Medicinal syringe actuating device

Abstract

A removable cylindrical carrier is longitudinally slidable within a cylindrical inner body which, in turn, is longitudinally slidable in a generally cylindrical outer body. The carrier accepts and mechanically operates various conventional hypodermic syringes. A combination of springs and latches impart, restrain or release forces which cause the device to operate the syringe, impelling the syringe plunger to expel the syringe load when the syringe needle fully penetrates the user's flesh as the carriage moves in the outer body upon release of the carrier latch. The body has interchangeable locator tips to act as guides to determine the attitude of the syringe needle with respect to the flesh.

Description

BACKGROUND OF THE INVENTION

The invention relates to devices for use by persons compelled to self-administer hypodermic injections, but is equally useful for those who administer injections to others, since the device of the invention compensates for lack of manual dexterity and overcomes psychological inhibitions because its operation makes injections essentially painless. Heretofore small children, arthritic patients, elderly chronic patients, diabetics and others have depended upon professional medical personnel for injections, at high cost of time and money, because the conventional hypodermic needle plunger properly should be advanced at a steady rate while in the flesh. The areas of the body that are medically preferred because they have fewer large blood vessels and are sufficiently muscular to receive and dissipate solution injections such as those used by diabetics, are awkward to reach with the two handed technique normally necessary for proper injections. Additionally, frequent injections in the same area over long periods result in toughening of the flesh in those areas where the injections are made, increasing the tendency to inject only in that area of decreased sensitivity, instead of promoting complete healing of an area by using each medically presecribed area in turn. The desired steady rate of injection of the fluid requires quick, straight insertion and withdrawal and steady holding of the needle in place in the flesh. The present invention has as its objective the provision of a hypodermic syringe actuating device which may be used and re-used and which accepts many of the conventional hypodermic syringes and is also adapted to use by one hand.

This invention was the subject of a disclosure made under the Document Disclosure Program submitted in a three-page paper entitled "Disclosure Document" dated Apr. 10, 1972 and signed by Jack H. Ritterskamp.

SUMMARY OF THE INVENTION

The invention contemplates a hypodermic syringe actuator comprising a generally cylindrical outer body in which a second cylindrical body is movable and which, in turn, carries a slidable cylindrical carrier to which the conventional hypodermic syringe is attached. A properly filled syringe is placed in the movable carrier which is then assembled with the inner cylinder and the outer body. The carrier has a spring-loaded retraction spool which guides the syringe in part and aids in latching the cylinder. Compression springs and latches impel and restrain, respectively, the plunger actuator and a carrier impeller. A trigger suitable for operation by a single digit unlatches the carrier for effecting insertion of the syringe needle. An automatically released latch restrains the plunger actuator during the insertion stroke of the carrier.

Preferably the outer body terminates at its injecting end in a hollow nose section to which a guide tip is removably attachable. Various length tips are provided so that various length syringes may be accommodated with only tip change. The detachable tip also is a sterilizable or sanitarily replaceable body contact element. Spring means on the carrier retain the syringe in the carrier in removable fashion. The carrier latch engages the inner cylindrical body at either of two slots, that are rearward of the first slot, which the trigger tang engages.

Wings on the inner cylinder protrude through longitudinal ways in the outer body, affording cocking grips to load the carrier and inner cylinder against the impelling insertion spring that dwells in an elongate chamber at the outer periphery of the outer body. Shrouds protect both trigger and plunger actuator latch against accidental displacement.

The device of the invention can be made in a great part from conventionally molded plastic or like materials and from stamped metal parts and conventional springs. Its cost is low and its usage simple, so that its benefits are easily available to all who need it.

