Vent plugs and related catheter systems

A vent plug for a catheter system, comprising:

• a distal end comprising a hole, wherein the hole is sized to pass air but not blood;
• a proximal end;
• a lumen extending proximally from the hole through the proximal end;
• and
• an air-permeable plug disposed within the lumen, wherein the air-permeable plug comprises polyurethane foam.

A catheter system, comprising:

• a catheter adapter, comprising a distal end and a proximal end;
• a catheter extending distally from the distal end of the catheter adapter;
• a vent plug in fluid communication with the catheter, wherein the vent plug comprises:
• a distal end comprising a hole, wherein the hole is sized to pass air but not blood;
• a proximal end;
• a lumen extending proximally from the hole through the proximal end;
• and
• an air-permeable plug disposed within a proximal end of the lumen, wherein the air-permeable plug comprises cellulose or polyurethane foam.