Patent ID: 6283941
Filing Date: 2001-09-04
Classification: A61M

Abstract:
A single-use and aspirating-capable syringe comprising:a hollow barrel having an interior cylindrical sidewall, a distal end and a proximal end opposite to said distal end,a needle tip at said distal end of said barrel;a basically cylindrical, plunger rod extending beyond said barrel and having a longitudinal axis located within said barrel for axial movement therein for drawing fluid into and expelling fluid out of said barrel through said needle tip, said plunger rod having at least one ratchet tooth and also having a barrel sidewall-scaling piston at its distal end near said needle tip end of said barrel, said plunger rod comprising an aspirating gap comprising a smooth wall of reduced diameter of said plunger rod with respect to said ratchet tooth, said aspirating gap being proximally located with respect to said ratchet tooth;a radially, resilient, open-walled spring locking clip initially mounted about said aspirating gap of said plunger rod, said spring locking clip having ratchet tooth-engaging means and at least one, outwardly-directed locking barb having a sidewall contact point, said spring locking clip being forced to move distally along with said plunger rod after said plunger rod is first moved sufficiently proximally with respect to said barrel and said spring locking clip such that said tooth engaging means of said spring locking clip mechanically engages said ratchet tooth of said plunger rod;said plunger rod being free to reciprocate for aspiration when said spring locking clip is located on said aspirating gap of said plunger rod, said locking spring clip being held in position within said barrel by the frictional digging of said contact point into said sidewall as said plunger rod moves proximally and distally but the latter only while said spring locking clip is located about said aspirating gap and prior to mechanical engagement of said spring locking clip with said ratchet tooth, and, thus distal movement of said plunger rod, after sufficient proximal movement of said plunger rod such that said spring locking clip is mechanically engaged with said ratchet tooth, causes distal movement of said spring locking clip by mechanical interconnection of said ratchet tooth-engaging means with said spring locking clip;whereby aspiration can be accomplished and said spring locking clip and plunger rod permit the syringe to be loaded with medication in the volume of said barrel defined by a predetermined location of said spring looking clip on said plunger rod by proximal movement of said plunger, and, after mechanical engagement between said spring locking clip and said ratchet tooth, distal movement of said plunger rod expels said medication and distally moves said spring locking clip within said barrel such that said plunger rod is prevented from a second full barrel length movement by said piston abutting said spring locking clip such that frictional digging in between said contact point and said interior cylindrical sidewall results.