These and other advantages of the invention are apparent from the following detailed description and accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is an elevational view of a conventional hypodermic needle syringe with protective cap in place over the needle;

FIGS. 2 and 3 are elevational views of alternative conventional syringes with capped needles;

FIG. 4 is an exploded view of the syringe actuating device of the invention showing in perspective the separable elements thereof;

FIG. 5 is a longitudinal sectional view of the device of the invention showing the loaded syringe combined with the injector body and carrier; and the inner cylinder cocked;

FIG. 6 is a longitudinal section showing final preloading of the retraction spool and latching of the carrier to the inner body;

FIG. 7 shows in longitudinal section the insertion of the syringe needle and the start of the injection of fluid after trigger actuation;

FIG. 8 illustrates the condition of the device in longitudinal section as the last of the fluid is expelled from the syringe;

FIG. 9 is a longitudinal section illustrating retraction of the empty syringe from the user and the extended position of the carrier prior to removal from the inner cylinder;

FIG. 10 is a plan view, partly in section, of the embodiment of FIG. 4 in the insertion condition of FIG. 7;

FIG. 11 is a bottom plan view, partly in section and partly broken away, showing the latch slots in the inner cylinder;

FIG. 12 is a fragmentary plan section, similar to FIG. 10, showing the inner cylinder in cocked attitude;

FIG. 13 is transverse sectional elevation, taken along line 13--13 of FIG. 7 illustrating the plunger actuator latch;

FIG. 14 is a transverse sectional elevation taken along line 14--14 of FIG. 7;

FIG. 15 is a transverse sectional elevation taken along line 15--15 of FIG. 7;

FIG. 16 is a transverse sectional elevation taken along line 16--16 of FIG. 7, showing the syringe retaining leaf spring; and

FIG. 17 is a fragmentary sectional elevation of an alternate embodiment of the invention having friction-reducing cylinder fins.

In the various Figures like parts are given like reference characters.

In the specification a particular hypodermic syringe is presumed in all Figures. However, the terms "syringe," "case," "plunger," "needle," and "needle cap" are common to all conventional syringes and are so used.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Conventional hypodermic syringes 11, 12 and 13 are shown in FIGS. 1, 2 and 3, respectively. Each has a case 14, usually of plastic or glass, in which a plunger 15 is slidable to expel a medicinal fluid (not shown) from the case through needle 16. A protective cap 17 is conventionally provided for each syringe to prevent contamination and preclude injury. Each case has a flange 18. Although similar in function, the flanges of conventional syringes may vary in shape and size. The illustrative embodiment of the invention has a flange receptacle adapted to several syringes, but receptacles of differing configuration may be provided, if necessary to accommodate the syringes with which the syringe actuator is used.

Reference to FIG. 4 establishes the relationships between the conventional syringe 11A, the syringe carrier 21 in which the syringe is received after filling to the prescribed dosage and setting for the purposed injection, and the outer body and inner cylinder assembly 22 into which the carrier and the syringe are loaded for injection. The Figure also shows a removable tip 24, one means by which the invention provides for syringes of differing lengths.

Assembly 22 comprises an outer body 26 having a hollow nose 27 adapted to receive tip 24 or other like tips. Stops like stop 28 on the nose locate the tip with respect to the other components of the outer body. Opposite the nose the outer body terminates in an open end 29 best comprehended in FIGS. 5 through 11. Only cocking wing 31 of the inner cylinder is visible in FIG. 4, extending out through one of a pair of elongate slots 32 in the body adjacent end 29. FIG. 12 shows fragmentarily inner cylinder 34 within body 26 in cocked position, the wings 31 being to the rear of the slots 32. The exterior wall of the peripheral chamber 36 is seen from FIG. 4 to extend for most of the length of the outer body. For purposes of clarity that end of the actuator that contacts the user from which the hypodermic needle extends shall be called the "front" of the device and that end into which the carrier and syringe is loaded (end 29) shall be called the "rear" of the actuator. Thus, chamber 36 stops short of front end 37 of the outer body.

The carrier 21 of FIG. 4 has a cylindrical outer wall 39 in which a plunger actuator 41 resides. The actuator has a shaft 42, an external knob 43 on the shaft and a contact head 44 bearing a resilient cushion 45 for cushioning shock to glass syringes. A compression spring 46 surrounds the shaft portion within the carrier wall, bearing against the contact head and an end web 47 of the carrier, seen in FIG. 5. The front of the carrier has a syringe case flange receptacle 48 with slotted transverse walls 49, 51, wall 49 being the end wall of the carrier front. A longitudinal opening 52 in the cylindrical outer wall 39 opens from end wall 49 and extends to a narrowed portion 53 near the rear end of the carrier. The front end of the opening affords loading access for the syringe, as well as visual inspection of the association of the syringe plunger and the actuator contact head. The function of the portion 53 will be discussed later.

