[Work of breathing in noninvasive proportional assist ventilation in patients with respiratory insufficiency].

Background: The aim of the present study was to evaluate if Proportional Assist Ventilation (PAV), when applied noninvasively via face mask, can reduce ventilatory effort in patients with respiratory failure. We present preliminary results of an ongoing study.
Patients and Methods: In 5 patients with respiratory failure due to different underlying disorders (pulmonary fibrosis, bilateral diaphragm paralysis, COPD) we compared the transdiaphragmal pressure-time integral. PTdi (integral off Pdi dt) after 15 minutes of noninvasive PAV to the baseline values without ventilatory support.
Results and Conclusion: Four patients showed reduction of PTdi to various extend. One patient who presented low diaphragmal activity at baseline due to diaphragmal paralysis showed a slight increase in PTdi during ventilation. Mean PTdi decreased by 26.7%. PaCO2 in the 5 patients showed no significant change after 15 minutes of ventilation, thus indicating that with noninvasive PAV patients can maintain constant ventilation with reduced effort.