel. For example, the slot can be located so that in use the back of the syringe or cartridge is positioned to the rear of the front end of the pusher member when the pusher member is in its rearmost position. This is in contrast to the situation where the pusher contact is coaxial with and at the front of the pusher member, where the rear of the syringe or cartridge must be in front of the front end of the pusher member in order for the plunger rod to be pushed. This arrangement thus allows the syringe to be positioned further back than when the pusher contact is coaxial with the pusher member. As a result, the weight of the syringe and its contents then produces a much smaller moment around the point of support, and so the injector has less tendency to tip forwards when a syringe is installed in the support portion, and is better balanced.

Preferably, the support portion is disposed above the body. As a result, when a filled syringe is received in the slot of the support portion, the syringe is generally disposed above the body, and so there is no off-centre load on the user's hand. Further, as the syringe is positioned above the body of the injector, it is easier to see the plunger of the syringe, and thus easier to keep track of how much fluid has been injected. This is particularly useful if the syringe has markings indicating the volume of material remaining in the syringe printed or moulded thereon.

The injector may be constructed to receive a particular size of syringe or cartridge. Advantageously, however, the thickness of the slot may be variable to accommodate flanges of different thickness. This may be done with spacers, shims or the like. For example, an annular disc may be inserted over the barrel of the syringe or cartridge and positioned adjacent to the flange so as to take up some of the thickness of the slot. Spacer discs can also be inserted into the slots, to take up some of the thickness of the slot. To prevent these spacer discs from being mislaid, they can be attached to the injector, and in one preferred embodiment they are hingedly attached in such a way that they can be swung over into and out of the slots as required. Alternatively, the slot may have a wall adjustable in the longitudinal direction. Once the adjustment has been made for a particular thickness of flange, loading and unloading of syringes or cartridges having that type of flange is a simple operation for the user.

Advantageously, means for varying the diameter or depth of the slot may be provided to accommodate flanges of different size. This may be useful in making the injector readily adjustable for different sizes of syringe or cartridge.

An additional or alternative way of providing an injector which is suitable for syringes or cartridges is for the support portion to be removably attached to the body of the injector. Thus different support portions may be provided for use with one body.

In certain embodiments, however, it may be desirable to manufacture the support portion as an integral part of the body (e.g. an integrally moulded part) , in which case it will not be removable from the body. In this case, a plurality of slots can be provided in the support portion. These slots can be of differing widths and/or depths, to allow the support portion to accommodate syringes of various sizes. This arrangement is advantageous as there is then no need to use shims, spacers or the like to accommodate syringes of different sizes. Spacers and shims can easily be lost or mislaid, which can be inconvenient if they are needed to adapt the injector for a syringe of a particular size. By having a plurality of different sized slots, there is no danger that the injector will not be able to be used with a particular sized syringe as a result of parts being missing.

In general the slot will be defined between a front wall and a rear wall. Preferably, the front wall projects laterally beyond the rear wall. This can assist location during loading, whilst giving a good hold on the syringe or cartridge once loaded. Where the slot is a drop-in slot into which the flange of the syringe or cartridge is inserted from above, the lateral projection of the front wall will be in the upward direction.

In a preferred arrangement, the flange of the syringe is insertable into the slot and the syringe is then rotatable to lock it into place on the injector. This reduces the risk of the syringe falling out of the slot.

Preferably, the injector has a latch mechanism having a latched state in which said pusher member is prevented from moving rearwardly and an unlatched state in which said pusher member is free to move, said latch mechanism and said drive mechanism being operable by a user of the injector using one hand. Providing such a latch mechanism allows pressure to be released using the hand which holds the injector, so that pressure can be released quickly and easily should this prove necessary. Thus, for example, the injector may have a grip which in use is cradled in the palm of a user's hand, a manually actuatable lever which is urged by the user's fingers towards the grip to move the pusher member forwardly, and a latch mechanism which is operable by the user's thumb to release pressure if desired.

Preferably, said latch mechanism comprises a latch member pivotally attached to the body and having an aperture therein, the pusher member passing through said aperture, said latch member being biased towards its latching position and having a sideways lateral extension. By providing such a sideways lateral extension, finger or thumb access for a user may be facilitated.

Preferably, two such lateral extensions are provided, one on each side of the body. The latch can then be used with equal facility by left-handed and right-handed people. Alternatively, the latch member can be disposed centrally, behind the body, and can be reached with equal ease by the thumb of the user, irrespective of which hand is being used.

Preferably, the aperture is provided in a first portion of the latch member and the lateral extension is disposed forwardly of said first portion. This can further improve access.

In a further preferred embodiment, the latch mechanism can be disposed inside the body. This affords some protection to the latch mechanism, and can reduce the risk of damage. Further, it reduces the risk of material being dispensed from a syringe getting into the latch mechanism and fouling it.

The lateral extension may be connected to the latch member by a forwardly extending part, which may be disposed inside or outside the body.

