A new system for ventilating with high-frequency oscillation

We describe simple high-frequency oscillation systems that incorporate a CO₂ absorber and supply O₂ on a need basis. These systems have the advantage of easy control of mean airway pressure and airway hydration and negligible loss of oscillatory tidal volume. Experiments done at constant tidal volume showed that as frequency (and hence total ventilation) increased, arterial CO₂ tension (Pa(CO₂)) decreased. The fall in Pa(CO₂) occurred until frequency reached approximately 20 Hz; above 20 Hz further increases in frequency had little or no effect on Pa(CO₂). Because of their practical advantages the techniques described here may be quite useful in a clinical setting where an oscillator, rather than jet-type high-frequency, ventilation system is desired.