CPAP stands for Continuous Positive Airway Pressure. It is a form of non-invasive ventilation in which mild, consistent air pressure is applied through a mask to keep the airway open and maintain oxygenation.
BiPAP stands for Bilevel Positive Airway Pressure. This is similar to CPAP but alternates periods of higher and lower pressure to make it easier for the patient to exhale.
CPAP and BiPAP are being used in the treatment of patients that have difficulty breathing, but these methods are being discouraged for treating COVID-19 patients.
CPAP and BiPAP increase the risk of aerosolizing the virus. If the virus gets airborne, then a higher percentage of other patients and caregivers will get infected. Optimal mask fit can minimize the risk, but cannot eliminate it.
It is also important to keep in mind that CPAP and BiPAP may not support patients enough. They might still need mechanical ventilation.