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. (C) 2011 Asociacion Espanola de Pediatria. Published by Elsevier Espana, S.L. All rights reserved.