Textile seal with air-assisted biasing portion

1. A patient interface for sealed delivery of a flow of air at a continuously positive pressure with respect to ambient air pressure to an entrance to a patient's airways including at least entrance of a patient's nares, wherein the patient interface is configured to maintain a therapy pressure in a range of about 4 cmH2O to about 30 cmH2O above ambient air pressure in use, throughout a patient's respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing; said patient interface comprising:

a cushion assembly including:

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 a 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 pressure-assisted 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 a 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 seal-forming structure includes a flexible support structure to hold the textile membrane in a predefined curved shape, the textile membrane being configured to seal with an underside of the patient's nose including the patient's subnasale and the patient's pronasale,

wherein the seal-forming structure includes a seal biasing portion extending along a perimeter of the cushion assembly at least in lateral regions of the cushion assembly, the seal biasing portion being formed of a material that is different than a material of the textile membrane, the seal biasing portion being less rigid than adjacent portions of the support structure such that the seal biasing portion is configured to inflate upon pressurization of the cavity in use thereby allowing the seal biasing portion to extend a reach of the textile membrane and decouple the textile membrane from external forces applied to the plenum chamber when activated in use, and

wherein the seal biasing portion is configured to extend the reach of the textile membrane a greater distance in the lateral regions of the cushion assembly than in at least a portion of a central region of the cushion assembly such that when the seal biasing portion is activated in use the central region forms a bending or flexing area thereby allowing the textile membrane in the lateral regions to cradle or pinch the patient's nasal alar.

2. The patient interface of claim 1 , wherein the textile membrane in the lateral regions is configured to extend in a posterosuperior direction and a left-right direction to facilitate cradling or pinching the patient's nasal alar when the seal biasing portion is activated in use.

3. The patient interface of claim 1 , wherein, in use, the textile membrane is configured to press against the patient's face such that the patient's nose is not received in the cavity.

4. The patient interface of claim 1 , wherein the seal biasing portion is omitted in at least a portion of the central portion of the cushion assembly.

5. The patient interface of claim 1 , wherein the seal biasing portion extends around an entire perimeter of the cushion assembly.

6. The patient interface of claim 1 , wherein a size of the seal biasing portion varies around the perimeter of the cushion assembly.

7. The patient interface of claim 1 , wherein the seal biasing portion is larger in the lateral regions and smaller in the central region of the cushion assembly.

8. The patient interface of claim 1 , wherein the size of the seal biasing portion tapers from a larger seal biasing portion in the lateral regions to a smaller seal biasing portion toward the central region of the cushion assembly.

9. The patient interface of claim 1 , wherein the seal biasing portion comprises an indented channel or recess.

10. The patient interface of claim 1 , wherein the seal biasing portion comprises an external protrusion.

11. The patient interface of claim 1 , wherein the seal biasing portion comprises at least one fold, pleat, or undulation.

12. The patient interface of claim 11 , wherein the at least one fold, pleat, or undulation allows the textile membrane to telescope towards the patient's face in use when the seal biasing portion is activated.

13. The patient interface of claim 11 , wherein the seal biasing portion comprises a plurality of folds, pleats or undulations.

14. The patient interface of claim 13 , wherein the plurality of folds, pleats or undulations form a sinusoidal wave in cross section.

15. The patient interface of claim 1 , wherein the seal biasing portion comprises a step and a wing, the step and wing being angled with respect to one another.

16. The patient interface of claim 1 , wherein the seal biasing portion is disposed between the support structure and the textile membrane.

17. The patient interface of claim 1 , wherein the seal biasing portion is disposed between the plenum chamber and the support structure.

18. The patient interface of claim 1 , wherein the cushion assembly includes a stem that projects from the plenum chamber to support the seal-forming structure.

19. The patient interface of claim 1 , wherein the seal biasing portion extends through the lateral regions of the cushion assembly at an angle α with respect to a plane extending along an anterior side of the cushion assembly.

20. The patient interface of claim 19 , wherein the angle α is between 30°-60°.

21. The patient interface of claim 1 , wherein the seal-forming structure is arranged such that the textile membrane has a saddle shape configured to accommodate the underside of the patient's nose in use.

22. The patient interface of claim 1 , wherein the support structure and the seal biasing portion comprise silicone.

23. The patient interface of claim 1 , wherein the textile membrane is attached to the support structure along an outer perimeter of the textile membrane such that the textile membrane extends radially inwardly beyond the support structure.

