Estimation of Respiratory Mechanics Parameters during HFPV

The respiratory mechanics parameters (resistance and elastance) are important for adequate mechanical ventilation settings and for a correct clinical diagnosis. High-frequency percussive ventilation (HFPV) is a non-conventional ventilatory strategy characterized by inspiratory high frequency pulsatile flow, while the expiratory phase is passive. It associates the beneficial aspects of conventional mechanical ventilation with those of high-frequency ventilation. This bench study, as preliminary to patients study, aimed to estimate respiratory mechanics parameters through a non-invasive method, during HFPV at different working pressures, frequencies and mechanical (resistive and elastic) loads. For such purpose, a multiple linear regression method to estimate parameters of the Dorkin high frequency pulmonary model was applied, starting from in vitro measured pressure and flow signals, considering inspiratory phase exclusively. The results encourage further in vivo studies of this methodology, which has to be clinically assessed. The low rmse% values confirm validity of Dorkin three element model during HFPV.