Disclosed is a respiratory pressure treatment apparatus. The apparatus comprises a flow generator to generate a flow of breathable gas to a patient interface a sensor (4270) to measure the flow of breathable gas and a controller (4230) to control the flow generator to deliver a flow of breathable gas at a patient interface. The flow of breathable gas comprises inspiratory portions and expiratory portions. The breathable gas during an expiratory portion is at a pressure generally lower than that during an inspiratory portion, and an expiratory portion comprises a pressure rise. The controller (4230) is configured to control the pressure rise of the expiratory portion with a function of a tidal volume and a difference between a baseline pressure and a target expiratory pressure setting.
