Abstract: A gas delivery system and method are provided that include a therapeutic gas delivery device, and a high-frequency ventilator delivering a breathing gas to a respiratory circuit. The therapeutic gas delivery system also includes a flow sensor assembly having a single interior chamber. The flow sensor assembly includes a flow sensor connected with the therapeutic gas delivery device and configured to measure a flow rate of the breathing gas. The flow sensor has a sensor gas inlet and a sensor gas outlet. The flow sensor assembly further includes a one-way flow valve disposed downstream of the sensor gas outlet. The one-way flow valve includes a valve gas inlet and a valve gas outlet. Inner diameters of the valve gas inlet and the valve gas outlet are greater than or equal to an inner diameter of at least one of the sensor gas inlet and the sensor gas outlet.