Single-use syringe with aspirating mechanism

Details Single-use syringe with aspirating mechanism Single-use syringe with aspirating mechanism

1998-10-14

2001-09-04

Kennedy, Sharon (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S209000

Reexamination Certificate

active

06283941

ABSTRACT:

RELATED APPLICATIONS
This is a continuation-in-part application of application Ser. No. 08/195,302, filed Feb. 14, 1994, now U.S. Pat. No. 5,531,691 entitled Single-Use Syringe Assembly and application Ser. No. 08/232,749 filed Apr. 25, 1994 now U.S. Pat. No. 5,562,623 also entitled Single-Use Syringe Assembly Comprising Spring Clip Lock and Plunger. Both of the applications are incorporated herein by reference as if fully presented.
BACKGROUND OF THE INVENTION AND DESCRIPTION OF THE PRIOR ART
This invention relates generally to hypodermic needles and syringes, and more particularly the invention relates to a spring locking clip and associated plunger which can be used to convert a plastic hypodermic syringe barrel into a single-use, difficult to reuse, inexpensive syringe made of already medically approved material. For the purposes of this invention the term single-use means that the full maximum dosage placed into the syringe can only be administered one-time. The syringe, however, can administer medication multiple times, each time, however, delivering only a portion of the full medication capable of being drawn into the syringe by a single, full proximal drawing of the plunger rod with respect to the syringe barrel. For short hand notation, the term single-use means a single full dispensing of the entirety of medication drawn into the barrel and includes one or more possible uses, with each use delivering less dosage than the maximum. The cumulative total of delivered dosages obtained by all uses can not exceed the maximum or full dosage drawn into the syringe by a single rearward reciprocation of the plunger rod with respect to the barrel. The syringe is a one-time use syringe when the maximum or full dosage of the syringe (determined by the barrel capacity and/or the position of the spring clip on the plunger) is fully administered in a first and only usage. If that occurs, the spring clip is moved to its full distal position and all reuses are blocked. Where less than the maximum dosage is drawn into the barrel is delivered on the first or succeeding dosage deliveries, the succeeding dosages administered are necessarily less than the maximum. There can be only one full distal movement of the plunger rod, to administer medication made up of individual administrations of medication. The sum of all medication dispensed cannot exceed a single dosage capacity of the barrel of the syringe. In this manner, the device is a “single-use” syringe.
The safe, one-time use and subsequent disposal of hypodermic needles and syringes are immediate concerns in the medical and health professions. Accidental needle stick injuries following use of a syringe pose a significant risk to patients, physicians and nurses. The risk is a source of great anxiety due to the current HIV and hepatitis infection concerns of the general public. Thus, extreme care must be taken in the safe handling and disposal of used needles and syringes. Toward this end, the present invention represents a single-use needle and syringe assembly. After the needle and syringe (hereinafter collectively referred to as the syringe) are used once, the mechanism of the present invention precludes further uses. It will, therefore, be more likely properly discarded than if further use were possible. The possibility of patient to patient cross contamination and drug user to drug user cross contamination are reduced.
The present invention is compact and, therefore, is capable of being implemented into syringes of extremely small size barrel capacity, including syringes capable of administering dosages as low as 0.1 cc. The prior art, on the other hand, as will be more fully explained hereinafter, cannot be easily and/or economically downsized while maintaining the effectiveness of the one-time use only mechanism they describe and, therefore, they have not been commercially introduced in sizes smaller than standard 3 cc syringe bodies. The initial axial location of the locking mechanism with reference to the syringe barrel of the prior art single-use syringes, was the means for limiting a 3 cc conventional syringe to a maximum 1 cc dosage. However, it is clearly desired to have smaller maximum dosage syringes where the size of the syringe, not only the location of the clip, determines the maximum dosage capacity. It should be appreciated, however, that the present invention can also be adapted for use with 3 cc or other maximum dosage syringe barrels and, yet, the present invention has particular applicability to syringes of low dosage barrel capacity even those as low as 0.1 cc capacity.
It is generally recognized that a low cost syringe is essential to meet the needs of less developed countries and to contribute to the reduction of health costs worldwide. A low cost would mitigate syringe re-use now encountered with disposable syringes. The cross contamination resulting from patient to patient reuse of the same syringe would be obviated by a single-use only syringe. It would also reduce patient anxiety resulting from suspected potential infection from prior syringe use.
The present invention provides a simple and inexpensive mechanism for limiting the usage of a syringe (with or without needle) to one-time or single-use only. The syringe is intended to be assembled at the manufacturing facility and provided to the physician (or nurse, patient, etc.) for use. The user fills the syringe with the appropriate medication in the conventional manner, i.e., by withdrawing the plunger with respect to the cylindrical barrel of the syringe, thereby drawing medication through the needle tip and into the chamber of the barrel. According to the present invention, the plunger can be repeatedly reciprocated, for aspirating, prior to loading with medication. Once the user makes the decision that the amount of aspirating reciprocations have been sufficient, a positive movement of the plunger with respect to the barrel ensures the operation of the single-use locking mechanism. Then, again, using conventional technique, the needle is inserted to pierce the patient's skin. The plunger is manually moved with respect to the cylindrical barrel thereby forcing a piston toward the distal end of the syringe. The piston forces the medication out through the needle tip.
During the dosage administration portion of the procedure, according to the present invention, as will be more fully explained hereinafter, a locking spring clip travels along with the plunger shaft and, when it reaches the distal position, locking or contact points are held against the interior sidewall of the cylindrical barrel with the piston abutting the base of the locking spring clip. A second attempted retraction of the plunger with respect to the cylindrical barrel of the syringe is blocked. Thus, no further medication can be pulled into the syringe and, therefore, the syringe is incapable of being used a second time. A simple, inexpensive single-use syringe is provided. The locking mechanism, precluding reuse, is automatic, ire., it operates to block reuse, after aspiration, without a conscious operation by the user to engage its operation.
The design of an economically producible syringe assembly having the feature of single-use and whose safety or one-time use operation is difficult to defeat has been the subject of numerous patents and efforts. Such a syringe should be easy to manufacture and assemble, function in a standard manner, be able to deliver different volumes of fluid, utilize materials which are universally approved for medical use, preferably require standard equipment to manufacture such as used for making syringes in current use, and, importantly, be low in cost.
The present invention accomplishes the above objects by utilizing a new and unique plunger in association and in combination with a new and unique spring locking clip. The plunger comprises a plurality of cylindrical i.e., frusto-conical ratchet teeth or in an alternate embodiment, beads. The spring clip is located by the manufacturer at a particular location along the axis of the plunger so as to lim

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