Patent Application
20100010450
1. Field
The present invention pertains to safety medical syringes and, in particular, to syringes that are limited to a single use.
2. Description of the Related Art
Retractable and/or other types of single use syringes have become increasingly important and desirable for use in hospitals and medical facilities for a number of reasons. In retractable syringes, a hypodermic needle of the syringe is typically withdrawn into the syringe after aspiration and injection of a fluid, thus preventing multiple uses of the syringe and the potential transmission of human immunodeficiency virus (HIV) as well as other diseases from patient-to-patient. The retraction of the needle within the syringe after use also shields the needle and prevents inadvertent needle sticks from occurring to patients and health care providers.
A variety of different retractable or other types of single use syringe devices have been designed to effectively withdraw the needle within the syringe after use. For example, one example of a retractable syringe that is effective in ensuring a single use is described in co-pending U.S. patent application Ser. No. 11/249,741, the disclosure of which is incorporated herein by reference in its entirety.
The challenge exists to continuously improve upon the retractable syringe technology to design a single use syringe that is simplistic in design and assembly without sacrificing safety of the syringe, where the syringe can be produced on a large production scale while minimizing manufacturing costs.
In one example embodiment, a syringe comprises a hollow barrel including a proximal end with an opening and a distal end configured to receive a syringe needle, wherein a portion between the proximal and distal ends of the barrel defines a fluid cavity to receive and expel fluid from the barrel distal end, a plunger extending into the proximal end opening of the barrel and axially movable within the barrel toward and away from the barrel distal end, wherein the plunger includes a proximal end and a distal end that extends within the barrel and is movable toward and away from the barrel distal end to facilitate drawing fluid into and forcing fluid from the fluid cavity within the barrel, and a needle assembly that is partially secured within the barrel, the needle assembly including a needle holder, a resilient member biasing the needle holder toward the proximal end opening of the barrel, and a retaining member releasably secured to the needle holder, wherein the retaining member includes a first material that connects the retaining member to the needle holder and a second material that engages an interior wall section of the barrel, the second material having a Shore A or Shore D durometer hardness value that is less than a Shore A or Shore D durometer value of the first material.
In another example embodiment, a syringe comprises a hollow barrel including a proximal end with an opening and a distal end configured to receive a syringe needle, wherein a portion between the proximal and distal ends of the barrel defines a fluid cavity to receive and expel fluid from the barrel distal end, a plunger extending into the proximal end opening of the barrel and axially movable within the barrel toward and away from the barrel distal end, wherein the plunger includes a proximal end and a distal end that extends within the barrel and is movable toward and away from the barrel distal end to facilitate drawing fluid into and forcing fluid from the fluid cavity within the barrel, and a needle assembly at least partially secured within the barrel, the needle assembly including a needle stem, a resilient member biasing the needle stem toward the proximal end opening of the barrel, a needle holder connectable to the needle stem during assembly of the syringe and that is further securable to a needle, and a cap that is dimensioned to surround the needle secured to the needle holder and a portion of the needle holder during assembly of the needle holder with the needle stem.
In a further example embodiment, a needle assembly is provided for use with a syringe comprising a hollow barrel including a proximal end with an opening and a distal end configured to receive a syringe needle, a portion between the proximal and distal ends of the barrel defining a fluid cavity to receive and expel fluid from the barrel distal end, a plunger extending into the proximal end opening of the barrel and axially movable within the barrel toward and away from the barrel distal end, the plunger including a proximal end and a distal end that extends within the barrel and is movable toward and away from the barrel distal end to facilitate drawing fluid into and forcing fluid from the fluid cavity within the barrel, and a needle stem and a resilient member biasing the needle stem toward the proximal end opening of the barrel. The needle assembly comprises a needle holder that is connectable to the needle stem during assembly of the syringe and that is further securable to a needle, and a cap that is dimensioned to surround the needle secured to the needle holder and a portion of the needle holder during assembly of the needle holder with the needle stem such that the needle is shielded by a portion of the cap when the needle holder with needle is secured to the needle stem of the syringe.
