US20050240150A1 - Safety syringe - Google Patents

Abstract

A hypodermic syringe provides a simple mechanism for manually retracting its needle into the syringe after injection has been completed. The syringe preferably has an elastomeric barrel to exert a radial bias to seal on a retractable needle carrier and the plunger. Attachment components on the plunger and needle carrier engage such that withdrawal of the plunger releases the needle carrier for withdrawal into the syringe barrel.

Description

RELATED APPLICATIONS
• This application is a continuation of U.S. application Ser. No. 10/350,961, filed on Jan. 24, 2003, which claims the benefit of U.S. Provisional Application Ser. No. 60/401,742, filed on Aug. 6, 2002, both of which are hereby incorporated herein in their entirety by reference.
FIELD OF THE INVENTION
• The present invention relates to medical devices and more particularly to hypodermic syringes designed to provide cross contamination protection to others by way of a retractable needle assembly that prevents accidental contact with the needle after use.
BACKGROUND OF THE INVENTION
• Inadvertent needle stick injuries form used syringes may present a significant health hazard to others if infectious blood products are transmitted. Such accidental needle sticks may spread hepatitis, AIDS and other communicable diseases to health care workers and patients. In certain instances, the resulting disease may be life threatening. Further, the emotional distress from the fear of contracting such diseases can be significant. Still further, in the event of a stick, series of diagnostic blood tests may have to be performed to determine if cross-contamination has occurred in a needle stick injury. In many cases, the victim often is required to receive injection of gamma globulin to prevent further infection and to cure the patient. This is uncomfortable, inconvenient, and expensive to the victim.
• According to the prior art, the usual technique has been to, after use of the needle, to break off the needle and dispose of the needle and syringe in a “sharps” container for secured disposal such as by incineration or stabilization in, for example, plastic of concrete.
• Efforts have been made to develop syringes which attempt to prevent inadvertent sticks. In Chen, U.S. Pat. No. 6,432,082 issued Aug. 13, 2002, there is disclosed a safety syringe having a needle holder which is retractable into the barrel of the syringe. The needle holder is secured to the syringe barrel by a frangible component. After use, the uses forces the plunger to couple with the needle holder and withdraws the plunger to rupture the frangible component so that the portion of the holder mounting the needle (cannula) can be withdrawn into the barrel. A drawback of this design is that the frangible portion of membrane must be manufactured to tolerances such that (1) the pressure imposed by the plunger during aspiration of the medicine into or injection of the medicine out of the syringe does not rupture the seal and (2) still provide for rupturing the portion during withdrawal of the plunger without the plunger first separating from the needle holder. It is submitted that such requirements contribute to the expense of such a device. Further, the inability of the health card provider to rupture the portion will cause frustration and abandonment of the operation to withdraw the needle.
• In Jenson, U.S. Pat. No. 5,540,660 issued Jul. 30, 1996 there is disclosed another syringe where a needle holder is captured by the plunger for withdrawal into the syringe barrel. In one embodiment of this disclosure, the plunger makes and interference fit into a tapered sleeve such that withdrawal of the plunger withdraws the sleeve and needle into the barrel. A drawback of this arrangement is that it would be difficult to aspirate medicine into the syringe without creating an interference fit between the plunger and sleeve thus disabling the syringe before injection of the medicine. In another embodiment an snap connection is utilized to couple the plunger to a needle holder. In either embodiment, close tolerances must be adhered to during manufacture to provide the seal between the sleeve and needle holder. Further, for either embodiment, an arcuate cannula is required to prevent re-use of the device.
• Mazur, U.S. Pat. 5,205,824 issued Apr. 27, 1993 discloses another syringe where the needle holder is retained at the end of the syringe barrel only by the friction between the o-rings and the barrel which, it is believed, would (1) make secure attachment of the needle to the holder difficult since the holder may tend to rotate as the needle is threaded thereon. Further there remains a risk that insertion of the needle into a bottle of medicine for aspiration of medicine into the syringe would dislodge the needle holder and interfere with the seal.
