Expiratory LAP
In the patients under sedation, the inspiratory LAP was easily influenced by a decline in the intra thoracic pressure, however, the expiratory LAP theoretically would not. Therefore, the expiratory LAP in patients under sedation was thought to be almost identical to the LAP in those in an awake state.
The expiratory LAPs after the ASV were slightly lower than those before the ASV. From the aspect of the mechanism of noninvasive positive pressure ventilation, a positive expiratory pressure might reduce the venosus return and decreased the LAP. However, whether a positive expiratory pressure influences the LAP immediately after the initiation of the ASV remains unclear and requires further investigation in terms of the hemodynamic status.