If the latch mechanism is to be disposed inside the body, then it is preferred that the lateral extension projects through an aperture formed in the body. Preferably, the pusher member has a knob at the end opposite the pusher. For safety reasons this is preferable to an end of small diameter, and can also assist handling.

As mentioned above in connection with the latch mechanism, the injector may have a grip which in use is cradled in the palm of a user's hand. The user must support the entire weight of the injector, the syringe or cartridge and its contents through this grip, normally by maintaining a light pressure on the grip. If the injector also has a manually actuatable lever which is urged by the user's fingers towards the grip to move the pusher member forwardly, then the user must support the weight of the injector using finger pressure while also squeezing the grip and handle together. Accordingly, it is further preferred that the injector comprises a grip projecting downwardly from the body, and projections are provided extending outwardly from the sides of the body above the grip, said projections being arranged to rest on a user's hand when the injector is in use.

The weight of the injector, the syringe or cartridge and its contents are thus automatically borne by the hand of the user. The act of supporting the weight of the injector does not interfere with the act of dispensing material from the syringe.

This feature is considered to be of inventive merit in itself, and thus according to a further aspect of the invention, there is provided a hand-held injector for use with a syringe or cartridge, comprising a body, a grip extending downwardly from the body, and projections extending outwardly from the sides of the body above the grip, said projections being arranged to rest on a user's hand when the injector is in use.

The projections are preferably sized and positioned such that, in use, when the user puts his or her hand around the grip, the projections rest on the thumb and index finger. A further projection may be provided on the handle, to rest on the user's index finger when the injector is being used.

Additionally, the feature of the pusher being offset from the axis of the pusher member is considered to be of independent inventive merit, and so according to a further aspect of the invention, there is provided a hand-held injector for use with a syringe or cartridge comprising a barrel having a front end with a nozzle and a rear end with a flange, and a plunger, the injector comprising: a pusher member supported on the injector and longitudinally movable relative thereto, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly, the pusher being offset from the axis of the longitudinally movable pusher member; and a manually-operated drive mechanism comprising a manually-actuatable lever operatively connected to said pusher member whereby, in use, actuation of said lever moves the pusher member.

Preferably, said drive mechanism comprises a drive plate which is urged into engagement with the pusher member on actuation of said lever, further motion of said lever causing motion of the drive plate and thus of the pusher member.

It is further preferred that said lever is arranged to pivot about a fulcrum, and that actuation of said lever causes the lever to contact the drive plate to urge the drive plate into engagement with the pusher member, the point of contact between the lever and the drive plate being on a different side of the pusher member from the fulcrum. This arrangement reduces the mechanical advantage of the lever, and so reduces the force exerted on the syringe, thus allowing the syringe to be made of less robust material. Further, the arrangement gives a greater travel of the drive plate with each stroke, and so allows more liquid to be dispensed from the syringe or cartridge with each stroke.

This feature is considered to be of independent inventive merit, and so according to a further aspect of the invention there is provided a hand-held injector for use with a syringe or cartridge comprising a barrel and a plunger, the injector comprising a pusher member supported on the injector longitudinally movable relative thereto, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly, and a manually-operated drive mechanism comprising a manually-actuatable lever and a drive plate which is urged into engagement with ^* the pusher member on actuation of said lever, further motion of said lever causing motion of the drive plate and the pusher member, wherein said lever is arranged to pivot about a fulcrum, and wherein actuation of said lever causes the lever to contact the drive plate to urge the drive plate into engagement with the pusher member, the point of contact between the lever and the drive plate being on a different side of the pusher member from the fulcrum.

Viewed from another aspect, the invention provides a hand-held injector for use with a syringe or cartridge comprising a barrel having a front end with a nozzle and a rear end with a flange, and a plunger, the injector comprising a support portion having a slot for receiving the flange of the barrel so as to prevent forward and rearward longitudinal movement thereof, a pusher member longitudinally movable relative to said support portion, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly, and a manually-operated drive mechanism comprising a manually-actuatable lever operatively connected to said pusher member whereby, in use, actuation of said lever moves the pusher member forwardly.

Preferably the pusher member, the drive plate, the latch member and the pivot pin connecting the lever to the body are formed from plastics material.

The invention also provides a method of injecting a patient with a physiologically acceptable product using a hand-held injector as described above. Preferably the product is an imaging agent.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which: -

Figure 1 is a side view of a first preferred embodiment of the injector, with its pusher rod partially extended;

Figure 2 is a plan view of the first embodiment of the injector, with its pusher rod partially extended;

Figure 3 is a front view of the first embodiment of the injector; Figure 4 is a side view of the first embodiment of the injector with a syringe installed;

Figure 5 is a plan view of a second embodiment of the injector, with its pusher rod partially extended;

Figure 6 is a plan view of a variant of the syringe support ;

Figure 7 is a side view of a third embodiment of the injector;

Figure 8 is a plan view of the third embodiment of the injector; Figure 9 is a rear view of the third embodiment of the injector;

Figure 10 is a side view, similar to Figure 7 but showing details of the drive mechanism,- and

Figure 11 is a side view of the third embodiment of the injector, with a syringe installed ready for injection.

nE.ςCRIPTTON OF THE PREFERRED EMBODIMENTS

According to a first embodiment, the injector, indicated by the reference numeral 10, generally comprises a body 12, which houses a friction drive mechanism 14, and a syringe support 60 which extends forwardly from the front of the body 12. A pusher rod 16, which is driven by the drive mechanism, extends through the body 12 and along the syringe support 60, and has a pusher 18 at its front end.

