Gas washout and pressure waveform characteristics of high-frequency oscillation.

High-frequency oscillation (HFO) minimizes tidal volume. To investigate whether ventilation can proceed when tidal movement (volume) is eliminated, a nondistensible physical model of interconnected chambers was constructed. During HFO, ventilation was related to pressure waveform characteristics recorded within the separate chambers. Ventilation increased up to a critical frequency related to the time constant of the system. Beyond this frequency, ventilation dropped off rapidly.