The invention relates to an intravenous catheter apparatus comprising: a catheter hub (12) arranged at a proximal end of a catheter tube (10), the catheter hub (12) having an inner surface (14) defining a chamber (16)； a needle (20) defining an axial direction and having a needle tip (24), the needle (20) extending through the chamber (16) and the catheter tube (10) when in a ready position； a needle guard (32) slidably arranged on the needle (20) and at least partially received in the chamber (16) when the needle (20) is in the ready position, the needle guard (32) including a base portion (34) and first and second arms (36, 38) extending from the base portion (34), wherein the first arm (36) is deflected radially outwards by the needle (20) against a restoring force when the needle (20) is in the ready position whereby the needle guard (32) is brought into retaining contact with the catheter hub (12)； and wherein the catheter apparatus includes a valve which separates a distal space arranged in distal direction from the valve from a proximal space arranged on proximal direction from the valve. The invention further provides that the valve opens based on a pressure differential between the pressure prevailing in the distal space and the pressure prevailing in the proximal space.
