 HFOV is characterized by high respiratory rates between 3.5 and 15 hertz (210 - 900 breaths per minute) and having both inhalation and exhalation maintained by active pressures.The rates used vary widely depending upon patient size, age, and disease process.In HFOV the pressure oscillates around the constant distending pressure (equivalent to mean airway pressure [MAP]) which in effect is the same as positive end-expiratory pressure (PEEP).