In still another embodiment, a method of securing a needle to a syringe is provided, the syringe comprising a hollow barrel including a proximal end with an opening and a distal end configured to receive a syringe needle, a portion between the proximal and distal ends of the barrel defining a fluid cavity to receive and expel fluid from the barrel distal end, a plunger extending into the proximal end opening of the barrel and axially movable within the barrel toward and away from the barrel distal end, the plunger including a proximal end and a distal end that extends within the barrel and is movable toward and away from the barrel distal end to facilitate drawing fluid into and forcing fluid from the fluid cavity within the barrel, and a needle stem and a resilient member biasing the needle stem toward the proximal end opening of the barrel. The method comprises installing a needle holder including a needle secured to the needle holder within a cap such that the cap shields the needle, and securing the needle holder to the needle stem of the syringe while the cap is shielding the needle.
The invention facilitates easier assembly of the needle stem including the two-piece or two-material retaining member within the barrel of the syringe and maintaining a fluid tight seal at the engagement between the retaining member and the interior of the barrel. In addition, the needle assembly facilitates easy needle interchangeability with the syringe while still allowing for needle retraction after a single use of the syringe to inject fluids within a patient.
The above and still further examples, features and advantages of the present invention will become apparent upon consideration of the following detailed description of a specific embodiment thereof, particularly when taken in conjunction with the accompanying drawings wherein like reference numerals in the various figures are utilized to designate like components.
a is a side view of an alternative embodiment of a needle stem and a side view in cross-section of an alternative embodiment of a barrel for the retractable syringe of
In accordance with the present invention, a single use retractable syringe is provided that facilitates easy retraction of portions of a needle assembly within the barrel of the syringe and also maintains a fluid tight seal between components within the syringe during use. An example embodiment of a single use retractable syringe of the invention is described below.
Referring to
The plunger 130 includes a resilient seal 132 encircling the plunger near its distal end. A fluid cavity 150 is defined within the barrel 122 between the resilient seal 132 and other distal end portions of the plunger and a distal end 125 of the barrel main body portion 124, where the fluid cavity varies in volume based upon axial displacements of the plunger with respect to the barrel. A sheath 168 is removably secured to the distal end of the barrel 122 to enclose needle 160 secured within the barrel prior to use of the syringe. The barrel, plunger, resilient seal, sheath and all other components of the syringe may be constructed of any suitable medical grade materials (e.g., plastics and/or stainless steels) that facilitate operability of the syringe as described below. Further, the syringe can be designed with a suitable fluid cavity to meet any fluid volume capacity for a particular application (e.g., 1 cubic centimeter or cc, 3 cc, 5 cc, 10 cc, etc.).
The proximal end of plunger 130 includes a convex surface or domed thumb pad 138 and a radially extending flange 139 that facilitates engagement with the fingers and/or thumb of the user during operation of the syringe. Similarly, the main body portion 124 of the barrel includes a radially extending flange 128 disposed near its proximal end for facilitating engagement with the fingers and/or thumb of the user during operation. An extended barrel portion 127 extends between flange 128 and the proximal end of the barrel and is slightly greater in internal diameter in comparison to the remainder of main body portion 124. The extended barrel portion 127 is also of a sufficient longitudinal dimension, and is slightly smaller in internal diameter than the transverse dimension of the plunger defined at the flange 139. When the plunger 130 is fully depressed within the barrel, an outer peripheral portion of the plunger flange 139 can be designed to flex or bend slightly so as to permit the flange to enter the extended barrel portion. Alternatively, the barrel can be designed to flex slightly so as to permit entry of the plunger flange within the barrel.
Optionally, two diametrically opposed sections can be removed from extended barrel portion 127, as shown in
An annular groove 129 is disposed along interior wall sections (e.g., wall sections that are separated by the cut-out sections) of the extended barrel portion near the proximal end of the barrel. Upon complete depression of the plunger within the barrel and retraction of the syringe within the plunger, the plunger flange 139 engages in a snap-tight locking relationship with annular groove 129 to prevent removal of the plunger from the barrel.
