A method for measuring tidal volume during high frequency jet ventilation.

A new method has been developed to measure tidal volume during high frequency jet ventilation. A pneumotachograph is placed in the expiratory limb of the breathing circuit. Using a model lung, the results from this method did not differ from the tidal volume calculated from pressure changes measured within the model lung. The results from the two methods correlated well (r = 0.99). The method enables the gas volumes entrained and spilled out of the airway during inspiration, true I:E ratios and mean driving pressures to be determined. The method is non-invasive and could easily be applied clinically.