Syringe with multi-function plunger handle

Abstract

A medical syringe useful for injection or withdrawal of bodily fluids, the syringe including a barrel, a plunger assembly, and a needle assembly having a selectively retractable needle, the plunger assembly including a plunger handle having a plunger seal and a distal tip extending forward of the plunger seal, the distal tip extending through the barrel and through an annular fluid seal disposed in a recess between the barrel and the forwardly projecting needle to reduce dead space within the syringe forward of the plunger seal and to secure the annular fluid seal within the recess.

Description

[Technical field]

[0001] The present invention relates to a medical syringe having a barrel having a front opening and a rear opening, a plunger insertable into the barrel via the rear opening, and a needle assembly removably attachable to a front portion of the barrel. The syringe of the present invention may be selectively configured for injecting medical fluids into a patient or port, or for withdrawing bodily fluids, such as blood, from a patient for testing or other purposes. More specifically, the present invention relates to a medical syringe having a selectively retractable needle and a multi-function plunger handle including a distal tip that projects forward of a plunger seal, the distal tip being configured to reduce the amount of dead space within the syringe when the plunger is fully advanced within the barrel during an injection. When the syringe of the present invention is used to inject medicines or vaccines, this syringe and plunger configuration advantageously reduces and substantially eliminates internal dead space, thereby increasing the number of doses that can be injected into a patient from a single vial in some circumstances.

[0002] Another aspect of the invention is that the forwardly projecting tip of the plunger seal of the plunger handle is preferably configured to project forwardly through and beyond the nose of the barrel, the tip being adapted to be guided into a coaxially aligned fluid flow passage through an annular fluid seal disposed or seated in a recess disposed between the nose and the needle assembly, and serving to secure the fluid seal when the needle is laterally repositioned for retraction after use. The syringe of the invention is provided with a needle assembly having a needle retraction mechanism actuated by lateral movement of the needle assembly relative to the annular fluid seal toward an offset needle retraction chamber. During such lateral repositioning, the forwardly projecting tip of the plunger handle also serves to prevent fluid leakage between a front end of the annular fluid seal and an opposing contact surface of the needle assembly. After the needle is retracted, the fluid flow path into and out of the syringe barrel is blocked at the interface between the forwardly extending end of the annular fluid seal and the opposing contact surface of the needle assembly.

[0003] Another aspect of the invention relates to a medical syringe that combines an integrated needle retraction and fluid seal mechanism with a plunger handle having a distal tip that extends forward of the plunger seal. When the invention is used to draw blood, the plunger advances within the barrel and the forward tip of the plunger handle blocks a portion of the fluid flow path through the annular fluid seal and the nose of the barrel prior to venipuncture. After venipuncture, the plunger is withdrawn within the barrel to allow blood to flow into the fluid chamber in front of the plunger seal, thus reducing dead space between the needle and the plunger seal and thus minimizing air bubble formation. The invention can be provided and used both without and with a filter, and a coating of an anticoagulant, such as heparin, can be placed within the barrel. [Background technology]

[0004] Syringes are well known and include a barrel, a plunger handle, an elastomeric plunger seal seated on the plunger handle and slidably engaging the inner wall of the barrel, and a forwardly projecting needle in fluid communication with a fluid reservoir disposed within the barrel. When a medical fluid is drawn into the syringe and then expelled from the syringe during an injection, a relatively small amount of fluid typically remains in the fluid path through the syringe after the injection, even if the plunger is fully depressed within the barrel. The volume of liquid remaining in the syringe after an injection is often referred to as "dead space." The amount of dead space within a syringe can vary widely depending on the design, configuration, and performance characteristics of a particular syringe barrel / plunger / needle combination, and is desirably less than about 0.03 mL for a 3 mL syringe. Reducing the amount of dead space within the syringe's fluid delivery system is desirable because it reduces the space within the syringe for air bubbles to form and increases the number of doses of medication that can be administered to a patient from a single vial. Reducing the amount of dead space within a syringe has long been recognized as a desirable goal, but has become an even greater consideration given the large volumes of vaccines being administered during the COVID-19 pandemic.

