Vent device for use with a respiratory device

A vent device suitable for use with a respiratory device for delivering a supply of air or breathable gas to the entrance of a patient's airways for the amelioration or treatment of a respiratory disorder comprising:

• a first vent configured with a first variable cross-section area on a plenum chamber of a mask for communicating a flow of breathable gas, the first vent including a first actuator assembly on the mask to automatically vary the first variable cross-section area in response to a first control system signal for adjusting the first variable cross-section area;
• a second vent configured with a second variable cross-section area on a plenum chamber of the mask with the first vent, the second vent including a second actuator assembly on the mask to automatically vary the second variable cross-section area in response to a second control system signal for adjusting the second variable cross-section area;
• a control system configured to set the first vent and the second vent;
• and
• a first sensor configured to output a first signal;
• wherein the vent device is configured so that the first cross-section area and/or the second cross-section area are determined as a function of the first signal,
• wherein the control system is configured to control an operation of the first actuator assembly and the second actuator assembly, and wherein the operation is configured to change a size of the central aperture of the first vent distinctly from a size of the central aperture of the second vent by coordinating (a) an increase in size of the cross-section area of one of the first vent and the second vent, with (b) a decrease in size of the cross section area of the other one of the first vent and the second vent.