Breathing apparatus and method for the use thereof

1. A breathing apparatus comprising:

at least one volumetric member pressurizable from a first pressure to a second pressure;

an expiratory flow path communicating with said at least one volumetric member;

a pressure relief valve communicating between said at least one volumetric member and ambient air at a location spaced from said expiratory flow path, wherein said pressure relief valve is moveable from a closed position to an open position in response to a predetermined pressure, wherein said pressure relief valve is adjustable between at least a first and second configuration, wherein said predetermined pressure is varied between at least first and second predetermined pressures corresponding to said first and second configurations of said pressure relief valve, wherein said pressure relief valve comprises:

a magnet spaced apart from a non-magnetic valve seat;

a valve head engaged with said valve seat and magnetically attracted to said magnet when said pressure relief valve is in said closed position; and

a control mechanism actuatable to adjust the spacing between the magnet and the non-magnetic valve seat between at least a first and second distance, wherein said first distance corresponds to said first configuration and said second distance corresponds to said second configuration.

2. The breathing apparatus of claim 1 wherein said at least one volumetric member comprises a first volumetric member, and further comprising a second volumetric member, wherein said first volumetric member pressurizes said second volumetric member as said first volumetric member is pressurized from said first pressure to said second pressure;

an inspiratory flow path communicating with said second volumetric member; and

at least one intake portal communicating with said second volumetric metric member.

3. The breathing apparatus of claim 2 wherein said first volumetric member is an inner volumetric member and said second volumetric member is an outer volumetric member surrounding at least a portion of said inner volumetric member.

4. The breathing apparatus of claim 3 wherein said inner volumetric member is expandable between a first volume and a second volume.

5. The breathing apparatus of claim 2 further comprising a one-way inhalation valve positioned in said inspiratory flow path.

6. The breathing apparatus of claim 2 further comprising a one-way valve positioned at a junction between said inspiratory flow path and said second volumetric member.

7. The breathing apparatus of claim 2 further comprising a patient interface communicating with said expiratory and inspiratory flow paths.

8. The breathing apparatus of claim 7 , wherein the patient interface comprises at least a one-way ambient air inhalation valve.

9. The breathing apparatus of claim 1 further comprising a one-way exhalation valve positioned in said expiratory flow path.

10. The breathing apparatus of claim 1 further comprising a return spring biasing said pressure relief valve to said closed position.

11. The breathing apparatus of claim 10 wherein said return spring is adjustable such that a return force of said spring biasing said pressure relief valve is adjustable.

12. The breathing apparatus of claim 11 further comprising a control coupled to said spring, wherein said control is moveable so as to adjust said return force of said spring.

13. The breathing apparatus of claim 1 wherein said control mechanism comprises a screw, wherein said screw is rotatable in opposite directions to adjust the spacing between the magnet and the non-magnetic valve seat.

14. The breathing apparatus of claim 13 wherein said screw is rotatable about an axis extending transverse to a direction of movement of said pressure relief valve.

15. The breathing apparatus of claim 1 further comprising a connector located between said pressure relief valve and said at least one volumetric member, wherein said connector is configured to receive a device to monitor expiratory pressure.

16. The breathing apparatus of claim 1 wherein said magnet comprises a first band, and wherein said valve seat comprises a second band.

17. The breathing apparatus of claim 16 wherein said first and second bands are curved.

18. The breathing apparatus of claim 1 wherein said non-magnetic valve seat is disposed between said valve head and said magnet.

19. The breathing apparatus of claim 18 wherein said valve seat is made of plastic.

20. The breathing apparatus of claim 1 wherein said first and second predetermined pressures are between 3 cm H 2 O and 30 cm H 2 O.

21. The breathing apparatus of claim 1 wherein the position of said magnet is fixed, and wherein said non-magnetic valve seat is movable toward and away from said magnet by said control mechanism.

22. A method of assisting the breathing of a user comprising:

exhaling an exhaled gas into a volumetric member and thereby pressurizing said volumetric member;

moving a pressure relief valve from a closed position to an open position in response to a predetermined pressure in said first volumetric member; and

adjusting said pressure relief valve to vary said predetermined pressure, wherein said adjusting said pressure relief valve comprises adjusting a spacing between a magnet and a non-magnetic valve seat.

23. The method of claim 22 further comprising biasing said pressure relief valve to said closed position with a return spring.

24. The method of claim 23 further comprising adjusting a return force of said return spring.