US2554744A - Hypodermic syringe - Google Patents

Description

May 29, 1951 N. B. JoRGENsEN HYPODERMIC sYRINGE Filed Aug. 14, 1950 E. if o II -i www@ IN VEN TOR. /V/LS JOHV JOPENSEN TTOQMEY- Patented May 29, ,1951

UNITED STATES PATENT OFFICE HYPODERMIC SYRINGE Niels Bjorn Jorgensen, Los Angeles, Calif.

Application August 14, 1950, Serial No. 179,323

This invention relates to hypodermic syringes of the type disclosed in my pending application Serial No. 80,044, led March 7, 1949, now Patent No. 2,526,365, dated October 17, 1950, of which the present application is a continuation in part. In this type of syringe, the barrel of a medicine ampule becomes the cylinder of the syringe and the stopper of the ampule (of yieldable material such as rubber) becomes the piston of the syringe. Movement is transmitted to theV piston from a plunger by pressure contact between the end of the plunger and the piston, and without any connection between the plunger and the piston by means of which the piston could be withdrawn by the plunger. Accordingly, the conventional syringe of this type can be operated only to inject iiuid from the syringe into a patient, and is not reversely operable to Withdraw fluid from the patient into the syringe. Such Withdrawal operation is a desirable characteristic, since, in the injection of some medicaments, it is necessary to avoid injection into a blood vessel. This is imperative in the case of anesthetics such as the morphine and cocaine derivatives, since injection of such anesthetics into a blood vessel can result in death.

The common method of testing to determine whether the needle of the syringe has entered a blood vessel is to advance the piston only a slight distance and then to withdraw it to the beginning of its stroke. In the event that the needle has entered a blood Vessel, blood will be drawn back into the syringe and will, by its characteristic red color, Warn the operator of that fact. But such an operation requires a connection between the plunger and the piston by which the Withdrawal movement may be transmitted to the piston. One prior proposal has been to Iutilize a claw in the form of a cork screw for engaging the piston and connecting it to the end of the plunger. However, such devices have not proven satisfactory, and there has .for many years existed a definite need for a reversely operable syringe of relatively simple yet fully .dependable construction and operation. The primary object of my invention is to provide such a syringe.

Another object is to provide an improved form of the syringe disclosed in the above identified pending application. Y Y

In contrast to prior proposals such as that referred to above, my invention embodies the concept of providing a piston` assembly including a main piston and an auxiliary piston (or its equivalent, such as a diaphragm) carried by the main piston and adapted to coact with the 7 claims. (c1. 12s- 218) plunger which is adapted to initially transmit to the auxiliary piston a limited movement While the main piston remains stationary and, when thev limit of such movement has been reached, to transmit movementto the main piston. The invention also provides means acting yieldingly between the auxiliary piston and the main piston to retract the auxiliary piston and plunger to their initial positions when the pressure on the plunger is released. It is this retracting movement of the auxiliary'piston which functions to apply suction which results in the withdrawal of fluid from the patients body into the syringe, and the range of limited movement of the auxiliary piston is just sufficient to provide an adequate withdrawal capacity to assure the passage of a body uid through the hollow needle of the syringe back into the transparent barrel. A flirther characteristic of the invention is the balancing of the force of the yielding retracting means against the frictional grip of the cylinder upon the main piston so that the former cannot overcome the latter and transmit movement to the main piston prior to the movement of the auxiliary piston to its full range of movement relative to the main piston.

vWhen its contents are exhausted, the medicament ampule is of course discarded. In many cases the contents of an ampule may be used up in a single injection. The cost of the ampule with its Stoppers is added to the cost of the medicament,

and it is a fundamental requirement that the cost of the ampule and the Stoppers be held at a minimum. Accordingly, a further object of the invention is to provide a syringe embodying the features pointed out above-in a construction that is relatively simple and inexpensive, sufliciently so that the cylinder and piston portion of the syringe (the ampule) may be discarded after one f ull stroke of the piston.

A further object is to provide, as a renewable part of a syringe having the features discussed above, a novel and improved medicament ampule stopper functioning as a reversely operable piston, Without the necessity for the use of means to `establish' a physical connection between the stopper and the syringe plunger.

Other objects will become apparent in the ensuing speeications and appended drawings in which:

Fig. 1 is a longitudinal sectional View through a syringe embodying the invention; Fig. 2 is a sectional view through a, portion of the same showing adierent position of operas tion;

Fig. 3 is a sectional view through a portion of the syringe embodying a modied form of the invention; and

Fig. 4 is a side view of the stopper-piston.