The body has a front face 20 and a rear face 22, and a grip portion 24 extends downwardly from the rear face 22. A lever 26 is pivotally attached to the grip 24 by means of a pin 28. The lower part of the lever forms a handle 30, and the handle 30 and the grip 24 can be squeezed together manually to a point where the handle 30 abuts against the grip 24 to prevent further movement. The front of the handle is formed with grooves for receiving a user's fingers, and may be curved slightly to further fit the shape of a human hand. In use, the grip fits against the ball of the user's hand, and the user's fingers fit into the grooves . The handle and grip can then be squeezed together in a comfortable manner.

The upper part 32 of the lever, which is considerably shorter than the lower part, engages with the lower end of a drive plate 34. The drive plate 34 has an aperture 36 therethrough, through which the pusher rod 16 extends. The aperture 36 has a slightly greater diameter than the rod 16. A compression spring 38, surrounding the pusher rod 16, is positioned between the front face 20 of the body 12 and the drive plate 34, and biases the drive plate backwards. Normally, the drive plate 34 is pushed back by the force of the spring against the rear face 22 of the body 12. However, the drive plate does not lie flush against the rear face 22, as the upper part 32 of the lever is trapped between the drive plate 34 and the rear face 22 of the body 12. The lower part of the drive plate is thus spaced away from the rear face 22 of the body 12, while the upper end of the drive plate is urged into contact with the rear face 22 of the body 12 by the spring, as shown at 40.

When the handle 30 and the grip 24 are squeezed together, the upper part 32 of the lever forces the drive plate 34 away from the rear face 22 of the body 12, against the force of the spring 38. Because of the different lengths of the handle 30 and the upper part 32 of the lever, the force exerted by the upper part 32 of the lever 24 on the drive plate 34 is considerably greater than the force exerted on the handle 30 by the user. The force exerted on the lower end of the drive plate can be further increased simply by lengthening the handle, which in turn makes the injection process easier.

As the upper end of the drive plate 34 is in contact with the rear face 22 of the body 12, the drive plate 34 tends to pivot about this point of contact, and so the drive plate tilts. As a result, the lower part of the aperture 36 comes into contact with the lower part of the pusher rod 16, and the upper part of the aperture 36 comes into contact with the upper part of the pusher rod 16. As the handle 30 and grip 24 are squeezed together further, the aperture 36 in the drive plate 34 jams firmly against the pusher rod 16. This occurs after a relatively small movement of the upper end 32 of the lever.

Further squeezing of the handle 30 and grip 24 forces the upper end 32 of the lever 26 further forwards. This in turn pushes the drive plate 34 forwards, and as the drive plate 34 is jammed against the pusher rod 16, this is also pushed forwards. The pusher rod 16 continues to be pushed forwards as the grip 24 and handle 30 are squeezed together, until the handle 30 reaches the end of its permitted travel and abuts against the grip 24, at which point further movement of the handle 30, and so further forward motion of the pusher rod 16, is prevented. It will be appreciated that the pusher rod 16 is pushed forward by a certain distance when the grip 24 and handle 30 are squeezed together fully from their initial position. The pusher rod 16 can be moved a greater distance simply by releasing the grip 24 and handle 30 and then squeezing them together again. Attached to the rear of the body 12 is a one-way latch mechanism 42, which prevents the pusher rod 16 from moving backwards until the latch is released. The one-way latch mechanism 42 comprises a latch plate 44 with an aperture therethrough, the pusher rod 16 passing through the aperture . The aperture has a diameter slightly greater than that of the pusher rod 16. The upper end of the latch plate 44 is pivotally connected (at 46) to the rear of the body 12. A compression spring 48 is provided between the latch plate 44 and the rear of the body 12, and surrounds the pusher rod 16. As a result of the top of the latch plate 44 being pivotally attached to the rear of the body, the force exerted on the latch plate 44 by the compression spring 48 tends to make the latch plate 44 pivot about its upper end, and as a result the lower and upper parts of the aperture are normally urged respectively against the lower and upper parts of the pusher rod 16 so as to jam against it. This jamming between the latch plate 44 and the pusher rod 16 is sufficient to prevent the pusher rod 16 from moving backwards .

To release the one-way latch 42, the lower end of the latch plate 44 is pushed forwards towards the body 12 against the force of the compression spring 48. This releases the jamming, and allows the pusher rod 16 to be moved. The lower end of the latch plate 44 may be provided with extensions 50 as shown in Figure 5, which extend forwardly and outwardly from the latch plate. These allow the user of the injector 10 easily to operate the latch with a finger or thumb of the hand holding the handle 30 and grip 24 without removing that hand from the injector 10. If the latch plate is not provided with these extensions, as in Figures 1, 2 and 4, then it is still possible to release the latch using a finger or thumb of the hand holding the handle and grip without removing that hand from the injector, but this may be less convenient for the user.

