Retractable needle and syringe combination

A syringe comprising an outer barrel having a forward end and rearward end, said forward end having an opening and at least one wedge element carried in said opening,

• an inner barrel having a forward end and a rearward end adapted for insertion into the rearward end of said outer barrel, said inner barrel having an expandable collet mounted on said forward end thereof,
• spring means positioned between said outer and inner barrels so as to bias said inner barrel rearwardly with respect to said outer barrel,
• said collet having a forward end adapted to engage said opening in said forward end of said outer barrel, said opening constricting said collet as said collet is biased rearwardly through said opening, a fluid seal between said inner barrel and said outer barrel so as to contain fluid in a fluid containment chamber between and inner surface of said outer barrel and the exterior of said inner barrel,
• a needle retracting holder element having a forward end adapted to receive a needle and a shoulder trap edge, said forward end of said needle retracting holder having a diameter, said diameter of said needle retracting holder forward end being larger than a diameter of said needle, said needle retracting holder having a tubular body and a fluid port contained therein, said fluid port communicating with said fluid containment chamber and said needle, said needle retracting holder inserted into said inner barrel and engaged by said expandable collet at said shoulder trap edge,
• second spring means for biasing said needle retracting holder rearwardly positioned between said inner barrel and said needle retractor, and
• a plunger element having a forward end and a rearward end adapted for insertion into said containment chamber for pressurizing said fluid containment chamber whereby forward movement of said inner barrel with respect to said outer barrel releases said needle retractor element rearwardly into said inner barrel.