Referring to
As can be seen in
The plunger plug 144 includes a convex and frusto-conical surface 145 that extends toward the distal end of the barrel and engages with a generally complimentary, concave and frusto-conical cavity portion 159 of needle assembly 156 when the plunger is fully depressed into the barrel as described below. As noted in the previous embodiments described above, the end wall may alternatively be formed with any suitable outwardly or inwardly extending surface (e.g., conical, convex, V-shaped, multifaceted, etc.) or even a flat or planar surface as desired for a particular application. However, complimentary engaging surface features of the plunger plug and the needle assembly are preferred in order to minimize or eliminate open or “dead” space within the fluid cavity during removal of fluid from the fluid cavity.
At least one notch 146 is formed on the plug at the base of the frusto-conical surface. The notch 146 can extend around the periphery of the plug at the base of the frusto-conical surface or, alternatively, consist of a single notch or one or more spaced notch sections. The notch basically serves to provide a fluid flow path between the fluid cavity within the barrel and the fluid channel in the needle assembly when the plunger is substantially or completely engages with the needle assembly. In addition, the notched plunger plug minimizes or eliminates the potential for an increase or build-up of hydraulic pressure within the fluid cavity during movement of the plunger toward the needle assembly.
Needle assembly 156 includes a needle stem 158 that connects with a syringe needle 160 and is affixed within the distal end extension 126 of the barrel such that the needle 160 extends from the distal end of the barrel prior to and during use. The needle stem 158 and needle 160 preferably releasably engage with each other via any suitable fluid tight engagement. In an example embodiment, the releasable engagement between the needle stem and the needle is a threaded engagement, where the needle stem includes a male threaded configuration and the needle includes a female threaded connector or needle hub to releasably connect with the needle stem. This connection, which is depicted in FIGS. 1 and 4-7, differs from conventional syringe needle connections, such as Luer Lock configurations. In addition, this threaded configuration provides an easy, universal connection with needles of various gauges and types. However, it is noted that the needle can also be attached to the needle stem in any other suitable releasable or non-releasable manner. Additional examples for releasably engaging a needle including a needle holder or needle hub with the needle stem are described below.
A cavity 157 extends axially from a proximal end of the needle stem 158 to the connection point with the needle 160 in order to facilitate fluid communication between the needle and fluid cavity 150 within the barrel. In addition, cavity 157 includes a widened portion 159 at the proximal end of needle stem 158 that is frusto-conical in configuration and widens toward the proximal end of the barrel so as to be generally aligned and complimentary with the frusto-conical surface 145 of the plunger 130. As noted above, when the plunger is depressed toward the needle assembly, the frusto-conical surface 145 of plug 144 generally aligns and engages with widened portion 159. When the plunger plug is brought toward and fully engages widened portion 159 of the needle assembly, notch 146 defined on plug 144 ensures a fluid flow path exists between fluid cavity 150 and needle assembly cavity 157 and reduces or eliminates any build-up of hydraulic pressure within the fluid cavity.
The needle stem 158 further includes a radially extending flange 162 at its proximal end that is suitably dimensioned to engage with a block or ledge 121 disposed along an interior surface of the distal end extension 126 in order to limit movement of the needle assembly distally beyond ledge 121 during depression of the plunger toward the distal end of the barrel.
A stem ring 164 is secured to and extends radially from the flange 162 of needle stem 158 to engage with the interior wall surface of distal end extension 126 of the barrel. A portion of stem ring 164 is preferably formed or molded as a part of flange 162 and needle stem 158 and includes notched, webbed or scored sections 165 at the connection point of stem ring 164 and needle stem 158, where the scored sections are formed on opposing surfaces of both the needle stem flange and the stem ring. The scored sections 165 define a thin membrane or reduced material section that is torn or broken during operation of the syringe to facilitate retraction of needle assembly 156 in the manner described below. The stem ring 164 is preferably dimensioned to facilitate a partial sliding of a broken portion of the stem ring along the interior wall surface of the barrel when the plunger is depressed to engage with needle stem 158 as described below.
