Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1996-12-02
1998-08-11
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604195, A61M 500
Patent
active
057921075
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a disposable safety syringe.
Disposable safety syringes in which the needle is automatically retracted into the tubular body of the syringe to a safe position after the injection are known.
However, such known disposable syringes have complex needle-retraction means. Moreover, these needle-retraction means are either positioned on the exterior of the syringe body (for example coaxially with the syringe plunger rod), and are therefore exposed to undesirable handling, or else, if positioned inside the syringe body, are in contact, during the injection, with the injection fluid, and as a result the latter can become contaminated.
In addition, in the known syringes of the type indicated, after the injection has been completed, the needle prior to its retraction--is advanced axially, presenting a possibly serious risk of injury to the patient, in order to disengage the needle from the means by which it is held in the active position. <<Please insert page 1a>>
The chief object of the present invention is therefore to provide a disposable safety syringe which will ensure that the needle is automatically retracted after the injection to a safe position inside the tubular body of the syringe, without allowing the syringe to be reused, and this by the use of structurally simple means that will operate safely and reliably.
Another object is to provide a disposable safety syringe as specified, in which the automatic needle-retraction means are not accessible to the operator and are never, at any point during the injection, in contact with the substance to be injected.
Yet another object is to provide a disposable safety syringe as stated, in which at the end of the injection the needle is not advanced axially, in order to guarantee the patient's safety.
Still another object is to provide a disposable safety syringe as indicated that is also suitable for use as a dispenser of a fluid, for example for mixing substances into powders or granules prior to injecting the latter. U.S. Pat. No. 5,114,410 discloses a disposable safety syringe which includes a tubular syringe body with a needle-supporting head through which a hollow needle passes and slides, a hollow piston which slides through the inside of the syringe body, and--before and during the injection--three non-communicating chambers, namely: a first chamber defined in the needle-supporting head and which contains retaining means that engage the needle so as to hold it in a fixed position--with tip extended from said head--in opposition to the action of return means; a second chamber defined in the tubular syringe body between said first chamber and said piston, and a third chamber inside the piston.
The first chamber and the second chamber are variable during the injection and separated by a discoid part, which is able to slide axially and leak tightly inside the front part of the syringe body.
The discoid part receives the head of the needle, which passes through it, and has fixed disengaging means to disengage said retaining means.
The discoid part and the needle as a whole are pushed forward by the piston and the volume of the first chamber reduces, when the piston completes its operative run.
At this stage, the discoid part, and the needle with it, move slightly forward as they are pushed by the piston and the disengaging means disengage the retaining means from the needle, thereby releasing the needle, which is suddenly introduced into the piston's cavity (i.e. the third chamber) through the action of the return means.
In other words, as the piston completes its operative run, it before pushes forward the needle and immediately after springs a mechanism which automatically and suddenly introduces the needle into the axial cavity inside the piston.
However, during the completion of the piston operative run, the injection has not yet been completed and the needle axially advanced--prior to its retraction--presents a serious risk of injury to the patient (e. g. a vein could be pierced).
Furthermore, since no control or
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patent: 4955870 (1990-09-01), Ridderheim et al.
patent: 5114410 (1992-05-01), Caralt-Batlle
patent: 5180369 (1993-01-01), Dysarz
patent: 5338304 (1994-08-01), Adams
patent: 5487732 (1996-01-01), Jeffrey
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