Systems and methods for providing respiratory therapy with varying flow rates are disclosed. A system comprises a source of breathing gas, a patient interface, and a flow control device. The flow control device is configured to automatically change a rate of the flow of breathing gas. The flow control device may vary the rate of the flow of breathing gas at a frequency slower than a frequency of breathing of the patient. A method comprises coupling a patient interface to the patient, providing the flow of breathing gas to an inlet port of the patient interface, and automatically changing a rate of the flow of breathing gas with a flow control device in communication with the flow of breathing gas. The method may also comprise varying the rate of the flow of breathing gas at a frequency slower than a frequency of breathing of the patient.