The stem ring 164 includes an inner first ring portion 250 that is connected with flange 162 and an outer second ring portion 252 that connects with and extends radially outward from the first ring portion 250. The first ring portion 250 is preferably molded with so as to be integral or a single component with needle stem 158 and flange 162.
The inner first ring portion 250 of stem ring 164, needle stem 158 and flange 162 are preferably constructed of a suitable medical grade polymer material that has sufficient hardness, strength and durability to connect with a needle and retract with the needle into the plunger cavity in the manner described below during operation of the syringe. Examples of polymer materials suitable for forming the stem ring, needle stem and flange are polystyrene, polycarbonate and acrylonitrile butadiene styrene (ABS).
The second ring portion 252 is constructed of a different polymer material in relation to the first ring portion 250. In particular, the second ring portion is preferably constructed of a suitable polymer material having a lower hardness (e.g., measured as a Shore A or Shore D durometer hardness value) and greater flexibility in comparison to the first ring portion so as to facilitate compression and/or flexing of the second ring portion during movement of the stem ring within the barrel as described below. Example polymer materials that can be used to form the second ring portion include medical grade thermoplastic elastomers, preferably latex-free thermoplastic elastomers (e.g., polyurethane elastomers). The second ring portion is secured to the first ring portion in any suitable manner that prevents separation of the first and second ring portions from each other during use of the syringe. In an example embodiment, the second ring portion is formed with the first ring portion in a co-molding process that secures the two different material portions together.
The size of the first and second ring portions can be selected based upon a selected syringe embodiment. However, it is noted that the radial dimension of material forming each of the first and second ring portions (i.e., the difference between the outer radius and inner radius of each ring portion) is selected such that the radial dimension of material forming the second ring portion is no greater than about 50% of the radial dimension of materials forming the entire stem ring (i.e., the difference between the outer radius of the second ring portion and the inner radius of the second ring portion). In particular, the radial dimension of material forming the second ring portion is preferably from about 1% to about 50%, and more preferably from about 5% to about 10%, of the radial dimension of the entire stem ring.
The diameter of the entire stem ring is slightly larger than the diameter of the interior wall surface of distal end extension 126 at the location where the stem ring engages the barrel such that the second ring portion 252 of stem ring 164 is slightly compressed or is flexed slightly toward or away from the plunger proximal end while maintaining sliding contact or fluid-tight engagement with the barrel so as to ensure an effective fluid tight seal. The dimensions of the stem ring are further selected to provide a compression fit/fluid tight seal at the stem ring/barrel interior wall interface while facilitating a sliding of the stem ring with the barrel interior wall surface when the plunger is completely depressed within the barrel.
A radial protrusion or annular shoulder 166 is disposed along the interior surface and near the proximal end of the distal end extension 126 of the barrel. The shoulder 166 forms a retaining ledge that engages with one or both of the first ring portion 250 and the second ring portion 252 of stem ring 164 to prevent movement of the needle assembly toward the proximal end of the barrel while the stem ring remains attached with needle stem 158. A resilient member 184 (e.g., a coil spring) is disposed between the flange 162 of needle stem 158 and an interior ledge 186 disposed on the interior surface of the distal end extension 126 at a location between ledge 121 and the distal end of the barrel. When the needle assembly 156 is press fit into the distal end extension 126 of the barrel (as described below) such that stem ring 164 is extended distally beyond the radial protrusion 166 (retaining ledge) of the barrel, resilient member 184 is compressed to bias the needle assembly toward the proximal end of the barrel.
Referring to
Alternatively, the syringe can be provided with other needle stem and barrel configurations that provide a locking engagement between the needle stem and the barrel. For example, the needle stem and barrel can include suitable complimentary protrusions and/or grooves to achieve a configuration that prevents any rotational movement of the needle stem within the barrel when the needle stem is suitably mounted within the barrel.
