Patient interface

A seal-forming structure for a patient interface, the 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, the seal-forming structure constructed and arranged to maintain a therapeutic pressure of at least 6 cmH2O above ambient air pressure inside the seal-forming structure throughout the patient's respiratory cycle in use, the seal-forming structure being constructed from a soft, flexible, resilient material, the seal-forming structure comprising an exterior surface and an interior surface opposite the exterior surface, the exterior surface including a patient-contacting region configured to engage and seal against the patient's facial skin,

• wherein a posterior opening is formed in the seal-forming structure at the patient-contacting region such that during use a flow of air at said therapeutic pressure is directed through the posterior opening and into the patient's nares,
• wherein the seal-forming structure includes a support structure joined to an edge of the posterior opening and to the interior surface of the seal-forming structure such that an interior surface of the support structure and the interior surface of the seal-forming structure form a continuous loop,
• wherein the seal-forming structure is configured to leave the patient's mouth uncovered,
• wherein the seal-forming structure at least partly forms a gas chamber that is open through the posterior opening,
• extends partly across the posterior opening is configured to be positioned adjacent to or in contact with the patient's columella during use to prevent the patient's nose from protruding into the gas chamber, and
• wherein a superior portion of the seal-forming structure is structured to engage the patient's nose inferior to the patient's nasal bone.