Cartridge syringe
A cylinder ampoule syringe (manufacturer's name from Bayer: Karpulenspritze ) is a special type of syringe . It is used especially in dentistry, mostly for local anesthesia, e.g. B. before a tooth extraction .
construction
The carpule syringe is not "drawn up" like a normal syringe, but is filled by inserting a cylinder ampoule . This cylinder ampoule is a glass cylinder that is already filled with the drug in a sterile manner by the pharmaceutical manufacturer . The front end of the cylinder ampoule is closed with a puncture membrane (rubber or plastic) which is pierced by an injection needle for injection like an injection vial . The rear end of the cylinder ampoule is closed by a thick rubber stopper, which can be pressed into the cylinder like a piston by the pressure of the plunger of the carpule syringe. The system of the cartridge syringe is very similar to that of an insulin pen , as it is often loaded with disposable ampoules and injected with a disposable needle. The only difference is the choice of dose.
Special cannulas (carpule cannulas) are required for the carpule syringe. On the long side, they resemble a completely normal cannula (bevelled hollow tube) with which the local anesthetic is injected, and at the other end have another short, beveled hollow tube with which the puncture membrane of the cylindrical ampoule is pierced. The cartridge cannulas are screwed onto the cartridge syringes.
Loading the syringe
Depending on the model, the carpule is either inserted into the carpule syringe from behind after the plunger has been folded to the side, or the ampoule is pushed into the syringe from the side - for this purpose, the plunger is pulled all the way back.
volume
The cylindrical ampoules have a volume of 1.7 ml. Compared to disposable syringes, they are relatively narrow and long. This requires a long syringe plunger that also has this long stroke. As a result, the carpule syringes are very long overall. On the other hand, the great length with the long stroke allows more precise dosing and slower spraying.
Aspiration sample
With local anesthesia of the lower jaw, aspiration is mandatory - after the puncture to the final position, suction is performed slightly to check whether the cannula is not in a blood vessel, which should be avoided at all costs.
The aspiration test with the carpule syringe requires additional design effort, since the plunger of the syringe is not firmly connected to the rubber stopper of the cylinder ampoule from the outset. This problem does not exist with single-use syringes because the pull on the syringe plunger directly creates a negative pressure in the syringe.
In terms of design, the problem with the carpule syringe is solved by rotating the syringe plunger and an inner axis in the syringe plunger extending three hooks (aspiration hooks), which claw into the rubber stopper of the cylinder ampoule. For this purpose, the rubber stopper of the cylinder ampoule has a deep cylinder-shaped hole on the non-sterile back.
Another, somewhat simpler constructive solution consists of a barb. There are no moving parts (inner axis, three moving hooks), but instead of the three moving hooks a barb is attached (harpoon shape or flat square plate) that claws into the deep, cylindrical hole of the rubber stopper.
This provisional connection between the syringe plunger and the cylinder ampoule stopper allows a slight negative pressure to be built up in the cylinder ampoule for the purpose of an aspiration test.
Since the dentist usually holds the mirror in the other hand to hold the cheek or lip away, the aspiration test must be carried out with one hand. That is why newer models of carpule syringes are usually provided with a thumb ring.
Anoint
In addition to the administration of anesthetic syringes, carpule syringes are also used in dentistry to apply ointments to the gum area. Since only very little ointment is required here, the cylinder ampoule is used for several patients. Only the carpule cannula needs to be replaced. The carpule cannula for ointment application is blunt at the working end, without a bevel, and therefore more like a cut tube. Only the piercing side of the cannula (towards the cylinder ampoule) is pointed.
advantages
The main advantage is that it makes work easier. Since the medication does not have to be drawn out of an ampoule first, but is "loaded" much more easily by inserting the cartridge, a small amount of time is saved. It is also easier for the dentist to reload a second cartridge himself - without the assistance of his assistant, if his hands are already contaminated with saliva or blood from working on the patient. Eliminating the need for opening reduces the risk of non-sterility. Mix-ups are less common, as the drug always remains in the ampoule produced by the manufacturer and is not transferred to an unlabeled, disposable plastic syringe.
The ring for the thumb at the end of the syringe plunger, which facilitates the aspiration test, is advantageous.
The long design of the carpule syringe, due to the narrow cylinder ampoules, also enables the dentist to inject clearly. He can keep his squirting right hand well outside his mouth, even if he is making an injection far back in the mouth (e.g. in the area of the wisdom tooth). With a short syringe, he would have to put his hand halfway into the patient's mouth, which in turn would hinder the illumination and the field of view.
disadvantage
In the dental field in particular, patients are more or less widespread fear of dental treatment and also of injections. Since carpule syringes are relatively large, sight of them can greatly increase the patient's anxiety. It may be helpful to point out that it is actually just a large handle that makes the syringe look so big, and that the cannula tip is "identical" to a normal syringe. In the case of very anxious children, it is even advisable in individual cases for psychological reasons to forego the carpule syringe and to administer the anesthetic from a normal disposable syringe, which is much smaller. However, most children can easily be anesthetized with a carpule syringe through open, trusting interaction.
Another disadvantage is the slightly higher cost of the local anesthetic in the cartridges and the slightly more expensive cartridge cannulas.
The costs for the carpule syringe (stainless steel) are also disadvantageous and can conflict with practice hygiene. Either a new carpule syringe must be available for each patient or the syringe must be disinfected or sterilized after each patient.
Another disadvantage is the unwieldiness of the carpule syringe due to its size.
Individual evidence
- ↑ Carpule for receiving a drug , WO 2001030418 A2, Google Patent. Retrieved September 7, 2014
- ↑ Rüdiger H. Schönfeld: The examination knowledge of dental assistants: area of treatment assistance, examination preparation and revision course; [1,100 exam questions] . Schlütersche, 2005, ISBN 978-3-89993-600-1 , p. 156–.
