High-frequency percussive ventilation (HFPV) is
a non-conventional ventilatory modality which has proven
effective and safe in patients with acute respiratory failure.
HFPV associates the beneficial aspects of conventional mechanical
ventilation with those of high-frequency ventilation.
At the present time, HFPV ventilator provides only analog
airway pressure waveform and digital output of peak and the
mean airway pressures. Currently, the latter is the only parameter
that allows an indirect comparison between conventional
volume controlled ventilation (VCV) and HFPV treatment
set up.
The aim of this pilot study was to measure in vivo the main
respiratory parameters, in order to use them for a new bedside
monitoring of HFPV treatment. For such purpose pressure,
flow and volume were measured in five patients undergoing
HFPV. Lung resistance and compliance were estimated using
multiple linear regression method on Dorkin high frequency
pulmonary model, while endotracheal tube pressure drop was
estimated using Blasius model.
The results of this study showed that during the transition
from conventional VCV to HFPV the tidal volume delivery can
significantly change, although the same mean airway pressure
was setup. Thus the volume measurement is clinically important
during HFPV treatment. The validity of the Dorkin model
during HFPV was confirmed in vivo. Moreover, the estimation
of resistance, compliance and endotracheal tube pressure
drop through non-invasive method represents an important
step towards personalized HFPV treatment.