• There is a need for safety syringe which is easy and inexpensive to manufacture, which provides for withdrawal of the needle into the barrel of the syringe, which can be re-used if desired, which has a positive coupling to provide for attachment of the needle and retention of the needle during aspiration and injection, which provides for a positive stop during withdrawal of the needle to indicate full withdrawal of the needle and which overcomes the drawbacks noted above.
SUMMARY OF THE INVENTION
• There is, therefore, set forth according to the present invention, a safety hypodermic syringe designed to provide cross contamination protection to others by way of a retactable needle assembly obviating accidental contact with the needle to another person and which is of simple and inexpensive construction.
• Toward this end the safety syringe is disclosed which includes a hollow barrel having a forward and rear end. Proximate the forward end a first retention structure is provided which may be in the form of a circumferential groove or ridge or other suitable structure. A first coupling structure is also provided at the first end. Proximate said rear end is a second retention structure which may also be in the form of a circumferential groove or ridge.
• A needle carrier is disposed at said forward end and has a third retention structure configured to engage with the first retention structure to releaseably retain the needle carrier at the forward end and to engage the second retention structure to retain said needle carrier in a position withdrawn into the barrel. To prevent the needle carrier from rotating in the barrel at the first end, the barrel and needle carrier have cooperative coupling structures which may be embodied as engaging tabs or teeth. Also provided is a mounting for mounting a needle such as a threatened or luer lock connection as is known in the art.
• A plunger is disposed in the barrel and has a head to slideably seal within the barrel for aspiration of fluid into an out of the barrel. At the head and at the needle carrier are cooperative attachment components which, when engaged, attach the needle carrier to the plunger for withdrawal thereof. Withdrawal of the plunger disengages the third retention structure from the first retention structure to release the needle carrier to be withdrawn a position in the barrel where the third retention structure engages the second retention structure to retain the needle carrier with its needle in the withdrawn position.
• The barrel may be rigid but is preferably fashioned from an elastomeric material such as plastic or the like to be radially biased at least in the regions of the first and second retention structures for engagement with the third retention structure. The barrel may also be rigid with an elestomeric liner.
• Accordingly, the health care provider positions the plunger adjacent the needle carrier and secures the needle to the needle carrier. The needle is inserted into a vial of fluid and the plunger is withdrawn to aspirate the fluid to be injected into the barrel. The needle is withdrawn from the vial and, for example, inserted into a patient. The plunger is pushed through the barrel to aspirate the fluid from the barrel through the needle into the patient. At the forward end the plunger is positioned such that the cooperative retention structures on the head and needle carrier engage to capture the needle carrier to the plunger. Thereafter the plunger is withdrawn disengaging the needle carrier from the forward end of the syringe barrel and continued withdrawal of the plunger withdraws the needle carrier and needle to a position nested within the barrel whereat the needle carrier engages the second retention structure to retain the needle carrier within the barrel. In this position the needle is safely withdrawn into the barrel to prevent inadvertent sticks. The syringe may then be disposed of in a sharps disposal container. If desired, the syringe may be sterilized and re-used.
DESCRIPTION OF THE DRAWINGS
• These and other features and advantages will become better understood with reference to the description, claims and drawings wherein:
• FIG. 1 is a front perspective view of the syringe without a needle;
• FIG. 2 is a side, perspective, partial section view of the needle carrier;
• FIG. 3 is a side section view of the needle carrier mounted in the barrel of the syringe ofFIG. 1;
• FIG. 4 is a side view of the plunger for the syringe ofFIG. 1;
• FIG. 5 is an end view of the plunger ofFIG. 4;
• FIG. 6 is a section view of the fluted shaft of the plunger ofFIG. 6 taken along line6-6;
• FIG. 7 is a side section view of the syringe with the plunger in a first position;
• FIG. 8 is a side section view showing capture of the needle carrier by the plunger and withdrawal into the barrel; and
• FIG. 9 is a perspective, partial cutaway view of the barrel for the syringe.
DESCRIPTION
• Turning to the drawings,FIG. 1 shows thesafety syringe10 according to the present invention. Thesyringe10 includes abarrel12 which may be cylindrical and rigid such as by being manufactured from a hard plastic. Alternatively and preferably, the barrel may be constructed from an elastomeric or elastically deformable material such as vinyl, soft polyurethane or other elastically, radially biased, deformable plastic. The deformable plastic should be somewhat elastic but still able to retain its overall cylindrical shape and should be selected to withstand sterilization processes. Still alternatively, thebarrel12 may be rigid with an interior, elastic, lining. Thus, the elastic characteristic permits thebarrel12 to impose a radial bias against expansion and to be contractile to a degree.
