Peripheral airway pressure during high frequency ventilation.

Abstract

Peripheral airway pressure (Pp) was measured during high frequency ventilation (HFV) (open system) (1-20 Hz) by retrograde catheters in eight excised dog lungs. Central airway pressure (Pc) and pleural pressure (Ppl) were measured simultaneously. We found a significant increase in peripheral end-expiratory pressure at frequencies 5 Hz and higher, when the minute ventilation was increased. Mean Pc and mean Pp remained unchanged during ventilation at different frequencies with constant minute ventilation, although tidal volume decreased. With increasing tidal volume Pc, Pp, and Ppl (mean) increased at all frequencies. The increase in end-expiratory pressure indicates an "auto-PEEP" effect, which may contribute to the better gas exchange described during HFV.