Bipap and Sp02 desats

Hi, just need your input on this. I work nites on LTC, we had this lady who has COPD with chronic resp. failure who is on the bipap 14/6 settings at night.
She would always have sats of around 65-75% while sleeping, appears not to be in any respiratory distress, though her RR's would be around 25, with shallow breathing. I usually will have to rouse her from sleep, make her do some deep breathing/coughing, sat would gradually come up. Or if that does not work, her sats would usually come up on 0xygen at 2 liter flow on nasal cannula. I have already put a report on this to the NP, so far little has been done, they put her on an antibiotic for respiratory tract infection, and they have discontinued tapering her off her prednisone. I feel so stressed out with her on the bipap at night, coz I have to check on her every hour at night, make sure the face mask is snug and fit, and everything is connected and the O2 bleeds 2 liter on the bipap. Treatment order states by the way that her sat should be between 88-92%. And to add pressure she is a full code with poor lung reserve, and the family is always breathing down your neck. Need help, pls. Thanks!!!