BACKGROUND OF THE INVENTION

Field of the Invention

The present technology is related to dental syringes. More specifically, the technology is a patient-friendly safety syringe that can easily be deployed with one hand.

Description of the Related Art

There are many designs for safety syringes. Some allow for the needle to be covered prior to use, others cover the needle after use, some break the needle after use and some have a number of needle positions.

Many safety syringes include detents. For example, US Patent 6,416,323 discloses proximal, intermediate, and distal sets of detent pockets that are molded into the body, the intermediate set of detent pockets having sloping proximal and distal edges for facilitating sliding the detents out of the intermediate set of detent pockets to direct the shield towards one of the retracted and fully extended positions. The distal set of detent pockets preferably have substantially blunt proximal edges for preventing proximal movement of the shield once the set of detents are received in the distal set of detent pockets. Levers are provided to allow for repetitive extension and retraction of the needle. Unfortunately, this requires squeezing the levers with a second hand. Further, before use the needle is in the extended position.

In US 5,306,258 a system of slots and pegs is provided to releasably retain a protective sheath in a first distal position and to releasably retain the protective sheath in a proximal position. Also a system to retain and lock the protective sheath in a second distal position after use whereby the needle is protected by the sheath is provided. To retract the sheath the user positions the thumb within a finger loop and the index and middle fingers respectively in one of the aspirating loops. Thereafter, the index finger and middle finger are separated in opposite directions to release pegs located on strips from slots on the body of the syringe. The finger motion which releases the pegs is opposite the inward natural resilient force provided by strips, which are formed out of sheath and are resiliently biased toward the body.

In US Publication No. 2007/0078409 a syringe cover that interacts with the hub of the needle to retract and extend the needle is disclosed. The hub has biasing members that hold the cover in a given position. There is also a channel to ensure that the cover moves in the direction desired that can be linear, spiral or helical. There are stops at both ends. The cover has a protrusion to engage with the channel. The cover also has engagement elements that interact with the biasing members. Use of this cover requires two hands.

In order to overcome the deficiency of requiring two hands to operate the safety syringe, more complex designs have been developed. For example, in US Publication No. 2011/0054398, a needle assembly has a hub, a hollow needle fixed in the hub, and a spring seated between the distal end of the barrel and the hub is disclosed. A membrane is between the hub and the opening of the piston. A locking member is lodged between the barrel and the needle assembly, holding the needle assembly within the barrel to compress the spring. The piston is displaceable through functional positions in which the piston (a) forces serum out through the needle, (b) urges the membrane against the hub, and (c) dislodges the locking member thereby releasing the needle assembly such that the spring displaces the hub and at least a portion of the membrane into the cavity and withdraws the needle tip into the distal end of the barrel. While the needle is automatically retracted, and therefore the action is one handed, before use, the needle is in the extended position. Another example can be seen in US Patent 6,863,659 where a fluid actuating mechanism is employed. The operation cycle of the hydraulic retractable syringe is that the user removes plunger rod stop and fully depresses the plunger rod assembly to fully deploy the hypodermic needle through the opening in the first end of elongated hollow barrel. The user then aspirates injection fluid into the syringe and performs an injection in the conventional manner. During the injection stroke the hydraulic pressure of the injection fluid is raised forcing the activating ring with three molded pistons against the release activating slide, which convert the axial pressure of the activating ring with three molded pistons to a radial pressure acting on the catch ends of respective legs. This radial pressure displaces the catch ends of three-legged retaining clip from the recesses of the release activating slide into the grooves on the outside of spring retaining cup thus allowing the springs to expand when the hydraulic pressure falls at the completion of the injection stroke. Thus the springs force the slideable body on which hypodermic needle is mounted away from the first end of, and fully into, elongated hollow barrel. Three-legged retaining clip has two of its three legs preset so as to force the spring separating plate against hypodermic needle causing it to be axially misaligned and incapable of re- emerging through the opening in the first end of elongated hollow barrel. While this allows for one handed use, it is a complex mechanism and does not allow for repeated use.