As an example of a preferred form in which the invention may be embodied, I have shown in Figs. 1 and 2 a syringe embodying la holder, indicated generally at 6, and a medicament ampule indicated generally at 1. Theholder 6 includes a barrel'. 8v having one end closed by anendwall 9 having la needle receiving neck I0, :and having its opposite end open to receive the ampule 1. To the open end of thebarrel 8 is hinged, upon trunnions I I, a yoke I2 having projecting ringer gripsy I3 and a bearing I4 in which is slidably mounted a plunger I5. The conventionalV hypodermic needle IB is mounted in a cap I1 which is threaded onto the neck I0. The needle I 5 is adapted to pierce the stopper I-8 (of soft rubber or equivalent.

material) which seals one end of the ampule 1. The foregoing` features are conventional features of the type of syringe which .incorporates the ampule as an operative part thereof;

In such a conventional` syringe, there isjordinarily a plain solid rubber stopper normally closing the ampule opposite the stopper I. land adapted to function as a piston Instead of this plain rubber stopper, my invention provides a stopper-piston I9 whichis generally cup shaped, including in general, a main body member in the form of an annular cylindrical;lateralwall member 20 and an end member 2| closing the outer extremity of the stopper.Lateral wall portion 20 has a cylindrical outer wall tofit the inner wall of thecylindrical barrel 22 ofthe ampule. The diameter of thezouter wall oflateralmember 20, in its unstressed condition, is atleast as great, and preferably a trifle greater than the diameter of the inner wall ofbarrel 22,wherebylateral member 20, when installed within.barrel 22, will frictionally engage the inner wall of barrelv 2-2 (preferably under some compression) sufficiently to establish. a. tightA hermetic seal|` between 'the stopper-piston and the barrel. Suchl seal.- must be adequate to prevent; anyy escape-of, liquid and to protect the body of medicament-23 within the ampule. against contamination; and'must be suficient to establish a. substantial frictionali grip oflateral member 20 upon the Wall of barrel.22., for a purpose which` will be explained.- hereinafter. The hermetic seal is made more effective by utilizing a pair of' axiallyspacedannular grooves 24, 24' in the outer wall oflateral member 20.

Lateral member 20 includes, at the openv endfof the stopper-piston, a relatively thick annular collar `25 and, betweencollar 25 andl end member ZI, a relatively thinintermediate wall portion 26. Dened betweencollar 25 andintermediate wall portion 26 is ashoulder 21 ofn offset form.y A cavity 39 is defined Within the inner wallofthin Wall portion 26, betweenshoulder 21 and end member 2 I.

End member 2l includesa. relatively. thick, cylindrical centralbutton element 23- functioning as an auxiliary piston, and' arelatively thinpe.-ripheral diaphragm element 29whichconnects button element 28 to theend ofthe relatively thinintermediate wall portion 26.

The diameter ofbutton element 28 is less than the internal diameter of thin cylindrical.wall portion 26 by an amount approximatelyv` equalto-the thickness ofdiaphragm 29.. Thismakesitpossible for the button element 2a. to, be projected into the cavity 30' under pressure appliedY thereto by plunger I5, so as to function as an auxiliary piston, which term will hereinafter be used in r-eferring tobutton element 28. In moving intocavity 30,auxiliary piston 28 will drawdiaphragm 29 =with it into the cavity,diaphragm 29 being accommodated between the periphery ofauxiliary piston 23 and thinlateral wall member 26 as indicated in Fig. 2. The end portion oflateral wall member 26 will also be folded back within itself and drawn into the` cavity." 30" by the pull ofdiaphragm 29, after the latter has stretched to a point where its resistance to further stretch matches the resistance oflateral wall member 26. to,Y being thus infolded.Wall member 26 is sufficiently thin to yield to the pull ofdiaphragm 29'. tending to. double it back inside itself. This makes. it possible for theauxiliary piston 28 to travelv its full stroke to the point where it contactsshoulder 21.

An inner limit of movement ofauxiliary piston 29 into cavity 39' is` determinedby engagement of the inner4 sidefofauxiliary piston 28 against shoulder 21:. Since the inner wallofk collar member 25` is approximately as small` or smaller in diameter than the peripheral diameter of `aux-- iliary pistona2f8r, itwillbe impossible for the 'latter tomovebeyondshoulder 21.

