Apparatus for controlling pressurized gas delivered to a patient

1. A respiratory therapy system to provide a flow of pressurized breathable gas to a patient via the patient's airways, the respiratory therapy system comprising:

a patient interface comprising:

a seal-forming structure configured to seal against the patient's face around an entrance to the patient's airways;

a plenum chamber in pneumatic communication with the seal-forming structure; and

a positioning and stabilising structure connected to the plenum chamber and configured to hold the seal-forming structure in sealing position on the patient during use;

a conduit connected to the plenum chamber, an inspiratory flow path being formed inside of the conduit and configured to allow inspiratory flow to enter the plenum chamber through the conduit during use, an expiratory flow path being formed inside of the conduit and configured to allow expiratory flow to exit the plenum chamber through the conduit during use, and the conduit being structured such that the inspiratory flow path and the expiratory flow path are separate from one another; and

an exchanger configured to recover heat and/or moisture from gas exhaled by the patient during use, the exchanger being positioned at least partially within the plenum chamber and at least partially within the conduit such that a first side of the exchanger is in pneumatic communication with the inspiratory flow path and a second side of the exchanger is in pneumatic communication with the expiratory flow path.

2. The respiratory therapy system of claim 1 , wherein the plenum chamber has a first side, the conduit being connected to the plenum chamber at the first side, and a second side opposite the first side relative to the plenum chamber,

wherein the exchanger extends from the first side of the plenum chamber to the second side of the plenum chamber to reduce dead space in the respiratory therapy system.

3. The respiratory therapy system of claim 1 , wherein the inspiratory flow path and the expiratory flow path are arranged coaxially within the conduit.

4. The respiratory therapy system of claim 1 , wherein the expiratory flow path is positioned internally of the inspiratory flow path.

5. The respiratory therapy system of claim 1 , wherein the inspiratory flow path and the expiratory flow path are arranged to be parallel and adjacent to one another.

6. The respiratory therapy system of claim 1 , wherein the exchanger comprises a gas impermeable material.

7. The respiratory therapy system of claim 1 , wherein the exchanger is positioned at least partially within the plenum chamber such that exhaled gas from the patient's airways bypass the exchanger before reaching the expiratory flow path.

8. The respiratory therapy system of claim 1 , wherein the exchanger is positioned at least partially within the plenum chamber such that exhaled gas from the patient's airways only reaches the expiratory flow path by passing through the exchanger.

9. The respiratory therapy system of claim 8 , wherein the exchanger comprises a gas permeable material.

10. The respiratory therapy system of claim 1 , wherein the exchanger comprises a moisture permeable and/or heat conductive material.

11. The respiratory therapy system of claim 1 , wherein the conduit comprises a heater and/or thermal insulation.

12. The respiratory therapy system of claim 1 , wherein shared walls of the inspiratory flow path and the expiratory flow path comprise a gas impermeable material that is moisture permeable and/or thermally conductive.

13. The respiratory therapy system of of claim 1 , wherein the inspiratory flow path and the expiratory flow path are contained within an external wall of the conduit.

14. The respiratory therapy system of claim 1 , wherein the exchanger comprises a tube that is impermeable for gas and moisture.

15. The respiratory therapy system of claim 1 , further comprising a vent to wash out exhaled carbon dioxide.

16. The respiratory therapy system of claim 1 , wherein the patient interface is non-vented.

17. The respiratory therapy system of claim 1 , wherein the seal-forming structure is a nasal mask, full-face mask, or nasal pillows.

18. The respiratory therapy system of claim 1 , wherein the exchanger is positioned between an end of the inspiratory flow path proximate to the patient interface and an end of the expiratory flow path proximate to the patient interface.

19. The respiratory therapy system of claim 1 , further comprising an aperture positioned along the expiratory flow path and in pneumatic communication with the plenum chamber, said aperture having an aperture size that is variable between a first configuration that is open and at least one second configuration that is different from the first configuration.

20. The respiratory therapy system of claim 19 , further comprising a controller and a controllable valve configured to be controlled by the controller,

wherein the controllable valve is adapted to release pressurized gas from the expiratory flow path through the aperture to atmosphere in the first configuration, and

wherein the controllable valve is adapted to prevent a release of pressurized gas from the expiratory flow path through the aperture to atmosphere in the second configuration.

21. The respiratory therapy system of claim 1 , wherein the seal-forming structure is constructed from silicone, the seal-forming structure extending from the plenum chamber.

22. The respiratory therapy system of claim 1 , wherein the exchanger is positioned at least partially within the conduit.