Vascular access instrument and related devices and methods

A catheter system, comprising:

• a catheter hub, comprising a distal end, a proximal end, a side port disposed between the distal end of the catheter hub and the proximal end of the catheter hub, and a lumen extending through the distal end of the catheter hub and the proximal end of the catheter hub;
• a catheter extending distally from the distal end of the catheter hub;
• a Y-adapter, comprising a distal end, a first port, and a second port;
• an extension tube, comprising a distal end integrated with the side port and a proximal end integrated with the distal end of the Y-adapter;
• and
• a septum disposed within the Y-adapter, wherein the septum comprises a distal end, a proximal end, a lumen extending through the distal end of the septum, a side opening in fluid communication with the lumen of the septum, and a vent extending from the proximal end of the septum, wherein the septum is movable between a prime position and an infusion position, wherein in response to the septum being in the prime position the vent is aligned with the side port, wherein in response to the septum being in the infusion position, the side opening is aligned with the side port.