In order to facilitate moving the pusher rod 16 backwards, it is provided with a graspable portion at its rear end. This portion may take the form of a knob 52 attached to the end of the pusher rod, or may simply be formed by having the end of the pusher rod bent over. The graspable portion also serves to limit the forward motion of the pusher rod 16 by abutting on the latch plate 44.

The drive mechanism and the one-way latch mechanism 42 co-operate so that repeated operation of the drive mechanism (by squeezing the grip 24 and handle 30 together) moves the pusher rod 16 incrementally forwards, as follows.

When the grip 24 and the handle 30 are squeezed together, the pusher rod 16 is advanced a certain distance, as described above. When the pressure urging the grip 24 and the handle 30 together is released, the force exerted by the upper end 32 of the lever 26 on the drive plate 34 reduces slightly, and as a result the spring 38 between the drive plate 34 and the front of the body 12 urges the drive plate 34 backwards slightly. This releases the jamming engagement between the aperture 36 in the drive plate 34 and the pusher rod 16, and as a result the drive plate 34 and the rod 16 can move independently of each other. However, the pusher rod 16 is prevented from moving backwards by the jamming engagement between the latch plate 44 and the rod 16.

As the pressure on the handle 30 is further released, the spring 38 urges the drive plate 34 further backwards along the pusher rod 16. The force exerted on the drive plate 34 also acts on the upper end 32 of the lever 26, and this force also moves the handle 30 back to its original position. However, a separate return spring could be provided to move the handle 30 if that was desired. As the pressure on the handle 30 is completely released, the spring 38 pushes the drive plate 34 back to its original position.

Thus, the cycle of squeezing and releasing the handle 30 causes the pusher rod 16 to advance a certain distance during the initial squeezing, the rod 16 then being prevented from moving backwards during the release part of the cycle by the one-way latch mechanism 42. The use of a friction drive system as described above has a number of advantages. It is easy to vary the speed at which injections are given, simply by squeezing more or less firmly on the handle. As the pusher rod is advanced by a certain distance during each cycle of squeezing and releasing the handle, it is easy to regulate the amount of fluid to be injected. In addition, if the injection pressure has to be released rapidly (for example, if the patient is in discomfort or pain) , then the one-way latch mechanism can be operated and the pusher rod drawn back very quickly.

The syringe support 60 is in the form of a generally semi-cylindrical hollow member 62, whose axis is parallel to that of the pusher rod 16. The rear end of the syringe support is connected to the body 12 in such a way that the pusher rod 16 may extend along the syringe support 60.

The front end 64 of the syringe support 60 is arranged to retain the syringe 70 in the injector 10 and prevent it from moving forwards . In the embodiment shown, a slot 66 is formed extending across the support 50 perpendicular to the axis of the support. Injection syringes (such as the one shown attached to the injector in Figure 4 and denoted by the reference numeral 70) comprise a barrel 72 in which a plunger 80, attached to a plunger rod 78, is disposed. The barrel 72 is generally formed with a flange 74 at its distal end, distant from the nozzle 76 to which a needle or catheter is to be attached. During manual injection, the user's index and middle fingers engage on the proximal side of these flanges 74 and the user's thumb presses on the end of the plunger rod 78, to urge the plunger 80 into the barrel 74 of the syringe 70 and thus carry out the injection. These flanges 74 are used to locate the syringe 70 in the support 60 in the embodiment shown, by locating in the slots 66 at the front end of the syringe support 60.

As the slots 66 are provided at the front end of the support 60 and the flanges 64 are at the rear end of the syringe 70, the syringe will project forwardly from the support. As a result, any length of syringe can be used in the injector. This would not be the case if the support engaged with the front end of the syringe, for example .

The support 60 may extend forwardly of the slots, so that the barrel 72 of the syringe 70 is accommodated in the semi-cylindrical hollow member 62, as shown in Figure 6. The entire syringe seats in the support, rather than just the flanges 74 engaging in the slots

66, which may be convenient for a user when installing a syringe.

It is also possible to use the injector with pre- filled cartridges, which are generally similar to syringes except they do not have a plunger rod. A plunger rod is normally attached to the plunger to allow an injection to be carried out. However, it is also possible to use the cartridge without a plunger rod, in which case the pusher 18 on the pusher rod 16 contacts the plunger of the cartridge directly. Obviously it is necessary that the pusher has a smaller diameter than the barrel of the syringe if the injector is to be used in this way.

In order to accommodate the cartridge and prevent longitudinal motion of the barrel, the injector can be provided with slots adjacent to the body 12. The injector can then be shorter, as it is not necessary to provide the elongate support 60 to locate the slots at a forward position. The width of the slots 66 is ideally slightly greater than the thickness of the flanges 74 of the syringe 70 (or cartridge) to be used, so that the syringe 70 is located firmly in place but can easily be removed when the injection is complete. Ideally, the depth of the slots 66 is such that the axis of the pusher rod 16 and the axis of the syringe plunger rod 78 are coincident .