Opposed arcuate openings 54, 54A extend from opening 52 in each direction betweenthe transverse walls 49, 51. A compound leaf spring 55 has an upstanding bifurcated portion 57 in the space between walls 49 and 51. The portion 57 holds the syringe case flange 18 between itself and wall 51, securing the syringe in place in the carriage. Various syringes may require differing arcuate opening configurations.

Only the actuating tang 59 of a latch disc 61 shows in FIG. 4, extending through a notch 62 in carriage wall 39. The tang resides beneath a protective shroud 63 to preclude accidental actuation. A similar shorter tang 64 (FIG. 5) engages wall 39 in a notch 65 opposite notch 62.

The phantom lines of FIG. 4 indicate the assembly procedure for the components -- syringe 11A is fitted into carrier 21, the carrier is fitted into body and cylinder assembly 22 and tip 24 is fitted to nose 27.

The other elements of the inventive actuator are illustrated in the drawings following FIG. 4. For instance, in FIG. 5, in which the charged syringe, fitted in the carrier, is concealed with the outer body, the configuration of the inner cylinder 34 is shown in section. The inner cylinder is seen to be a hollow cylinder with a slightly frusto-conical front end 66 terminating in an annular wall 67. The annular wall retains a retraction spool 69 at the end of the inner cylinder. The spool surrounds the syringe, and in some measure, guides the syringe in alignment with the hollow nose 27. A compression spring 70 rides on a barrel 71 of the spool between opposite end flanges 72, 73, bearing on the annular wall 67 of the inner cylinder 34. The compression spring resists elongate motion of the carrier toward the body nose, the wall 49 of the carrier and spool flange 72 being adapted to meet.

FIGS. 10 and 11 illustrate opposite surfaces of the inner cylinder or body 34. In FIG. 10 the cylinder is seen to have the wings 31 protruding through the slots 32 of the outer body, as described with respect to FIG. 4. A cylindrical boss 76 projects inwardly from the inner wall of the inner cylinder about transversely even with the wings. The boss 76, shown in broken lines in FIGS. 10 and 12, registers in narrowed portion 53 of carrier 21 to limit rotation of the carrier with respect to the inner cylinder to assure radial alignment of slots 81 and 82 with trigger tang 88.

It is obvious from the indicated construction that the inner cylinder 34 must be placed in the outer body 26 when that body is in two halves, prior to the final fixing of the halves together. The inner cylinder, while movable axially of the outer body is thus not removable from it. Similarly, retraction spool 69 is assembled with inner cylinder 34 prior to the final assembly of the cylinder. Other assembly steps and techniques in conformance with sound fabrication practices are utilized in the making of the device of the invention.

The reverse side of inner cylinder 34 is seen in FIG. 11, where outer body 26 is partly broken away. A forward slot 81 in the wall of the cylinder is aligned with a rearwardly displaced second slot 82. An opening 84 of the carrier coincides with second slot 82. When carrier 21 is in latched position a latch portion 85 of the previously referred to compound leaf spring 55 resides in and extends beyond opening 84 and is engaged in slot 82 in the actuator attitude of FIGS. 7, 10 and 11. In phantom lines the tang 88 of a control trigger 89 overlies the latch portion 85, extending from the trigger thrust disc 91.

The inner cylinder also has a rear and retainer aperture 93 axially aligned with the forward slots 81, 82 (FIG. 11). Retainer sperture 93 engages latch portion 85 when the carrier is actuated rearwardly at the end of syringe penetration and injection as described later. An off-axis extension slot 95 admits the latch portion 85 when the carrier is rotated, the carrier then being in position for removal from the body-inner cylinder assembly.

