Vent valve apparatus
View Patent ↗A vent valve apparatus ( 10 ) for use with a system for supplying breathable gas pressurized above atmospheric pressure to a human or animal. The apparatus ( 10 ) includes a gas washout vent ( 15 ), a vent valve ( 18 ) adapted to progressively restrict the flow area of the washout vent ( 15 ), and a pressure sensitive vent valve control means ( 20,22,23 ). The control means is adapted to progressively cause the vent valve ( 18 ) to restrict the flow area of the gas washout vent ( 15 ) in response to increases in the pressure of the gas supply, thereby substantially regulating the volumetric flow of gas and/or CO 2 gas through the washout vent ( 15 ) over a range of gas supply pressures.
1. A method for supplying pressurized breathable gas to a patient with a CPAP apparatus including a flow generator structured to generate a supply of pressurized gas, a mask adapted to provide a seal with the patient's face, and a conduit that interconnects the flow generator and the mask, the method comprising:
generating a supply of pressurized gas with the flow generator;
sealing the patient's face with the mask;
interconnecting the flow generator and the mask with the conduit;
controlling gas washout by progressively moving a vent valve within a gas washout vent based on the pressure of the gas supply; and
controlling gas washout includes restricting gas washout in response to increases in the pressure of the gas supply.
2. The method according to claim 1 , wherein moving the vent valve includes moving one of two complementary shaped parts.
3. The method according to claim 2 , wherein the two complementary shapes are cones.
4. The method according to claim 1 , wherein controlling gas washout includes expanding gas washout in response to decreases in the pressure of the gas supply.
5. The method according to claim 1 , wherein the supply of pressurized gas is in a range of about 4-22 cmH 2 O.
6. The method according to claim 1 , further comprising generating the supply of pressurized gas at a constant pressure.
7. The method according to claim 1 , further comprising:
generating the pressurized gas at two pressure levels with the flow generator; and
synchronizing the two pressure levels with patient breathing.
8. The method according to claim 1 , further comprising continuously varying the pressure of the pressurized gas with the flow generator.
9. The method according to claim 1 , wherein the gas washout vent vents from the conduit.
10. The method according to claim 1 , wherein the gas washout vent vents from the mask.
11. The method according to claim 1 , further comprising moving the vent valve with an elastic diaphragm that responds to the pressure of the gas supply.
12. The method according to claim 1 , further comprising rotationally displacing an aerodynamic member connected to the vent valve to move the vent valve.