In the operation of the syringe, plunger I5 is pressed against auxiliary piston` 28, projecting the sameiintocavity 3.0 so as-toexpelfrom cavity 30 the' liquid contained therein. The volume of cavity y30,- is such that the amount of` liquid injected` into the patient. will not be sufliciently great to cause injury, and` yet is such that a corresponding volume ofv blood; drawn back through; thefneedle I6, will enter the barrel 2220i the ampulesuiiciently to become plainly visible throughthe transparent wall` thereof.

In the operation of thesyr-inge, the ampule is first installed inthe-syringe barrel 8 inr the. conventional manner,V withA needlel I6r piercing.; stopper I1: andvwith plunger I5. in position-to engage stopper-pistonv I9; After customary sterilizing measureshave. been observed, theneedle inserted into thebody ofthepatient, and pressure is applied to plunger I5, such pressure being transmittedy fromhead 34 thereof` toYauxiliary piston 28 of stopper-piston. I2. The plungerV is carefully pressed inwardly a. distance not. greater than. the axialvdistance-between auxiliary piston 2B andshouldery 21. During this initial stroke, thel frictional engagementof lateral-body' member 2of stopper-piston I9=against the inner wall; of cylinder 221` willi maintain theforward portion. of stopper-piston I9 stationaryewithin ampule.barrel 22 while auxiliaryA piston 282is pushed'into cavity 3l!a The thickened collar member. 25.I provides a resistance to` radial compression which insures adequate outward pressure thereof' against the inner wall ofI`cylinder 22, so as to insure the grip'- ping of the ampule-barrelZ-Z'sufficiently to'immobilizec'ollar'member 25 withinampule barrel 22 duringl this initialL stage ofoperation. As' aux'-iliary piston 28 ispushedinto'cavity 30;annular diaphragm 29 will` be stretched and drawn into the cavity and'a portion' of the thinlateral wall memberl 26 willy likewise-bedrawn intocavity 30, being folded in upon itself; under the tension applied to it through diaphragml 29:

The engagement of: auxiliary piston' 28; with shoulder 21' establishes aA limit for this initial stroke of plungerl Ilwhicliflimit may' be readily detected, through the sensitive' fingers of a4 surgeon; by the increase resistanceto forward vmovement which is-thereby` developed in the deformation thereof will cause theparts 26, 28, 29

to spring back to their initial positions, establish-V ing suction incavity 30 which willcause a suliicient quantity of fluid to be drawn back thereinto to replace that which was expelled therefrom in' the initial plunger stroke. This reverse flow of the liquid within the ampule causes a corresponding amount of fluid to be drawn from the patients body through needle I6 back into theampule barrel 22, and if the needle has entered a blood vessel, this fluid will include a sufficient quantity of .blood to color the. uid within the ampule and thereby disclose the fact that a vessel has been punctured'. l

Collar 25, in addition to its two functions indicated above (providing theshoulder 21 which limits forward movement ofauxiliary piston 28, and providing adequate outward pressurek againstcylinder 22 to give the proper braking grip uponcylinder 22 in the initial stage of operation) has the further function of providing maximum sealing engagement of the forward end of stopperpiston I9 withincylinder 22, so as to reduce to a minimum any seepage of liquid past the stopper. Sealing groove 24' is located within the axial confines ofcollar 25, whereby there are two sealing .edges (the edge at the forward end of lateral body member and the edge defined at the rear side of groove 24') both subjected to the outward pressure ofcollar member 25 so as to provide maximum sealing effect.

Fig. 3 illustrates a modified form of the invention in which, instead ofauxiliary piston 28, there is provided on the inner end face of plunger head 34a, a reduced diametercylindrical nose portion 28a projecting axially for engagement with the end member of stopper I9a, which in this case is in the form of a relativelythin diaphragm 29a extending entirely across the end of the stopper. The diameter ofnose member 28a is substantially the same as the diameter ofauxiliary piston 28, i. e., smaller than the diameter of the inner wall of thinlateral wall portion 26 of stopper I9a, by substantially the thickness ofdiaphragm 29a. The axial length ofnose member 28a is suicient so that the limit of the initial stroke of plunger I5 may be determined by the engagement ofdiaphragm 29a againstshoulder 21. Preferably, the length is such that theshoulder 35, dened between reducednose member 28a and head 34a, will engage the doubled portion oflateral wall member 26 at the same time thediaphragm 29 engages shoulder 2'I, so that the further stroke of the plunger may transmit movement through the entire stopper for delivering the medicament into the patients body.