To enable the injector 10 to be used with various sizes of syringes, shims and/or spacers or the like can be provided to allow thinner or smaller flanges to be located firmly in place. As an alternative, the syringe support 60 or cartridge support could be arranged to be removable, so that different syringes 70 or cartridges could be accommodated by removing the support and attaching a new one. The syringe support 60 or cartridge support can be attached to the body 12 by means of screws 58. The injector 10 is operated as follows.

Firstly, the one-way latch mechanism 42 is operated to release the engagement between the latch plate 44 and the pusher rod 16, and the rod 16 is then pulled backwards to its rearmost position. A filled syringe 70, with its plunger rod 78 withdrawn, is then installed into the injector 10. In the embodiment illustrated, the flanges 74 of the syringe 70 fit into the slots 66 at the front end 64 of the syringe support 60. It will be understood that when the syringe 70 is installed, it will project forwardly from the front of the injector 10, allowing the user to observe motion of the syringe plunger 80 in the syringe barrel 72, while the syringe plunger rod 78 lies inside the syringe support 60. It is preferred that the axes of the syringe plunger rod 78 and the pusher rod 16 are coincident. A needle, catheter or the like can then be attached to the syringe to allow the injection of liquid into the patient to take place.

The grip 24 and handle 30 are then squeezed together, to push the pusher rod 16 forwards. As discussed above, the pusher rod 16 is then advanced in steps, one step for each cycle of squeezing and releasing the grip 24 and the handle 30. Movement of the pusher rod 16 has the initial effect of bringing the pusher 18 into contact with the distal end of the syringe plunger rod 78. Further movement pushes the syringe plunger rod 78 into the syringe barrel 72, as motion of the syringe barrel 72 is prevented by the engagement between the barrel 72 and the syringe support 60. As a result, fluid is urged from the syringe. The squeeze/release cycle can be repeated as many times as * necessary to inject the appropriate amount of fluid into the patient.

Once the injection has been completed, the one-way latch mechanism 42 is released again, and the pusher rod 16 is pulled back. The syringe 70 can then be removed and a new one fitted, in preparation for a further injection. Alternatively, if the syringe was not emptied during the injection, then it can be left in the injector and used for further injections. The injector 10 is particularly intended for use with pre-filled single-dose syringes. A corresponding method is used if it is desired to inject from a cartridge.

The third embodiment, shown in Figures 7 to 11, is generally similar to the first and second embodiments . The injector 110 generally comprises a body 112, which houses a friction drive mechanism 114. However, the syringe support 160 is mounted above the body, rather than at its front. A pusher bar 116, which is driven by the drive mechanism and extends through the body 112, has a pusher 117 at its rear end. In this embodiment, the bar has a rectangular cross-section,- however, bars of any cross-sectional shape can be used. It is advantageous for the bar to be relatively wide, as this reduces the pressure on the bar, and also reduces slippage, as a result of the increased area of contact. The bar is guided by apertures formed in the front and the rear of the body.

A grip portion 124 extends downwardly from the body 112, and a lever 126 is pivotally attached to the grip 124 by means of a pin 128. The pin may be integrally formed with the lever or the grips, or it may be separate. The lower part of the lever forms a handle 130, and the handle 130 and the grip 124 can be squeezed together manually as in the first embodiment. The handle and grip can also be shaped to fit a user's hand, as in the first embodiment.

An additional feature of the third embodiment is ^* the provision of wing-like projections 154, which extend laterally from each side of the body 112 above the grip 124. When a user's hand is around the grip 124 and handle 130, these projections 154 rest on the user's thumb and index finger, so that the weight of the injector 110 and the syringe 60 is supported. A further projection 156 is provided on the handle 130, and this also rests on the user's index finger when the injector is being used.

In the third embodiment, the upper part 132 of the lever 126 is longer than in the first and second embodiments. The pusher bar 116 extends through an aperture in the upper part 132 of the lever 126, and the aperture is of sufficient size that the upper end 132 of the lever 126 does not contact the pusher bar 116 as the lever 126 moves. The upper end 132 of the lever 126 engages with a drive plate 134. As in the first embodiment, the drive plate 134 has an aperture 136 therethrough, through which the pusher bar 116 extends, the aperture 136 having a slightly greater diameter than the bar 116. The apertures are of course rectangular to match the cross-section of the bar. A compression spring 138, surrounding the pusher bar 116, is positioned between the front face of the body 112 and the drive plate 134, and biases the drive plate backwards against the upper part 132 of the lever 126. When the handle 130 and the grip 124 are squeezed together, the upper part 132 of the lever 126 is pushed against the drive plate 134 to move the drive plate forwardly, as in the first embodiment. However, because the top end of the upper part 132 of the lever 126 is furthest from the pin 128, it travels furthest forwards, and as a result the upper end of the drive plate is moved further forwards than the lower end. Because of this, the drive plate 134 tilts, so that the lower part of the aperture 136 comes into contact with the lower part of the pusher bar 116, and the upper part of the aperture 136 comes into contact with the upper part of- the pusher bar 116. As the handle 130 and grip 124 are squeezed together further, the aperture 136 in the drive plate 134 jams firmly against the pusher bar 116. This occurs after a relatively small movement of the upper end 132 of the lever 126.

