A vent assembly for a respiratory therapy system

A vent assembly for a respiratory therapy system, the vent assembly being configured in use to convey a vent flow of gases exhaled by a patient from a first volume interior to the respiratory therapy system to ambient, the vent assembly comprising:

• a vent base having formed therein a vent base aperture;
• a flexible membrane mounted within the vent assembly and spanning across the vent base aperture, wherein the membrane has formed therein a membrane aperture to allow the vent flow to pass therethrough;
• and
• a vent cap connected to the vent base, wherein the vent cap is located downstream of the membrane relative to the vent flow, and wherein the vent cap is positioned in the path of the vent flow through the membrane aperture;
• wherein, in use, the pressure of gas in the first volume acts on the membrane such that changes in the pressure of the gas in the first volume causes the membrane to flex thereby varying a position of the membrane relative to the vent cap in order to control the vent flow through one or more vent outlets to ambient;
• wherein the membrane comprises a non-planar portion having a first side facing towards the first volume in use and a second side facing away from the first volume in use;
• wherein, at least in the absence of a pressure difference between the first volume and ambient, the first side of the non-planar portion is concave and the second side of the non-planar portion is convex.

A patient interface comprising:

• a plenum chamber pressurisable to a therapeutic pressure of at least 6 cmH2O above ambient air pressure, said plenum chamber including a plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for breathing by a patient,
• a seal-forming structure constructed and arranged to form a seal with a region of the patient's face surrounding an entrance to the patient's airways, said seal-forming structure having a hole therein such that the flow of air at said therapeutic pressure is delivered to at least an entrance to the patient's nares, the seal-forming structure constructed and arranged to maintain said therapeutic pressure in the plenum chamber throughout the patient's respiratory cycle in use;
• and
• a vent assembly configured to convey a vent flow of gases exhaled by the patient from an interior of the plenum chamber to ambient, said vent assembly being sized and shaped to maintain the therapeutic pressure in the plenum chamber in use,
• wherein the patient interface is configured to allow the patient to breath from ambient through their mouth in the absence of a flow of pressurised air through the plenum chamber inlet port, or the patient interface is configured to leave the patient's mouth uncovered;
• and
• wherein the vent assembly comprises:
• a vent base having formed therein a vent base aperture;
• a flexible membrane mounted within the vent assembly and spanning across the vent base aperture, wherein the membrane has formed therein a membrane aperture to allow the vent flow to pass therethrough;
• and
• a vent cap connected to the vent base, wherein the vent cap is located downstream of the membrane relative to the vent flow, and wherein the vent cap is positioned in the path of the vent flow through the membrane aperture;
• wherein, in use, the pressure of gas in the plenum chamber acts on the membrane such that changes in the pressure of the gas in the plenum chamber causes the membrane to flex thereby varying a position of the membrane relative to the vent cap in order to control the vent flow through one or more vent outlets to ambient;
• wherein the membrane comprises a non-planar portion having a first side facing towards the plenum chamber in use and a second side facing away from the plenum chamber in use;
• wherein, at least in the absence of a pressure difference between the plenum chamber and ambient, the first side of the non-planar portion is concave and the second side of the non-planar portion is convex.