Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
1999-09-08
2001-11-20
Kennedy, Sharon (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S110000
Reexamination Certificate
active
06319234
ABSTRACT:
SUMMARY OF THE INVENTION
The present invention relates to a disposable safety syringe, comprising:
a) a cylindrical syringe barrel;
b) an injection needle, being integral with a needle-carrier, which is attached to the fore end of the syringe barrel;
c) a plunger which is slidable in the syringe barrel and has an injection stroke which extends from a retracted utmost syringe-filling position, wherein the liquid medicine has been aspired, to a forwardmost position, and is fitted at its back with a manually drivable stem, driven out of the syringe barrel through the open rear end thereof;
d) a needle-covering sleeve, which is axially fitted on the syringe barrel, so as to slide from a retracted rest position, in which it leaves the needle exposed, into an advanced safety position, in which it entirely covers the needle;
e) plunger-clamping means, consisting of hook-like interacting means, which are provided at the rear side of the syringe barrel and at the rear side of the needle-covering sleeve, and are initially engaged with each other so as to retain the needle-covering sleeve in its retracted rest position, whereas they are automatically disengaged from each other by the plunger stem, in the last portion of the injection stroke of the plunger, thereby releasing the needle-covering sleeve;
f) a spring, interposed between the rear of the syringe barrel and the needle-covering sleeve, which stresses the needle-covering sleeve, once it is released from the hook-like means, towards its advanced safety position, first by making it elastically adhere to the patient body, and then by progressively advancing it, on extracting the needle from the patient body, at the end of the injection, until it entirely covers the extracted needle.
The invention has the object to provide a disposable safety syringe of the type described hereinbefore, which has a simpler and cheaper construction and an easier and safer operation.
This object is achieved by the invention with a disposable safety syringe of the type described hereinbefore, in which:
g) the needle-covering sleeve has a rear rim having the shape of an outwardly projecting hook-like tooth, cooperating with one or more complementary inwardly projecting hook-like teeth, provided on retaining tongues, which extend forwardly in the longitudinal direction of the syringe from a head located at the rear end of the syringe barrel and are automatically movable from a radially retracted hooking position, in which their teeth hook the rim of the needle-covering sleeve, holding it in its retracted rest position, into a radially opened out releasing position, in which their teeth are released from the rim of the needle-covering sleeve and disengage it;
h) the rear end of the plunger stem is provided with means which cooperate with the retaining tongues and automatically cause these tongues to move from their radially retracted hooking position, into their radially opened out releasing position, at the end of the injection stroke of the plunger;
i) the needle-carrier has at least one lateral locking projection, which projects radially outwards, and slidably engages in a longitudinal slot, formed in the needle-covering sleeve, whereas, at the rear end of said slot, there are provided automatic stop means, engaging said lateral locking projection, preventing any axial movement thereof with respect to the needle-covering sleeve, in the advanced safety position thereof, thus securing at least the needle-carrier to the needle-covering sleeve.
The syringe according to the invention is provided with an automatic needle coverage, the needle-covering sleeve, which is released from the plunger stem when the latter, at the end of the injection, reaches the end-of-stroke position, for injecting the medicine. Once the needle of the syringe has been extracted from the muscle or vein of the patient and, at the latest, once the pressure of the syringe-controlling fingers has been released, the needle-covering sleeve immediately and automatically covers the needle, locking it therein. Any attempt to remove the needle protection would cause it to be torn away from the syringe, therefore the needle would be well protected ad locked in its protective needle-covering shell.
A preferred embodiment of the syringe according to the invention is based on the acknowledgement that the needle-covering sleeve, which is only free to snap forwardly to its advanced safety position, when the syringe plunger has run the whole injection stroke, cannot prevent the syringe from being used for more than one user, by injecting each one with only a part of the total volume of liquid, aspirated by the syringe. Therefore, said embodiment of the invention is aimed at providing a disposable safety syringe which ensures the prevention of a shared use thereof, causing the needle-covering sleeve to snap forwardly to its needle-covering position, even when smaller doses of the maximum contents of the syringe are injected.
The invention achieves the above objects by providing a syringe according to claim
1
, further having the following characteristics:
k) the cooperating plunger-clamping means, provided at the rear end of the plunger stem and of the syringe barrel are arranged to fasten the plunger stem to the syringe barrel, so as to prevent it from being unlocked in either direction;
l) the plunger stem and the syringe barrel are provided at their rear end with cooperating safety means, which are manually removable or disengageable, and initially (in the syringe supplied condition) prevent any forward movement of the plunger stem, retaining it in a rest or starting position, in which the plunger-clamping means, on the plunger stem and on the syringe barrel are disengaged from each other and from which position the plunger stem may be caused to run (once the safety means have been released) a terminal forward stroke, substantially corresponding to the minimum medicine dose which can be injected by the syringe, and thereafter the plunger-clamping means on the plunger stem and on the syringe barrel engage with each other and secure the plunger stem to the syringe barrel,
m) the plunger stem has a length between
a maximum length, wherewith, in the initial rest position of the plunger stem, the fore end of the plunger is set back from the bottom of the syringe barrel, at a distance substantially corresponding to the above mentioned terminal forward stroke of the plunger stem, and the greatest quantity of medicine that can be injected by the syringe corresponds to the quantity drawn in, and
a minimum length, wherewith, in the initial rest position of the plunger stem, the fore end of the plunger is set back from the bottom of the syringe barrel, at a distance substantially corresponding to the longest possible further backward stroke of the plunger, from this position to the retracted utmost syringe-filling i.e. aspirating position and the greatest quantity of medicine that can be injected by the syringe substantially corresponds to the terminal forward stroke of the plunger stem (smallest injectable dose).
Advantageously, the syringe is associated to a package of liquid medicine, and the stem of its plunger has such a length that the maximum syringe-filling volume of medicine which can be aspirated is at the most equal to the volume of the medicine contained in the package or preferably smaller.
Syringes for injecting predetermined medicine doses, or smaller, may be provided with stems having a corresponding fixed length, and being by turns fitted in the syringe barrel during the syringe manufacturing process.
The stem may be advantageously provided with a variable length, for example with a telescopic adjustment.
The advantages of the present invention are apparent from the above description. By a single type of syringe, the problem related to the shared use of syringes may be obviated, particularly when the doses to be injected are smaller than the utmost filling dose. Particularly, when syringes are sold together with the medicine, the length of the plunger may be determined in such a way as to on
Restelli Sergio
Righi Nardino
Creighton Wray James
Kennedy Sharon
Narasimhan Meera P.
Serke Catherine
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