[os″ĭ-la´shun] a backward and forward motion, like that of a pendulum; also vibration, fluctuation, or variation.high frequency oscillation a type of ventilation" >high frequency ventilation characterized by the use of expiration" >active expiration.
high fre·quen·cy os·cil·la·tion
(HFO) (hī frē'kwĕn-sē os'i-lā'shŭn) A type of mechanical ventilation.