VENT ARRANGEMENT FOR RESPIRATORY MASK

The present invention relates to an apparatus for automated control of gas washout of a patient interface of a respiratory treatment apparatus comprising: a vent assembly having a variable exhaust area defined by one or more apertures of the vent assembly, the vent assembly being associated with a patient interface to vent expiratory gas. The apparatus additionally comprises an actuator to manipulate said one or more apertures of the vent assembly and a controller including a processor, the controller coupled with the actuator, the controller configured to operate the actuator to change the exhaust area of the vent assembly. The controller is configured to switch between a treatment setting for the variable exhaust area and a comfort setting for the variable exhaust area. The comfort setting further includes one or more of a humidity setting, a pressure setting and a temperature setting