An indwelling intravenous needle having two blood backflow passage routes. One is an internal cavity of a metallic internal needle, which is the basic construction of an indwelling intravenous needle of a conventional type. The other is being a groove provided on the surface of the internal needle extending...http://www.google.de/patents/US5279572?utm_source=gb-gplus-sharePatent US5279572 - Indwelling intravenous needle with two blood-backflow passage routes