• To provide for aspiration of the desired amount of fluid, e.g. medicine, into thebarrel12, the barrel should transparent or semi-transparent and include graduation markings to indicate volume within thebarrel12.
• Thesyringe10 also includes aneedle carrier14, the details of which will hereafter be described.
• To provide for aspiration of fluid into an out of thesyringe barrel12, thesyringe10 includes a plunger16, the details of which will hereafter be described.
• Thebarrel12 is hollow and preferably cylindrical having aforward end18 andrear end20. At the rear end20 a pair of finger loops22a, bmay be mounted to thebarrel12 to receive the fingers of the health care provider using thesyringe10.
• With reference toFIGS. 3, and7-9, thebarrel10 includes proximate the forward end18 a rearward facing, circumferential should24 which defines a first coupling structure the purposes of which will hereinafter become evident. Theshoulder24 may haveteeth26, tabs, notches or other cooperative structure to engage with structure on theneedle carrier14 to prevent coaxial rotation thereof relative to thebarrel12.
• Disposed rearward of theshoulder24 inside thebarrel12 is afirst retention structure28 illustrated as one or more circumferentially arranged, radial projections fashioned within thebarrel12. As shown in the drawings, thefirst retention structure28 may be a continuous, circumferential ridge or projection. Alternatively the first retention structure may be discontinuous.
• Disposed proximate therear end20 of thebarrel12 and inside thereof is asecond retention structure30. Thesecond retention structure30 has a construction similar to thefirst retention structure28. Thesecond retention structure30 is disposed such that, as hereinafter described, theneedle carrier14 and attached needle can be fully withdrawn into thebarrel12.
• In an alternative embodiment, the first andsecond retention structures28,30 may be embodied as continuous or discontinuous circumferential grooves in the inside wall of thebarrel12.
• Turning toFIGS. 2 and 3, an embodiment of theneedle carrier14 is shown. Theneedle carrier14 is generally cylindrical to be received at theforward end18 of thebarrel12. In a cylindricalfirst portion32 there is disposed athird retention structure34 shown as embodied as acircumferential depression36 dimensioned to closely receive the first andsecond retention structures28,30 of thebarrel12 to releasably retain and capture theneedle carrier14 therein. Where the first andsecond retention structures28,30 are grooves or depressions, thethird retention structure34 would be a projection to be received into the grooves.
• Thefirst portion32 transitions to a smaller diametersecond portion38 at a circumferential, axially and forwardly directed,surface40 defining a second coupling structure. Thesurface40 is cooperatively configured to engage with the first coupling structure of theshoulder24 and itsteeth26 to couple theneedle carrier14 to thebarrel12 against axial rotation. Thus thesurface40 includesteeth42 as well. It should be noted that the first and second coupling structures could have any suitable configuration for coupling thereof such as one or more interlocking tabs, pins, or the like.
• At the forward end of the needle carrier there is defined a mounting structure suitable for mounting of a needle42 (FIGS. 7 and 8) or cannula. Accordingly the forward end of the needle carrier includes an axially projecting, hollow,nipple44. Thenipple44 is supported by aradial substrate46 which extends to acylindrical wall48 which extends axially spaced from thenipple44. The inside surface of thewall48 includesthreads50. Theneedle42 has an exteriorly threadedcap52 which is received over thenipple44 and is threaded into thewall48 with cooperating threads. Thecap52 andthreads50 define a standard luer lock connection for the needle as is known in the art. As shown inFIG. 7, when theneedle42 is mounted to theneedle carrier14, a fluid passageway is defined through thenipple44 andneedle42 for fluid to be aspirated into and from thesyringe barrel12 through theneedle42.
• Opposite thenipple44 theneedle carrier14 has afirst attachment component70 adapted for coupling theneedle carrier14 to the plunger16. With reference toFIG. 3, the first attachment component is defined as anellipsoidal recess72 defined in theneedle carrier14 and which intersects with the hollow of thenipple44. Therecess72 opens to the inside of thebarrel12 through a reducingneck74 defined by a circumferential, and radially inwardly directednose76. At spaced locations, e.g. at 90 degrees intervals, radially directed,deformable wings78 extend into therecess72. Each wing includes a radial slot80.
