CA1295200C - Self-blunting needle assembly and device including the same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A self-blunting needle assembly comprises a hollow needle, which may be of conventional construction having a needle mouth and a needle shank terminating in a puncture tip, has mounted within it a blunting member including an elongate probe which slidably fits within the bore of the needle shank. The probe terminates in a distal tip which is initially positioned short of the puncture tip of the needle so as not to interfere with injection of the needle either into a patient or into a connecting device. After injec-tion, the blunting member is advanced to an extended posi-tion in which its distal tip protrudes beyond the puncture tip, thereby effectively blunting the needle. This protrud-ing probe disables the needle from a re-use and blunts it sufficiently to prevent or greatly reduce accidental needle-stick wounds. A mechanical extension member, such as a pin or fluid flowing through the needle may be used to advance the blunting member to its extended position.

Description

BACKGROUND OF THE INVENTION

Field Of The Invention The present invention is concerned with a self-blunt-ing needle assembly especially suited for use as a hypoder-mic needle, and with hypodermic syrlnges including such nee-dle assemblies. More particularly, the present invention is concerned with a needle assembly which is self-blunting and disabled a~ter a single use.
Description o~ Related Art Hypodermic syringes designed to prevent reuse, i.e., designed to be effective for only a single use, are known.
For example, U.S. Patent 4,367,738 discloses a hypodermic syringe in which the plunger rod is fitted with flexible spikes which expand as the plunger is depressed in order to lock the plunger rod within khe barrel portion of the sy-ringe, thereby preventing retraction of the plunger rod ~or reuse of the syringe.
U.S. Patent 3,478,937 discloses a syringe in which the plunger stem 23 has a collar unit 25 secured thereon ~hich, when the p~unger is pushed thrDugh the barrel ll o~
~he hypo~erm~c syr~nge> passes thr~ugh r~ng 22 mounte~ at ~ne end ~ the barrel to pre~rent subsequent retL~actlon of iF'i--7 ` ` ~ S ~
5~^~ the plunger ~or ~eæ~4 o~ the devlce.
i' . U.S, Patent 4,233,975 discloses a syringe in which a plug is positioned in or ad~acent to the mouth of the needle so that movement of the plunger rod to expel fluid ~rom the syringe seats a plug which blocks the liquid flow path from the syringe barrel to the needle mouth, thereby disabling the device from ~urther use.
U.S. Patent 4,391,273 discloses a hypodermic syringe in which the plunger carries a protruding pin 67 which punc-tures a lower wall of the barrel in order to prevent reuse of the hypodermic syringe.
U.S. Patent l, 654~ 905 discloses a measuring syringe in which a tapering needle 9 has an enlarged head l0 and is 2~0 mounted ~or sliding movement within a hollow tube 3, between the positions shown in ~igures 2 and 3 o~ the patent. As explained beginning at page 1, line 72 of the patent, the needle 9 acts as a valve to meter a premeasured quantity of liquid into tube 3, and seats with the tip 16 o~ the needle 9 extending beyond the tip of tube 3. The syringe is then placed against the surface onto which fluid is to be applied and this forces back the tip 163 expelling liquid ~rom the tube 3.
1~ The art also shows syringes which are equipped with means intended to prevent accidental sticking of persons, ~uch as the operator, with the needle. It is estimated that over 2,000 accidental needle-stick wounds are sustained by health care workers in the United States each day. The problem is aggravated by the trend of moving treatment out of hospitals and into doctors' offices and neighborhood clinics as part of a program to reduce health care costs.
This trend increases the number and dispersion of health care workers who administer inJections and draw blood sam~
ples, while reducing the frequency of such in~ections per individ~ual health care worker. As a consequence, a larger ~h number o~ less experienced people are administering injec-tions and/or taking blood samples. Although in the past an occasional serious illness such as that caused by the hepa-~5 titis B virus was sustained as a result of an accidental needle-stick wound, the problem was not considered to be a serious one until the advent of the spreading of human im-munode~iciency virus (HIV) infection and the knowledge that this virus is transmissible to health care workers through ~a needle-stick wounds from a contaminated needle. The HIV
causes acquired immune deficiency syndrome (AIDS ?, a disease hich, insofar as is presently known~ is invariably fatal and which has already killed tens of thousands and infected possibly millions more. ~IV is often referred to simply as "the AIDS virus" and the Surgeon General of the Unlted States of America noted in a published (September, 1987) in-terview that there is no better way to become infected with :~29 5iZ~

the AIDS vlrus than to take blood from an AIDS patient and accidentally inflict a needle-stick wound with the contam-inated needle.
This situation has stimulated activity to develop de-vices which reduce or eliminate the possibility of accident-al needle-stick wounds without excessively increasing the unit cost of needles. U.S. Patent 3,890,971 discloses a single use, safety syringe which includes a plunger which is permanently lockable by detent members when the plunger has been operated to expel liquid from the barrel portion of the syrlnge. The disclosed structure further includes a slida-ble needle cap which is also permanently lockable by detent members to encase the needle within the sleeve.
Brochures distributed by ICU Medical Inc., of Mission Vie~o, California, show a hypodermic syringe which has a sheath carried on the needle. Insofar as can be discerned ~rom the brochure, which contains the notation "Patent Pend-ing", the needle extends beyond the sheath for use, and the sheath is grasped by the operator upon withdrawing the nee-~O dle in order to retract the needle within the sheath uponwithdrawal of the needle from the patient. In this way, the sheath guards against accidental pricking of the operator with the withdrawn needle.

2~ SUMMARY OF THE INVENTION
Generally, the present invention provides for a nee-dle assembly containlng a blunting member which is movable, either by fluid flow through the needle or by mechanical pressure, e.g., mechanical pressure applied by the plunger 3~ o~ the hypodermic syringe, from a retracted position in which the bluntlng member probe does not interfere with the r~ ~uncture tip of the needle~to an extended position, attained ~ter in~ection of the needle, in which the probe extends beyond the puncture tip thereby self-blunting the needle.
Preferably, the blunting member is moved to its extended po-sition prior to removing the needle so that the possibility of an accidental stick-wound is avoided. The devices of the ,, "