The latch and trigger function is more easily comprehended in view of FIG. 5, where trigger 89 is shown housed in the forward end of peripheral chamber 36. A circular shroud 97 surrounds the disc to guard against accidental contact with the thrust disc. The shroud is open at 98 and the trigger extends through the opening to the tang 88. Between the tang and the disc the trigger is pivoted upon a pin 99. A spring 101 with base legs 102, 103 and thrust yoke 104 (see FIGS. 15 and 16) is secured on the pin and loads the trigger toward the slots 81, 82, that is, toward the center of the actuator. As seen in FIG. 5, the trigger tang 88 engages forward slot 81, holding the inner cylinder in cocked position, the wings 31 being drawn to the rear of the outer body slots 32. A carrier spring 106 is secured between forward and rear lugs 107, 108, respectively, on a rod 109. The spring is compressed, in the position of FIG. 5, between rear lug 107 and a depending leg 111 of the cylinder 34. The leg is bifurcated to fit about the rod 109. A cushion 112 absorbs force engendered when the cylinder and carrier are spring-impelled from the position of FIG. 5 to the insertion position of FIG. 7.

The latch and release mechanism for the plunger actuator assembly can be detailed with respect to FIGS. 5 and 7, FIG. 5 showing the actuator assembly loaded and latched, and FIG. 7 showing the latch released. FIG. 8 shows the actuator discharged.

Within the protection of shroud 63 the actuator assembly latch 61 relates to the actuator shaft 42 in a canted position. This is a conventional latch arrangement, wherein the edges of the latch central aperture 115 bind on shaft 42 when the latch is at an angle to the shaft, but clear the shaft when the latch is perpendicular to it. The bottom tang of the latch is fixed in wall 39. The actuating tang 59 is held forward by the pressure of a spiral compression spring 119 held between the latch and the rear wall 21A of the carrier. The spring and latch are in a rear chamber of the carrier defined by wall 39 and 21A and partition web 47 forward of the latch. The actuator shaft passes through openings in both wall 21A and web 47. It is released to the urging of spring 46 when the inner cylinder and carrier move forward under the pressure of spring 106 and tang 59 impinges upon the end 29 of the outer body as shown in FIG. 7 and FIG. 8.

OPERATION OF THE DEVICE

In operation, the user first fills the syringe with the prescribed fluid volume, indicated by the conventional syringe markings 131 in FIG. 4. The actuating plunger of the carrier is then retracted to place contact head 44 at least as far back on the index markings 132 on the interior wall of the carrier (FIGS. 5 and 10) as the load of the syringe. Retracting plunger assembly 41 loads spring 46. Average loading is in the range of 2-6 pounds, the amount needed to assure a steady, quick expulsion of the fluid in the syringe into the flesh of the user. The syringe, with its cap 17 over needle 16, is then placed in the carrier.

The syringe is gripped by its flange 18 in the receptacle 48 of the carrier between walls 54A and 49 of the carrier. Leaf spring portion 57 insures a snug fit. The rest of the syringe barrel extends from the carrier in cantilever fashion.

The cocked and loaded carrier is then placed into the body and cylinder assembly 22 after the inner cylinder has been pulled to rear position against the pressure of carrier spring 106. The trigger tang 88 springs into forward slot 81 of the inner cylinder, latching it in the position of FIG. 5. The latch portion 85 of leaf spring 55 remains in carrier aperture 84. At this point carrier 21 is moved forward in the outer body as in FIG. 6, latched by the engagement of latch portion 85 in the second axial slot 82. The projecting cap 17 (phantom lines, FIG. 6) is then easily removed from the needle by way of nose 27, the nose piece or tip 24 having been positioned before installing the syringe in either tapered or blunt presentation (see below). The needle is hidden from view by the extension of the body and nose piece beyond the carrier.

The device of FIG. 6 is ready for actuation, with nose piece 24 rotatable on nose 27 to position in the most conveient attitude with respect to the flesh line 78 of the user. The nose piece 24 has a tapered face 134 which seats on the flesh, helping to maintain a selected attitude of the device with respect to the flesh. The nose piece may also be reversed on the nose to present perpendicular face 135 to orient the actuator for striaght-in injection. It has been found that the nose piece pressure on the flesh acts as a counter-irritant, lessening the perceived impact of the needle.

