US3045674A - Hypodermic syringe piston - Google Patents

Description

July 24, 1962 s. D. GOLDBERG HYPODERMIC SYRINGE PISTON Filed Nov. 24, 1958 INVENTOR. 55c SAMUEL D GOLDBERG UQS Tin

3,04%74 nrronnnmrc sYnrNon risroN Samuel ll). Goldberg, West Henipstead, N.Y., assignor to This invention relates generally to improvements in hypodermic syringes to be used in parenteral administration of therapeutic and other agents in the diagnosis, prevention and control of diseases.

More particularly, it is concerned with hypodermic syringes of the type that comprise ampules containing the liquid to be parenterally administered, closed at one end by a partial or semi-closure that may be pierced by a double ended hypodermic needle or an equivalent structure and closed at the opposite by a plunger or piston that seals the ampule hermetically and is adapted to move axially within the ampule to expel the liquid therein contained.

Parenteral administration of liquids by means of a hypodermic syringe may be classified into two categories: the administration of liquids intravenously and administration of liquids subcutaneously but not intravenously. In the first category the liquids administered are those that may be introduced directly into the blood stream without untoward effects; Whereas in the second category the liquids administered are those that must not be introduced directly into the blood stream, either because they would produce acute or even fatal toxic effects or because they would be so rapidly excreted that the desired therapeutic levels could not be obtained for any appreciable period.

For example, local anesthetics are administered subcutaneously, but never intravenously, because venously their dissemination through the blood stream would be so rapid as to-preclude local development of adequate concentration to effect anesthesia and, moreover, the venous toxicity of these substances is appreciable.

When using a hypodermic syringe for administering liquids intended for absorption from subcutaneous tissues, it is customary for the technician to insert the hypodermic needle in the selected place on the skin and then, to assure that-the needle is not in a vein, to retract the plunger slightly before beginning forward movement of the plunger to effect administration of the liquid. If the needle is in a vein, blood will be drawn within the ampule, thus warning the technician that administration should not he continued without readjusting the position of the needle. The technician then withdraws the needle and inserts it in another place in the skin and repeats the operation above mentioned to assure that intravenous administration of the material will not take place. When a suitable place has been found, the contents of the ampule are expelled through the needle into the tissue by forcing the plunger axially forward Within the ampule toward the partial closure end thereof.

in accordance with present day manufacturing methods, ampules are produced by automatic machinery that accepts irregular lengths of glass tubing, grades it as to size, cuts it to the desired length for producing an ampule of the needed capacity, shapes one end of the cut tubing, applies a semi-closure on this shaped end, inserts a plunger or piston closing the other end of the ampule, cleans, sterilizes and loads the ampules with the liquid to be used therein, and packs the loaded sterilized ampules in suitable containers for shipment, these operations not being performed in the sequence mentioned.

Hypodermic syringe plungers or pistons ordinarily are substantially cylindrical masses of rubber or the like having at one end a flat surface adapted to face the liquid to 3,045,674 Patented July 24, 1962 be placed within the ampule and provided at the opposite end with means engageable with a suitable piston actuating member whereby the piston may be advanced axially within the ampule and also may be retracted as may be needed for reasons aforementioned. Inasmuch as these opposite ends of 'the piston are dissimilar and non-equivalent in syringes of the types heretofore known, it has been deemed necessary in syringe manufacturing operations as heretofore practiced to provide classifying means within the ampule assembling machine that would differentiate between the dissimilar piston ends in the assembly operations and assure that the proper end of the piston was inserted in the ampule. This has resulted in complications of equipment with resultant need for what are now found to be unnecessarily large investments in machinery, increased hazards of breakdown and notice able elements of delay in the manufacturing operations as compared with such operations if such classification were not necessary.

One of the objects of this invention is to provide a novel ampule piston that, although of identical configuration on both ends, is nevertheless engageablewith piston actuating means for the purposes both of moving the piston axially forward within the ampule to expel the ampule contents and of moving it in a reverse direction to permit retraction if desired.