~2~0 present invention will usually be employed to inject liquids such as medications into patients or to withdraw body fluids therefrom. In some cases, they may be used to inject or withdraw gases although withdrawn gases will usually contain liquids entrained therein.
In accordance with the present invention there is provided a self-blunting needle assembly device which is suitable for attachment to a fluid flow means, such as a hypodermic syringe, pump, vacuum pump or the like for flowing fluids such as body fluids or liquids. The device comprises the following components. A needle member terminates in a punct~re tip and has a needle bore extending therethrough and definin~ a fluid flow path extending through the needle to the puncture tip. A blunting member is comprised of an elongate probe having a transfer means associated therewith, the blunting member being mounted within the needle member for movement of the probe by the transfer means axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of and thereby blunts the puncture tip. The probe is dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough. Locking means are dimensioned and configured to engage the blunting member so as to permit its movement in an outflow direction but prevent its return movement in an inflow direction thereby to retain it in its extended position.
In one aspect of the invention, the transfer means comprises a piston from which the probe axially extends, and the blunting member is mounted with its piston disposed in the fluid flow path for movement of the blunting member to its extended position by fluid flowing through the flow path. The transfer means may be dimensioned and configured to drive the blunting member from its retracted position to its extended position by outflow movement of fluid, e.g., liquid, along the flow path, i.e., in the direction from the mouth to the puncture tip, or it may be dimensioned and configured to so drive the blunting member by inflow movement 129~;2 o~ ~luid, e.g., liquid, along the flow path, i.e., in the direction from the puncture tip to the mouth. The piston may have one or more flow passages extending therethrough to permit the passage of liquid along the flow path past the piston.
In another aspect of the invention, the transfer means comprises an extension member mounted within the nee-dle member to transfer mechanical force applied to the ex-tension member to the blunting member, for movement thereof to its extended position.
In another aspect of the invention, the probe and the needle bore are each dimensioned and configured to provide therebetween an annular clearance for passage of liquid ~round the probe and through the needle bore. In a related aspect of the invention, the blunting member has a probe bore extending therethrough to define at least a segment of the fluid flow path through the needle member.
In accordance with another aspect of the invention, there is provided an improvement in a hypodermic syringe de-vice comprising (i) a hollow needle member having a shank which terminates in a puncture tip and through which a nee-dle bore extends, (ii) a barrel member providing a liquid reservoir and connected in liquid flow communication with the needle, and (iii) pressuri~ing means to impel liquid ~long a liquld flow path including the barrel member and the needle bore. The improvement comprises providing the syr-~6~
inge ~n~ with a needle assembly, blunting member and lock-ing means substantially as described above.
Other aspects of the invention are set forth in the drawings and in the detailed description given below.
As used herein and in the claims, the following terms have the stated meanings.
The term "outflow" used to characteri~e the direction of fluid or liquid flow through a needle member, syringe or the like means such flow therethrough in a fluid-dispensing d~reoting, i.e., in the direction from the needle mouth to-wards the puncture tip of the needle.

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The term 11inflow" used as above, means such fluid flow in a sample-taking direction, i.e., fluid flow in the direction from the puncture tip of the needle towards the needle mouth.
B~IEF DESCRIPTION OF T~E DRAWINGS
Figure l is an elevation view partially in cross sec-tion of a hypodermic syringe having one embodiment of a nee-dle member of the invention attached thereto;
1a Figure lA is a view in cross section on an enlarged scale of portion A of the needle of Figure l;
Figure lB is a view taken along line B-B of Figure lA;
Figure lC is a cross-sectional view taken along line C-C of Figure l;
Figure lD shows on an enlarged scale the needle of Figure l with the blunting member in its retracted position;
Figure lE is a view correspond~ng to Figure lD but showing the blunting member in its extended position to self-blunt the needle;
Figure lF is an exploded view, with a part broken away and on a further enlarged scale, of the blunting member and adapter of the needle member of Flgure l;
Figure lG is a partial view of the puncture tip end of the needle member in the self-blunted condition of Figure lE, pressed against tissue;
Figure 2 is a view corresponding to Figure l but showing another embodiment of the present invention;
Figure 2A is an enlarged perspective view of parts of the device of Figure 2 including the blunting member in portion A of Figure 2;
Figure 3 is a view corresponding to Figure l but showing yet another embodiment of the present invention;
Figure 3A is an elevation view in cross section of one component of the device of Figure 3;
Figure 3B is a plan view taken along line B-B of Fig-ure 3A;

zoo Figure 3C is an enlarged view in cross section of portion C of Figure 3;
~igure 3D is an enlarged view in elevation with parts broken away o~ another component of the device of ~igure 3;
~igure 4 is a partial view on an enlarged scale of another embodiment of the invention in which an extension member is carried on the plunger head of the syringe;
~igure 5 is a perspective view in cross section of a portion of another embodiment of the lnvention corresponding la to portion A of ~igure 2;
Figure 6 is a perspective view in cross section on an ~nlarged scale corresponding to portion A of Figure 2, but o~ another embodiment of the invention; and Figure 6A is a perspective view of a component of the embodiment of Figure 6.

DETAILED DESCRIPTION OF THE
INVENTION AND PRFRERRED EMBODIMENTS
Referring now to the drawings, ~igure 1 shows a hypo-~0 dermic syringe generally indicated at 10 comprising a needle assembly generally indicated at 12 and attached to a plung-er-type syringe 18. Needle assembly 12 includes a shank 14 attached at one end to a needle mouth 16 which is dimension-ed and configured to be attached in fluid flow communication to the syringe 18.
Plunger-type syringe 18 comprises a barrel member 20 whlch is generally of hollow, cylindrical configuration and terminates in a barrel no~zle 22 of tapered configuration and of smaller diameter than the main bore 20a of barrel 3~ member 20. At the end of barrel member 20 opposite that which carries barrel nozzle 22, a finger rest 23 is provided in the form of a laterally extending rim or shoulder extend-ing transversely of barrel member 20. A sealing plunger 24 is mounted for sliding, reciprocal movement within main bore 20a of barrel member 20 and is comprised of a plunger arm 26 having a thumb rest 28 at one end thereof and a plunger head 30 at the opposite end thereof. Plunger head 30 is made of , ~ .

