Patent ID: 7717879

Claim:
An anesthetic syringe comprising: (a) a slide valve comprising a front element; (b) a feed piston longitudinally slidable within a carpule volume, said feed piston having a feed piston pressure plate; (c) a first hydraulic chamber connected to said feed piston pressure plate; (d) a second hydraulic chamber behind said first hydraulic chamber and connected to said first hydraulic chamber so as to allow for regulation of flow resistance; (e) a control hole having an opening between said first hydraulic chamber and said second hydraulic chamber; (f) a spring connected to said slide valve, said spring biasing said slide valve to a rest condition wherein the opening of the control hole between said first hydraulic chamber and said second hydraulic chamber is closed; and (g) a separator piston that is disposed behind the second hydraulic chamber and that is slidably mounted so as to be capable of reducing the size of the second hydraulic chamber; wherein said slide valve has a slide valve pressure plate connected to said first hydraulic chamber; wherein said front element protrudes into said first hydraulic chamber in order to allow for haptic feedback of pressure in said first hydraulic chamber; and wherein said slide valve is capable of closing or progressively opening the opening of the control hole between said first hydraulic chamber and said second hydraulic chamber.