GB2139708A

GB2139708A - Multi-barrel syringe

Info

Publication number: GB2139708A
Application number: GB08410632A
Authority: GB
Inventors: Matthew Moncrieff Shepherd
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-04-29
Filing date: 1984-04-26
Publication date: 1984-11-14
Also published as: GB8410632D0; GB2139708B

Abstract

A syringe 1 suitable for use in the accurate dispensing of liquids comprises a plurality of barrels 4 comprising at least one first barrel 2 and at least one second barrel 3, each said barrel having a dispensing end 6 and a second end 7. The dispensing ends 6 of said barrels are in communication with each other and with a common dispensing outlet 9. Each barrel has a respective plunger 11 with a drive means 12 therefor each first barrel 2 has a stop means 15, 16 for defining a predetermined fill level in said first barrel to a predetermined degree of accuracy. Each second barrel 3 has an associated calibration means comprising a plurality of spaced apart calibrations 18 for indicating the fill level of said second barrel to a corresponding predetermined degree of accuracy comparable to the degree of accuracy for said first barrel fill level(s). In use the syringe may be accurately filled with a desired volume of liquid corresponding to the sum of the predetermined fill level (s) in the first barrel (s) and a selected fill level (s) in the second barrel (s). <IMAGE>

Description

SPECIFICATION Multi-barrel syringe This invention relates to a syringe suitable for use in the accurate dispensing of liquids, for example, liquid medicaments.

In certain fields such as medicine there is a need for accurate dispensing of liquids since underdosing or overdosing can have adverse results such as reduced effectiveness of treatment or undesirable side effects respectively.

This problem is particularly acute in the case of insulin dispensing in the treatment of diabetics many of whom have defective vision. In this case the problem is magnified in that out of a typical dose of the order of even 100 units only 2 to 3 units may be effective in blood sugar control, the remaining 100 or so units being inhibited by insulinases in the body. Thus in order to obtain an accurate effective dosing of the 2 to 3 effective units it is necessary to obtain a correspondingly high degree of accuracy in the total dose of some 100 units. This is a particularly difficult task for the diabetic with defective vision since the volume corresnonding to an individual calibration on a 100 unit syringe could normally be much greater than that for an individual calibration on a 5 unit syringe if such were available.

It is an object of the present invention to avoid or minimize one or more of the above disadvantages.

The present invention provides a syringe suitable for use in the accurate dispensing of liquids which syringe comprises a plurality of barrels comprising at least one first barrel and at least one second barrel, each said barrel having a dispensing end and a second end remote from said dispensing end, the dispensing ends of said barrels being in communication with each other and with a common dispensing outlet, each said barrel having slidably movable therein a respective plunger means with a drive means for use in moving said plunger forwards and backwards in the barrel, each said first barrel having a stop means for defining a predetermined fill level in said first barrel to a predetermined degree of accuracy, each said second barrel having a plurality of spaced apart calibrations for indicating the fill level of said second barrel to a corresponding predetermined degree of accuracy comparable to the degree of accuracy for said first barrel fill level(s), whereby in use said syringe may be accurately filled with a desired volume of liquid corresponding to the sum of the predetermined fill level(s) in the first barrel(s) and a selected fill level(s) in the second barrel(s).

It will be appreciated that a syringe of the present invention may have any number of barrels from 2 upwards of which at least some, first, barrels will have predetermined stops and at least some, second, barrels will have calibrations. Nevertheless some or all of the first barrels may also have calibrations and some or all of the second barrels may also have predetermined volume stops.

In practice the syringe will usually have two barrels comprising a relatively large capacity first barrel and a relatively small capacity second barrel.

With a syringe of the present invention it is possible to readily obtain an increased degree of accuracy as a result of the smaller volume corresponding to individual calibrations and the automatic accurate determination of a large part of the dose to be dispensed.

Further preferred features and advantages of the invention will appear from the following detailed description given by way of example of a preferred embodiment illustrated with reference to the accompanying drawing in which: Fig. 1 is a partially sectioned schematic side elevation of a syringe of the invention.

Fig. 1 shows a syringe 1 having a first barrel 2 and a second barrel 3 joined together along adjoining sides 4 by a web 5. Each barrel 2,3 has a dispensing end 6 and a second end 7 remote therefrom. At the dispensing ends 6 the barrels communicate with each other via a small passage 8 and are provided with a common dispensing outlet 9 formed as a standard Luer fitting nozzle on which can be mounted a conventional hypodermic needle 10.

In each barrel there is disposed a resiliently deformable plunger 11 of known construction provided with a drive means in the form of an elongate drive member 12 drivingly connected to the plunger 11 and having a distal end provided with finger lugs 13. At its second end 7 the first barrel 2 is provided on its internal wall surface 14 with a small projection 15 which engages in a complementary recess 16 in the corresponding drive member 12 when this is fully retracted thereby to function as a stop means determining a predetermined fill level of liquid 17 in said first barrel 2.

The second barrel 3, which as may be seen in the drawing, is of considerably smaller capacity than the first e.g. one tenth thereof, is provided with a series of calibrations 18 in generally conventional manner.