Another object of this invention is to provide a hypodermic syringe piston that permits the use of these novel pistons in automatic ampule manufacturing and assembling equipment without need for auxiliary classifying means prior to insertion of the piston within the ampules.

Gne of the outstanding features of the novel ampule piston head according to the present invention is that when the ampule is used in standard procedure when administering a drug that is not to be administered intravenously, the piston head automatically functions to produce the effect of slight retraction of the piston, thus assuring that the needle end is in subcutaneous tissue and not in a vein.

Other objects, advantages and features of the novel hypodermic syringe piston according to this invention will be apparent hereinafter as the invention is described in detail.

Regarded in certain of its broader aspects, the novel ampule piston embodying the principlesof this invention comprises an essentially cylindrical shape formed of an intrinsically resilient material, provided with annular grooves on the side surfaces thereof in zones intermediate the ends, the ends of said piston being identical in configuration and each being provided with an axially extending opening adapted to receive and disengageably engage with suitable piston actuating means, the inherent resiliency of the material constituting the piston being such that when the piston is in place for sealing engagement with interior walls of an ampule, application of pressure by means of the piston actuating means engaged with one end of the piston distorts the shape of the opposite end of the piston from normalcy and, when application of pressure ceases, the intrinsic resiliency of the piston returns it to its normal shape. It will be understood that this distortion of the piston end is such that the liquidcontaining volume within the ampule is diminished; then when the application of pressure ceases, its normal volume is restored.

Suitable materials for use in making a hypodermic syringe piston. according to the present invention include soft synthetic and natural elastomers, of which rubber chiefly is preferred. In accordance with the preferred embodiment of this invention, the ampule pistons are provided at each end with an undercut opening that facilitates an interlocking engagement of the piston with the piston-actuating means.

of the subject matter of the present invention, reference now is made to the accompanying drawings, wherein:

FIG. 1 is an elevational view of a typical hypodermic syringe assembly including an ampule comprising a piston according to the present invention;

FIGS. 2, 3, 4 and 5 are partial sectional views of the piston-bearing portion of an ampule according to the present invention illustrating, respectively, the pistonactuating means and piston prior to interengagement, the piston-actuating means engaged, the piston and pistonactuating means as disposed when forward-directed pressure is applied to the piston, and the same when the pressure is reversed;

FIGS. 6, 7, 8 and 9 are a series of fragmentary sectional views similar to FIGS. 2, 3, 4 and 5, respectively, illustrating a modified embodiment of the present invention; and

FIG. 10 is substantially a vertical sectional view of a unit-dosage disposable syringe including a piston embodying the principles of this invention.

Referring now particularly to FIG. 1 of the drawing, it will be noticed that the hypodermic syringe therein illustrated and generally designated by the reference character 20, comprises a tubular body member 21 having cutaway sides, one of which is designated by the reference character 22, and provided at one end thereof, generally indicated by the reference character 23, with a tubular extension 24, upon which is mounted a conventional double pointed hypodermic needle 25, carried by a sleeve 26, substantially as illustrated.

The opposite end of the tubular body 21 is provided with a swinging head, generally designated by the reference character 27, radially pivotally mounted on the tubular body in a manner such that it may be swung into the position shown for operation of the hypodermic syringe or that it may be swung at an angle to the axis of the syringe body, thereby permitting insertion of an ampule into the interior of the syringe. The swinging head is provided with a pair of radially extending diametrically positioned lugs or ears 28, mounted on the head 29. The head 29 also carries an axially positioned plunger rod 30, provided with a cross bar or handle 21 at one end thereof and terminating at its opposite end in a piston engaging means 32 hereinafter described in detail.

An ampule 33 is positioned within the tubular body 21 and this ampule is provided with a piston 34 that frictionally engages with the interior wall of the ampule providing a liquid-tight seal thereby. It will be understood that the opposite end portion of the ampule is provided in a conventional manner with a partial or semiclosure, adapted to being pierced by one end of the hypodermic needle as is conventional in ampule types of hypodermic syringes.