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rubber or so~t plastic or other sultable material and is sized to provide a sliding seal within main bore 20a. Indi-cia I may be applied to barrel member 20 as illustrated in Figure 1 to indicate the volume o~ liquid contained within main bore 20a. The structure and configuration of plunger-type syringe 18 is thus entirely conventional; plunger-type syringe 18 may be made from a suitable plastic (synthetic organic polymerlc) material or it may be made of glass or metal or a combinatlon o~ such materials.
1~ Needle assembly 12, as best seen in the enlarged views of Flgures lD and lE, is constructed with shank 14 havlng one end thereof embedded within a base portion 16a of needle mouth 16 by belng fitted wlthin a bore (unnumbered) extending through base portion 16a. A cup portlon 16b o~
needle mouth 16 is sized to be mounted upon barrel nozæle 22 as lllustrated ln Figure 1. Needle bore 34 extends through needle mouth 16 and shank 14 and has a shank portion 34a and R mouth portion 34b which is of larger diameter than the ~hank portion and defines the cup-like configuration of cup ~n portion 16b- The end of shank 14 opposite that which is at-tached to needle mouth 16 terminates in a puncture tip 32 which, as is conventional, is formed at an angle to the lon-~itudlnal axis o~ shank 14 to provide a sharp puncture point in whlch the shank portion 34a of needle bore 34 (Figures lA
~nd lC) terminates. Cup portion 16b has a floor or base 16c to which shank 14 and shank portion 34a of needle bore 34 extend, to place the~shank portion 34a and mouth portion 34b oP needle bore 34 into flow communication wlth each other.
Needle mouth 16, like syringe 18, is thus of entirely con-ventional constructlon and may be made from any suitable ma-terlal. It is one of the advantages of the present lnven-tlon that conventional needles attachable to conventlonal syringes may readily be modlfied to be rendered self-blunt-lng in accordance with the teaching of the present inven-tlon.
A blunting member 36 (Figures lD, lE and lF) is mounted withln needle mouth 16 and comprises a transfer lZ9~Z(~
g means provided by a piston 38~ and a probe 40 which termin-ates in a distal tip 40a. Piston 38 has a pressure side 38a, a probe side 38b ~rom which probe 40 extends, and a plurality of ~low passages 42 (best seen in Flgures lA, lB
and lF) extending longitudinally therethrough. Probe side 38b, as best seen in Figures lA and lF, has a ce~tral re~c~ess r ~ J
A `~ormed therein to define a peripheral collar 39~whi-ch pro-`rudes axially of piston 38 so as to maintain flow passages 42 clear o~ floor 16c when piston 38 is seated thereon as illustrated in Figure lE. In this way, blockage or undue restriction of liquid flow through flow passages 42 is avolded. A plurality of detent means 44 (Figure lF) are formed about the periphery of piston 38. Detent means 44 may comprise a plurality of circular bands of shoulder-like protrusions which are wing- or wedge-shaped in cross-sec-tional profile, tapering from a thick cross section where they Join the body of piston 38 to a thin, distal edge which faces in a direction away from probe 40, i.e., ~aces upward-ly as viewed in Figures lF and lA.
~0 An adapter thimble 46 (Figure lF) is of generally tu-bular construction and has ~ormed about the exterior peri-phery thereo~ a plurality of mounting means 48 comprised of circular bands similar in construction to detent means 44.
Mounting means 48 thus comprise resilient structures which ~5 are wing- or wedge-shaped in cross-sectional profile, taper-ing from a thick cross section where they join the body of thimble 46 to a thin distal edge, and which project outward-ly from adapter thimble 46. Accordingly, when thimble 46 is wedged into place at the bottom (as viewed in Figures lA, lD
and lE~ of cup portion 16b of needle mouth 16, the resilient tendency of mounting means 48 to extend outwardly of adapter thimble 46 is resisted by the interior wall of cup portion 16b, thereby firmly retaining adapter thimble 46 in place.
In the case of needles which are manufactured specifically in accordance with the invention (as opposed to conventional needles which are adapted for use in the practice of the in-vention by insertion of a thimble 46 therein), the locking , 12~ 00 means may be made lntegral with needle mouth 16 or the base end o~ cup portion 16b may be made with detent members to ~irmly anchor thimble 46 in place. In any case, the inter-ior of adapter thimb~e 46 has formed therein locking means 50 comprised of a series of circular indented peripheral bands. The bands of locking means 50 are sized and config-ured relative to the detent means 44 of piston 38 to readily permit piston 38 to travel within adapter thimble 46 in an outflow direction o~ needle mouth 16, i.e., in a direction 1~ movlng ~rom needle mouth 16 towards the puncture tip 32 of ~hank 14 but, because of the con~iguration and resiliency of detent means 44, will prevent the reverse direction of move-ment o~ piston 38, i.e., inflow movement in the direction ~rom puncture tip 32 towards needle mouth 16.
1~ Thus, a conventional needle mouth 16 of the type il-lustrated in Figures 1, lD and lE, may be adapted for pur-poses o~ the invention by inserting an adapter th~mble 46 into cup portion 16b o~ needle mouth 16, forcing the adapter thimble 46 to the floor 16c of cup portion 16b, adjacent the ~0 mounted end o~ shank 14 as best seen in Figure lA. Blunting member 36 is then inserted into cup portion 16b o~ needle mouth 16 with probe 40 inserted into shank portion 34a o~
needle bore 34. Blunting member 36 may be positoned as il-lu~trated ln Flgures lA and lD, with the top or pressure ~lde o~ piston 38 (the side o~ piston 38 opposite that from which probe 40 extends) ~lush with the top o~ adapter thim-ble 46~ Alternatively, blunting member 36 may be positioned with a portion of piston 38 protruding outwardly ~rom the top of thimble adapter 46. Blunting member 36 will in any event be so positioned that the distal tip 40a (Figures lD, lE and lF) of probe 40 will lie short of puncture tip 32 as illustrated in Figure lD.
With needle assembly 12 mounted on a plunger-type sy-ringe 18 as illustrated in Figure 1, the hypodermic syringe 10 is operated in the conventional manner. For example, puncture tip 32 may be inJected through the seal o~ a bottle o~ liquid medication and plunger arm 26 retracted, i.e., o~

moved in an upward direction as viewed in Figure 1, to draw a required amount o~ medication into main bore 20a of barrel member 20. Blunting member 36 will remain stationary during this procedure because detent means ~14 are engaged with locking means 50 and will retain blunting member 36 against movement by the inflowing liquid which passes through needle bore 34 through flow passages 42 in piston ~8 thence into main bore 20a of barrel member 20. Typically, main bore 20a will be overfilled somewhat and a portion o~ the liquid ex-pelled by moving plunger 24 downwardly to insure the expul-sion of any air bubbles, the indicia on barrel member 20 be-ing used as a guide to leave a premeasured quantity of li-quid within main bore 20a. During this liquid expulsion step, blunting member 36 may move a small distance in an outflow direction. However, initial positioning of blunting member 36 is such as to allow for a limited amount of liquid outflow prior to distal tip 40a of probe 40 reaching the puncture tip 32.
Being thus prepared for use, hypodermic syringe 10 is then in~ected in the conventional manner into the patient and plunger 24 is pushed in the outflow direction (downward-ly as viewed in Figure 1) to expel the liquid from main bor-e 20a through needle bore 34 and flow passages 42 thence past puncture tip 32 and into the patient. In the embodiment il-lustrated, the diameter of probe 40, as best seen in ~lgure lC, is significantly less than the inside diameter of shank portion 34a of needle bore 34 so as to permit the flow of liquid through shank portion 34a in the annular space sur-rounding probe 40. Probe 40 is grooved in the illustrated embodiment, to provide additional annular flow space, and it alternatively may be of braided construction, for the same purpose. As liquid continues to move in the outflow direc-tion, piston 38 is moved by the flowing liquid from the po-sition shown in Figure lD to that shown in Figure lE, i.e. 9 to the position in which piston 38 becomes seated at the base of cup portion 16b of needle mouth 16.
Detent means 44 are sufficiently flexible so that s .

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-they can be deformed as piston 38 is moved in the out~low direction with a ratchet-like effect which permits piston 38 to move in the outflow direction under the ~orce applied by the pressure drop of the expelled liquid flowing through flow passages 42, until the probe side of piston 38 is seat-ed upon the ~loor 16c of cup portion 16b. At this point, as shown in Figure lE, distal tip 40a of probe 40 extends through shank 14 and outwardly of puncture tip 32. Distal tip 40a is o~ blunt con~iguration as best seen in Figure lF, ~0 and is locked in its extended position by the engagement o~
detent means 44 and locking means 50. There~ore, upon with-drawal o~ the needle from the patient puncture tip 32 is e~-fectively blunted by the protruding distal tip 40a. As il-lustrated in Figure lG, the protruding distal tip 40a o~
probe 40 blunts the needle mouth 16, thereby preventing re-entry of puncture tip 32 into tissue T in a needle-stick accident.
Referring now to Figures 2 and 2A, there is shown an-other embodiment o~ the invention wherein the transfer means ~0 is provided by an extension member which is mechanically ac-tuated, rather than by a piston which is actuated by the li-quid or fluid being transported through the device. Thus, a plunger-type syringe 18' is substantially identical to sy-ringe 18 described with respect to the Figure 1 embodiment and the corresponding parts thereo~ are identically numbered to those o~ Figure 1 except ~or the addition o~ a prime in-dicator. Similarly, needle mouth 16' and shank 14' are con-structed identically or similarly to the corresponding parts o~ the Figure 1 embodiment.
Re~erring to Figure 2A, an adapter thimble 461 is seated upon floor 16c' and mounted within cup portlon 16b' in a manner substantially identical to that explained in detail with respect to the embodiment o~ Figure 1. However, in the embodiment o~ Figures 2 and 2A, blunting member 52 comprises a piston 54 having piston vent passages 55 extend-ing therethrough and detent means (unnumbered, and best seen in Figure 2A) formed about its periphery. The detent means ~ ~.

