The present system comprises a pressure generator, an oscillator, sensors, and computer processors. The pressure generator generates a pressurized flow of breathable gas for delivery to the airway of a subject. The oscillator causes high frequency pressure level oscillations in the pressurized flow of breathable gas. The sensors generate output signals conveying information related to one or more parameters of the gas. The computer processors receive a base expiratory pressure level and a base inspiratory pressure level and control the pressure generator and the oscillator to generate the pressurized flow of breathable gas such that during exhalation the pressure level of the pressurized flow of breathable gas oscillates from or about the base expiratory pressure level and during inhalation the pressure level of the pressurized flow of breathable gas oscillates from or about the base inspiratory pressure level.