| 摘要 |
A method of controlling the pressure in the patient interface in a CPAP apparatus having a flow generator (10, 12), a patient interface (18), an air delivery conduit (16) for delivering air from the flow generator to the patient interface, a pressure sensor (30) for determining the pressure from the flow generator, a flow sensor (28) for determining the flow from the flow generator, and a control mechanism (24) that causes air to be delivered through the air delivery conduit at a desired pressure at the patient interface. The method comprises the steps of: sensing the pressure at the pressure sensor; sensing the flow at the flow sensor; estimating the pressure loss in the air delivery conduit based on the sensed flow; determining an estimated mask pressure based on the sensed pressure at the pressure sensor and the estimated pressure loss in the air delivery conduit; calculating the derivative of flow, dQ/dt at run time; setting a converted derivative of flow value based on whether the value of the derivative of flow is positive or negative; calculating a pressure discrepancy value delta P based on the converted derivative flow value; determining an adjusted mask pressure at the patient interface based on the estimated mask pressure and the determined pressure discrepancy delta P; and controlling the flow generator by maintaining the adjusted mask pressure substantially equal to the desired pressure. |