Further squeezing of the handle 130 and grip 124 moves the pusher bar 116 forwards, as in the previous embodiments .

As the drive plate 134 is acted on at its upper end, rather than its lower end as in the first embodiment, the mechanical advantage is lower (around 3:1 as opposed to 7:1) . As a result, the drive plate travels further with each cycle of squeezing and releasing the handle 130 and grip 124, and thus more fluid is dispensed in each cycle. The number of cycles required to inject a given volume of fluid is thus reduced. Further, the mechanical advantage and thus the amount of fluid dispensed in each cycle can be changed by changing the position of the pivot point, and this applies to all of the embodiments.

In addition, the reduction in mechanical advantage reduces the force exerted on the syringe and in particular on the flanges thereof . This allows the syringe to be less robust .

Of course, the first embodiment could be modified so as to reduce the mechanical advantage simply by increasing the length of the upper part 32 of the lever 26. However, such an increase in length would increase the overall size of the injector, and may make it cumbersome to use . By providing the point of contact between the lever and the drive plate on the side of the pusher bar opposite to the pivot pin, the injector can be made more compact .

At the rear of the body is a one-way latch mechanism 142, which as in the first embodiment prevents the pusher bar 116 from moving backwards until the latch is released. However, in contrast to the first embodiment, the one-way latch mechanism is disposed inside the body, rather then behind it. This provides some protection for the mechanism, and also allows greater travel for the pusher bar.

As before, the one-way latch mechanism 142 comprises a latch plate 144 with an aperture therethrough, the pusher bar 116 passing through the aperture. The size of the aperture is slightly greater than that of the pusher bar 116. The upper end of the latch plate 144 can be pivotally connected to the rear of the body 112, for example by means of lugs engaging in a recess or by locating between tabs. Alternatively, the latch plate may simply rest against the rear face of the body.

A compression spring 148 is provided to urge the latch plate against the rear of the body, and is positioned between the latch plate 144 and a slidable bushing 149 which engages the upper part 132 of lever 126, surrounding the pusher bar 116. The latch plate 144 is arranged such that when it is pushed against the rear face of the body by the spring 148, the lower and upper parts of the aperture are urged respectively against the lower and upper parts of the pusher bar 116 so as to jam against it, thus preventing the pusher bar 116 from moving backwards.

At the lower end of the latch plate 144 are provided lateral extensions 150, which extend through apertures 151 formed in the sides of the body 112. To release the one-way latch 142, one or both of the lateral extensions 150 is pushed forwards against the force of the compression spring 148. This releases the jamming, and allows the pusher bar 116 to be moved. As mentioned in connection with Figure 5, these extensions allow the user of the injector 110 easily to operate the latch with a finger or thumb of the hand holding the handle 130 and grip 124 without removing that hand from the injector 110. In addition, providing an extension 150 on each side of the body allows the latch plate 144 to be released with equal ease, irrespective of whether the user is holding the injector 110 in his or her left or right hand.

At the rear end of the pusher bar 116 is a pusher 117. The lower part of the pusher is connected to the pusher bar 116, and the pusher 117 extends upwardly from the bar. At its upper end, the pusher 117 has a pushing surface 118, perpendicular to the axis of the pusher bar 116, for engaging the rear surface of a plunger rod 78 of a syringe 60. The pushing surface 118 extends forwardly of the front surface 119 of the pusher 117. When the pusher bar 116 is fully extended, this front surface 117 contacts the back 122 of the body 112 to limit motion of the pusher bar 116. The pusher 117 also serves as a graspable portion, enabling the user to grip and pull it to withdraw the pusher bar 116.

The front end of the pusher bar 116 is rounded to prevent damage or injury. The rounded part may be in the form of a round knob 152.

On occasion, when the user pulls back with one hand on the pusher bar to withdraw it, the other hand remains on the lever and can exert a force on it . This force can jam the drive plate against the pusher bar, and prevent it from being withdrawn. To avoid this, an interlock device can be provided between the latch plate and the lever, to allow the user to withdraw the pusher bar even if the user's other hand is still on the lever. As an alternative, a projection 158 (shown in phantom in Figure 10) can be provided for the user to rest the index finger on while the pusher bar is pulled backwards .

As mentioned above, the syringe support 160 is positioned above the body 112. It consists of two upstanding members 162, integral with and extending upwardly from the body 112 and disposed symmetrically about the vertical centre line of the body. Between them, the members 162 define a generally semi- cylindrical hollow 164, whose axis is parallel to that of the pusher bar 116. The inner surfaces of the members are formed with slots 166a, 166b and 166c, and the grooves are sized and configured so as to accept the flange 74 of a syringe 70. The slots can extend around the entire length of the hollow 164, as shown, or may only be formed at the sides. The multiplicity of slots 166a, 166b and 166c can be of varying widths and depths, to accommodate different sized syringes 70. The syringe is inserted into the slot and then rotated to lock its flanges into place.

