A continuous high-frequency oscillation breathing device delivers therapy during both inhalation and exhalation in order to assist in clearing secretions from the lungs. A fixed shrouded-venturi patient interface circuit (11) is combined with medicated aerosol (21) to deliver continuous high-frequency oscillation therapy. Fixed open apertures (14,15) in the patient interface circuit allow ingress and egress of flow, and are calibrated to allow exhalation and prevent stacking of successive breaths. <；IMAGE>；
