Hi there! I was on Bi-Pap for quite some time before I was trached and vented. Allie is right, it is a machine that gets rid of CO2 and is used for a variety of conditons ranging from COPD, CF to those with muscular problems that inhibits their breathing. It stands for Bi level positive airway pressure, it essentially operates on two pressures. One pressure is for when you are inhaling, it helps your breathing effort. Then there is a second lesser pressure that kicks in when you are exhaling. It goes from a higher pressure to a lower pressure. The presssures are set by your doctor and are adjusted depending how you respond.
This machine helps with the work of breathing because of those pressures. It is also what is called non invasive ventilation, which means it doesn't involve any vents with endotracheal tubes. It is in a sense a ventilator because it helps with the exchange of your gases. With myself, it got to the point where I was on the Bi-Pap most of the day, when I was off and on my O2, my sats would drop to the 70's. Besides my CF, I do have neuromuscular disease which put me on the vent in the first place, which explains why I am on a vent and had to use a BiPAP most of the day before then.
I hope I have helped and not confused you. It is always good to ask questions. Hugs, Jenn <img src="i/expressions/face-icon-small-smile.gif" border="0">