Figure 2.
Description of how ventilator performance was assessed during noninvasive ventilation. The onset of pressure support allows measurement of the triggering delay, the flow to trigger, and the pressure to trigger, and calculation of the inspiratory pressure-time product (PTPt). The maximal delivered pressure and the tidal volume were measured from the ASL-5000 airway pressure and piston volume. The total work of breathing (WOB) corresponds to the checkerboard area (combination of patient and ventilatory work). Pmus = muscular pressure.