Abstract: An oro-nasal ventilation face mask worn by a patient includes a first chamber receiving airflow from an air source, a second chamber in fluid communication with the first chamber, a restrictive element positioned between the first chamber and the second chamber, and a headgear securing the first chamber and the second chamber to the patient. The second chamber includes a vent. Air flows between the first and second chambers through the restrictive element. When the first and second chamber are secured to the patient, the first chamber has a first air pressure, the second chamber has a second air pressure, and the first air pressure is greater than the second air pressure.