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 measures properties of the flow of gas at the outlet port or being delivered to the patient. A controller is operatively connected to the flow generator and the at least one sensor, and is 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.
