US Patent 7641637 Controlled volume injection/aspiration device

A controlled volume injection/aspiration device includes a syringe having a body for containing a medicament, a needle and a piston slidably disposed within the body. A shell is provided for receiving the syringe body and a plunger rack is disposed within the shell. A manually operated control is disposed in an operative relationship with the plunger rack for moving the plunger rack in a stepwise forward direction causing the piston to eject discrete doses of medication from the syringe body through the needle. The manual operated control is also operative for moving the piston in a stepwise reverse direction causing the piston to aspirate fluid into the syringe body through the needle.