SUMMARY OF THE INVENTION

A safety syringe is provided that allows for a cover to be moved in relation to the needle independent of movement of the plunger. This reduces the risk of accidently ejecting the contents of the carpule and needle stick injuries. Movement of the cover in relation to the needle can be done with one hand. This reduces patient stress, as it can be done as the practitioner approaches the injection site. The syringe utilizes many standard parts including a plunger, a finger hold, and a body for accepting a carpule. The improvement to the syringe is the capsule and retractor. The capsule and retractor can be reversibly attached to one another, allowing for the needle to be exposed and covered repeatedly. The capsule comprises a cover, a needle cannula, with its needle and hub, an annular ring and a biasing member. The cover comprises an open distal end, an open proximal end, a bore therebetween, and a releasable member. The cover is in slidable engagement with the annular ring and moveable between a covered position and an administering position. The cover is biased by the biasing member to the covered position. The annular ring is located on the hub, and is optionally integral with the hub and comprises an opening for releasably retaining the releasable tab. The biasing member is housed within the cover and biases the cover to the covered position. There is a retractor. The retractor slidably engages the body and comprises at least one pull and a slider extending distally therefrom. The slider comprises a lifter distally for releasing the releasable member from the opening on the annular ring and concurrently engaging the opening. There is at least one releasable mating pair having a first member on the slider and a second member on the cover. Preferably, the lifter comprises a chamfered distal end to assist in lifting the releasable tab.

In order to better retain the cover on the retractor, there are two releasable mating pairs, each releasable mating pair comprising a lateral ridge in the vicinity of the distal end of the slider and a corresponding tab in the vicinity of the proximal end of the cover.

Advantageously, the slider and opening in the annular ring and the lateral mating pairs are reversibly releasable. Preferably, the annular ring comprises at least one guide member and the cover comprises at least one longitudinal guide in slidable engagement with the guide member to assist in coaxial or essentially coaxial movement. An oval bore further assists in alignment as do at least one guide member and one longitudinal guide in slidable engagement with the guide member on the slider and body. Alternatively described, the technology provides a syringe comprising a plunger, a finger hold, and a body for accepting a carpule, the improvement being a capsule and a retractor. The capsule comprises a cover, a biasing member, a needle cannula and an annular ring, wherein the cover is biased to a covered position. The retractor comprises a slider and a finger pull, wherein the needle cannula or annular ring is configured for reversibly mating with each of the cover and the slider, and the slider is configured for concomitantly releasing the needle cannula from the cover and mating to the cover.

The capsule itself is also provided. The capsule is for use with a syringe that has a retractor. The capsule comprises a cover, a biasing member, an annular ring, a needle and a hub. The cover comprises an open distal end for exposing the needle, an open proximal end, a bore therebetween, a releasable tab in the vicinity of the proximal end and at least two lateral releasable tabs for releasably mating with a retractor. The cover is in slidable engagement with the annular ring and moveable between a covered position and an administering position. The cover is sized for slidable, coaxial engagement with a syringe body. The biasing member biases the cover to the covered position. The annular ring is located on the hub and comprises an opening for releasably retaining the releasable tab and for releasably retaining the retractor. The biasing member is housed within the cover and biases the cover to a covered position.

Preferably, the biasing member is a spring disposed between a shelf in the cover and the annular ring.

The capsule can be provided as a sterilized unit.

In another embodiment a method of preparing a syringe for use The needle is covered before injecting and after injecting, thereby reducing patient stress and the risk of needle injury. The method comprises: i) threading a capsule onto a syringe body, the capsule comprising an annular ring, a cover and a needle cannula, wherein the needle cannula comprises a needle and a hub and is optionally integral with the annular ring; ii) urging a retractor distally; iii) concurrently disengaging the cover from the annular ring and engaging the retractor to the annular ring; and iv) drawing the retractor towards a finger hold on the syringe, thereby urging the cover substantially axially along the syringe body and exposing the needle for use. Preferably, the method also allows a biasing member to urge the cover over the needle after use. The needle can then be re-exposed, by drawing the retractor proximally, or the capsule can be removed in preparation for disposal by holding the cover and drawing the retractor proximally, thereby disengaging the retractor. BRIEF DESCRIPTIONS OF DRAWINGS

Figure 1 is an isometric view of an embodiment of the present technology;

Figure 2 is a longitudinal sectional view of the syringe of Figure 1 ;

Figure 3 is an isometric view of the distal area of the slider; Figure 4 is a longitudinal sectional view of the capsule and distal end of the slider; Figure 5 is a longitudinal sectional view of the capsule; Figure 6 an exploded view of the capsule and slider; Figure 7 is a cross sectional view of the body and slider;

Figure 8 is an isometric view of a practitioner holding the syringe of Figure 1 in position to uncover the needle;

Figure 9 is an isometric view of a practitioner holding the syringe of Figure 1 in the administering position; and Figure 10 is longitudinal views showing the relationship between the plunger, the finger pull and finger hold and the cover during the steps of attaching the slider to the cover, exposing the needle, injecting and re-covering the needle, wherein the arrows indicate direction of movement for the numbered element.

DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

A syringe, generally referred to as 8 is shown in Figure 1. The syringe 8 has a plunger 10 with a thumb ring 12 at a proximal end 14 and a shaft 16 that extends distally to a carpule 18 along a longitudinal axis 20 of the syringe 8. A finger hold 22 is located at a proximal end 24 of the body 26 of the syringe 8 and is either affixed to the body 26 or is integral with the body 26.

As shown in Figure 2, the finger hold 22 has an aperture 28 for slidably engaging the shaft 16. The finger hold 22 may be, but is not limited to a ring or L-shaped or T- shaped. The body 26 has opposing side rails 30 defining a cavity 36 extending at least partially between the proximal end 24 and a distal end 34 of the body 26 for accepting the carpule 18. A spring 38 may be located in the cavity 36 to assist in retaining the carpule 18. A capsule, generally referred to as 40, slidably engages the body 26. The capsule 40 is coaxial with the body 26. A slider 42 and a finger pull 44 are referred collectively as a retractor 46. The finger pull 44 is a ring. The retractor 46 has a proximal annular ring 48 attached to the slider 42 for slidably engaging the body 26. As can be seen in Figure 7, the slider 42 is hemispherical to permit viewing of the carpule 18. As shown in Figure 3, the distal end 50 of the slider 42 has a lifter 52 that is raised above and extends distally from the slider 42. The lifter has a chamfered edge 54. The distal end 50 also has two lateral ridges 56 and proximal to them, two stops 58. A guide 94 on the slider 42 can be seen for directing the slider 42 coaxially along the body 26. Returning to Figure 2, as would be known to one skilled in the art, a double-ended needle cannula comprises a needle 64 and a cannula hub 70. The cannula hub 70 positively engages an annular ring 62. The cannula hub 70 and annular ring 62 may be molded as a unit or may be separate units that are glued or threaded or clicked together or are otherwise positively attached to one another. The hub 70 of the cannula 71 threadedly engages the body 26.

As shown in Figures 4 and 5, the capsule 40 has a cover 60, the annular ring 62, the needle cannula 100 and a spring 68. The capsule 40 is preferably provided as a sterilized assembly and is ready to use. The cover 60 is releasably retained on the annular ring 62. A shoulder 66 on the annular ring 62 engages the spring 68 proximally, and a shelf 63 in the cover retains the spring 68 distally. The cover 60 has an open distal end 72, an open proximal end 74 for engaging the distal end 50 of the slider 42 and a bore 77 therebetween.

The details of the relationship between the annular ring 62, the cover 60 and the slider 42 can be seen in Figures 4, 5 and 6. As shown in Figures 5 and 6, the cover 60 has a release tab 76, which is resiliently flexible or otherwise allows for some flexing about its length. The release tab releasably and reversibly mates with a T-shaped groove 78 in the annular ring 62. The lifter 52 of the slider 42 lifts the release tab 76 from the T-shaped groove 78 and mates with the T-shaped groove 78. As shown in Figure 4, the cover 60 also has lateral tabs 80 that releasably and reversibly mate with the lateral ridges 56 of the slider 42. The stops 58 assist in locating the cover 60 on the slider 42.

Also shown in Figure 5 guides or grooves 82 on the annular ring 62 slidably engage guide members or grooves 84 in the cover 60, to help direct movement of the cover 60 distally and proximally. As shown in Figure 1 , the outer surface 86 of the cover 60 preferably has indents 88 for the user to grasp the cover 60. The cover 60 is preferably oval in cross section to encourage proper alignment on the body 26. The cover 60 is preferably translucent or transparent or has a window 61 to allow a practitioner to view the carpule 18 when injecting to ensure that a blood vessel has not been entered. As shown in Figure 7, a groove 92 in the body 26 extends along at least part of the longitudinal axis 20 of the syringe 8. The corresponding guide 94 on the slider 42 directs the slider 42 linearly along the groove 92. In use, a practitioner unwraps the sterilized capsule 40, and threads the cannula hub 70 onto the body 26 by rotating the capsule 40. The indents 88 assist the practitioner in grasping and aligning the capsule 40. The practitioner then slides the slider 42 distally, thereby lifting the release tab 76 from the T-shaped groove 78 and engaging the lifter 52 with the T-shaped groove 78. Concurrently, the lateral tabs 80 mate with the lateral ridges 56 of the slider 42 and the stops 58 assist in locating the cover 60 on the slider 42. The practitioner then pulls the slider 42 proximally. As the cover 60 is now attached to the slider 42, it moves proximally, exposing the needle 64. The guides or grooves 82 on the annular ring 62 that slidably engage the guide members or grooves 84 in the cover help direct movement of the cover 60 distally and proximally.