As may also be seen in the drawing, the finger lugs 13 of the drive members 12 are formed and arranged for radially overlapping disposition so that as the drive member 12 in the first barrel 2 is driven forward (for dispensing) its lugs 13 engage the lugs 13 of the second barrel drive member 12 so that the latter drive member is automatically driven forward also thereby ensuring complete dispensing from the second barrel at the same time as from the first.

In use of the syringe air is expelled there from in more or less conventional manner.

Then with both plungers fully forward, the first barrel 2 is filled by retracting the plunger 11 and drive member 12 thereof until the latter engages the stop means 15 which accurately and automatically determines a predetermined fill level such as a volume containing 100 units. The first barrel member 12 is now retained in position by the stop means while the second barrel drive member is withdrawn until a volume of liquid corresponding to a desired number of units e.g. 5 units is present in the second barrel as may be determined by reading off the calibrations 18 in the normal way. The contents of the syringe may then be disposed by driving forward the second barrel drive member followed by the first one.

It will be appreciated that various aspects of the construction of the above syringe may be of generally conventional construction, e.g.

the barrel may conveniently be of a generally transparent plastics material such as polystyrene or polyacrylate whilst the plunger is of a natural or synthetic polymeric resiliently deformable material. Accordingly such features need not be described in any further detail herein.

It will also be appreciated that the syringe of the invention may be used for dispensing various liquids requiring accurate dosing other than medicaments, for example chemical or biological reagents.

Further preferred and alternative forms of construction of the above described syringe which may be mentioned include the use of multiple syringes wherein a single common wall separates the contents of adjacent barrels, the barrels being as it were 'fused' together without the need for any intervening web. Also the hypodermic needle may be fused into the end of the barrel thereby obviating the need for a Luer or other fitting, connection between the needle and the barrel.

In order to ensure that the second syringe plunger is driven fully home during discharge of the second barrel where the first plunger is provided with lugs 13 for driving engagement of the second plunger lugs, the former are desirably made slightly flexible.

Other, alternative, forms of stop means for the first barrel could comprise an annular groove in the internal wall of the barrel into which a ridge on the plunger engages in click- stop manner, or an annular ridge or small flange for abutment with the rear side of the plunger.

As will already be apparent any desired form of barrel cross-section may be used, in general those forms lending themselves to economy and ease of manufacture being preferred. One further form which may be mentioned comprises a small diameter second barrel inside a large diameter barrel, the first barrel being constituted by the remaining part of the large barrel not occupied by the second barrel.

A further advantage of the invention that may be mentioned include increased strength and/or the possibility of a lighter weight of construction due to the mutual reinforcing of the barrels. It will also be appreciated that in addition to and/or instead of, the possibility of reducing the volume corresponding to individual calibrations, the spacing of these can be increased thereby facilitating reading thereof.

Claims

1. A syringe suitable for use in the accurate dispensing of liquids which syringe comprises a plurality of barrels comprising at least one first barrel and at least one second barrel, each said barrel having a dispensing end and a second end remote from said dispensing end, the dispensing ends of said barrels being in communication with each other and with a common dispensing outlet, each said barrel having slidably movable therein a respective plunger means with a drive means for use in moving said plunger forwards and backwards in the barrel, each said first barrel having a stop means for defining a predetermined fill level in said first barrel to a predetermined degree of accuracy, each said second barrel having an associated calibration means comprising a plurality of spaced apart calibrations for indicating the fill level of said second barrel to a corresponding predetermined degree of accuracy comparable to the degree of accuracy for said first barrel fill level(s), whereby in use said syringe may be accurately filled with a desired volume of liquid corresponding to the sum of the predetermined fill level(s) in the first barrel(s) and a selected fill level(s) in the second barrel(s).

2. A syringe according to claim 1 wherein one of at least one said first barrel and its associated plunger means is provided with a plurality of stop means elements formed and arranged for releasable engagement with a coS operating stop means element on the other of said first barrel and associated plunger means for defining a plurality of different predetermined fill levels.

3. A syringe according to claim 1 or claim 2 wherein the calibration means are disposed along the barrel wall.

4. A syringe according to claim 1 or claim 2 wherein the calibrations are disposed along the plunger shaft.

5. A syringe according to any one of claims 1 to 4 which has one relatively large capacity first barrel and one relatively small capacity second barrel.

6. A syringe according to claim 5 wherein the first barrel has a capacity of from 5 to 50 times that of the second barrel.

7. A syringe according to any one of claims 1 to 6 wherein each plunger has laterally extending digitally engagable lug means of said first barrel(s) overlapping the lug means of said second barrel(s) so that when the first barrel plunger(s) is driven forward for dispensing it carries the second barrel plunger(s) along thereby simultaneously dispensing from both first and second barrels.

8. A syringe according to any one of claims 1 to 7 wherein the first and second barrels are formed integrally together with each other.

9. A syringe according to any one of claims 1 to 8 wherein said second barrel is at least partly surrounded by said first barrel.

10. A multi-barrel syringe for use in the accurate dispersing of liquids which syringe is substantially as described hereinbefore with particular reference to the accompanying drawing.