Patent ID: 7152598

Claim:
A system for delivering a breathing gas to a patient interface comprising: a pressure sensor; a blower; a valve; a controller connected to the sensor, blower and valve, the controller comprising a memory having a plurality of executable instructions, wherein the executable instructions comprise: a first set of instructions sensing a pressure associated with the delivery of the breathing gas to the patient interface; a second set of instructions changing the valve position in response to a change in the sensed pressure; a third set of instructions detecting a start of inhalation state by determining if the valve position has increased beyond a start of inhalation state threshold value; a fourth set of instructions detecting an end of inhalation state by determining if the valve position has fallen below an end of inhalation state threshold value; a fifth set of instructions delivering the breathing gas at least at a first positive pressure above ambient pressure after detection of the start of inhalation state; and a sixth set of instructions delivering the breathing gas at least at a second pressure after detection of the end of inhalation state wherein the second pressure is less than the first pressure.