[0005] No. 9,814,841 discloses a prior art device having an attachable needle assembly, but the device does not disclose the multi-function plunger handle of the present invention, nor does it disclose the integrated fluid tight and fixed fluid seal features provided in combination with a laterally slidable needle assembly to achieve retraction of a used needle. EasyPoint® syringes utilizing a laterally repositioning needle assembly relative to a needle retraction chamber are currently manufactured by and sold through Retractable Technologies, Inc. Summary of the Invention

[0006] <Summary of the Invention> The disclosed medical syringe includes coaxially aligned components of a barrel, a plunger assembly, an annular fluid seal, and a needle assembly that cooperate to reduce dead space, conserve medication, control post-injection fluid leakage, and protect patients and medical personnel from potential infection or contamination from accidental needle sticks. A primary feature of the present invention is an improvement over the plunger handle disclosed in the prior art in that a distal tip integrally molded into the plunger handle projects forwardly beyond the plunger seal, through the nose of the barrel, and into a longitudinally extending fluid path through the annular fluid seal seated between the nose of the barrel and the needle holder, anchoring the fluid seal to the syringe barrel when the needle is repositioned prior to retraction. In one satisfactory embodiment of the invention, the annular fluid seal engages a rearward facing surface of the slide member which is repositioned laterally after injection and before the needle is forced into a needle retraction chamber which is laterally offset from the axial fluid path to block the fluid path through the annular fluid seal.

[0007] In accordance with another satisfactory embodiment of the present invention, the disclosed syringe includes a syringe barrel and a plunger assembly having a plunger handle with a reduced diameter distal tip, the distal tip protruding forward of a plunger seal, such that when the plunger handle is fully advanced within the barrel, more injection fluid disposed within the nose of the syringe barrel can move than would move without the distal tip. In a preferred embodiment of the present invention, a 3 mL syringe, the dead space in front of the plunger seal is reduced to less than 0.025 mL, and in some cases less than 0.020 mL, to 0.018 mL or less. In accordance with another satisfactory embodiment of the present invention, a second portion of the distal tip of the plunger handle has a diameter smaller than that of the first portion and protrudes forward from the first portion of the distal tip into a coaxially aligned passageway through an annular fluid seal disposed between the barrel and the needle assembly, thereby allowing more injection fluid to move forward into and through the needle. It also serves to secure the annular fluid seal against lateral movement relative to the syringe barrel while the needle assembly is being repositioned prior to needle retraction.

[0008] The outer diameter of the first portion of the distal tip of the plunger handle is preferably slightly smaller than the inner diameter of the barrel tip, so that as the plunger advances forward within the syringe barrel during an injection, fluid is forced forward from the barrel tip. The length of the first portion of the distal tip of the plunger is preferably such that when the plunger handle is fully advanced within the barrel, it reaches or slightly extends beyond the forward end of the barrel. The front of the plunger handle is preferably configured to fit with minimal clearance within the inner surface of the front of the barrel, such that when the plunger handle is fully advanced within the barrel, the front of the plunger seal abuts against a surface configured to cooperate with the interior of the barrel in opposition thereto. This allows the drug fluid to move from the barrel tip into the fluid passageway extending through the needle when the plunger seal is fully depressed into the nose end of the barrel. Forward movement of the plunger handle distal tip first portion through the interior of the barrel distal end helps guide the coaxially aligned, narrower, forwardly extending second portion of the distal tip into alignment with the rearwardly facing opening of the fluid passageway that extends coaxially through the annular fluid seal disposed between the barrel distal end and the rear end of the needle holder.

