NL8006197A - Injector for throw-away ampoules - has trigger operated to move ampoule piston forward and released to retract it for aspiration check - Google Patents

Abstract

The mechanism is intended for administering an injection using a throw-away ampoule. It is provided with means which permit automatic aspiration (withdrawal of ampoule piston to check whether the injection needle has entered a blood vessel). Aspiration can be effected at any point over the entire stroke of the piston without this affecting the position of the needle. The mechanism may comprise a trigger-operated push rod with barbed plunger to engage the piston, the trigger operating the rod via a spring-loaded friction element during the injection stroke, whilst a further spring-loaded friction element retracts the rod when the trigger is released to aspirate.

Description

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Philippus Poppink, Delft

Syringe with automatic aspiration control.

The invention relates to a syringe device for medical use and suitable for disposable carpules / ampoules of the type known, for example, according to Dutch patent 77799.

Arrangements are made to intermittently change the direction of the ram driving the plunger to allow aspiration control throughout the plunger trajectory, the controls being designed to require minimal hand movement to achieve both injection and aspiration.

The desired aspiration control - the withdrawal of the syringe plunger to check whether the needle tip is in a blood vessel or not - is in principle impossible in many embodiments of the syringes according to the cartridge system, because in those constructions no coupling device between punch and piston is fitted. In versions where a coupling device, for example a barb, is fitted, it is necessary to aspirate to change the grip on the handle in order to convert the driving piston movement into a pulling movement.

The spraying device and thus the inserted needle usually undergo a change of position. In view of the usually extremely small diameters of the blood vessels, aspiration control must in that case remain surrounded by doubts.

The present invention is based on the idea of improving the spraying device in such a way that these drawbacks are obviated by starting from such a design that the most stable position in the hand during function 30 is ensured.

The mechanism for injecting and aspirating has been adapted and of such a construction that it can be activated with extremely simple hand / finger movements.

Needle tip position changes during the two functions 35 are thus up to. reduced to a minimum, even when injecting into very rigid tissues.

The spraying device according to the invention is characterized by two sliding frictional catches on the punch rod which drive the piston of the carpule towards the needle tip 40 and a coupling device between punch and piston to transfer both the reciprocating movement of the punch to the piston bring.

The syringe handle with actuator is disposable in all positions relative to the combination ram rod carpule needle 45 to provide the opportunity to position the handle in the ergonomically best position to prevent unwanted movement of the needle during function. minimize.

One friction detent provides the propulsion of the piston / ram rod combination, the other friction detent 50 ensures the retraction of this combination to achieve the aspiration control.

80 06 19 7 *, - '· »· 2» * I »1 With reference to the enclosed schematic drawing, a possible embodiment is further explained.

In the handle 6, the outrigger rod 4 with outrigger 3 can move back and forth from left to right.

5 The cartridge 7 can be attached to the handle with a coupling. In the starting position shown, the barb 5 then drops into the piston. The needle is then mounted. Friction ratchet 1 consisting of. a pierced metal plate with a slightly larger bore as the diameter of the outrigger rod 10. 4 is pressed against the stop cam 9 by a spring 8 arranged over the outrigger rod.

When the cock 10 is tightened, pawl 1 tilts, whereby the friction between the punch rod and the bore edge in the pawl takes on such a value that the punch rod is taken along and the piston 15 is driven via the punch towards the needle tip.

Friction pawl 2 follows this movement against the spring tension of spring 11, but in doing so runs up against breech cam 9, whereby a tilt of 2 is created such that the friction between the pawl and the ram rod just decreases and thus does not hinder the driving movement.

At the end or during the stroke length of cock 10 it is released. Spring 8 tilts pawl 1, the friction between pawl and rod decreases and the pawl slides back to the starting position bounded by stop cam 9.

Spring 11 tilts pawl 2, increasing the friction ratchet rod, and the rod is carried by pawl 2, where the piston receives an opposite movement to the expelling direction. The volume in the carpule 7 increases, the pressure decreases and if the needle tip is in a blood vessel, blood will flow into the carpule and become visible there as a red cloud.

The return movement of 2 is limited by adjusting screw 12 with which the aspiration stroke length can be adjusted.

Each repetition of the cock movement offers the possibility of aspiration control over the entire piston trajeet.

The movements and shifts are repeated until the plunger has reached the end of the carpule.

40- The cartridge and needle are disconnected and discarded.

Press the release button 13 to loosen the friction catch 2 - outrigger rod and the outrigger rod can be returned to the starting position by pulling the button 14.

80 06 19 7

Claims (5)

1 Injection device for use with automatic aspiration control cartridges on the entire piston traret characterized by frictional catches on the outrigger to move them back and forth. The syringe device according to claim 1, wherein a frictional catch acts as a follower of the outrigger rod in the forward direction, activated by an actuator and a second frictional catch which, at the end of the operating stroke of detent 1, automatically releases a return movement of the outrigger rod. accomplished, creating aspiration. 3 Injection syringe device according to 1 and 2 with possibility to adjust the length of the return aspiration stroke. Injection syringe device according to the preceding claims, characterized in that the handle and operating members can be placed in any position with respect to the direction of the needle and the cartridge for reasons of ergonomic nature. Injection syringe device according to previous claims 20, characterized in that, by choosing the transmission ratios advantageously, it is also possible to inject into very rigid tissues with minimal effort and little chance of changes of position of the needle. % 8 0 06 19 7