- IPAP increases ventilation and helps to blow off CO2
- CPAP increases FRC and therefore keeps the lungs open so the next breath comes in easier
- Both IPAP and CPAP help to reduce work of breathing
- Both the IPAP and CPAP help reduce work of heart
So, how does BiPAP reduce work of heart because the increased intrathoracic pressure decreases preload to the heart, thereby decreasing cardiac output, and thereby decreasing blood pressure. In this way, it helps to decrease the patients work of heart. That is how it helps with heart failure. It does not force fluid out of the lungs. It does not increase blood pressure.