[0009] In accordance with another satisfactory embodiment of the present invention, a syringe is disclosed that includes a barrel, a plunger assembly, and a needle assembly. The barrel has a cylindrical sidewall, a rear opening defined by opposed radially extending finger flanges, and a forward facing female threaded luer connector that is coaxially aligned and integrally molded with a forwardly projecting tapered nose within the female threaded luer connector. The plunger assembly includes a plunger handle insertable into the rear opening of the barrel and an elastomeric plunger seal that slidably engages an inwardly facing surface of the cylindrical barrel to define a fluid reservoir between the tapered nose and the plunger seal. The needle assembly is selectively attachable to the barrel and further includes a body, a rearwardly projecting chamber luer that is removably attached to the female threaded luer connector, and a slide member that slidably engages both the body and the rearwardly projecting chamber luer. The slide member provides a seating surface for a needle holder having a forwardly projecting needle and a needle retraction compression spring disposed about the front of the needle holder. The female threaded luer connector provides a seating surface for an annular fluid seal disposed between the tapered nose of the barrel and the rearward facing face of the needle holder. The body of the needle assembly further includes a rearwardly extending needle retraction chamber having an open forward facing end that receives the needle holder, needle, and the expanded compression spring when needle retraction occurs.

[0010] Prior to use of the medical syringe of the present invention, the barrel, plunger assembly, chamber luer, annular fluid seal, needle holder and needle are preferably all coaxially aligned and cooperate to define a longitudinally extending fluid flow path through the syringe. The needle is preferably protected from inadvertent contamination, bending or discoloration by a removable, frictionally engageable needle cover prior to use of the device. For infusion use, after removal of the needle cover, a fluid is drawn into the fluid reservoir of the syringe from an external source, such as a vial, and expelled from the front of the syringe by advancing the plunger assembly within the barrel. When the plunger handle is fully advanced within the barrel, the forwardly projecting distal tip of the plunger handle passes through the nose of the barrel and into the rearwardly facing opening of the annular plunger seal, acting to secure the seal while simultaneously moving fluid forward through the needle holder and needle to reduce dead space. When used to withdraw intravascular fluids from a patient, the forward facing venipuncture needle is inserted into the patient and the plunger assembly is withdrawn rearwardly within the barrel, allowing fluid to flow through the fluid flow path to a fluid reservoir located forward of the plunger seal of the syringe. In this embodiment of the invention, the forward protruding distal tip of the plunger handle is useful for reducing the likelihood of air bubbles forming in front of the plunger seal.

[0011] Optionally, the open end of the needle retraction chamber is configured to receive a rearwardly projecting locking arm from the needle cover that frictionally engages the slide member to limit relative sliding movement between the slide member and the body to prevent unintentional (premature) needle retraction prior to use of the device to inject or collect fluids. It will also be apparent to those skilled in the art after reading this disclosure that other equally effective structures can also prevent or limit unintentional relative sliding movement between the slide member and the body of the needle assembly to prevent accidental needle retraction prior to use.

[0012] After using the syringe of the present invention to either inject or withdraw fluid, the slide is repositioned laterally relative to the barrel by applying digital pressure to the lateral pad at the free end of the slide, aligning the needle holder and needle with the open end of the needle retraction chamber, at which point the compressed retraction spring expands to move the needle holder and needle into the needle retraction chamber. During this repositioning of the slide relative to the barrel, the rearward facing surface of the slide contacts the fluid flow path through the annular fluid seal, sealing the fluid passageway and preventing fluid from leaking out the front of the barrel and contaminating others. [Brief description of the drawings]