Disc 91 of trigger 89 is depressed by a digit 136, in this case a forefinger, and tang 88 releases from slot 81. Spring 106 impels the carrier and the inner body forward, carrying the needle into the flesh. The depth of penetration is controlled by the relationship between the axial length of the particular nosepiece and the combined syringe and needle length. By continually using the same syringe and needle with the same nose piece, the medically desirable repeated injection to the same depth in the flesh can be achieved.

Simultaneously with the forward motion of the body and carrier, locked together by the association of carrier leaf spring 55 and body slot 82, latch disc 61 and its actuating tang 59 approach contact with rear end 29 of the outer body 26. FIGS. 7 and 8 show the contact position. In FIG. 7 contact has released plunger shaft 42 of the actuating assembly 41, as previously described, and spring 46 impels contact head 44 against the syringe plunger 15, forcing expulsion of fluid from the syringe barrel into the flesh 78 surrounding the needle. The rate of expulsion is a balance between the spring pressure and the resistance to flow of the small needle bore and the flesh density. Discharge is steady and quick under the spring pressure. In FIG. 8 discharge is complete, the contact head 44 having caused plunger 15 to reach the end of its forward stroke.

Note that in both FIG. 7 and FIG. 8 the digit continues to depress the trigger disc. Leaf spring 85 is thus able to contain the carrier in forward position despite the retracting spring 70 because of the association of the leaf spring portion 85 and second cylinder axial slot 82.

Once the user observes the forward position of knob 43, he may release the digit pressure on the trigger, assured that the injection is complete. The conventional time lapse between penetration of the needle and injection of the fully filled syringe contents is about four or five seconds, varying with needle gauge. Upon release of digit pressure, spring 101 urges tang 88 against leaf spring portion 85, removing it from slot 82. Retraction spring 70 urges carrier 21 rearwardly, as shown in FIG. 9, until spring portion 85 is checked by the wall 138 of rear axial slot 93, arresting the carrier in the body with needle 16 withdrawn from the flesh. A slight rotation of the carrier aligns the portion 85 with extension slot 95, in position for withdrawal from the body-cylinder assembly 22.

The withdrawn carrier can then be relieved of the exhausted syringe, which may be either discarded or refilled in accordance with its nature.

The operational process may now be repeated for successive injections.

Because of the cooperative arrangement between the trigger and the latch on the carrier, the user may stop the injection if a malfunction of penetration or fluid level is detected by releasing the trigger disc, forcing the trigger tang to expel the latch portion 85 so that retracting spool 69 impels the carrier and syringe rearwardly, extracting the needle from the flesh. Additionally, because of the unique combination of elements comprising the invention, the syringe plunger cannot be withdrawn so as to aspirate (draw in air), obviating the risk of injecting any embolism-causing air bubble into the blood stream.

The syringe plunger cannot be withdrawn because displacement of actuator latch tang 59 from end 29 of the outer body immediately relatches the plunger actuator shaft against displacement in the carrier, holding the syringe plunger at its most forward position achieved at the instant of trigger release.

In the case of some materials of fabrication friction between the peripheries of adjacent elements, such as the outer body and the inner cylinder, or the inner cylinder and the carrier, may inhibit free relative motion, as may entrapment of dust or other foreign matter. It may therefore be desired to lessen friction contact by lessening the area of contact. In the embodiment of FIG. 17, shown fragmentarily, frictional contact is reduced by means of longitudinal fins on the exterior peripheries of the inner cylinder 34A and the carrier 21A. For instance, a plurality of fins such as the fins 141 may protrude at circumferentially spaced points from the outer periphery of inner cylinder 34A, and only the lands 142 of each fin bear on the body inner surface. Similarly, a plurality of fins like fin 145 of FIG. 17 may emerge at circumferentially spaced points from the surface of carrier 21A with only the lands 146 of each fin in contact with the inner surface 148 of the inner body.

These and other modifications within the scope of the invention will occur to those skilled in this particular art. It is therefore desired that the invention be measured by the appended claims rather than the illustrative description and drawing disclosed in this specification.