When the flanges 74 of a syringe 70 are inserted into the hollow 164, the syringe 70 is supported above the body of the injector 110, extending parallel to the pusher bar 116. The height of the members 164 and the depth of the slots 166a, 166b and 166c are arranged so that the end of the plunger rod 78 of the syringe 70 is at approximately the same height above the pusher bar 116 as the pushing surface 118 of the pusher 117, as shown in Figure 10. This avoids the syringe 70 being subjected to non-axial forces, which could lead to jamming of the plunger in the barrel 72 of the syringe. As in the first embodiment, shims and/or spacers or the like can be provided to allow thinner or smaller flanges to be located firmly in place. However, the provision of a plurality of slots of differing sizes will reduce or possibly obviate the need to use such spacers or shims . Operation of the injector 110 is generally similar to that of the first embodiment. Firstly, the one-way latch mechanism 142 is operated to release the engagement between the latch plate 144 and the pusher bar 116, and the bar 116 is then pulled backwards to its rearmost position by a user grasping the pusher 117 and pulling it backwards. A filled syringe 70, with its plunger rod 78 withdrawn, is then installed into the injector 110, with the flanges 74 of the syringe 70 fitting into one of the slots 166a, 166b and 166c in the upstanding members 162. As the syringe 70 is disposed above the body of the injector 110, with no parts of it covered, the user of the injector 110 can easily observe motion of the syringe plunger 80 in the syringe barrel

72. A needle, catheter or the like can then be attached to the syringe to allow the injection of liquid into the patient to take place.

The grip 124 and handle 130 are then squeezed together to push the pusher bar 116 forwards, as in the first embodiment. Movement of the pusher bar 116 has the initial effect of bringing the pushing surface 18 into contact with the distal end of the syringe plunger rod 78. Further movement pushes the syringe plunger rod 78 into the syringe barrel 72, as motion of the syringe barrel 72 is prevented by the engagement between the flanges of the barrel 72 and the slot. As a result, fluid is urged from the syringe. The squeeze/release cycle can be repeated as many times as necessary to inject the appropriate amount of fluid into the patient. Once the injection has been completed, the user releases the handle 130, and releases the one-way latch mechanism 142 by pressing on one of the lateral extensions 150. The syringe 70 can then be removed and a new syringe inserted as necessary.

It will be noted that the injector 110 of the third embodiment is not suitable for use with cartridges, as when the pusher bar 116 is fully extended the pushing surface 118 would not extend into the cartridge. If a cartridge is to be used with the injector of the third embodiment, then it is first necessary to connect a plunger rod to the plunger of the cartridge .

A number of the components of the injector of the third embodiment are made from moulded plastic, preferably from Delrin™, a strong plastic which has good fatigue characteristics. Other suitable plastics could also be used. The lever 126 is formed as a single moulded plastics part, and the body 112 is formed from two moulded plastics halves. In assembly, the friction drive mechanism 114, including the lever 126, the pin 128, and the pusher bar 116, together with the latch ^* mechanism 142, is installed in one moulded half of the body. The pin 128 may be integrally moulded with the lever 126 or with one half of the body. The second half is then joined thereto. The halves can be joined by any suitable means, such as adhesive, but are preferably joined by screws, which may be metal or plastic. The pusher bar 116 is made from a material of suitable strength, such as stainless steel or titanium alloy, or filled or unfilled high-performance plastics. If the bar is made of metal, then the pusher 117 at the rear end and the rounded knob 152 at the front can be made from moulded plastic, and joined to the rod in suitable ways. Alternatively, the entire bar 116, including the pusher and the rounded knob, may be formed from a single plastics moulding.

Certain other parts of the drive mechanism, including the latch plate 144 and the drive plate 134, may also be made from plastic, although it is preferred that they be made from metal . It is particularly preferred for the plates 134, 144 and the bar 116 to be made from titanium alloy, and for the springs 138, 148 to be nickel plated beryllium copper springs. In this way, the entire injector can be made from non-magnetic materials. Of course, this is also the case if the plates and the bar are formed from high-performance plastics. Thus it will be seen that the various embodiments of the invention provide a hand-held injector which can be operated by hand without requiring any additional power sources, which is mechanically simple and robust, and which is easy to load and unload.

Claims

C AIMS

1. A hand-held injector for use with a syringe or cartridge comprising a barrel having a front end with a nozzle and a rear end with a flange, and a plunger, the injector comprising: a body,- a support portion in fixed relationship to said body and having a slot for receiving the flange of the barrel so as to prevent forward and rearward longitudinal movement thereof ,- a pusher member supported on said body and longitudinally movable relative thereto, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly; and a manually-operated drive mechanism comprising a manually-actuatable lever operatively connected to said pusher member whereby, in use, actuation of said lever moves the pusher member forwardly.

