Needle with vent filter assembly

Claim 1

A needle with a vent filter assembly for use in the aspiration of a drug solution from a supply into a syringe after an outer needle shield is removed so that an injecting needle is exposed and ready for use with an attached syringe containing said drug solution and for the injection of said drug solution into a patient, this vent filter assembly including: (a) a metal injecting needle of conventional construction and configuration and fixedly attached to a hub portion conventionally formed with a recess adapted to mount on the discharge end of a syringe; (b) a large barrel shaped tubular vent housing of molded plastic and having an open rear end and front end and a through passageway for the injection needle, the rear end formed with a rear bore extending inwardly from the rear end, with said bore sized and adapted to extend a short distance inwardly from termination of the rear end and adapted to be slideably mounted on the forward end of said needle hub, and in which there are provided and formed a plurality of inwardly-extending ribs which engage and secure a tubular filter membrane in a desired intermediate position within said molded housing, said ribs on their inner extents providing a guideway for the insertion of and withdrawal of the injecting needle, this tubular vent housing having its midportion formed with a plurality of through apertures providing for passage of air from the exterior to the interior and from the interior to the exterior through said secured filter membrane, and configuring these ribs so that at their rearward face each rib terminates in a formed surface to provide a stop abutment surface, these abutment surfaces positioned a short distance inward from the rear termination of the vent housing; (c) a hydrophobic filter membrane of a tubular configuration having an interior diameter larger than the needle hub and held in position in the midportion of said housing so that all air from and to said supply is caused to pass through said filter; (d) a rigid cannula portion which is molded with and hub is molded and is an integral part of the vent housing, said cannula sized and positioned so as to provide a forward reduced diameter portion of the housing, this cannula providing a slide guide and surrounding wall member for said injecting needle, said cannula and said injecting needle providing an annular space therebetween sufficient for a pathway along which air can and does flow, said rigid cannula, when said tubular vent housing is in mounted condition, having its entering end terminating before a sharpened end portion of the injecting needle, said sharpened end and rigid cannula sized so as to pierce a stopper and the like of a vial; (e) a resilient O-ring mountable in said rear bore and sized to engage said bore and the abutting surface of the molded ribs, and in mounted condition to be substantially within said bore, said O-ring providing for hermetically sealing the hub of the injecting needle and the tubular vent housing to prevent an unwanted flow of air while with manipulation being able to separate and withdraw the injecting needle from the rigid cannula; (f) a plurality of shallow exterior grooves formed in the larger barrel portion of the tubular vent housing, said grooves extending from the formed vent filter apertures to a forward end of said larger barrel portion housing, these shallow grooves providing air flow paths to and from the filter, and (g) a thin, tubular shrink-wrap retainer which is positioned and with heat is affixed to the larger barrel portion of the molded tubular vent housing and with said shrink-wrap open to the front so that said shallow grooves are open to the front of the housing, with said shrink-wrap providing an exterior protective member of and for the outwardly-exposed surface of the filter membrane, and with the rear end of the shrink-wrap extending rearwardly of the tubular vent housing so that when the shrink-wrap film is affixed this extending portion is caused to be turned inwardly and transversely on the outer surface of said tubular vent housing this shrink-wrap portion extending sufficiently inward to provide a retaining means for the mounted O-ring seal, the retained O-ring stopped in its forward travel by the abutment surfaces formed on the inwardly-extending ribs, and in mounted and retained condition said O-ring engages the bore of the housing and the needle hub portion to effect and provide a seal of said passageway so there is provided a protected pathway for air to pass to and from the outside atmosphere to the interior of said tubular vent housing, with said filter removing unwanted contaminants from said air pathway.