A respiratory assistance device is disclosed. There is a variable speed blower with an output, and a patient ventilation interface configured for fitment on a patient respiratory passageway. A gas passage conduit couples the output of the blower to the patient ventilation interface. A pilot line from the gas passage conduit is coupled to a piloted exhalation valve of the patient ventilation interface. A pressure sensor measures a mask pressure in the patient ventilation interface, and a blower speed sensor measures a speed of the blower. A pressure controller in communication with the pressure sensor and the blower speed sensor detects a patient inspiratory phase and a patient expiratory phase from at least one of the measured speed of the blower and a set speed of the blower. The pressure controller adjusts an operating speed of the blower and actuates the piloted exhalation valve based upon the measured mask pressure.
