Effect of Frequency and Tidal Volume on Pleural Pressure in Rabbits during High Frequency Ventilation

摘要: Regional effects of the chest wall on airway pressure transmission were studied during high frequency ventilation in anesthetized rabbits. We measured (Paw), esophageal (Pes), and costal pleural (Ppl) by a rib capsule flow volume with calibrated pneumotachograph. Using closed circuit, pressures at varying frequencies (2–80 Hz) tidal volumes (2–20 ml). Mean Pes Ppl increased amplitude above 100–250 ml/s, whereas mean Paw decreased, consistent air trapping. Paw, Pes, amplitudes monotonically except 400–500 where decreased suddenly. The latter occurring simultaneously sudden fall indicated limitation regions. Flow instabilities large increase phase difference between its variability, frequency. By contrast, variability relatively small. These differences from responses might be caused impedance airway-mediastinum pathway or direct tracheal oscillations to esophagus. former suggests that constraints offered mediastinum cage resulted nonuniform ventilation.