Stick-free syringe and associated methods

Abstract

A stick-free blood collection system includes elongated inner and outer sheaths and a syringe, including a needle and blood collection tube, mounted with the inner sheath. The inner sheath--and hence the syringe--are axially moveable within the outer sheath. The outer sheath has a small aperture at the distal end thereof to permit passage of the needle through the outer sheath and into the patient. The outer sheath also includes an angled flat portion at the distal end to mount the outer sheath onto the patient in a practical fashion whereby the needle can be telescopically injected into the patient. During operation, the outer sheath is mounted at an angle relative to the surface of the patient, and the needle enters the surface at that angle to draw blood therein. The inner and outer sheaths have mating interconnections which engage when a user twists the inner sheath relative to the outer sheath, thereby preventing axial displacement of one sheath relative to the other sheath. Via this twisting motion, a user of the invention secures the needle within the outer sheath so as to prevent inadvertent contact with the used needle. The interconnections also generate an audible 'click' when becoming engaged, thereby indicating that the system is safely locked. An aiming slot provides for visual access of the needle along the elongated axis; and the slot and the interface section provide a target site to predict the entry point of the needle into the patient. A lip at the distal end of the inner sheath provides for convenient handling of the inner sheath and syringe, and provides for smooth control of the system during replacement of the blood collection tube, e.g., a vacu-chamber.