24. The patient interface of claim 1 , wherein the support structure comprises silicone and the textile membrane is molded to an inner edge of the support structure.

25. The patient interface of claim 1 , wherein the at least one hole in the textile membrane comprises two holes, and a bridge portion is disposed between the two holes in the textile membrane.

26. The patient interface of claim 1 , wherein the textile membrane comprises a membrane layer applied to a textile material to make the textile material substantially air impermeable.

27. The patient interface of claim 1 , wherein the plenum chamber comprises silicone and is formed in one piece with the support structure.

28. The patient interface of claim 1 , further comprising a positioning and stabilising structure to provide a force to hold the seal-forming structure in a therapeutically effective position on the patient's head, the positioning and stabilising structure comprising a tie, the tie being constructed and arranged so that at least a portion overlies a region of the patient's head superior to an otobasion superior of the patient's head in use.

29. The patient interface of claim 1 , further comprising a vent structure to allow a continuous flow of gases exhaled by the patient from an interior of the cavity to ambient, said vent structure being sized and shaped to maintain the therapeutic pressure in the cavity in use.

30. The patient interface of claim 1 , wherein the plenum chamber and seal-forming structure form a nasal cushion.

31. A treatment system used for treatment of sleep disordered breathing, comprising:

the patient interface according to claim 1 ;

a respiratory pressure therapy (RPT) device to supply breathable gas at positive pressure; and

an air delivery tube to pass the breathable gas from the RPT device to the patient interface.

32. A patient interface for sealed delivery of a flow of air at a continuously positive pressure with respect to ambient air pressure to an entrance to a patient's airways including at least entrance of a patient's nares, wherein the patient interface is configured to maintain a therapy pressure in a range of about 4 cmH2O to about 30 cmH2O above ambient air pressure in use, throughout a patient's respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing; said patient interface comprising:

a cushion assembly including:

a plenum chamber at least partially forming a cavity pressurisable to a therapeutic pressure of at least 6 cmH 2 O 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; and

a seal-forming structure having a sealing portion constructed and arranged to form a pressure-assisted 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 sealing portion having a 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 seal-forming structure includes a flexible support structure to support the sealing portion, the sealing portion being configured to seal with an underside of the patient's nose including the patient's subnasale and the patient's pronasale,

wherein the seal-forming structure includes a seal biasing portion such that both the sealing portion and the seal-biasing portion are disposed along a posterior patient-facing surface of the cushion assembly, the seal biasing portion including at least one of fold, pleat or undulation extending between the sealing portion and the support structure, and

wherein the seal biasing portion is configured to inflate upon pressurization of the cavity in use thereby causing the sealing portion to extend or telescope beyond other portions of the posterior patient-facing surface of the cushion assembly in a direction towards at least a portion of the patient's face.

33. The patient interface of claim 32 , wherein the seal biasing portion comprises a plurality of folds, pleats or undulations that form a sinusoidal wave in cross section.

34. The patient interface of claim 32 , wherein the seal biasing portion is disposed at least in lateral regions of the cushion assembly.

35. The patient interface of claim 34 , wherein the sealing portion is configured to extend or telescope a greater distance in the lateral regions of the cushion assembly than in a central region of the cushion assembly such that when the seal biasing portion is activated in use the central region forms a bending or flexing area thereby allowing the sealing portion in the lateral regions to cradle or pinch the patient's nasal alar.

36. The patient interface of claim 32 , wherein a size of the seal biasing portion varies around the perimeter of the cushion assembly.

37. The patient interface of claim 32 , wherein the seal biasing portion is larger in the lateral regions and smaller in the central region of the cushion assembly.

38. The patient interface of claim 32 , wherein the seal biasing portion extends around an entire perimeter of the cushion assembly.

39. The patient interface of claim 32 , wherein the seal biasing portion is omitted in at least a portion of the central portion of the cushion assembly.

40. The patient interface of claim 32 , wherein the support structure and the seal biasing portion comprise silicone.

41. The patient interface of claim 32 , wherein the sealing portion comprises a textile membrane.

42. The patient interface of claim 32 , wherein, prior to pressurization of the cavity during use, a posterior-most portion of the seal biasing portion does not protrude posteriorly beyond the sealing portion.