• To provide for aspiration of fluid and for withdrawing theneedle carrier14, thesyringe10 also includes the plunger16 as shown inFIGS. 4-6. The plunger16 includes at one end a thump loop54 to receive the thumb of the health care provider for manipulation of the plunger16. Ashaft56 may be orthogonally fluted or of any other suitable shape.
• At thehead58 there are disposed axially spaced and radially extending first andsecond seals60a, bwhich are, when thebarrel12 is rigid, elastically deformable to engage and seal against the inside surface of thebarrel12. Where thebarrel12 is elastomeric or includes an elastomeric lining, theseals60a, bmay be rigid.
• Forward of theseals60a, b, thehead58 includes aradially extending stop62. Forward of thestop62 is a radially extending,deformably disk64 of a size to (1) deform to pass through theneck74 and to expand to engage into the slots80 for coupling theneedle carrier14 to the plunger16. Thedisk64 defines a second attachment component for thesyringe10. Forward of the disk is an end piece66 which is adapted to be received into therecess72.
• With the foregoing in the mind the operation of thesyringe10 will now be described. Thesyringe10 is assembled with theneedle carrier14 disposed in theforward end18 of thebarrel12. In this position the first retention structure of the barrel, e.g. the radially projecting projection, is received into the depression of theneedle carrier14 defining the third retention structure. The elastomeric character of thebarrel12 constricts to retain the components. Thus, to displaced theneedle carrier14, i.e. disengage the first and third retention structures, and first axial displacement force is required. This force may act to locally expand thebarrel12 or, if thebarrel12 is rigid, compress thefirst portion32 of theneedle carrier14 or both. In a preferred embodiment the interference retention of theneedle carrier14 in thebarrel12 is with a force F₁greater than that required for insertion of the needle into a medicine vial, patient or other intended use. That is, during aspiration, theneedle carrier14 remains retained by the engagement of the first and third retention structures.
• As manufactured, the plunger16 is retained in thebarrel12 for example in the position as suggested inFIG. 7 in readiness for aspiration of medicine into thesyringe10.
• Theneedle42 is threaded onto theneedle carrier14, also as suggested inFIG. 7. Theneedle carrier14 is retained against rotation during the mounting of theneedle42 by the coupling between theshoulder teeth26 and the teeth of thesurface40. Once theneedle42 is secured to theneedle carrier14, theneedle42 is inserted into a medicine vial, for example, and the plunger16 is withdrawn in thebarrel12 to aspirate medicine into thebarrel12. Theseals60a, bseal theplunger head58 within thebarrel12. Any air remaining in thebarrel12 is aspirated from thebarrel12 by forward movement of the plunger16.
• Theneedle42 is then inserted into the patient and the medicine is aspirated from thebarrel12 by forward motion of the plunger16 and injected into the patient. The elastomeric character of thebarrel12 helps seal against the plunger16. At the end of the injection, the plunger16 is displaced to cause thehead58 to approach theneedle carrier14. Thedisk64 deforms to pass through the neck47 and ultimately snap outward to engage into the slots80 of thewings78 to thereby attach theneedle carrier14 to the plunger16 as shown inFIG. 8. The stop63 engages theneedle carrier14 to limit and guide the insertion of thehead58 components into therecess72. The plunger16 may then be withdrawn with a force greater than F₁to overcome the retention force offered by the engagement by first andthird retention structures28,32 to dislodge theneedle carrier14 for withdrawal into thebarrel12. Continued withdrawal of the plunger16 pulls theneedle carrier14 into thebarrel12. When thesecond retention structure30 is engaged by the third retention structured34 of theneedle carrier14, theneedle carrier14 is retained within thebarrel12. With theneedle carrier14 in the withdrawn position, theneedle42 is nested within thebarrel12 from the openforward end18 preventing inadvertent sticks by theneedle42.
• As can be appreciated, the force F₂necessary to separate the plunger from theneedle carrier14 must be greater than F₁in order for the plunger to withdraw theneedle carrier14.
• To re-use the syringe, it would be sterilized by suitable means such as an autoclave (steam or suitable gas) and the plunger would be re-positioned to locate theneedle carrier14 such that the first and third retention structures engage as do theteeth26 and43. Theneedle42 is removed. Theneedle holder nipple44 is held while the plunger is withdrawn with a force sufficient to overcome force F₂thereby releasing the plunger16 from theneedle carrier14 for re-use thereof.
• It should be noted that the present invention is subject to many modifications without departing from scope of the invention as expressed in the claims. For example, thebarrel12 need not be cylindrical. Further, only a portion of thebarrel12 may be elastromeric or coated with an elastomeric liner.