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of piston 54, which has a pressure side s4a and a probe side s4b connected by vent passage 55, correspond to detent means 44 of the Figure 1 embodiment and are dimensioned and configured to engage locking means (unnumbered) corresponding to locking means 50 of Figure lA and formed on the interior of adapter thimble 46'.
A probe 56 extends from the probe side 54b o~ piston 54, terminates in a distal tip 56a thereof, and is received within the shank portion 34a' of the needle bore. The needle bore is not separately numbered in Figures 2 and 2a (apart from shanX portion 34a' thereof) but corresponds to needle bore 34 of Figure ld and of course extends entirely through the needle assembly 12'. Probe 56 is hollow and has a probe bore 58 extending therethrough. An extension member 60, which extends from the pressure side 54a of piston 54 and terminates in a distal tip 60a, is comprised of a segment of an integral member, the other side of which extends from probe side 54b as the probe 56. Obviously, the extension member 60 and the probe 56 could be comprised of two separate parts respectively joined to opposite sides of piston 54. Probe bore 58 extends through both probe 56 and extension member 60.
Accordingly, in operation, as plunger 24' is moved downwardly, medication or other liquid contained within main bore 20a' is expelled through probe bore 58, passing through extension member 60 and then probe 56 for discharge from puncture tip 32'. When plunger head 30' engages the distal tip 60A of extension member 60, continued movement of plunger head 30' in the outflow direction forces extension member 60 and thus piston 54 downwardly until piston 54 is seated on floor 16c'; at this point, probe 56 is at its extended position, with its distal tip 56a protruding beyond puncture tip 32', in the manner illustrated in Figures lE
and lG with respect to the Figure 1 embodiment. Piston vent passages 55 allow liquid delivered to needle mouth 16' to displace air from chamber C formed between probe side 54b of piston 54 and floor 16c' of needle mouth 16'. During movement of blunting member 52 to its extended position, liquid in chamber ~ is expelled through piston vent passages 55 as chamber C is reduced in volume and then eliminated as piston 54 seats on lZ~.~ZOC~

floor 16c'. The detent means (unnumbered) associated with piston 54 and the locking means (unnumbered) associated with adapter thimble 46' permit movement in the outflow direction of piston 54, but prevent its return movement in the inflow direction so that probe 56 will be locked in its extended position, with piston 54 thereof in place in abutting con-tact with floor 16c'. In the illustrated embodiment, when plunger head 30' engages extension member 60 it will seal probe bore 58 against further liquid flow therethrough. In l~ an alternative embodiment, the distal tip 60a of extension member 60 could be formed in a crenalated configuration, or holes could be provided in extension member 60 to provide flow passages -to permit continued liquid expulsion there-through after plunger head 30' engages extension member 60.
,In the embodiment illustrated in Figures ~-3~, ~iquid flow is through needle bore ~ and probe bore 58. Alternatively, probe 56 could be made of a sufficiently small diameter to provide an annular liquid or fluid flow space between it and shank portion 34a of~needle bore ~. In such case, exten-~0 sion member 60 could be solid, the liquid flowing throughpiston flow passages 55.
Referring now to Figure 3, there is shown yet another embodiment of the invention, including a plunger-type sy-ringe 18~' which is of substantially similar construction to syringes 18 and 18' of Figures 1 and 2 and a needle assembly 12~ which is substantially similar in construction to nee-dle assemblies 12 and 12' of Figures l and 2. Accordingly, corresponding parts are identically numbered to those of the Figures l and 2 embodiments, except for the indication of a ~o double prime indicator. In this embodiment, blunting member 62 is similar in construction to blunting member 52 of the Figure 2 embodiment, except that, as best seen in Figure 3D, probe 66 terminates at the pressure side 64a of piston 64 and extends only from probe side 64b of piston 64. Probe 66 has a probe bore 67 extending therethrough and through pis-ton 64 so that it extends through blunting member 62 to pro-vide a liquid flow path therethrough, and terminates in dis-5~0 tal tip 66a. As seen ln Figure 3, blunting member 62 is po-sitioned initially flush with the top of adapter thimble 46 ", in the same relative position as illustrated in Figure lA with respect to blunting member 36. In this embodiment, a separate extension member 68 is provided and, as shown in Figures 3A, 3B and 3C, has a disc-shaped mounting head 70 at one end thereof and an extension arm 72 extending axially there~rom and through which an extension bore 74 extends.
Extension bore 74 also extends through mounting head 70 and la thus through the entire extension member 68. A plurality of radlal slits 76 are formed in mounting head 70 and extend to the periphery thereof. As best seen in Figure 3C~ extension member 68 is mounted within syringe 18 " by mounting means provided by a circumferential mounting shoulder 78 protrud-1~ ing from the inside wall of barrel member 20 " and having anlnside diameter which is slightly smaller than the outside diameter of mounting head 70. Shoulder 78 is seen to have an upper (as viewed in Figure 3C) inwardly tapering section ~nd a lower constant diameter section. Extension member 68 2~ may be made of plastic or a metal such as steel and mounting head 70, havlng the plurality of slits 76 formed therein, may readily be fltted in place by being force-fit against the inward tapering section of shoulder 78. Alternatively, a shallow groove may be formed within shoulder 78, generally con~orming to the area indicated by dash lines in ~igure 3C, to snap-fit and hold extension member 68 in place until it ls dislodged by plunger head 30 " as described below.
In operation, as plunger 24 " is pushed in the out-~low direction, liquid contained within main bore 20a " is 3~ ~xpressed through extension bore 74 (and s~ ts 76) into nee-~ Sle mouth 16 ", thence through probe bore ~ of blunting '~` mèmber 62 for eJection past puncture tip 32 ". As plunger 24 " approaches the end of its travel within barrel member 20 ", plunger head 30 " engages mounting head 70 of exten-sion member 68 and pushes it past shoulder 78, mounting head 70 and shoulder 78 being respectively dlmensioned and con-flgured to enable readily dislodging extenslon member 68 ~z~

