Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Patent
1999-05-25
2000-07-04
Yasko, John D.
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
604218, A61M 500
Patent
active
060832002
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a medical syringe made up of elements allowing one injection but preventing the use of the same syringe for any subsequent injection. In brief, this is a non-reusable syringe, which self-destructs without special manipulation by the operator.
Naturally, for obvious reasons, hospital and medical environments have for a long time been using disposable syringes which are used once only. However these environments are not the only ones to use syringes and trusting the user's self-discipline alone to ensure once-only use is far from adequate in the real world. For example it is well-known, according to WHO studies, that in developing countries so-called disposable syringes are often re-used up to 50 times.
That is why numerous proposals have been made to make syringes which, through-the way in which they are designed or constructed, physically prevent their being used a second time.
The choice of the means to be adopted to this end is very limited. In fact there is really only one way, namely fitting the chamber of the syringe, basically the head of the piston, with a provisional blocking unit which ensures that the chamber is sealed for the first injection but which is definitively de-activated once the first injection has been made.
The simplest version of this design is described in patent application FR-A-2, 606, 643, relating to a syringe with an eccentric nozzle, where the head of the piston is equipped with an orifice, initially stopped with a moveable cork which is ejected from the chamber when it encounters a centre punch when the piston reaches the end of its path and the chamber reaches its minimum volume.
More sophisticated proposals have also been made, in particular using a membrane held by the piston, which is then either displaced by the pressure of the liquid or punctured at the end of the first injection. Such proposals are to be found in European Patent 0345159 and in Patent application FR-A-2, 606, 643.
The number and variety of proposals of the prior art might suggest that the problem has been fully dealt with. However this is not so. In fact it is not sufficient to design a syringe which can function on this principle or one of the many variants thereof, it then has to be produced by an industrial process which entails a very low cost. In this respect it should be remembered that the industrial manufacture of syringes has to meet two requirements: first of all the quantities are truly astronomical and amount to hundreds of thousands of units in order to achieve simply a modest cost in this context. Secondly, the syringes must be packed in high grade sterile packaging, in spite of the enormous manufacturing output. It is no doubt due to the fact that they did not comply with these two conditions that the proposals of the prior art have not led to any significant production, whereas the need is absolutely well-known and absolutely urgent.
It is from this angle that the criticism of the previous proposals should be made, since it is indeed the case that these proposals do not meet the needs which the world is actually experiencing. In order for a non-reusable syringe to truly meet the need, it is necessary for the unit sale price to be at least comparable with that of a conventional disposable syringe, but it is also necessary for it to be equally reliable. It would actually be ridiculous to allow major production initiatives if the physically unique nature of the use were not guaranteed and remained uncertain, as is the case with the proposals of the prior art.
The use of a membrane is disqualified in an industrial context because these have to be plastic articles and therefore their elasticity is an uncontrollable parameter, in particular over a period of time. Therefore one cannot guarantee stable properties and thus one would be exposed either to the impossibility of making the first injection properly or to the uncertainty of preventing the second injection in all cases. For example in the case of the syringe proposed in European patent 0345159, because t
REFERENCES:
patent: 5026346 (1991-06-01), Bates
patent: 5078686 (1992-01-01), Spanner et al.
patent: 5226881 (1993-07-01), Pickhard
patent: 5944692 (1999-08-01), McGary et al.
Grimm Edgardo
Moro Olinto
Browning Clifford W.
Yasko John D.
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