Blood sampling assembly having porous vent means vein entry indicator

摘要: A blood sampling assembly is provided which has a cannula designed for intravenous penetration, mechanism applying negative pressure to the cannula, chamber located between and source of pressure, one-way valve positioned within chamber, venting member allows air as enters but does not allow passage blood. person drawing enabled visually determine when needle properly inside vein through transparent walls chamber. Spillage avoided with present by resistance flow distally from cannula.