from shoulder 78. As extension member 68 is thus forced to move in the outflow direction, the distal end 72a o~ arm 72 thereof engages piston 64 of blunting member 62 and forces it in the outflow dlrection to move it and probe 66 from its retracted to its extended position, in which distal tip 66a of probe 66 protrudes past puncture tip 32 " in a manner as illustrated in Figure lE with respect to the Figure 1 embod-iment. Thus~ in the embodiment of Figure 3, the extension member 68 is separate from the blunting member 62 but serves 1~ the same function as the integral extension member 60 of the Flguré 2 embodiment.
Figure 4 shows yet another embodiment of the inven-tion in which the extension member is separate from the blunting member but, in this embodiment, is mounted on and 1~ carried by the plunger head. Thus, a plunger 24';' compris-es a plunger arm 26" ' having a conventional mounting lug 84 on which a plunger head 82 is carried for sllding, sealing movement within a barrel member 20 "'. Plunger head 82 is sho~n in cross section to reveal a conical-shaped head ~a mounting recess 85 which serves to hold plunger head 82 in place on lug 84.
Plunger head 82 also has a conical-shaped extension mounting recess 86 formed therein within which is mounted an extension member 88 which has a disc-shaped head 90 which is snap-~itted within recess 86. Plunger head 82 is made of æ
resilient, elastic material, such as rubber or a suitable 50~t plastic material, so that the respective openings (un-numbered) of recesses 85 and 86 may be deformed for inser-tion of, respectively, lug 84 and head 90 therein, and will then regain their original shapes to securely hold lug 84 and extension member 88 in place within plunger head 82.
Extension member 88 has an elongate extension arm 92 extend-ing therefrom; extension arm 92 terminates in a distal tip 92a and has a plurality of longitudinally extending grooves 35 94 formed therein. A needle assembly 12 ' " which, in the illustrated embodiment, is identical to needle assembly 12' ~
o~ the Figure 3 embodiment is mounted in fluid flow communi-~;~95~0 [) cation with barrel member 20 "'. Needle assembly 12 " ' con-tains a blunting member 62' therein, which is substantially identical to the blunting member 62 of the Figure 3 embodi-ment.
In operation, as plunger head 82 is advanced in the outflow direction forcing liquid contained within main bore 20a ~ ' in the outflow direction through needle assembly 12 "' ~or dispensing therefrom, downward movement is contin-ued until the distal tip 92a of extension arm 92 engages the piston 64' of blunting member 62' and forces it in the out-~low direction to move it from its retracted to its extended position as described above with respect to the Figure 3 em-bodiment. As plunger 24 " ' approaches the end of its travel within barrel member 20 "' and extension arm 92 enters a 1~ narrow barrel nozzle 22 "', the grooves 94 enable the pass-age of liquid past extension arm 92 and into and through needle assembly 12 " '. In an alternative embodiment, barrel nozzle 22 " ' can be made of larger diameter as illustrated, for example, in the Figure 3 embodiment, and a suitable guide means having flow passages formed therein could be positioned within barrel member 20 "' adjacent barrel nozzle 22 "' in order to receive and guide extension arm 92 into contact with piston 64' of blunting member 62'.
Figures 5 and 6 respectively show-portions of two other embodiments of the invention; the portions shown gen-erally correspond to portion A of Figures 1 and 2, i.e., the portion showing the piston of the blunting member received within an adapter thimble mounted in the needle mouth 16.
Whereas the embodiments of Figures 1-4 illustrate devices in which the transfer means is dimensioned and configured to drive the blunting member from its retracted to its extended position by outflow movement of liquid along the flow path, e.g., when dispensing medication ~rom the device into a pa-tient or conduit, the embodiments of Figures 5 and 6 illus-trate devices wherein the transfer means is dimensioned and configured to drive the blunting member from its retracted position to its extended position by inflow movement of li-2(~ [3 quid along the flow path. That is, the embodiments of Fig-ures 5 and 6 will operate the blunting member when liquid s drawn into the device, such as when a blood sample is taken.
Referring now to Figure 5, there is shown a section of the needle mouth 16~ the base portion 16a of which con-tains the shank 14 o~ the needle assembly and cup portion 16b which defines the mouth portion 34b of the needle bore extendin~ therethrough. In this embodiment, adapter thimble 1~ 96 is comprised of a cylindrical body portion 97 closed at one end by a disc-shaped end wall 98 having a flow passage 100 formed therein. Adapter thimble 96 is ~itted within base portion 16a o~ needle mouth 16 by a rim portion 96a which is force-~itted within cup portion 16b of needle mouth 16. The open end of cylindrical body portion 97 opposite that closed by end wall 98 is seated upon floor 16c of nee-~le mouth 16. Rim portion 96a may have resilient mounting means thereon, such as mounting means 48 of the embodiment illustrated in Figure lF. A blunting member 102 is compris-~a ed of a piston 104 and a probe 106 which is hollow to definea probe bore 108 which extends to and through piston 104.
Piston 104 has a probe side 104b ~rom which ~probe 106 ex-tends and an opposite, pressure side 104a. Detent means 110 are formed about the periphery of piston 104 and are dimen-sioned and configured to engage locking means 112. Detent means 110 and locking means 112 are analogous to, and may be substantially identical to, detent means 44 and locking means 50, best seen in Figure lF. Piston 104 is positioned with pressure side 104a closely spaced from the inside sur-3~ ~ace o~ end wall 98 to form a pressure chamber P therebe-tween. At the end of body portion 97 adjacent to ~loor 16c, there is provided a plurality o~ first vent passages 114 which place the portion of adapter 96 which is enclosed be-neath piston 104, into ~low communication with an annular space 116 formed between the outer wall o~ adapter 96 and the inner wall o~ cup portion 16b. A plurality o~ second vent passages 118 are formed abou~ the perlphery of end wall ~.

