The present invention includes an apparatus and method for breaking up mucus in a lung comprising: a chamber having an inlet and an outlet; a pressure oscillating unit in fluid communication with the chamber for supplying and vacuuming air into/out of the chamber, wherein the pressure oscillating unit creates ultrasound waves; a control unit for selecting a positive air pressure or a negative air pressure from the pressure oscillating unit, a fluid container in fluid communication with the chamber; a pressure sensor in fluid communication with the chamber; and an outlet connected to the chamber to send respiration gas to a patient, ultrasonic waves in the respiration gas are capable of breaking up mucus in the lung.