[0013] The device of the present invention will be further described and illustrated in relation to the following drawings. [Figure 1] FIG. 1 is a top view of a preferred embodiment of a syringe of the present invention with the plunger handle fully advanced within the syringe barrel. [Diagram 2] FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. [Diagram 3] FIG. 3 is an enlarged detail taken from FIG. [Figure 4] 4 is a top view of the plunger handle of FIG. 1 prior to placement of the plunger seal of FIGS. 2 and 3 on the plunger seal seating surface of FIG. 4. FIG. [Diagram 5] FIG. 5 is a cross-sectional view similar to FIG. 2, but with the needle cover removed and the central portion of the needle omitted, showing the plunger handle moved rearwardly relative to the barrel to show a fluid chamber formed in the barrel forward of the plunger; and [Figure 6] FIG. 6 is an enlarged detail view showing the surface coating that is placed on the inside wall of the barrel when the syringe of the present invention is used, for example, for drawing blood. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Detailed Description of Preferred Embodiments With reference to FIG. 1, the medical syringe 10 of the present invention includes a barrel 12, a plunger assembly 14, an attachable needle assembly 16, and a locking needle cover 18. The barrel 12 is available in many different forms, as is well known in the art, with a plastic barrel being preferably a unitarily molded plastic of transparent or translucent plastic. In the illustrated embodiment, the barrel 12 further includes a body 20, a forwardly extending cylindrical collar 22, a radially extending finger flange 26, and molded or printed indicia 74 indicating graduated dose volumes up to 3 mL. With reference to FIGS. 2 and 3, the cylindrical collar 22 is internally threaded and configured to threadably mate with a chamber luer 44, the rearward facing portion of which is adapted to have a tapered slit-fit inner surface 70 (FIG. 3) cooperate with an outwardly facing tapered surface 72 of the nose 24 of the barrel 12 to provide a fluid-tight seal.

[0015] 1-5, and in particular FIG. 4, the plunger assembly 14 further includes an integrally molded ribbed plastic plunger handle 28 having a rearwardly facing thumb cap 32, a plunger seal seating surface 34, and a front tip 30 including a first portion 36 and a second portion 38. With reference to FIGS. 2-3 and 5, the plunger seal 40 is preferably an elastomeric annular seal that seats and frictionally engages the plunger seal seating surface 34 (FIG. 4). When the plunger assembly 14 is inserted into the opening defined by the finger flange 26 at the rear of the barrel 12, the plunger seal 40 preferably forms a fluid-tight seal with the inwardly facing surface 65 of the body 20 of the barrel 12 as the plunger handle 28 advances within the barrel. With reference to FIG. 5, the medical syringe 10 is shown with the needle cover 18 (FIG. 2) removed and a portion of the plunger assembly 14 inserted into the barrel 12. A fluid reservoir 66 is disposed within the barrel 12 between the front of the plunger assembly 14 and communicates through a fluid passage 68 coaxially aligned within the nose 24 with the coaxially aligned needle 56 projecting forwardly therefrom within the needle assembly 16.

[0016] 1-3, the needle assembly 16 further comprises a body 46, a rearwardly projecting chamber luer 44 removably attached to the internally threaded luer connector of the cylindrical collar 22, and a slide member 42 slidably engaged with both the body 46 and the chamber luer 44. The slide member 42 provides a seating surface for a needle holder 58 about a front portion of which is disposed a forwardly projecting needle 46 and a compressed needle retraction spring 60. The forwardly facing portion of the chamber luer 44 provides a sufficient seating surface for an annular fluid seal 62 disposed between the nose 24 of the barrel 12 and a rearwardly facing surface 78 of the needle holder 58. The body 46 of the needle assembly 12 further includes a rearwardly extending needle retraction chamber 48 which at its forwardly opening end through the body 46 receives a locking support arm 52 of the needle cover 18 prior to use of the medical syringe 10. After the needle cover 18 is removed from the needle assembly 16 in order to use the medical syringe 10, the forward-facing opening to the needle retraction chamber 48 receives the needle holder 58, needle 56 and a tensioned compression spring 60 (not shown, but described below) during needle retraction.

[0017] The slide member 42 is positioned for lateral sliding engagement with the body 46. As shown in Figures 2-3, the slide member 42 supports a needle 56 disposed within a needle holder 58 having a central bore coaxially aligned with a fluid passageway 64 passing through an annular fluid seal 62. A needle retraction spring 60 is compressed behind the head of the needle holder 58 and provides the driving force for moving the needle holder 58 and needle 56 rearwardly into the needle retraction chamber 48 when the slide member 42 is laterally repositioned after an injection or blood draw. The annular fluid seal 62 seats in and is supported by a cylindrical recess 84 provided in the forward facing portion of the chamber luer 44.

