Abstract: An arterial blood sampling syringe consisting of a barrel and a plunger assembly in which the plunger is hollow and provided at its distal end with two annular rings which cooperate with the hollow plunger and each other to maintain a sealing ring and gas-pervious but liquid impervious membrane in position at the end of the plunger. The plunger position in the barrel may be preset to receive any desired blood sample volume. Further blood flow is halted when the barrel of the syringe fills to the volume desired.

Abstract: An intravenous needle assembly and an associated manufacturing method, wherein the needle assembly comprises a hypodermic needle attached to a hub at its trailing end, a transparent blood detection chamber integral with the hub, a catheter disposed around the needle and the needle hub and a plug closing the blood detection chamber, the plug having air breathing capacity so that upon venipuncture blood from a vein may flow through the needle into the blood detection chamber without substantial air resistance to such flow to visually confirm the accuracy of the introduction of the needle into a vein. The plug is centrally hollow and has an axially directed leading projection connected to an annular shoulder or flange. The projection comprises a symmetrical hollow truncated conical extension with a hollow interior and walls having pairs of longitudinally directed ribs insuring ready passage of air from the flashback chamber along the outside of the projection under pressure of the heart.

Abstract: An intravenous needle assembly and an associated manufacturing method, wherein the needle assembly comprises a hypodermic needle attached to a hub at its trailing end, a transparent blood detection chamber integral with the hub, a catheter disposed around the needle and the needle hub and a plug closing the blood detection chamber, the plug having air breathing means so that upon venipuncture blood from a vein may flow through the needle into the blood detection chamber without substantial air resistance to such flow to visually confirm the accuracy of the introduction of the needle into a vein. The plug is centrally hollow and has an axially directed leading breather projection connected to an annular shoulder or flange. The breather projection comprises a symmetrical hollow truncated conical extension with a hollow interior and walls having a plurality of narrow slits permitting ready passage of air under pressure of the heart while substantially preventing the passage of blood through the slits.