It will be understood, further, that the hypodermic syringe illustrated in FIG. 1 of the drawings is to be loaded and used as follows: The plunger rod is withdrawn by means of the handle 31 and the swinging head of the syringe is disposed at an angle relative to the axis of the syringe body 21. An ampule is inserted in the syringe body with its partial closure end leading and its piston-sealed end following. The swinging head then is returned to the position illustrated and the plunger rod 30 is advanced axially within the syringe body toward the needle bearing end, whereby the end portion of the piston actuating means is caused to engage with the piston of the ampule and the ampule in toto is advanced axially within the syringe body whereby the near end of the double-pointed hypodermic needle pierces the partial closure of the ampule. Upon further application of forward-directed pressure to the piston through the plunger rod, the contents of the ampule are caused to be expelled through the bore of the hypodermic needle.

Reference now is made to FIGS. 2, 3, 4 and 5 of the drawings which illustrate details of the novel ampule shown.

4 piston according to this invention and the manner of engagement thereof with the piston actuating means.

In FIG. 2 it will be noticed that the syringe plunger rod 30 is provided with a piston engaging head 32, mounted thereon by coacting threaded elements substantially as The piston engaging head comprises a conical shape, generally indicated by the reference character 32a, terminating in a shank portion 32b carrying a hemispherical integrally-formed head 320. The essentially-cylindrical piston 34, it will be noticed, is provided with a plurality of annular grooves 34a, formed at spaced intervals in the side surfaces of the cylinder and serving to facilitate fluid-tight sealing of the ampule. It will be noticed that these annular grooves are disposed substantially midway and equidistant from the piston ends 34b and 34c. It will be noticed that the opposite ends 34b and 34c of the piston are essentially flat and that each is provided with an axially-extending under-cut opening 34d, formed in the piston body essentially as shown. It will be noticed, further, that the piston is symmetrical with regard to its axis and that its cross-sectional outline, taken along the axis, is symmetrical with regard to a line vertical to the axis and intersecting it at a point midway between the piston ends. It follows, therefore, that the opposite ends of the piston are related to each other as mirror-images.

Referring now to FIGS. 2, 3, 4 and 5, it will be noticed that in the first of these figures, the piston engaging means is positioned near, though not in engagement with, the piston; in FIG. 3, the piston engaging means is shown in engaged relationship to the hemispherical bulbous head 32c in engagement with the top opening 34d formed with the piston. In FIG. 4, the piston is represented in its distorted form, produced by application of forward-directed pressure to the piston actuating means. It will be noticed that the leading surface 340 of the piston is slightly convex as a result of this application of pressure. It will be understood that when the application of such pressure ceases, the inherent resiliency of the material from which the piston is made will cause it to be restored to its normal planar configuration, thus exerting a slight aspirating effect upon the ampule contents. In most cases, this slight aspiration is sufiicient to inform the technician whether or not the syringe needle end is in a vein. If, however, this slight aspiration is insufficient for this purpose, slight retraction of the piston will sufiice and, when such retractive force is applied, the piston is distorted so that the leading face 340 becomes concave, substantially as shown in FIG. 5.

It will be understood, further, that the frictional engagement of the piston with the interior walls of the ampule is such that the piston can be advanced or withdrawn by deliberate and gradual application of force to the piston actuating means, whereas the application of sudden force to the piston actuating means, depending upon its direction, will serve to cause engagement or disengagement of the piston engaging means with the piston.

Reference now is made to FIGS. 6, 7, 8 and 9 of the drawings. It will be noticed that a piston engaging means 32 is threadably mounted upon a plunger rod 30 and said engaging means comprises a frustoconical portion 32a, terminating in a shank portion 32b, which carries a bulbous head, generally indicated by the reference character 320. This portion of the device functionally is substantially the same as the piston actuating means described in connection with FIGS. 2, 3, 4 and 5.

