Apparatus and methods are disclosed for controlling pressure delivery to a user such as a patient. A flow generator generates an outlet flow at an outlet port for delivery to a patient, at least one sensor for measuring properties of the flow of gas exiting the flow generator through the outlet port or being delivered to the patient measures the flow properties. A controller operatively connected to the flow generator and connected to the at least one sensor and adapted to operate according to a pressure control mode in which the controller controls the flow generator to output a substantially steady pressure, or a flow control mode in which the controller controls the flow generator to output a substantially steady flow. The controller operates in the flow control mode when a patient may be awake and in the pressure control mode when the patient may be asleep.