Claims (10)

1. A safety syringe comprising:

a hollow barrel having a forward and rear end, said barrel including proximate the forward end a first retention structure and a first coupling structure and proximate said rear end a second retention structure;

a needle carrier disposed at said forward end and including (i) a third retention structure engaging the first retention structure to releaseably retain the needle carrier at said forward end and to engage the second coupling structure to retain said needle carrier in the barrel, (ii) a second coupling structure to engage the first coupling structure to prevent rotation of the needle carrier at said forward end, (iii) a mounting for mounting a needle and (iv) a first attachment component disposed opposite said mounting; and

a plunger having a head to slideably seal within the barrel for aspiration of fluid into an out of the barrel and a second attachment component to engage the first attachment component of the needle carrier to attach the needle carrier to said head, withdrawal of the plunger disengaging the third retention structure from the first retention structure to release the needle carrier and needle to be withdrawn a position in the barrel where the third retention structure engages the second retention structure to retain the needle carrier and needle in the withdrawn position.

2. The safety syringe ofclaim 1 comprising said first and second retention structures include radial projections in said barrel and said third retention structure includes a cooperative radial depression in said needle carrier to receive said projections.

3. The safety syringe ofclaim 2 comprising said first and second retention structures include radially projecting ridges and said third retention structure includes a radial groove in said needle carrier.

4. The safety syringe ofclaim 1 comprising said first and second retention structures include grooves in said barrel and said third retention structure includes a radial protuberance to engage into said grooves.

5. The safety syringe ofclaim 1 comprising said barrel is constructed from an elastomeric material.

6. The safety syringe ofclaim 1 comprising said first and second attachment components includes a deformable tab snap-engaging a cooperative recess.

7. The safety syringe ofclaim 1 comprising said mounting is a luer lock mounting.

8. The syringe ofclaim 1 comprising said first and third retention structures cooperating to release the needle carrier at a first withdrawal force and said second and third retention structures cooperating to release the needle carrier at a greater, second withdrawal force.

9. A safety syringe comprising:

a hollow cylindrical barrel having a forward and rear end, said barrel including proximate the forward end a first radial projection and a first coupling structure and proximate said rear end a second radial projection;

a needle carrier disposed at said forward end and including (i) a depression to receive the first projection to releaseably retain the needle carrier at said forward end and to receive the second projection to retain said needle carrier in the barrel, (ii) a second coupling structure to engage the first coupling structure to prevent rotation of the needle carrier at said forward end, (iii) a mounting for mounting a needle and (iv) a first attachment component disposed opposite said mounting; and

a plunger having a head to slideably seal within the barrel for aspiration of fluid into an out of the barrel and a second attachment component to engage the first attachment component of the needle carrier to attach the needle carrier to said head, withdrawal of the plunger disengaging the third retention structure from the first retention structure to release the needle carrier and needle to be withdrawn a position in the barrel where the third retention structure engages the second retention structure to retain the needle carrier and needle in the withdrawn position.

10. A safety syringe comprising:

a hollow barrel having a forward and rear end, said barrel including proximate the forward end a first groove and a first coupling structure and proximate said rear end a second groove;

a needle carrier disposed at said forward end and including (i) a protuberance to engage into the first groove to releaseably retain the needle carrier at said forward end and to engage into the second groove to retain said needle carrier in the barrel, (ii) a second coupling structure to engage the first coupling structure to prevent rotation of the needle carrier at said forward end, (iii) a mounting for mounting a needle and (iv) a first attachment component disposed opposite said mounting; and

a plunger having a head to slideably seal within the barrel for aspiration of fluid into an out of the barrel and a second attachment component to engage the first attachment component of the needle carrier to attach the needle carrier to said head, withdrawal of the plunger disengaging the third retention structure from the first retention structure to release the needle carrier and needle to be withdrawn a position in the barrel where the third retention structure engages the second retention structure to retain the needle carrier and needle in the withdrawn position.

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