Claims

I claim:

1. A hypodermic syringe actuator for use with a conventional syringe having a case for fluid, a case flange at one end thereof, a fluid-expelling plunger, a hypodermic needle and a protective needle cap, the actuator comprising an elongate outer body, a front body opening, a rear body opening, an inner cylinder movable longitudinally in the outer body, a spring holder on said outer body, a bearing leg on said inner cylinder, a spring between the holder and the leg, the leg and holder being urged apart by the spring to springload said inner cylinder for motion longitudinally of said body toward the front opening; means releasably securing said inner cylinder in springloaded condition in said outer body, a syringe-receiving carrier removably lodged in said inner cylinder, means for latching said carrier to move with said inner cylinder, means for unlatching said carrier from said inner cylinder to move therein, retraction means biasing said carrier along said inner cylinder; syringe-receiving means at one end of said carrier adapted to grip the syringe at its case flange, a syringe plunger actuator extending from the other end of said carrier, spring means biasing said plunger actuator toward said syringe-receiving means; a latch defeating means operable during elongate motion of the inner cylinder and carrier toward the forward body opening; means limiting motion of the carrier with respect to the inner cylinder, and means limiting motion of the inner cylinder with respect to the outer body.

2. Apparatus in accordance with claim 1 wherein the means for latching the carrier to move with the inner cylinder comprises a compound leaf spring in the carrier, a latch portion at an end of the leaf spring, an aperture in the carrier, a first forward slot in the inner cylinder, said aperture and slot coinciding when the retraction means and the springloading means are activated.

3. Apparatus in accordance with claim 2 further comprising a second inner cylinder slot forward of the first slot and axially aligned with the first slot, a trigger pivotably secured in the outer body, an externally operable trigger thrust disc, a trigger tang, and a trigger load spring biasing the trigger tang into latching engagement with the first and second inner cylinder slots, said tang being adapted to expel from slot engagement the latch portion of the compound leaf spring when thrust is withdrawn from the trigger thrust disc.

4. Apparatus in accordance with claim 3 wherein said leaf spring extends from the latch portion to a forward bifurcated portion oriented at right angles to the latch portion and so adapted to contact the case flange of a syringe in the carrier.

5. Apparatus in accordance with claim 1 wherein the syringe plunger actuator comprises a shaft in the carrier, a shaft plunger, spring, a latch plate in the carrier about the shaft, surfaces centrally of the plate defining a lock aperture adapted to bind the shaft against the pressure of the plunger spring when the latch plate is askew with respect to the shaft and to release the shaft when the plate is normal to the shaft, a spring loading said plate into skewed attitude, a tang on said plate, and an end on the outer body, said tang contacting said end upon forward motion of the inner cylinder and the carrier to change the attitude of the latch plate to normal of the shaft.

6. Apparatus in accordance with claim 5 further comprising a contact head on the shaft, and a cushion on the head.

7. Apparatus in accordance with claim 1 wherein the carrier retraction means comprises an annular wall on the front end of the inner cylinder, a retraction spool with flanged ends, a spring on the spool bearing between the annular wall and a spool flange; said spool being hollow to surround a syringe held in the carrier, and a forward wall on the front end of the carrier adapted to be thrust upon by the spool when the carrier is unlatched from the cylinder.

8. Apparatus in accordance with claim 1 wherein the inner cylinder comprises a longitudinal wall, a front annular wall, a flanged spool circumscribed by the annular wall, a spring between the annular wall and a spool flange, an open rear wall, a first front slot, a second front slot, a rear slot, all of said slots being longitudinally aligned in the longitudinal wall, a wall of the rear slot defining a stop surface for the latch portion of the carrier leaf spring, a rear slot extension unaligned with said slots but connected to the rear slot, and an inwardly extending boss adapted to align the carrier.

9. Apparatus in accordance with claim 1 wherein the carrier comprises an elongate cylindrical wall, a rear end wall, a front end wall, an intermediate rear wall, an intermediate front wall, circumferential openings in the cylindrical wall between the front wall and the front intermediate wall adapted to receive the case flange of a hypodermic syringe, a flange retaining spring adjacent the front wall, a spring latch, a latch aperture, an elongate pair of spaced wall surfaces in the cylindrical wall defining a guide groove diametrically opposed to the latch aperture, said groove narrowing rearwardly of the carrier, a plunger actuator shaft journalled in the rear wall, an acuator spring, a shaft latch, a contact head on the shaft, and means for defeating the latch.