- 12~520~

98 so as to place annular space 116 in ~low communication with the mouth portion 34b of the needle bore.
The needle assembly o~ which needle mouth 16 ~orms a part is fitted onto any sultable barrel nozzle, such as bar-rel nozzle 22 "' of the ~igure 4 embodiment.
In operation, the puncture tip (not shown) of the shank 14 is in~ected into a patient or other source of li-quid so that the puncture tip enters, e.g., a vein, from which blood is to be drawn. The plunger of the barrel mem-1~ ber (not shown) to which the needle assembly is attached isthen moved in an inflow direction, i.e., in a direction away ~rom needle mouth 16, thereby creating a partial vacuum or reduced pressure within the main bore of the barrel member ~nd thus within mouth portion 34b of the needle bore.
1~ ~lood, or other fluid being drawn, enters the shank 14 then passes through probe bore 108 into the pressure chamber P, between the pressure side 104a of piston 104 and the interi-or of end wall 98. The blood or other liquid being sampled will flow through the flow passage 100 through mouth portion 2~ 34b thence into the barrel member or other collector to which the needle assembly is attached. However, the rate of blood flow thro~ugh flow passage 100 is attenuated because of the small flow 3iamt!~R of passage 100~ and the resultant pressure lncrease in the pressure chamber P will force pis-ton 104 downwardly, thereby moving blunting member 102 and its associated probe 106 from its retracted position to its e~tended position to blunt the puncture tip as illustrated in Figure lG with respect to the ~igure 1 embodiment. As blood or other fluid is drawn through probe bore 108 into 3~ the chamber formed between piston 104 and end wall 98 and forces piston 104 downwardly, air trapped between piston 104 and floor 16c may escape through first vent passages 114 thence through annular space 116 and second vent passages 118. In the embodiment illustrated in ~igure 5, the interi-or walls of cup portion 16b, i.e., the walls defining mouth portion 34b of the needle bore, divergQ outwardly in an in-~ c~L~oQ~c~L h~ P ~D~
flow direction and the~ ~d_~ 97 of thimble adapter 96 may ~2~;2010 have a substantially constant, circular cross section. This configuration provides a tapering annular space 116. If cup portion 16b has a constant~diamete mouth bore 34b, the cyl-~ ~ ~,~ 0~ p~6~ T~ L~ 9~
`indrical~portion 97~is made with a somewhat smaller diameterto provide the annular space 116. When piston 104 is driven downwardly to where it seats on floor 16c, the needle is blunted by the protrusion of the distal tip (not shown) of probe 106, but the device is capable of continuing to draw blood or the other sample being taken until the desired 1~ ~uan~ity of sample is received within any barrel member. At that point, the needle is withdrawn from the patient.
Referring now to Figures 6 and 6A, there is shown yet another embodiment of the present invention. In this embod-iment, an adapter thimble 120 (Figure 6A) comprises a cylin-drical body portion 122 having a series of adapter flow pas-sages 124 formed about the periphery of the base 126 thereof so that the base of body portion 122 has a crenalated ap-pearance. An end wall 128 closes the end of cylindrical body portion 122 opposite the base 126 and is of larger dia-2~ meter than the outside diameter of body 122 to provide aperipheral shoulder portion 128a having a circular shoulder sidewall 128b. A series of end wall apertures 130 are form-ed in end wall shoulder 128a and are equally angularly spac-ed about the periphery thereof. Adapter thimble 120 is force-fitted within a needle mouth 16 which, like needle mouth 16 of the Figure 5 embodiment, includes a cup portion 16b and a base portion 16a having a floor or base 16c which is in communication with the bore of shank member 14. The force-fit within cup portion 16b is attained by engagement of shoulder sidewall 128b against the interior walls of cup portion 16b. As in all the other illustrated embodiments, cup portion 16b also serves to define mouth portion 34b of the needle bore. Locking means 132, similar to locking means 112 of the Figure 5 embodiment, are formed on the in-terior wall o~ cylindrical body portion 1?2. Cylindricalbody portion 122 is of smaller diameter than the inside di-ameter of mouth portion 34b within which it is positioned, ~5~ 0 to provlde an annular space 125 between the inner wall of needle mouth 16 and the outer wall of cylindrical body por-tion 122.
A blunting member 134 comprises a piston 136 having a probe 138 extending radially therefrom, the peripheral side-wall of piston 136 having detent means 140 formed thereon.
Detent means 140 and locking means 132 are respectively di-mensioned and configured, and cooperate with each other in a m~nner described in detail with respect to the Figure 1 em-1~ b~diment, so that blunting member 134 can move in an outflowdirection but is locked against retrograde movement in the inflow direction.
Probe 138 defines a probe bore 139 which extends therethrough from the distal tip (not shown) of probe 138 to 1~ and through piston 136. Piston 136 has a probe side 136b ~rom which probe 138 extends into needle shank 14 in a man-ner similar to that shown and described in detail with re-spect to the embodiments of Figures 1, 2 and 3. Piston 136 has a pressure side 136a opposite probe side 136b, pressure 2~ side 136a and the interior of end wall 128 cooperating to de~ine a pressure chamber P therebetween.
In operation, the needle assembly of which needle mouth 16 is a part is affixed to a suitable liquid transfer means such as a barrel member similar or identical to any ona of the barrel members 20, 20', 20 " or 20 "'. With the plunger of the barrel member in its fully extending outflow position, i.e., at the end of its range of travel towards the needle assembly, the shanl~ 14 of the needle is inJected into the patient or into a connector to withdraw a sample of 3~ body fluids, e.g., into a vein to draw a blood sample. The plunger is then raised, thus forming a partial vacuum or re-duced pressure within the barrel member. Since end wall apertures 130 connect the annular space 125 with mouth por-tion 34b of the needle bore, a reduced pressure is effectu-ated within annular space 125 and this, in cooperation with.the blood or other body fluid entering as shop n by the un-marked arrows in Figure 6, into the chamber~defined between piston 136 and end wall 128, forces blunting member 134 in an outflow direction, i.e., downwardly as viewed in Figure ~ ~6. Liquid collects in the chamber between piston J~ and `~' ~ ` end wall 128 until outflow direction movement-of piston l3~
5 clears the adapter flow passages 124, thereby permlttlng the collected body fluids to flow through passages 124 thence through end wall apertures 130 into mouth portion 34b of the needle bore thence into the barrel member or o~her collect-6 ~3~
ing device. At this point, blunting member 134~will 10 have advanced to and be locked in the extended position ofprobe 138, thereby self-blunting the puncture tip (not shown) of needle shank 14 in a manner as described and il-lustrated, for example, with respect to Figures lE and lG.
Tests with conventional hypodermic syringe needles have shown that even when utilizing a solid probe and flow-ing a liquid in the annular space between the solid probe and the inside walls of the shank portion of the needle bore, an adequate delivery rate of liquid may be attained.
For example, stock hypodermic tubing (for the needle shank) ~ made of T304/T316 stainless steel is commercially available in a wide range of gauges. An 18RW gauge steel hypodermic tubing has a nominal inside diameter of 0.033 inches. The manufacturer's specifications (All-Tube Division, a Micro-group Company, of Midway, Massachusetts) call for an inside diameter range of 0.0315 to 0.0345 inches. A solid probe as illustrated, ~or example, in Figure lA of the invention, preferably including the striations or flutings therein il-lustrated, and having a diameter of, e.g., about 0.020 to 0.028 inches will provide a satisfactory self-blunting probe. At a given pressure applied to the plunger of a sy-ringe, a delivery rate of from about one-half to two-thirds of that which could be attained with an unencumbered needle bore is attained. A satisfactorily strong needle shank can also be made from 18XX gauge stainless steel stock hypoder-mic tubing which has a nominal inside diameter of 0.045inches, the manufacturer's specifications calling for an inside diameter range of from 0.044 to 0.046 inches. Within 12~5;2~1) this stock tubing a hollow probe made of l9XX gauge stock hypodermic tubing, which has a nominal outside diameter of 0.0425 inches, and a specification range of from 0.042 to 0.0~3 inches, may be utilized. The l9XX gauge stock tubing has a nominal inside diameter of 0.0375 inches, the specifi-cations calling for an inside diameter range of from 0.0365 to 0.0385 inches. Thus, a hollow tube probe made of l9XX
g~uge stock hypodermic tubing will slidably fit within a needle shanlc made of 18XX gauge hypodermic tubing and pro-vide a probe bore through ~hich the liquid may be flowed, asillustrated in the embodiment of Figures 2 and 3, of from 0~0365 to 0.0385 inches. This is larger than the inside di-~meter of an unencumbered 18RW gauge needle. This arrange-ment thus provides a larger flow diameter through the probe 1~ bore than would be provided through a conventional needle made o~ 18RW gauge stock hypodermic tubing.
While various embodiments of the invention have been described with particular reference to hypodermic-type nee-dles used primarily ~or injections directly into the body, those skilled in the art will appreciate that the invention is not so limited but, rather, is broadly applicable to pro-vide self-bluntlng needles regardless of the use to which the needles are put. For example, it is common practice to connect a needle to a catheter or intravenous (IV) device by lnsertlng the needle through a membrane seal of a catheter-or IV-connecting device, which of course exposes the needle to the body fluids being transported through the catheter-or IV-connecting device. Upon breaking the connection by removing the needle, an accidental needle stick wound can transmit infection ~rom the needle, even though the needle was never directly in~ected into the patient's body because it nonetheless was contacted by the body fluids and/or med-ication for which it served as part of a conduit.
The invention is also broadly applicable to needles connected to liquid transfer devices other than syringes as illustrated in Figures 1, 2 and 3, for example, it is appli-cable to the needle assemblies designed to be in~ected di-:~LZ~2(~

