Method and apparatus for injecting fluids into patients at a controlled rate from an ampule containing the injecting fluid with a sliding piston therein to force the fluid from the ampule into the patient using a drive system which incrementally and successively advances the piston in the ampule to meter...http://www.google.ca/patents/US4342312?utm_source=gb-gplus-sharePatent US4342312 - Method of injecting fluid
