Patient interface
A patient interface for delivery of a supply of pressurised air or breathable gas to an entrance of a patient's airways comprising: a cushion member that includes a retaining structure and a seal-forming structure permanently connected to the retaining structure; a frame member attachable to the retaining structure; and a positioning and stabilising structure attachable to the frame member.
1. A patient interface configured for sealed delivery of a supply of pressurized, breathable gas at a continuously positive pressure with respect to ambient air pressure to a patient's nares, the patient interface being configured to maintain a therapeutic pressure in a range of about 4 cmH2O to about 30 cmH2O above ambient air pressure in use, throughout the patient's respiratory cycle, while the patient is sleeping, to ameliorate sleep disordered breathing, said patient interface comprising:
a frame member comprising a gas washout vent configured to allow a flow of patient exhaled CO2 to an exterior of the patient interface to minimise rebreathing of exhaled CO2 by the patient;
a cushion member configured to deliver the supply of pressurized, breathable gas to the patient's nares, the cushion member further comprising:
a seal-forming structure and a plenum chamber at least partly forming a gas chamber, the seal-forming structure being configured to seal against the patient's face around both nares at an inferior periphery of the patient's nose such that the seal-forming structure contacts the patient's face below the bridge of the nose, at lateral sides of the patient's nose, and at the patient's upper lip, the seal-forming structure being configured not to enter the patient's nares in use, and the seal-forming structure having no undercushion; and
a retaining structure joined to the plenum chamber and configured to releasably engage with the frame member to releasably secure the seal-forming structure and the plenum chamber to the frame member; and
a positioning and stabilising structure comprising a strap configured to maintain the seal-forming structure in sealing contact with patient's face while maintaining the therapeutic pressure at the patient's nares;
wherein the seal-forming structure and the plenum chamber are made from one piece of a first material and the retaining structure is made from a second material, the first material being silicone and the second material being silicone with a higher durometer than the first material, such that the retaining structure is more rigid than the seal-forming structure and the plenum chamber; and
wherein the plenum chamber further comprises a sealing lip configured to contact the frame member, the sealing lip being configured such that an increase in air pressure within the gas chamber increases a sealing force of the sealing lip against the frame member.
2. The patient interface of claim 1 , wherein the plenum chamber is located between the retaining structure and the seal-forming structure.
3. The patient interface of claim 1 , wherein the frame member is made from a third material that is less flexible than the first material and the second material.
4. The patient interface of claim 1 , wherein the first material is more flexible than the second material.
5. The patient interface of claim 1 , wherein said seal-forming structure includes a recessed portion that is configured to receive the tip of the nose of the patient, the recessed portion being located at a region of the seal-forming structure that is thinner than laterally adjacent regions of the seal-forming structure that are configured to contact the patient's ala.
6. The patient interface of claim 5 , wherein said seal-forming structure comprises a compliant region located above the recessed portion, said compliant region being thin and flexible relative to the remainder of the seal-forming structure.
7. The patient interface of claim 1 , wherein said seal-forming structure has a varied thickness adjacent the nasal opening at predetermined positions around the perimeter of the nasal opening.
8. The patient interface of claim 1 , wherein said seal-forming structure comprises a pair of protruding ends extending symmetrically about the nasal opening, each protruding end configured to seal against a region of the patient's face where the ala of the nose joins to the patient's face.
9. The patient interface of claim 1 , wherein a lower portion of said seal-forming structure is concave in a relaxed state to seal against the upper lip of the patient and to follow a curvature of the upper lip of the patient.
10. The patient interface of claim 1 , wherein the frame member further comprises ribs and the plenum chamber further comprises notches corresponding to the ribs.
11. The patient interface of claim 1 , wherein the retaining structure is permanently joined to the plenum chamber with a chemical bond between the first material and the second material.
12. The patient interface of claim 1 , wherein the positioning and stabilising structure further comprises a pair of rigidiser arms, each joined to a corresponding lateral side of the frame member.
13. The patient interface of claim 12 , wherein the strap comprises a strap having comprises two ends, each end removably connected to a corresponding one of the rigidiser arms.
14. The patient interface of claim 12 , wherein the pair of rigidiser arms are constructed from a material that is different from a material of the frame member.
15. The patient interface of claim 12 , wherein the pair of rigidiser arms are permanently joined to the frame member with a mechanical interlock.
16. The patient interface of claim 1 , wherein the gas washout vent further comprises two groups of vent holes, each of the groups being positioned on a corresponding lateral side of the frame member.
17. The patient interface of claim 1 , wherein the frame member further comprises a port and a tube connected to the frame member at the port, the tube configured to direct the supply of pressurized, breathable gas through the port and into the gas chamber.
18. The patient interface of claim 1 , wherein the seal-forming structure further comprises a pair of thickened sections, each of the thickened sections being located on a corresponding lateral side of the seal-forming structure so as to contact the patient's face at or proximal to the patient's corresponding nasolabial sulcus in use.
19. The patient interface of claim 18 , wherein the thickened sections are thicker than adjacent portions of the seal-forming structure.
20. The patient interface of claim 1 , wherein the seal-forming structure consists of a single nasal opening configured to provide the supply of pressurized, breathable gas to both of the patient's nares during use.
21. The patient interface of claim 1 , wherein the frame further comprises a channel portion and the retaining structure further comprises a tongue portion, the tongue portion being configured to releasably engage the channel portion in a tongue and groove arrangement.