CPAP and BiPAP machines are both types of noninvasive positive airway pressure machines, or PAP machines. The difference is that CPAPs deliver single-pressure airflow and bilevel positive airway pressure (BiPAP) machines deliver dual-pressure airflow.
In addition to CPAPs and BiPAPs, automatic positive airway pressure (APAP) machines provide noninvasive ventilation or noninvasive positive pressure ventilation (NPPV).
Another difference between CPAP and BiPAP machines is that CPAPs are useful for hypoxemic respiratory failure, whereas BiPAPs are useful for patients with hypercapnic respiratory failure or a combination.
BiPAP machines:
BiPAP devices generally start with a lower pressure setting as you fall asleep and gradually ramp up to your prescribed pressure setting, where it stays throughout the night. This offers a more comfortable way to fall asleep.
APAP machines:
APAP machines have two pressure settings, a low- and high-range setting, and the machine automatically adjusts based on your sleeping position. APAP machines use algorithms that sense changes in your breathing during the night and adjust accordingly.
APAP machines are popular because most people don’t have the same breathing needs while they sleep. For example, an APAP machine can switch to lower pressure as you roll onto your side and readjust to a higher pressure as you sleep on your back.