Do you employ the use of noctournal oximetry to assess for a need for supplemental O2 in addition to auto PAP in patients with OSA who have not had an in lab CPAP titration study?  

Nocturnal hypoxemia noted on ONO on CPAP doesn't qualify patients for supplemental oxygen. I usually check ONO on CPAP on symptomatic patients who are also on daytime oxygen to assess the adequacy of supplemental oxygen at night.

I do not routinely do so. However, if there is a suspicion for persistent nocturnal hypoxemia due to daytime fatigue or if the patient has a diagnosis of COPD or OHVS and did not for some reason undergo a CPAP titration night, I do perform nocturnal oximetry on Auto-PAP.