Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1998-04-10
1999-09-21
Coggins, Wynn Wood
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604187, 604218, A61M 500
Patent
active
059546999
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an injection device for injecting fluid according to the preamble of claim 1.
Syringe-shaped injection devices for injecting fluids have been known for some time. They contain a bushing-shaped main body which can be screwed together at approximately the centre and can be divided into two main sections: mechanism and comprising at least one rod-shaped driven member having a structured surface (e.g. a screw rod), a hollow cylindrical counter component corresponding to the driven member, provided with a structured internal sleeve (e.g. a screw nut) and a control button; and administered and a movable piston.
At the proximal end of the main body, a needle and a needle holder are attached, allowing the fluid to be discharged from the device; known needles of this type are for instance PENFINE.RTM. needles as described in WO95/01812.
The connecting member between the proximal and the distal section of the main body is the driven member, shifting the piston by the required dose in proximal direction and discharging the fluid through the needle.
Often the fluid to be injected is not directly contained in the main body but in an ampoule, with the fluid being stored between a piercable membrane and a piston displaceable by sliding.
Depending on the injection device, various features are expected from the discharge mechanism. There are devices allowing only a single discharge, devices allowing several discharges of the same dose and devices allowing freely selectable discharges.
For patients using injection devices allowing a change of ampoules, it is--irrespective of the complexity of the discharge mechanism--extremely difficult to wind back the driven member to the initial position in order to make the device ready for operation after the ampoule has been changed. Devices requiring the driven member to be rewound by the control button are known from WO93/16740. Devices allowing the threaded rod to be pushed back, as in publications U.S. Pat. No. 4,592,745 and EP-A-0 554 995, are more easily operated by patients. The disadvantage of these prior art devices is that due to the release of the distal section from the proximal section of the main body the threaded nut is spread, allowing the threaded rod to move freely without any conscious operation by the patient, with screwing together of both sections of the main body after replacement of the ampoule easily causing a premature unintentional discharge of fluid. Depending on the injection device, this could also result in an incorrect dosing which, in case of certain medication, could prove extremely hazardous to the patient's health.
The invention aims to remedy this situation. It is the object of the invention to provide an injection device in which the sliding back of the driven member requires a conscious operation by the patient, which releases the driven member and counter component from each other to prevent the hazard of an incorrect dosing.
The invention solves the set task by an injection device with a driven member which can be shifted freely in axial direction by forcibly opening the counter component.
The advantages achieved by the invention lie mainly in the fact that the free return of the driven member is only possible when the patient releases the driven member by activation of a slide, i.e. by a conscious additional operation.
A preferred embodiment of the invention is shown in the figures, where:
FIG. 1 shows an injection device according to the invention with a retained threaded rod;
FIG. 2 shows an injection device according to the invention with a free threaded rod;
FIG. 3 shows an injection device according to the invention in which the actuating device has been removed;
FIG. 4 shows a cross section along line A--A;
FIG. 5 shows a cross section along line B--B; and
FIG. 6 shows a cross section along line C--C.
In the subsequent description, the terms proximal and distal are used in their usual medical sense, i.e. proximal=facing the patient and distal=facing away from the patient.
As shown in FIG. 1, the injection
REFERENCES:
patent: 4865591 (1989-09-01), Sams
patent: 5084060 (1992-01-01), Freund et al.
patent: 5279585 (1994-01-01), Balkwill
patent: 5336183 (1994-08-01), Greelis et al.
patent: 5370629 (1994-12-01), Michel et al.
Burkhardt Hans
Jost Stefan
Renggli Christoph
Coggins Wynn Wood
Disetronic Licensing AG
Thanh Loan H.
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