[0018] FIG. 1 shows the medical syringe 10 in a pre-use condition, with the needle cover 18 placed over the needle prior to administration of an injection. A locking arm 52 extends laterally from a removable collar 50 of the needle cover 18 and is inserted through an opening into the front of the needle retraction chamber 48 to prevent lateral movement of the slide member 42 relative to the syringe barrel 12 prior to use. To prepare the syringe 10 for use (as shown in FIG. 5), the needle cover 18 is removed, the needle 56 is inserted into a vial (not shown), and an appropriate dose for injection is withdrawn from the vial. The plunger assembly 14 is withdrawn rearwardly relative to the barrel 12 until the appropriate liquid level is reached, as indicated by graduations 74 on the body 20 of the barrel 12. The needle 56 is then inserted into the patient, and an injection is administered by applying thumb pressure forward on the thumb cap 32. The finger flange 26 provides resistance to the thumb pressure, holding the syringe steady against the patient. After the injection, the slide member 42 is preferably moved laterally to reposition the needle 56 and needle holder 58 into alignment with the needle retraction chamber 48. This causes the compressed spring 60 to expand, moving the contaminated needle 56 rearwardly so that it is no longer exposed and will not accidentally stick the needle into the patient or caregiver administering the injection.

[0019] 2-4, in the present invention, when plunger handle 28 is moved forward inside barrel 12 to the position shown in Figures 2 and 3 during an injection (after needle cover 18 has been removed as described above), distal tip 30 of plunger handle 28 enters nose 24 of barrel 12, forcing the injected medical fluid forward out of that space and allowing the medical fluid to travel through fluid passageway 64 of annular fluid seal 62 and into needle 56. When plunger seal 40 of plunger handle 28 contacts the opposing surface of stop surface 80 at the front of body 20 of barrel 12, forward facing surface 76 of plunger handle 28 desirably contacts cooperating stop surface 82 configured at the transition region between body 20 and nose 24 of barrel 12. At the same time, the first portion 36 of the tip 30 desirably reaches the front 83 of the nose 24, and the second portion 38 of the tip 30 desirably extends forward beyond the first portion 36, through the annular fluid seal 62 and into the rearward opening of the fluid passage 64. This allows more medical fluid to move forward and into the needle 56, further reducing "dead space" within the syringe. By sizing and configuring the second portion 38 of the tip 30 to frictionally engage a portion of the inner surface surrounding the fluid passage 64 near the rear of the fluid seal 62, the second portion 38 can help hold or secure the fluid seal 62 in place within the recess 84 in the forwardly extending end of the chamber luer 44 when the needle 56 and needle holder 58 are laterally repositioned by the slide member 42 into alignment with the needle retraction cavity 48 upon needle retraction.

[0020] As previously mentioned, the medical syringe 10 is useful for withdrawing bodily fluids, such as blood, through the venipuncture needle 56 into a fluid reservoir 66, shown in Figure 5. When the medical syringe 10 is used for this purpose, it may be desirable to coat the inner surface 65 of the body 20 of the barrel 12 with a layer 68 that includes an anticoagulant, antioxidant, or other beneficial agent.

[0021] Since other changes and modifications to the preferred apparatus of the present invention will be apparent to those skilled in the art upon reading this disclosure in conjunction with the accompanying drawings, it is intended that the present invention be limited only by the broadest reasonable interpretation of the appended claims as interpreted in accordance with the specification. For example, if medical syringe 10 is intended to be used for drawing blood, a filter can be provided in the fluid flow path to further reduce the possibility of air entrapment or partial oxidation of the drawn sample prior to use.

Claims

1. A barrel, a needle assembly coupled to the barrel and including a needle holder and a needle, and a plunger assembly, the medical syringe comprising: the plunger assembly includes a plunger handle, a plunger seal, and a front tip extending forward of the plunger seal, the front tip includes a first portion extending through a fluid passage formed through a nose of the barrel and a second portion extending forward from the first portion, the second portion extending beyond the nose of the barrel and into an annular fluid seal disposed in a recess formed between a chamber luer coupled to the barrel and a rear surface of the needle holder, thereby reducing a dead space inside the medical syringe in front of the plunger seal and having an effect of fixing the annular fluid seal inside the recess. A medical syringe.

