A gas washout vent for a patient interface may be configured to allow a flow of patient exhaled gas to an exterior of the patient interface to minimise rebreathing of exhaled gas by the patient and the vent may include: a plurality of vent passages extending between a first and a second side of the vent, each vent passage may include: a plurality of first openings extending from the first side towards the second side, said first openings being uniform in size and shape； a plurality of second openings extending from the second side towards the first side, said second openings being uniform in size and shape； and wherein the first openings and the second openings partially overlap each other at an interface to form constricted passages therebetween.