In one example configuration shown in
The syringe 120 is designed so that complete depression of plunger 130 within barrel 122 facilitates a displacement of plunger plug 144 from the plunger and also a tearing or breaking away of the stem ring 164 from flange 162 of needle stem 158 to facilitate retraction of the needle stem and the needle 160 into the retraction cavity 148. In this embodiment, stem ring 164 of needle stem 158 includes at least one raised ridge 172 that extends from a proximal end of the needle stem and is configured to make initial contact with annular distal edge 178 of the plunger when the plunger is displaced within the barrel. While only one ridge 172 is depicted in
Plunger resilient seal 132 is further designed and suitably dimensioned and positioned around the plunger proximate the plunger distal end such that, upon complete depression of the plunger within the barrel, a distal end of the resilient seal engages and compresses slightly against a narrowing portion 190 of the interior barrel wall that defines a transition between main body portion 124 and distal end extension 126. The resilient seal does not slide with respect to the plunger, but rather compresses slightly against the barrel wall narrowing portion at the end of the plunger stroke that initiates needle retraction, and this serves to further minimize or eliminate “dead” space within the fluid cavity 150 as well as to displace any residual fluid from the fluid cavity into needle stem cavity 157.
The needle stem can be designed such that the ridge (or ridges) is aligned in any selected orientation with respect to the plunger distal end. The stem ring ridge(s), plunger and annular distal end of the plunger and needle stem are suitably dimensioned in the longitudinal direction of the syringe and further suitably aligned with each other to facilitate engagement of stem ring ridge(s) 172 and/or other proximal end surface portions of stem ring 164 with annular distal edge 178 of the plunger and plunger plug 144 with needle stem 158 upon complete depression of the plunger, which in turn facilitates a tearing or breakage of stem ring 164 from needle stem flange 158 at the scored sections 165 and a forcing of plunger plug 144 from its frictional engagement with plunger ledge 141 to initiate retraction of needle assembly 56 along with the plunger plug into retraction cavity 48 of the plunger.
Assembly of the syringe is achieved in a similar manner as the other syringe embodiments described above. Resilient member 184 and then needle assembly 156 (with or without the needle 160) are inserted into opening 123 at the proximal end of barrel 122, through main body portion 124 and into the distal end extension 126. As the stem ring 164 of needle stem 158 encounters the retaining ledge or annular shoulder 166 of the barrel, the first ring portion 250 and/or the second ring portion 252 of stem ring 164 is compressed and/or flexed slightly and forced distally beyond the shoulder 166 in a snap-fit engagement. Once stem ring 164 is forced distally beyond shoulder 166, the needle assembly 156 is locked in place within the distal end extension 126, and resilient member 184 is compressed to bias the needle assembly proximally within the syringe. The second ring portion 252 of stem ring 164 remains compressed or flexed to a selected degree between flange 162 and the barrel interior wall surface in this locked configuration and provides an effective fluid tight seal at its compressed fit contact point with the barrel.
Plunger 130 is assembled by inserting plunger plug 144 into the plunger such that the extending portion 147 of the plug frictionally engages plunger ledge 141 located at the open distal end of the plunger and a distal portion of the plunger plug (including plug surface 145 and notch 146) extends from the plunger. The plunger plug can be inserted directly into the open distal end of the plunger to its frictional fitting position. In the embodiment depicted in
After assembly of the plunger, the plunger is inserted into opening 123 of barrel 122 and is axially displaced a suitable distance to facilitate use of the syringe. The needle 160 may be connected with needle stem 158 prior to insertion of the needle assembly into barrel 122 (e.g., via the threaded engagement as depicted in
In operation, the distal end of the plunger is displaced a suitable distance toward the proximal end of the barrel to draw fluid from needle 160 into fluid cavity 150. Upon injection of the needle into an injection site, the plunger is then depressed toward the distal end of the barrel to force fluid from cavity 150 and through needle 160. Referring to
Complete depression of the plunger within the barrel further forces plunger annular distal edge 178 against surface portions of first ring portion 250 and/or second ring portion 252 of stem ring 164, causing a section of the first ring portion 252 of the stem ring that has already broken away from flange 62 to slide distally a short distance along the interior wall of the barrel so as to become oriented at a slight angle with respect to the central axis of needle stem 158. In addition, the portion of the stem ring that has not broken away is prevented from moving distally until it has become broken away from the needle stem. This sliding of the broken portion of the stem ring 164 along the interior wall of the barrel, in combination with the continued pressure applied by the fully depressed plunger to the stem ring, results in a progressive tearing or breakage of the stem ring in both directions along scored sections 165 until the stem ring is fully separated from tab 162. In addition, the forced engagement of plunger plug 144 with needle stem 158 results in further movement of the plunger plug from its frictional engagement with the distal end ledge 141 of the plunger, resulting in dislodging of the plunger plug from the plunger. Plunger resilient seal 132 compresses slightly against the narrowed portion 190 of the barrel interior wall to force residual fluid into the needle assembly, while plunger plug notch 146 provides a fluid flow path for such fluid when plunger surface 145 engages with needle stem 158 within widened cavity portion 159.