The piston 35 is disposed within the walls of the ampule 33 and frictionally engages therewith to provide a liquidtight seal. The piston, it will be noticed, is provided with a pair of annular grooves 35a, located intermediate the ends 3512 and 35c of the piston. These grooves facilitate the sealing of the ampule by frictional engagement of the piston with the ampule walls. The piston is provided with a pair of noncommunicating openings 35d of uniform bore, formed in opposite ends of the piston and extending axially therein.

It will be observed that this embodiment of the invention differs from the embodiment of the invention hereinabove described in that the axially extending openings in the first described embodiment of the invention were undercut, whereas in this embodiment they are of uniform bore.

Referring now to FIG. 6, it will be noticed that the piston-engaging means is "positioned near, but not yet in engagement with, the piston, whereas in FIG. 7, the bulbous head of the piston-engaging means has been brought into engagement with one of the openings 35d. It will be understood that the inherent resiliency of the material from which the piston is made is such that the bulbous head and shank of the piston-engaging means can be forced into the opening in the piston end and brought into engagement therewith without causing the piston to move within the ampule.

In FIG. 8, it will be noticed that the piston is represented in distorted shape, resulting from application of forward-directed pressure to the piston-actuating means, whereby the leading surface of the piston is distorted into a convex shape essentially as shown. It will be understood that when the force producing this distortion is released, the piston will restore itself to its original shape, thereby exerting an aspirating action upon the ampule contents sufiicient to enable the technician to determine if the syringe needle end is in a vein. In the event that this slight aspiration is insufiicient for this purpose, the piston may be slightly retracted and, when such retractive force is applied, the piston head becomes distorted so that its leading face is concave, substantially as illustrated in FIG. 9.

Reference now is made to FIG. of the drawings wherein 'a single-dosage disposable syringe is illustrated and generally designated by the reference character 36. It will be noticed that the syringe comprises a frame 37, adapted to receive an ampule 38 and carrying a doublepointed hypodermic needle assembly generally designated by the reference character 39. Piston actuating means, generally designatedby the reference character 40, are

mounted in suitable openings in the frame 37 whereby the piston 41 of the ampule 38 may be advanced or retracted within the ampule as desired.

primary significance from the viewpoint of the ampule manufacturer, that the opposite ends of the piston are identical and thus either end can be inserted in the ampule when assembling the ampule by use of automatic machinery. It further is to be noted that the piston includes no metallic inserts that, if in contact with a liquid in the ampule, might cause chemical reaction with, or deterioration of, the liquid contained therein.

Having thus described the subject matter of this invention, what it is desired to secure by Letters Patent of the United States is: 1. In combination with a hypodermic syringe ampule comprising a tubular body portion, the improvements which comprise a piston of essentially cylindrical shape, formed of an intrinsically substantially resilient material, having opposed end faces and annular grooves on the side surfaces in zones intermediate said end faces, to facilitate liquid-tight engagement with the walls of the ampule and sealing thereof, said end faces being identical in configuration and each being provided with an opening extending over a minor, central area of the end face, and axially extending deep into the piston, said openings being adapted to receive and disengageably engage a pistonactuating means, a piston actuating means having a head, said head having a semi-globular configuration whereby to cause, in conjunction with the intrinsic resiliency of the piston material and the shape and dimensions of said openings, the bottom portion of the piston surrounding the central opening therein to expand, and the inner leading end face of said piston to be rendered convex when the piston descends under pressure; the bottom portion and the inner end face of the piston to be restored to normalcy whereby to exert an aspirating effect when the pressure on the piston ceases, and the bottom portion to References Cited in the file of this patent UNITED STATES PATENTS 1,704,936 Cook Mar. 12, 1929 2,127,203 Brand Aug. 16, 1938 2,586,068 Lockhart Feb. 19, 1952 2,688,325 Lockhart Sept. 7, 1954

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