| 摘要 |
<p>The syringe body is suitable for inclusion in a dental cabinet for the injection of anaesthetics, drawing back of some of the blood is necessary to see if the needle has entered the vein, A syringe body contg. a preserved medicament between two plugs is known; one of these plugs acts as the piston and the other is intended to be perforated by the needle when press. is applied. No drawing back is possible because if the piston is drawn backwards the other plug is brought back to the position above the needle; in the new device the plug is retained on the needle, so that injection and re-aspiration can be practiced. For use the body is fixed to the head with the rod in the piston. The press. exerted on the latter brings the lower plug into the position in which it is pierced by the needle; it is maintained in this position by retaining means and any compressed air is evacuated through the orifice at the base.</p> |
