Safety syringe

Details Safety syringe Safety syringe

2001-02-22

2003-03-11

Mendez, Manuel (Department: 3763)

Surgery

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

Treating material introduced into or removed from body...

C604S110000, C604S220000

Reexamination Certificate

active

06530903

ABSTRACT:

BACKGROUND OF THE INVENTION
This application claims priority to, and incorporates by reference, Chinese Patent Application No. 00205827.8 filed on Feb. 24, 2000.
1. Field of the Invention
The present invention relates to a syringe, particularly, to a safety syringe, belonging to the medical device technical field. Safety syringes are designed for one-time use and are, therefore, not re-useable.
2. Background of the Art
In the medical field, there is a great need to avoid cross-contamination or infection which may be caused when a syringe is used more than once. Single use syringes have long been thought as being one way to avoid these potential problems. However, current single use syringes present a variety of problems. Some syringes which claim to be “single use” in actuality can be reused with user intervention. Some syringes are designated as “single use” solely because they are to be discarded after use pursuant to a regulation; nothing prevents their reuse. Some syringe designs expose the drug or bodily fluid contained therein to reactive components of the syringe (e.g. a spring used to retract the plunger). In addition, some syringes, although not capable of being reused, present health risks to the medical personnel handling them. Accordingly, there is a need for a single use syringe which is: (a) easy to use; (b) incapable of being reused; (c) presents little or no danger to medical personnel after use; (d) designed in such a way as to prevent contact between reactive syringe components and the fluid contained within the syringe; and (e) capable of being manufactured at low cost.
Currently, there are mainly two classes of safety syringes. One class of syringes, which employs a spring to retract a needle into the syringe, is represented in U.S. Pat. Nos. 5,769,822, 5,980,494, and 6,039,713. Although these syringes are effective and easy to use, the also have inherent disadvantages. First, the spring-loaded structure is complicated because of the number of parts involved creates difficulties in constructing the syringe. Second, due to the complicated structure, the costs of manufacturing are high making marketing difficult. Third, due to the location of the spring at the needle end of the syringe, it is difficult to position the fluid close to the inlet to the needle; this increases fluid residue and makes removal of air bubbles more difficult.
The second class of syringes employs a locking mechanism on the plunger which engages a corresponding structure at the base of the needle when the plunger is completely compressed. A subsequent withdrawal of the plunger pulls the needle into the syringe barrel. The structure of these syringes is simpler and the cost of production lower in comparison to the former class. However, this class of syringes also has disadvantages. For example, in Chinese Patent CN2270509Y, the corresponding parts of the locking mechanism between the needle and the plunger are exposed to fluid contained within the syringe. Accordingly, any burrs on the parts which result from manufacturing may fall into the fluid and be thereafter accidentally transmitted to the patient giving rise to a potentially dangerous situation. In addition, in many of these syringes, the locking mechanism can be disengaged and the syringe reused.
U.S. Pat. No. 5,601,534 discloses a one-time-use safety syringe comprising a simple structure which reliably releases gases and retains a very small amount of residual fluid. However, it also presents disadvantages. The structure employs an inward facing needle extension which is bent by an arrowhead attached to the plunger. The extension is bent into a cavity in the plunger such that when the plunger is pulled away from the needle, the needle is pulled into the syringe barrel.
A first disadvantage is that the size of the extension must correspond to the size of the needle; a large needle requires a large extension which is not as easily bent thereby degrading the integrity of the engagement with the plunger.
A second disadvantage is that the rubber stopper, which houses the cavity, is solid. Due to the solid nature of the stopper, the extension must completely pierce the stopper to create a strong engagement with the cavity. To create this strong engagement requires a strong compression of the plunger at the completion of the injection; this can be difficult when the needle and needle extension are large.
A third disadvantage results with large needles. A large compressive force needs to be applied to the plunger to complete an injection with a large needle. This force counteracts the force necessary for the needle extension to puncture the plunger. To address this problem, the needle's engagement with the barrel head needs to enhanced. However, by enhancing the needle's engagement with the barrel head, it becomes more difficult to withdraw the needle into the syringe barrel after the injection is complete.
Fourth, the engagement of the needle extension and the plunger is such that upon withdrawal of the needle into the syringe barrel, residual fluid in the barrel can leak out of the syringe.
Fifth, the size of the plunger cavity corresponds to the size of the needle. Accordingly, one plunger can not be used with a variety of needle sizes. Therefore, medical personnel must maintain an inventory of various sizes of plungers which is costly and which occupies precious storage space.
SUMMARY
A solution to the aforementioned deficiencies in the art are resolved by the safety syringe herein described. Specifically, the presently described syringe has the following advantages over the prior art: (a) the hooks within the stopper which engage the arrowhead are not in contact with the fluid contained in the syringe thereby reducing the potential for manufacturing burrs to fall into the fluid and thereby be injected into the patient. The structure is possible because the engagement of the needle holder and the plunger occurs when the arrowhead pierces the stopper membrane. After the completion of the injection thereby establishing this engagement, the syringe can not be reused. Moreover, the puncturing of the membrane requires a force which is much smaller than the force necessary to compromise the o-ring seal in the plunger neck; accordingly the counteractive force problems in the prior art are eliminated; (b) the o-ring positioned in the syringe neck prevents fluid from escaping when the needle is initially pulled toward the syringe barrel; (c) the syringe has a simple structure which is both easy to use and manufacture; (d) the cavity in the stopper and the arrowhead can be used with any size needle (i.e. the size of the cavity and the arrowhead is not dependent on the size of the needle); and (e) the size of the needle does not compromise the integrity of the locking between the plunger and the needle holder.
These and other advantages are made possible by a safety syringe comprising a syringe casing having a distal end and a proximal end. A plunger is channeled in the syringe casing and is capable of moving from an extended position to a compressed position. The plunger has a weak portion, a distal portion, and a coupling portion. A stopper, having a membrane, is affixed to the coupling portion of the plunger; the membrane is between the proximal end of the syringe casing and the plunger. A needle holder, initially coupled to the proximal end of the syringe casing, has a distally facing arrowhead and a proximally facing needle. When the plunger is moved from the extended position to the compressed position, the arrowhead punctures the membrane and lockingly engages the coupling portion of the plunger. Subsequently, when the plunger is returned to the extended position, the needle holder and needle are drawn into an interior of the syringe casing.
In the safety syringe above-described, the weak part of the plunger may include a plurality of tines. In this situation, when the plunger is returned to the extended position from the compressed position, the distal portion of the plunger may be disengaged from the weak portion by breaki

Affiliated with

Also associated with

Rating

Safety syringe does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Safety syringe, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Safety syringe will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3013244