Abstract
The efficiency of axial gas dispersion during ventilation with high-frequency oscillation (HFO) is improved by manipulating the oscillatory flow waveform so that intermittent oscillatory flow occurs. We therefore measured the arterial CO2 pressure and expired CO2 concentration during high-frequency intermittent oscillatory flow in rabbits to verify the intermittency augmentation effect on gas exchange. In this work, the oscillatory frequency was fixed at 15 Hz so as to apply the results to a HFO respirator. Tidal volume was varied from 2.0 to 3.0mL/kg. The waveform of the intermittent oscillatory flow was set using an intermittent parameter, τ=0.5, where τ represents the ratio of the advection to the oscillation period. When tidal volume was small, the arterial CO2 pressure was dependent on the flow patterns and decreased when using intermittent oscillatory flow. It was also found that the expired CO2 concentration becomes greater than that in sinusoidal oscillatory flow. In addition, the use of intermittent oscillatory flow effectively augments gas exchange for ventilation in surfactantdeficient rabbits.
