[Measuring tidal volume during paediatric oscillatory and jet high-frequency ventilation].

OBJECTIVE

To ascertain whether a spirometer can measure tidal volume (TV) during high frequency oscillatory ventilation (HFOV) and high frequency jet ventilation (HFJV), and to analyse the effect of changes in ventilator settings.

METHODS

The study was performed with paediatric porcine lung models submitted to HFOV with a Sensormedics 3100 ventilator and HFJV with a Paravent Pat(e)(R) ventilator connected to a D-Fend spirometer. Programmed frequency, amplitude, and mean airway pressure (MAP) were changed in the ventilator, and TV and pressures were recorded using the spirometer.

RESULTS

The spirometer measured TV in the paediatric lung models and piglets, but could not measure TV less than 8 ml, when the pressure amplitude was higher than 55 cmH(2)O or the MAP was higher than 30 cmH(2)O. With HFOV there was a correlation between amplitude and tidal volume, and a positive correlation between pressure and TV with HFJV. With both respirators there was a negative correlation between frequency and TV.

CONCLUSIONS

The D-Fend spirometer can measure tidal volume and pressure during HFOV and HFJV. However, it does not work with volumes lower than 8 ml, and high amplitude or mean airway pressure.