| 摘要 |
A hypodermic syringe for injection of anaesthetics must be designed in such a manner that aspiration can be made easily and preferably without the necessity to inject some of the anaesthetic prior to the aspiration. In syringes of the type intended for cooperation with a cylindrical ampoule having a displaceable plunger for closing one of its ends whereas the other end is closed by a diaphragm, it is further important to prevent the diaphragm and plunger from being damaged during injection so that air may enter into the ampoule. A syringe meeting these demands is provided in that a sleeve-shaped piston rod is adapted to be governed by the internal wall of the ampoule, the rod being fitted to an operating member which, however, is axially displaceable in relation to the rod and connectable directly to the plunger by means of a connecting device extending through the piston rod. The operating member is designed as a two-part plate, one part of which is shaped as a one-finger-maneuvered lever operating against projections in the piston rod and intended via the connecting device to bring about the required motion of the plunger for effecting aspiration. |