rectly into a patient and connected via a tube or other suitable connection to an IV bag or container, to a blood or other body fluid connector, or the like. Such needle assem-blies may also be provided with a blunting device in accord-ance with the invention, which blunting device or at least the probe thereof may be moved from its retracted to its ex-tended position either by liquid flow through the needle as-sembly or by mechanical manipulation. For example, an ex-tension member may be fitted to an IV or blood bag needle 10 ~nd aGtuated ~ust prior to removing the needle from the pa-tient. Generally, the self-blunting action of the protrud-ing probe has been found to be e~fective even when the probe protrudes a very small distance, as little as about fifty one-thousandths (0.050) of an inch, beyond the most distal 1~ portion of the puncture tip. A~cordingly, in most, if not all~ cases no patient discom~ort or harm will be sustained by having the probe in its extended, self-blunting position while the needle is still within the patient's body. None-~heless, at least the mechanical-actuating aspects of the invention permit deferring movement of the probe to its ex-tended position until immediately prior to removing the nee-dle from the patient. Alternatively, when equipped with a mechanical actuating device of the type illustrated in ~ig-ures ~ and 3, the blunting member may be moved to its ex-tended, self-blunting position simultaneously with or imme-diately after removal from the patient. However, this tech-nique involves the risk, albeit a minimal one, of an acci-den~al needle-stick wound sustained in the act of removing the needle ~ust prior to actuating the self-blunting device.
30 Normally, it is preferable and causes no discomfort or harm to the patient to have the blunting device moved to its ex-tended positlon prior to removal of the needle from the pa-. tient, at any time from immediately after injection of theneedle into the patient to immediately prior to withdrawing 35 it.
Generally, suitable configurations of the invention may be utilized with any liquid transfer means. For exam-~2~;~ZO~

)~
~j ple, vacuum tubes are known for utilization~the taking of body fluid samples~ such as blood samples. In such devices~
a needle is injected into a patient's vein and a sealed tube ~rom which air has been evacuated is mounted on a connector 5 which penetrates a vacuum seal member, such as a membrane~
on an open end o~ the tube. This exposes the needle to the vacuum or reduced pressure within the tube which acts in concert with the patient's blood pressure to fill the tube with a blood sample. The needles of the invention are of 10 course adaptable for use with such vacuum tube sampling de-vices as well as with any liquid transfer means including conventional plunger-type syringes, squeeze bulb syringes, vacuum sampling devices or pressurized fluid-dispensing de~
vices.
15~ Needles of the invention have broad utility for medi-cal, veterinary and other uses, such as autopsies and pre-paration of bodies for interment, generally whenever and ~her~ever a needle must be injected into tissue or into a A ~onnector or other device in which the needle and/or its tip ~0 is exposed to contamination, and it is desired to blunt the needle to prevent reinJection of it. The prevention of re-injection prevents both deliberate reuse and accidental nee-dle stick-wounds with a potentially contaminated needle.
Although the above-described embodiments use a mech-~5 anical or fluid force imposed axially on the blunting member to advance it to its extended position, a rotational action may also be utilized to axially advance the blunting member.
Thus, the blunting member may carry turbine-like blades as part of the transfer means and be mounted in a screw-thread-ed bore so that the blades are rotated by liquid passingthereover to rotate the blunting member. Rotation of the blunting member within the screw-threaded bore axially ad-vances the probe to its extended position.
~or example, a screw-thread may be carried on the piston of the blunting member and be received in a threaded bore so that movement of liquid past the blades of the transfer means rotates the screwthread to drive the blunting " 12~520~

member probe from its retracted to its extended position.
While the invention has been described in detail with re~erence to specific preferred embodiments thereo~, it will be appreciated that'such specific embodiments are illustra-tive only and the scope o~ the invention is more fully de-scribed in the appended claims.

Claims (29)

1. A self-blunting needle assembly device suitable for attachment to a fluid flow means comprises:
(a) a needle member terminating in a puncture tip and having a needle bore extending therethrough and defining a fluid flow path extending through the needle to the puncture tip;
(b) a blunting member comprising a elongate probe having transfer means associated therewith, the blunting member being mounted within the needle member for movement of the probe by the transfer means axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough; and (c) locking means dimensioned and configured to engage the blunting member so as to permit its movement in an outflow direction but prevent its return movement in an inflow direction, whereby to retain it in its extended position.

2. The device of claim 1 wherein the transfer means comprises an extension member mounted within the needle member to transfer mechanical force applied to the extension member to the blunting member for movement thereof to its extended position.

3. A self-blunting needle assembly device suitable for attachment to a fluid flow means comprises:
(a) a needle member terminating in a puncture tip and having a needle bore extending therethrough and defining a fluid flow path extending through the needle to the puncture tip;

(b) a blunting member comprising an elongate probe having associated therewith transfer means comprising a piston from which the probe axially extends, the blunting member being mounted with its piston disposed in the fluid flow path, whereby liquid flowing through the flow path acts on the piston to move the blunting member axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough; and (c) locking means dimensioned and configured to engage the blunting member and retain it in its extended position.

4. In a hypodermic syringe device comprising (i) a hollow needle member having a shank which terminates in a puncture tip and through which a needle bore extends, (ii) a barrel member providing a liquid reservoir and connected in fluid flow communication with the needle member, and (iii) pressurizing means to impel fluid comprising a liquid along a fluid flow path including the barrel member and the needle bore, the improvement comprising:
(a) a blunting member comprised of an elongate probe having a transfer means associated therewith, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to liquid flow therethrough, the blunting member being mounted in the device for movement of the probe by the transfer means axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, and (b) locking means carried within the hypodermic syringe device and dimensioned and configured to engage the blunting member and retain it in its extended position.

5. The device of claim 4 wherein the transfer means comprises a piston from which the probe axially extends, the blunting member being mounted with its piston disposed in the fluid flow path whereby liquid flowing through the flow path acts on the piston to move the blunting member to its extended position.

6. The device of claim 2 or claim 5 wherein the piston has one or more flow passages extending therethrough to permit the passage of fluid along the flow path past the piston.

7. The device of claim 3 or claim 5 wherein the piston has a probe side from which the probe extends and an opposite pressure side, and further has one or more piston flow passages formed therein to admit fluid therethrough between the pressure side and the probe side.

8. The device of claim 1, claim 3, claim 4 or claim 5 wherein the transfer means is dimensioned and configured to drive the blunting member from its retracted position to its extended position by outflow of fluid along the flow path.

9. The device of claim 1, claim 3, claim 4 or claim 5 wherein the transfer means is dimensioned and configured to drive the blunting member from its retracted position to its extended position by inflow of fluid along the flow path.

10. The device of claim 4 wherein the transfer means comprises an extension member mounted within the needle member to transfer mechanical force applied to the extension member to the blunting member for movement thereof to its extended position.