The design permits a user to use one hand to expose the needle 64, begin injecting, allow the syringe 8 to self-aspirate, and continue the injection. As shown in Figure 8, the practitioner positions a middle finger 200 or a third finger 202 on the finger pull 44 and then positions the index finger 204 or middle finger 200 on the finger hold 22. This is the position for moving the cover 60. The practitioner then draws the finger pull 44 towards the finger hold 22. This in turn moves the cover 60 proximally, thereby exposing the needle 64. The spring 68 is in compression when the needle 64 is exposed.

As shown in Figure 9, the practitioner can then locate their thumb 206 in the thumb ring 12 while retaining their fingers on the finger pull 44 and finger hold 22. By pushing distally on the thumb ring 12, the practitioner urges the shaft 16 of the plunger 10 distally into the cavity 36 until it abuts the carpule 18. Further pushing causes the contents of the carpule 18 to be injected into the patient. As the syringe is self-aspirating, the practitioner can look through the cover 60 to see whether there is blood entering into the carpule 18. If there is no blood, the practitioner can continue the injection. Alternatively, if there is blood, the practitioner can withdraw the needle 64 from the patient, and can easily cover the needle 64 with the cover 60 by releasing the finger pull 44. The compressed spring 68 then causes the cover 60 to re-cover the needle 64. The practitioner can then re-expose the needle 64 by positioning the middle finger 200 or third finger 202 on the finger pull 44, positioning the index finger 204 or middle finger 200 on the finger hold 22 and drawing the finger pull 44 towards the finger hold 22.

Once the injection is completed, the practitioner can either cover the needle 64 with the cover 60 in preparation for another injection or can prepare the capsule 40 and cannula for disposal. Both are effected by allowing the spring 68 to urge the cover 60 over the needle 64. For disposal, the capsule 40 is then removed from the body 26 by pulling the cover 60 and slider 42 away from one another, disengaging the lifter 52 from the release tab 76 and the lateral tabs 80 from the lateral ridges 56. The practitioner then pulls the slider 42 proximally and undoes the threaded connection between the cannula hub 70 and the body 26. The capsule 40 can then be discarded.

The relationship between the finger pull 44, finger hold 22, the plunger 10, and the cover 60 during the steps of attaching the slider 42 to the cover 60, exposing the needle 64 and re-covering the needle is shown in Figure 10. By sliding the finger pull 44 away from the finger hold 22, the practitioner is able to release the cover 60 from the annular ring/hub/needle cannula and attach the slider 42 to the cover 60. By drawing the finger pull 44 and the finger hold 22 towards one another, the practitioner is able to slide the cover 60 smoothly proximally relative to the body 26 of the syringe 8, thereby moving from a shipping position 320 (a covered position) to an administering position 322. The movement is independent of the position of the plunger 10 - there is no role for the plunger 10 in covering or uncovering the needle 64. The practitioner then urges the plunger 10 distally to inject the contents of the carpule 18. The syringe is then in the post- injecting position 324. In order to re-cover the needle 64, the practitioner allows the cover 60 to return. This is spring activated. The syringe 8 is then in the resting position 326 (again, a covered position) and can be used for another injection, as desired, or the capsule 40 can be removed and disposed. The needle 64 remains covered during the removal and disposal. As the needle 64 is covered during the assembly and disposal, and can indeed be covered between injections, needle stick injuries are minimized. Further, a patient does not see the needle 64, thereby minimizing the stress associated with injections. The foregoing is a description of an embodiment of the technology. As would be known to one skilled in the art, variations are contemplated that do not alter the scope of the technology. For example, the springs can be replaced with any biasing means. The finger hold and finger pull can be any shape, preferably ergonomic. Further, while the overall direction of movement of the cover relative to the body is substantially along the longitudinal axis of the body of the syringe, any non-linear guide, for example, but not limited to, a curved guide can be used. The guide may be a keyway, or a channel or ridge or any other structure that allows for guided travel of the cover.