Hi Paulette,
As I mentioned, there are very low tech (essential oils, cough stacking, humidification) and high tech (CoughAssist if secretions are an issue, DPS if he qualifies) things to try. Without seeing his BiPAP data, there may be improvements to be made there, in settings and/or mode and/or machine. Do you have access to his data card? What model does he have? And of course a sip ventilator during the day may help, but in the short term, for example, when my husband feels like he needs more air, we wheel him back to the bedroom and put on his BiPAP mask in his chair.