2. The medical syringe according to claim 1, wherein the medical syringe is configured to inject a drug solution into a user.

3. The medical syringe according to claim 1, wherein the medical syringe is configured to withdraw body fluid from a user.

4. The medical syringe according to claim 1, wherein the needle assembly further includes a body and a slide member slidably engaged with the body and providing a seating surface for the needle holder.

5. The medical syringe according to claim 4, wherein the body further includes a forward opening communicating with a needle retraction chamber extending rearward in a parallel relationship with the barrel.

6. The medical syringe according to claim 5, further including a compressed needle retraction spring seated inside the slide member.

7. The medical syringe according to claim 1, wherein the barrel includes a cylindrical collar formed with an internal thread, the nose is tapered, and projects forward through the cylindrical collar formed with the internal thread.

8. The medical syringe according to claim 7, wherein a chamber luer is removably attached to the cylindrical collar formed with the internal thread.

9. The medical syringe according to claim 8, wherein the recess is provided at a forward end of the chamber luer.

10. The medical syringe according to claim 4, wherein the slide member is selectively movable from a first position where the needle is arranged coaxially with the barrel to a second position where the needle is arranged coaxially with the needle retraction chamber.

11. The medical syringe according to claim 10, wherein the compressed needle retraction spring seated inside the slide member provides a biasing force for moving the needle holder and the needle rearward into the needle retraction chamber when the slide member selectively moves to the second position.

12. A medical syringe useful for injecting a medicament into a patient or a port of a fluid delivery system, the medical syringe comprising: a barrel; a plunger having a plunger seal that slidably engages the inner wall of the barrel and defines a fluid reservoir inside the barrel; a needle assembly disposed in front of the barrel and including a needle holder and a needle in fluid communication with the fluid reservoir inside the barrel; an annular fluid seal disposed in a recess formed between a chamber luer connected to the barrel and a rear surface of the needle holder, and being coaxially aligned; the plunger includes a plunger tip protruding in front of the plunger seal; the plunger tip includes a first portion extending through a fluid flow path formed through the nose of the barrel; the plunger tip is a second portion extending forward from the first portion, and when the plunger is fully advanced within the barrel, extends into a portion of the fluid flow path that extends beyond the nose of the barrel and through the annular fluid seal, and the plunger tip and the plunger seal cooperate to be configured to move sufficient fluid placed inside the barrel, and compared with a syringe without the plunger tip, the dead space inside the medical syringe is reduced.

13. A medical syringe useful for withdrawing body fluid from a patient, the medical syringe comprising: a barrel; a plunger having a plunger seal that slidably engages the inner wall of the barrel and defines a fluid reservoir inside the barrel; a needle assembly disposed in front of the barrel and including a needle holder and a needle in fluid communication with the fluid reservoir inside the barrel; An annular fluid seal disposed in a recess formed between a chamber luer connected to the barrel and a rear surface of the needle holder is coaxially aligned; The plunger includes a plunger tip that protrudes forward of the plunger seal; The plunger tip includes a first portion that extends through a fluid flow path formed through the nose of the barrel; The plunger tip is a second portion that extends forward from the first portion and, when the plunger is fully advanced within the barrel, extends beyond the nose of the barrel into a portion of the fluid flow path that extends through the annular fluid seal. When the body fluid is withdrawn into the fluid reservoir, the plunger tip and the plunger seal cooperate to reduce air uptake and bubble formation within the medical syringe compared to a syringe without the plunger tip. A medical syringe.

14. The medical syringe according to claim 13, further comprising a pharmaceutical substance disposed inside the barrel for adjusting the body fluid withdrawn into the fluid reservoir.

15. The medical syringe according to claim 14, wherein the pharmaceutical substance is selected from the group consisting of anticoagulants and antioxidants.

Images