2. An injector as claimed in claim 1, wherein said support portion extends forwardly of said body and said slot is provided at a front end of the support portion.

3. An injector as claimed in claim 1, wherein said slot of the support portion is provided adjacent said body.

4. An injector as claimed in claim 1, wherein said pusher contact is offset from the axis of said longitudinally moveable pusher member.

5. An injector as claimed in claim 4, wherein said support portion is disposed above said body.

6. An injector as claimed in any preceding claim, wherein the depth and/or thickness of said slot can be varied to accommodate differently sized flanges.

7. An injector as claimed in any preceding claim, wherein said support portion has a plurality of slots of differing depths and/or widths.

8. An injector as claimed in any preceding claim, wherein the or each slot is defined between a front wall and a rear wall, and wherein the front wall projects laterally beyond the rear wall .

9. An injector as claimed in any preceding claim, wherein the or each slot is arranged such that the flange of the barrel is insertable into the slot and the barrel is then rotatable to lock the syringe or cartridge in place.

10. An injector as claimed in any preceding claim, comprising a latch mechanism having a latched state in which said pusher member is prevented from moving rearwardly, and an unlatched state in which said pusher member is free to move, said latch mechanism and said drive mechanism being operable by a user of the injector using one hand.

11. An injector as claimed in claim 10, wherein said latch mechanism comprises a latch member having an aperture therein, the pusher member passing through said aperture, said latch member being biased towards its latching position and having a sideways lateral extension.

12. An injector as claimed in claim 11, wherein two sideways lateral extensions are provided, one on each side of the body.

13. An injector as claimed in claim 11 or 12, wherein said aperture is provided in a first portion of the latch member and the or each lateral extension is disposed forwardly of said first portion.

14. An injector as claimed in any of claims 11 to 13, wherein said latch mechanism is disposed inside said body.

15. An injector as claimed in claim 14, wherein the or each lateral extension projects through an aperture formed in the body.

16. An injector as claimed in any of claims 11 to 15, wherein said latch member formed from plastics material .

17. An injector as claimed in any preceding claim, wherein said injector has a grip projecting downwardly from the body, and projections extending outwardly from the sides of the body above the grip, said projections being arranged to rest on a user's hand when the injector is in use.

18. A hand-held injector for use with a syringe or cartridge comprising a barrel and a plunger, the injector comprising: a pusher member supported on the injector and longitudinally movable relative thereto, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly, the pusher being offset from the axis of the longitudinally movable pusher member,- and a manually-operated drive mechanism comprising a manually-actuatable lever operatively connected to said pusher member whereby, in use, actuation of said lever moves the pusher member forwardly.

19. An injector as claimed in any preceding claim, wherein said drive mechanism comprises a drive plate which is urged into engagement with the pusher member on actuation of said lever, further motion of said lever causing motion of the drive plate and thus of the pusher member.

20. An injector as claimed in claim 19, wherein said lever is arranged to pivot about a fulcrum, and wherein actuation of said lever causes the lever to contact the drive plate to urge the drive plate into engagement with the pusher member, the point of contact between the lever and the drive plate being on a different side of the pusher member from the fulcrum.

21. A hand-held injector for use with a syringe or cartridge comprising a barrel and a plunger, the injector comprising: a pusher member supported on the injector longitudinally movable relative thereto, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly; and a manually-operated drive mechanism comprising a manually-actuatable lever and a drive plate which is urged into engagement with the pusher member on actuation of said lever, further motion of said lever causing motion of the drive plate and the pusher member,- wherein said lever is arranged to pivot about a fulcrum, and wherein actuation of said lever causes the lever to contact the drive plate to urge the drive plate into engagement with the pusher member, the point of contact between the lever and the drive plate being on a different side of the pusher member from the fulcrum.

22. An injector as claimed in claim 19, 20 or 21, wherein said drive plate is formed from plastics material.

23. An injector as claimed in any preceding claim, wherein said pusher member is formed from plastics material .

24. An injector as claimed in any preceding claim, wherein said lever is pivotally connected to said body by means of a pin, said pin being formed from plastics material .

25. A hand-held injector for use with a syringe or cartridge comprising a barrel having a front end with a nozzle and a rear end with a flange, and a plunger, the injector comprising: a support portion having a slot for receiving the flange of the barrel so as to prevent forward and rearward longitudinal movement thereof ; a pusher member longitudinally movable relative to said support portion, said pusher member having a pusher contact for pushing to cause the plunger of the syringe or cartridge to move forwardly; and a manually-operated drive mechanism comprising a manually-actuatable lever operatively connected to said pusher member whereby, in use, actuation of said lever moves the pusher member forwardly.

26. A hand-held injector for use with a syringe or cartridge, comprising a body, a grip extending downwardly from the body, and projections extending outwardly from the sides of the body above the grip, said projections being arranged to rest on a user's hand when the injector is in use.

27. A method of injecting a patient with a physiologically acceptable product using a hand-held injector as claimed in any preceding claim.