The present invention relates to a
cushion assembly for
interfacing with a patient's airways including at least the patient's nares, the
cushion assembly being configured to maintain a therapy pressure above
ambient air pressure in use, throughout a patient's
respiratory cycle, while the patient is sleeping, to ameliorate
sleep disordered breathing, said
cushion assembly comprising: a
plenum chamber at least partially forming a cavity pressurisable to a therapeutic pressure of at least 6 cmH2O above
ambient air pressure, said
plenum chamber including at least one
plenum chamber inlet port sized and structured to receive a flow of air at the therapeutic pressure for
breathing by a patient; and a seal-forming structure having a
textile membrane constructed and arranged to form a seal with a region of the patient's face surrounding an entrance to the patient's airways inferior to a
nasal bridge region of the patient's face, said
textile membrane having at least one hole formed 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 cavity throughout the patient's
respiratory cycle in use, wherein the
textile membrane includes a textile material adapted to contact the patient's face and an air impermeable
silicone layer applied thereto, the textile material having an
interlock knit structure comprising 1) nylon and / or
polyester, and 2) elastane, and wherein the textile membrane has stretchability in both a direction of the wales and a direction of the course.