10. Apparatus in accordance with claim 1 wherein said latch securing said plunger actuator in the bias-loaded position comprises a latch disc, central offset grippers in the disc, and a compression spring biasing the latch disc and grippers into latching position; and said latch defeating means comprises a contact wall on said outer body, and a latch disc tang adapted to engage the contact wall upon forward longitudinal motion of said carrier, said latch disc being urged into latching position by the compression spring to arrest the plunger actuator upon reversal of longitudinal motion of said carrier.

11. Apparatus in accordance with claim 1 further comprising a tubular flesh contact tip, means at the front opening of the outer body for releasably receiving the contact tip, a first contact surface on the contact tip defined in a plane normal to the axis of longitudinal motion of the inner cylinder, and a second contact surface on the tip opposite the first contact surface defined in a plane at an acute angle to said axis of longitudinal motion of the inner cylinder.

12. Apparatus in accordance with claim 11 wherein said means for receiving the contact tips comprises a hollow front nose on the outer body, a pair of diametrically opposed registry stops on the hollow nose, said registry stops being adapted to engage either contact surface of a flesh contact tip.

13. Apparatus in accordance with claim 1 further comprising a second holder spaced from the spring holder, a spring retainer fixed between said holders, an inner cylinder wall, said bearing leg extending from said wall about said retainer and movable therealong and said spring between the bearing leg and the holder being a compression spring.

14. Apparatus in accordance with claim 13 further comprising a spring retaining rod comprising said spring retainer, and a carrier cushion between said bearing leg and one of the holders.

15. A hypodermic syringe actuator for use with a conventional syringe having a fluid case, a case flange at one end thereof, a fluid-expelling plunger, a needle and a needle cap, the actuator comprising an elongate outer body, an open front end, an open rear end, a removable nose piece, a contact surface on the nose piece, means on the body for releasably receiving the nose piece, an inner cylinder movable longitudinally in the body, an elongate cylinder wall, an open rear end on the cylinder, an annular restrictive wall on the front of the cylinder, a retraction spool held movably in the cylinder and restrained by the annular wall, a spring urging the spool into the cylinder, first and second latch slots in the cylinder wall, a rearward aperture in the cylinder wall axially aligned with the first and second slots, an aperture extension off-axis from the slots and aperture, a boss extending inwardly from the cylinder wall; a carrier in the inner cylinder and removable therefrom, a syringe receptacle on the carrier, a syringe plunger actuator on the carrier, an actuator latch, means for defeating the actuator latch, a latch hood, a syringe retainer spring on the carrier, a latch aperture in the carrier wall, a carrier latch adapted to protrude into and through the aperture to latch in an inner cylinder slot, a cocking shaft protruding from the carrier; said carrier including a pair of spaced peripheral walls extending from the syringe receptacle rearwardly of the carrier; a cylinder impelling spring, means on the outer body retaining the impelling spring, a bearing leg on the inner cylinder thrust upon by the impelling spring to load the cylinder forward, an outer body trigger springloaded to latch in a forward inner cylinder slot, said trigger including an engaging tang and a thrust disc, a trigger spring between the tang and disc; said tang latching said inner cylinder in a first cocked position and releasing said cylinder with the carrier containing a syringe for insertion of the needle responsive to pressure on the trigger thrust disc; said tang repelling said carrier latch from a cylinder slot upon release of the trigger; and a disc shroud on the outer body adapted to preclude accidental thrust upon the trigger disc.

16. Apparatus in accordance with claim 15 wherein said latch securing said plunger actuator in the bias-loaded position comprises a latch disc, central offset grippers in the disc, and a compression spring biasing the latch disc and the grippers into latching position; and said latch defeating means comprises a contact wall on said outer body, and a latch disc tang adapted to engage said contact wall upon forward longitudinal motion of said carrier, said latch disc being urged into latching position by said spring to arrest the plunger actuator upon reversal of longitudinal motion of said carrier by release of pressure upon the trigger thrust disc.