Method and apparatus for adjusting respiratory mask sealing force
View Patent ↗A mask assembly includes a mask with an inflatable bladder. The internal pressure of the inflatable bladder can be set to be higher than the delivered therapeutic pressure. The pressure offset may be constant, or it may vary over the range of therapeutic pressures. Thus, the force necessary to maintain a contact seal between the mask and the patient can be reduced, thereby providing a system that is more comfortable to the patient, which increases patient compliance.
1. A patient interface comprising:
a frame;
a cushion provided to the frame and defining a chamber structured to be in communication with a first source that is adapted to provide a first pressure to the chamber; and
a bladder associated with the cushion and configured to engage a face of a patient, the bladder having a side wall, and the side wall being thinner in a face contacting region of the bladder than in a face non-contacting region, the side wall thickness being progressively thicker from the face contacting region to the face non-contacting region,
wherein a rate of change in the thickness of the side wall varies around the face contacting region of the bladder, and
wherein the bladder is configured to be in communication with a second source that provides a second pressure to the bladder that is higher than the first pressure by a positive offset amount.
2. The patient interface of claim 1 , wherein the bladder is configured to receive gas from the chamber.
3. The patient interface of claim 2 , wherein the chamber is configured to be in fluid communication with both the first and second sources.
4. The patient interface of claim 3 , wherein the chamber comprises an inlet port configured to be in fluid communication with the first source and comprises an outlet port configured to be in fluid communication with the second source.
5. The patient interface of claim 4 , wherein the bladder includes an inlet port configured to be in fluid communication with the second source.
6. The patient interface of claim 1 , wherein the positive offset amount is fixed.
7. The patient interface of claim 6 , wherein the positive offset amount is about 5 cmH 2 O.
8. The patient interface of claim 1 , wherein the bladder is configured such that the second pressure variably changes with changes in the first pressure.
9. A mask assembly according to claim 8 , wherein the offset amount ranges from about 1-10 cmH 2 O.
10. A mask assembly according to claim 9 , wherein the offset amount ranges from about 3-8 cmH 2 O.
11. A mask assembly according to claim 1 , wherein the offset amount is dependent on a therapeutic pressure.
12. A method for sealing a patient interface with respect to a patient, comprising:
engaging the patient's face with the interface of claim 1 so that the bladder engages the patient's face in the face contacting region;
providing a first pressure to the chamber of the interface; and
pressurizing the bladder to a second pressure that exceeds the first pressure applied to the chamber of the patient interface such that the patient interface seals comfortably at any instantaneous pressure applied to the chamber of the patient interface.
13. The method of claim 12 , wherein a difference between the first pressure and the second pressure is kept constant.
14. The method of claim 13 , wherein the difference between the first pressure and the second pressure is achieved by at least one of a spring-loaded piston, a recoil pressure of a balloon and an impedance pump.
15. An apparatus comprising:
a first source configured to deliver a breathable gas at a first pressure to a patient;
a patient interface comprising:
a frame;
a cushion provided to the frame and defining a chamber, the cushion being adapted to engage a patient's face and being structured to be in communication with the first source; and
a bladder contained within the cushion, the bladder having a side wall that is thinner in a face contacting region of the cushion than in a face non-contacting region of the cushion, the side wall thickness being progressively thicker from the face contacting region to the face non-contacting region; and
a second source configured to deliver gas at a second pressure to the bladder that is higher than the first pressure by a positive offset amount,
wherein a rate of change in thickness of the side wall of the bladder varies around the face contacting region of the cushion.
16. The apparatus of claim 15 , wherein the first source is a blower.
17. The apparatus of claim 16 , wherein the second source comprises a spring-loaded piston.
18. The apparatus of claim 16 , wherein the second source comprises a balloon and the positive offset amount is generated by a recoil pressure of the balloon.
19. The apparatus of claim 16 , wherein the second source comprises an impedance pump.
20. The apparatus of claim 19 , wherein the impedance pump includes at least one of a centrifugal fan and an axial fan.
21. The apparatus of claim 16 , wherein the second source comprises an impedance pump provided with an impedance bypass that is configured to remove oscillations induced by the impedance pump.
22. The apparatus of claim 21 , wherein the impedance bypass comprises an adjustable shunt valve and/or at least one of a spring-loaded piston and a balloon, in parallel with the impedance pump.
23. The apparatus of claim 21 , wherein the impedance bypass comprises at least one of a spring-loaded blow-off valve and a water-trap blow-off valve, and/or at least one of a spring-loaded piston and a balloon, in parallel with the impedance pump.
24. The apparatus of claim 16 , wherein the second source is configured to generate a constant positive offset pressure over an entire range of first pressures.
25. The apparatus of claim 16 , wherein the second source is fluidly connected to an outlet of the first source at a position upstream of the chamber of the patient interface.
26. The apparatus of claim 16 , wherein the second source is fluidly connected to an outlet of the patient interface.