11. The device of claim 1, claim 3, claim 4 or claim 5 wherein the probe and the needle bore are each dimensioned and configured to provide therebetween an annular clearance for passage of fluid around the probe and through the needle bore.

12. The device of claim 1, claim 3, claim 4 or claim 5 wherein the blunting member has a probe bore extending therethrough to define at least a segment of the fluid flow path through the needle member.

13. The device of claim 1 wherein the locking means comprises a detent member and a detent recess, one of which is carried on the blunting member and the other of which is disposed within the needle member, the detent member and detent recess being dimensioned and configured to engage each other so as to prevent movement of the blunting member in the direction from its extended position towards its retracted position.

14. The device of claim 13 wherein the transfer means comprises a piston from which the probe axially extends and one of the detent member and detent recess is carried on the piston and the other is carried on a cylindrical thimble within which the piston is mounted for axial movement.

15. The device of claim 1, claim 3, claim 4 or claim 5 wherein the needle member has a mouth dimensioned and configured to attach the needle assembly in fluid flow communication to a fluid transfer means, and the locking means is disposed within the needle mouth.

16. The device of claim 4, claim 5 or claim 10 wherein the pressurizing means comprises a sealing plunger mounted for sliding movement within the barrel member.

17. The device of claim 10 wherein the piston has a probe side from which the probe extends and an opposite, pressure side, and the extension member is mounted on the piston and extends from the pressure side thereof.

18. A self-blunting needle assembly device suitable for attachment to a fluid flow means comprises:
(a) a needle member terminating in a puncture tip and having a needle bore extending therethrough and defining a fluid flow path extending through the needle to the puncture tip, the needle member having a mouth dimensioned and configured to attach the needle assembly in fluid flow communication to a fluid transfer means;
(b) a blunting member comprising an elongate probe having associated therewith transfer means comprising a position from which the probe axially extends, the blunting member being mounted with its piston disposed in the fluid flow path, whereby liquid flowing through the flow path acts on the piston to move the blunting member axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough; and (c) locking means comprising a cylindrical thimble within which the piston is mounted for axial movement, said locking means being disposed within the needle mouth and being dimensioned and configured to engage the blunting member and retain it in its extended position.

19. A self-blunting needle assembly device suitable for attachment to a fluid flow means comprises:
(a) a needle member terminating in a puncture tip and having a needle bore extending therethrough and defining a fluid flow path extending through the needle to the puncture tip;

(b) a blunting member comprising an elongate probe having associated therewith transfer means comprising a piston from which the probe axially extends, the blunting member being mounted with its piston disposed in the fluid flow path, whereby liquid flowing through the flow path acts on the piston to move the blunting member axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough;
(c) locking means dimensioned and configured to engage the blunting member and retain it in its extended position;
and (d) a pressure chamber within which the piston is mounted, the pressure chamber being in flow communication with (i) at least one chamber inlet passage to admit fluid from the needle member into the pressure chamber and (ii) with at least open chamber outlet passage to permit fluid to escape from the pressure chamber, the inlet and outlet passages having respective flow diameters dimensioned and configured to increase fluid pressure within the pressure chamber so as to drive the blunting member from its retracted position to its extended position.

20. The device of claim 19 wherein the chamber outlet passage has a smaller total cross-sectional flow area than the total cross-sectional flow area of the chamber inlet passage.

21. The device of claim 19 wherein the pressure chamber is dimensioned and configured to drive the blunting member from its retracted position to its extended position by outflow of fluid along the flow path.

22. The device of claim 19 wherein the pressure chamber is dimensioned and configured to drive the blunting member from its retracted position to its extended position by inflow of fluid along the flow path.

23. The device of claim 19 wherein the piston has a probe side from which the probe extends, the needle has a needle mouth within which an adapter is mounted, and the adapter is dimensioned and configured (a) to cooperate with the piston to define the pressure chamber between the adapter and the piston an (b) to expose the probe side of the piston to suction imposed on the needle mouth whereby the suction cooperates with pressure generated within the pressure chamber to impact a net force acting on the piston to urge it towards its extended position.

24. The device of claim 19 wherein the piston has a probe side from which the probe extends and an opposite pressure side, the piston is mounted within an adapter which cooperates with the piston to define the pressure chamber between the adapter and the pressure side of the piston, and the adapter has vent passages formed therein to vent the space formed between the adapter and the probe side of the piston.

25. A self-blunting needle assembly device suitable for attachment to a fluid flow means comprises:
(a) a needle member terminating in a puncture tip and having a needle bore extending therethrough and defining a fluid flow path extending through the needle to the puncture tip;
(b) a blunting member comprising an elongate probe having associated therewith transfer means comprising a piston having piston flow passages extending therethrough, the blunting member including a probe bore extending therethrough to define at least a segment of the fluid flow path through the needle member, the blunting member being mounted within the needle member for movement of the probe by the piston axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough;
(c) locking means dimensioned and configured to engage the blunting member and retain it in its extended position;
and said needle having a needle mouth having a floor, the piston being mounted within the needle mouth for seating on the floor thereof when the blunting member is in its extended position, and the piston having a stop member projecting axially from the probe side thereof to space the piston flow passages from the floor when the blunting member is in its extended position.

26. In a hypodermic syringe device comprising (i) a hollow needle member having a shank which terminates in a puncture tip and through which a needle bore extends, (ii) a barrel member providing a liquid reservoir and connected in fluid flow communication with the needle member, and (iii) pressurizing means to impel fluid comprising a liquid along a fluid flow path including the barrel member and the needle bore, the improvement comprising:
(a) a blunting member comprised of an elongate probe having a transfer means associated therewith, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to liquid flow therethrough, the blunting member being mounted in the device for movement of the probe by the transfer means axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip; and (b) locking means dimensioned and configured to engage the blunting member and retain it in its extended position;
the transfer means comprising an extension member mounted within the needle member to transfer mechanical force applied to the extension member to the blunting member for movement thereof to its extended position, the extension member being separate from and independent of the blunting member and slideably mounted in alignment with the blunting member for movement into engagement therewith to move the blunting member from its retracted to its extended position.

27. The device of claim 26 including a plunger dimensioned and configured to mechanically force fluid through the needle member, and the extension member is mounted on the plunger.

28. A self-blunting needle assembly device comprises:
(a) a needle member terminating in a puncture tip and having a needle bore extending therethrough and defining a fluid flow path extending through the needle to the puncture tip;
(b) a blunting member comprising an elongate probe having transfer means associated therewith, the blunting member being mounted within the needle member for movement of the probe by the transfer means axially along the needle bore from a retracted position in which the probe is short of the puncture tip to an extended position in which the probe protrudes outwardly of, and thereby blunts, the puncture tip, the probe being dimensioned and configured to be accommodated within the needle bore while leaving the bore open to fluid flow therethrough; and (c) locking means carried within the needle member and dimensioned and configured to engage the blunting member and retain it in its extended position.

29. The device of claim 28 wherein the transfer means comprises a piston from which the probe extends, the device includes a needle mouth suitable for attachment to a fluid flow means, and the locking means is disposed within the needle mouth and is dimensioned and configured to therein engage and retain the piston.