The use of a polymer material having a lower durometer and greater flexibility for the second ring portion 252 in relation to the polymer material used to form the first ring portion 250 of the stem ring 164 results in an enhanced fluid seal being achieved at the stem ring/interior barrel wall surface interface in comparison to using a single polymer material for the entire stem ring. In addition, the greater flexibility provided to the stem ring at the interface with the barrel wall surface reduces the contact pressure between stem ring and interior barrel wall surface and facilitates distal movement of a portion of the stem ring and progressive tearing or breakage of the stem ring from the needle stem with a reduction in requisite force to be applied to the plunger in order to achieve retraction of the needle into the syringe.
The design of the syringe can be configured such that the stem ring 164 is completely separated from needle stem 158 immediately prior to, substantially simultaneously with, or immediately after the complete dislodging of plunger plug 144 from the plunger. As shown in the series of
As can be seen from
As noted above, the needle can be releasably attached or affixed to the needle stem via a threaded engagement as shown in
In
In
In the embodiment of
The embodiment of
The two piece needle cap construction shown in
The needle attachment embodiments described above facilitate interchanging of one needle for another during use of a syringe. The snap-tight fit of the bump/groove configurations provides a fluid tight seal between needle hub and needle stem. In addition, these embodiments facilitate using a blunt or fill spike to fill the syringe with fluid, and then replacing the fill spike with a finer gauge needle for use in needle injections. In particular, a blunt or fill spike refers to a hypodermic (i.e., hollow) needle having a larger outer diameter (and a lower hypodermic needle gauge number) in relation to a hypodermic injection needle used for intravenous injection of fluids into a patient. The blunt or fill spike facilitates quick and easy filling of the syringe with fluid, and the syringes of the invention are designed to facilitate easy replacement of the fill spike with an injection needle so as to facilitate use of the syringe for injection of fluids from the syringe into a patient's body.
Referring to the embodiment of
The needle stem 504 in the embodiment of
In addition, the base 510-1 and spike holder 502 are connected to form a single, integral unit. The base 510-1 connects with the barrel 522 in a similar manner as the previous embodiment of
In the embodiment of
The blunt or fill spike can be formed of any suitable medical grade materials, such as medical grade polycarbonate, polystyrene or other suitable polymer materials.
The blunt or fill spike configuration can also be modified to include filter media disposed between portions of the fill spike fluid path so as to facilitate filtering of fluid passing through the fill spike into the syringe. The filter media can be formed of any suitable material that is capable of filtering particulate material or other matter of selected dimensions from the fluid prior to entering the syringe and prior to injection in a subject.
An example design of a blunt fill needle connection to a retractable syringe is depicted in
The base 610-1 includes a seat section 650 protruding from the distal end of the base, where the seat section 650 includes fluid pathway 611 and is designed to receive a proximal end of the spike holder 602 such that the fluid pathway 611 communicates with the fluid pathway of spike 660. The fluid pathway 611 further extends through portion 613 so as to provide a fluid pathway between the spike 660 and the needle stem 604. The seat section 650 includes a recessed portion and a rim surrounding the recessed portion, and the spike holder 602 includes a stepped portion 603 at its proximal end that has a reduced cross-sectional dimension in relation to the portion of the spike holder that connects with the shield portion 610-2 (via the bumps 612 and corresponding grooves), where the stepped portion 603 is configured to fit within the recessed portion of the seat section 650 when the spike holder 602 and shield portion 610-2 engage with the seat section 650 so as to connect the spike to the syringe.