After the testing operation, outlined above, has been completed, the plunger is again pressed inwardly, theauxiliary piston 28 being advanced into engagement withcollar 25, and further pressure is then applied. Such pressure, transmitted to collar 2.5 from auxiliary piston 28, will overcome the frictional grip of lateral body member 20 upon the wall of ampule barrel 22, causing the with ari ampule barrel and a plunger, a generally cup shaped stopper-piston including an annular body member received in and engaging the inner Wall of said barrel, and a yieldable end member positioned to be engaged by said plunger and to be moved inwardly with reference to said annular body member soas to function as an auxiliary piston for applying first pressure and then suction to the contents of said cylinder as the plunger is firstl pressed inwardly and then released, said annularbody member having an open end and including, at said open end, a radially inwardly extending collar and including a relatively thinner annular intermediate portion extending axially from said collar to said end member and defining a cavity therewithin, said annular body member engaging said cylinder Wall with a grip suflicient to hold it stationary while said end member is moved by said plunger, said stopper including Vmeans yieldingly opposing inward movement of Said end member and moving said end member back to its starting position when pressure on said plunger is released, to develop suction in said cavity for effecting reverse flow in said barrel, said end member being engageable with said collar to limit the initial stroke of said plunger, and to transmit axial movement to said annular body member in a subsequent stage of operation of said syringe in which said stopperpiston is moved bodily within said barrel to expel the contents thereof.

2. A syringe as defined in claim l, wherein said end member comprises an axially thick central button portion constituting an auxiliary piston and a relatively thin, annular diaphragm joining said auxiliary piston to one axial extremity of said relatively thin annular wall portion, with said auxiliary piston projecting axially :beyond said annular body portion, externally thereof, said auxiliary piston having a diameter sufficiently smaller than the diameter of the inner wall of said relatively thin annular wall portion so as to accommodate the thickness of said annular diaphragm portion between the periphery of said auxiliary piston and said inner wall as the diaphragm is drawn into the space within said relatively thin annular wall portion by the projection of said auxiliary piston thereinto under plunger pressure.

3. A syringe as dened in claim 2, wherein said relatively thin annular Wall portion is of suicient thinness to be doubled within itself and accommodated between the periphery of said auxiliary piston and its undoubled adjacent wall portion as said auxiliary piston is projected into said space.

4. A syringe as defined in claim 1, wherein said end member comprises a relatively thin diaphragm member throughout the cross sectional area of said stopper, and wherein said plunger has a portion for engaging said end member, said engaging portion being of a diameter sumciently smaller than the inner Wall of said relatively thin annular body member so as to accommodate the thickness of said diaphragm member as the latter is pushed into the space within said inner wall under the pressure of said engaging portion of the plunger.

5. A stopper for a hypodermic syringe, said stopperl being cup shaped and of a material having the general characteristics of soft rubber, said stopper comprising an annular body portion, open at its inner end, and having at its outer end an end member closing said outer end, said annular body portion including a relatively thick acm-e144 'collar ,portion adjacent said open vend and a relatively thin annular wall portion connecting said collar portion to said end member, said collar portion being joined to said relatively thin an nular portion by a shoulder inwardly oiset from the inner wall of said .relatively thin annular portion, said end member, said shoulder and `said inner wall cooperatively defining a cavityof sufllcient volume to provide for an indraft of fluid into the syringe from a patients body sufficient to visually establish communication with a blood vessel when suction to the extent of said volume is applied to the contents of the syringe, said end member including an annular peripheral portion in the form of a `relatively thin diaphragm joined to the closed end of said relatively thin wall portion and an integral central button portion constituting an auxiliary piston, of sufiicient axial thickness to be form retaining under pressure Afrom the syringe plunger, said auxiliary piston projecting from said diaphragm externally foi' the stopper, and .having a peripheral Idiameter sufliciently smaller than that of said inner wallto accommodate, between the periphery of said auxiliary piston and :said inner wall, the thickness of said diaphragm portion, drawn into said icavity by the projection of said auxiliary piston thereinto under plunger pressure, Asaid vend ymem- -ber being engagealole with ysaid shoulder to limit the inward projection of said auxiliary piston relative to said annular body portion.

6. A stopper as defined in claim 5, having an annular groove .in lthe peripheral face of said annular body portion, within the axial .confines of said collar iporti'on.

7. .A stopper as dened inclaim 6, having a second annular lgroeve in the peripheral face nf .said relatively thin annular Wall portion.

' NIELS BJORN JORGENSEN.

No references cited..

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