Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1982-10-12
1985-02-12
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604224, A61M 500
Patent
active
044989040
DESCRIPTION:
BRIEF SUMMARY
This invention relates to syringes, and to a dose metering device for use in conjunction with a syringe in place of the conventional manually-depressible plunger thereof.
The invention is particularly although not exclusively applicable to medical syringes for delivering doses of liquid, for example hypodermic syringes for injecting drugs in liquid form, such as insulin. Diabetics require to inject themselves repeatedly with insulin, and as each injection often has to be of a different amount from the last, it is necessary to draw up each injection dose separately from a multi-dose container into a syringe, check the amount in the syringe and then inject the dose.
It is an object of the present invention to provide a syringe with a dose-metering device which can be used to inject successive metered doses of the same or different preset volumes from the filled syringe. Whilst the invention is of particular application in connection with the injection of insulin, it may have other uses too, such as the metered delivery of a parenteral anaesthetic or analgesic, or of small variable doses of liquid in laboratories or factories.
According to the present invention, from one aspect, a dose metering device for a syringe comprises an axially movable plunger which in use drives the piston of the syringe to express a dose of fluid therefrom, the plunger being movable in successive axial steps of variable length by a rotary screw mechanism driven by successive respective operating strokes of corresponding length of a manual operating member whereby successive doses whose volumes correspond to the lengths of the respective operating strokes of the operating member will be expressed from the syringe, and the operating member acting through a unidirectional coupling which permits its retraction after each operating stroke to a starting point for the next stroke, and in which the length of each operating stroke of the operating member can be variably preset thereby presetting the volume of the corresponding dose.
The operating member is rotatable and effects angular operating strokes which are converted by the screw mechanism into corresponding axial steps of the plunger, and the presetting of the lengths of the operating strokes of the operating member is performed by selectively varying the angular position of the starting point of each operating stroke, the end of each stroke being determined by stop means.
The device includes scale means, for example an arcuate scale, preferably calibrated in volumetric units, and a cooperating pointer, preferably arranged to that the volume of each dose to be expressed, corresponding to the angle through which the operation member is rotated, can be directly indicated and pre-set on the scale.
In one construction, the operating member is coupled through the unidirectional coupling to a rotary screw mechanism, the selection of the starting point of each operating stroke being performed by rotating the operating member in the direction of retraction to its selected starting point on the scale. The screw mechanism may comprise an external helical screwthread formed coaxially on the plunger and a cooperating internal helical screwthread formed coaxially in the cylinder of the syringe or in a tubular part which in use is fixed to the cylinder.
The unidirectional transmission may conveniently comprise a ratchet and pawl mechanism.
Thus prior to each dose expression, the operating member is preset by being moved from the zero mark to the scale marking corresponding to a required dose size, the pawl riding over the tips of the ratchet teeth so that the plunger is not rotated. Then when the dose expression is required, the operating member is manually turned back through one operating stroke to the zero mark to engage the stop means, this movement driving the plunger via the ratchet mechanism and causing the preset, metered dose to be expressed from the syringe.
The piston may take the form of a sliding plug in the syringe cylinder by which a quantity of liquid to be expressed in successive d
REFERENCES:
patent: 2129675 (1938-09-01), Cole
patent: 3141583 (1964-07-01), Mapel et al.
patent: 3232117 (1966-02-01), Gilmont
patent: 3481510 (1969-12-01), Allen
patent: 4194505 (1980-03-01), Schmitz
patent: 4244366 (1981-01-01), Raines
patent: 4367739 (1983-01-01), Le Veen et al.
"Convenient Pocket Insulin Syringe", John S. Paton et al., The Lancet, 24th Jan. 1981.
Holman Rury R.
Stone Anthony B.
Turner Robert C.
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