In addition, the rim of the seat section 650 includes bumps 652 that are configured to engage with corresponding grooves on the stepped portion 603 of the spike holder 602 when the spike holder engages the distal end of the base 610-1. A suitable filter media material 690 is provided at a location between the engaging surfaces of the seat section 650 and stepped portion 603 of the spike holder 602. For example, the filter media can be provided over the stepped portion 603 or, alternatively, over the recessed portion within the seat section 650 such that, upon engagement of the spike holder 602 with the seat section 650 of base 610-1, the filter media 690 is “sandwiched” between the two components to effectively filter materials of selected dimensions from fluids flowing through the spike and into the syringe.
The spike holder 602 initially connects with shield 610-2 via the bump 612 and groove connections as shown in
In another embodiment shown in
After removal of the spike 760 from the needle stem 704, any suitable needle engaging structure (such as the types described above) can then be utilized with the needle stem. In the embodiment of
The needle changing/interchangeability features of the invention are not limited to the previous examples. Instead, it is noted that the connections between needle holder and needle stem, and needle holder and needle cap designs can have any suitable designs and configurations that facilitate connection of the needle to the syringe. For example, the bumps and grooves or recesses which achieve the snap-tight and fluid tight engagements can be reversed (e.g., the needle hub or holder can include a groove and needle stem a corresponding bump to facilitate a connection between these two components as shown in
Another important feature in retractable syringes such as the types described above is to prevent the needle stem from moving or “floating” within the barrel during use of the syringe and prior to retraction of the needle within the syringe. As noted above, the barrel of the syringe of the present invention includes a radial protrusion (e.g., retaining ledge or annular shoulder 166 as shown in
Another mechanism for preventing movement of the needle stem toward the barrel distal end is provided by the present invention. In particular, the spring that biases the needle stem toward the barrel proximal end can be designed and configured with a suitable tension such that the spring itself prevents movement of the needle stem distally (i.e., toward the distal end of the barrel) within the syringe. Such a design facilitates providing a larger diameter or open distal end for the barrel, since no ledge is necessary to ground the needle stem within the barrel. The larger diameter or open distal end for the barrel further facilitates providing a needle holder with larger transverse cross-sectional dimensions, which can facilitate easier design and construction of the needle holder. An example of this embodiment is shown in
In the embodiment of
In still another embodiment, shown in
In a modified design to the cap with ring embodiment, which is depicted in
In
Thus, the present invention facilitates connection of one or more needles of varying gauges to a retractable syringe with relative ease, in which a cap (or portion of a cap) shields the needle while the needle holder is connected with the needle stem of the syringe. The present invention further facilitates the use of a retractable syringe with a blunt or fill spike, removal of the fill spike and replacement with an injection hypodermic needle (i.e., a needle having a smaller outer diameter than a fill spike that is used for intravenous injections in a patient). The many different embodiments facilitate easy interchangeability of the syringe with different types and sizes of needles while maintaining safe enclosure of the needle during assembly and further while maintaining the retractable features of the syringe.
The present invention further provides an enhanced sealing mechanism for the retractable needle stem ring which engages the internal surface portion of the barrel wall. This two-piece needle stem ring construction renders the assembly of the needle stem within the barrel easier, maintains an effective fluid tight seal and can also possibly reduce the retraction force required to retract the needle stem, needle holder (or needle hub) and needle within the syringe.
While the invention has been described in detail and with reference to a specific embodiment thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
This application claims priority from U.S. Provisional Patent Application Ser. No. 61/061,224, entitled “Retractable Syringe With Improved Stem Ring and Needle Interchangability”, and filed Jun. 13, 2008. The disclosure of this patent application is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61061224 | Jun 2008 | US |
