I'm new to Allnurses.com, and I had a question from more experienced nurses. I work in the ED, I'm a new grad, and I was wondering what pulse ox reading you usually see to determine different supplemental oxygen therapies? For example, how low would the pulse ox have to be to apply a nasal cannula, a simple mask, a nonrebreather, etc.? Like how would I know that I need to go to a nonrebreather automatically vs. a simple mask or just a nasal cannula? I know how many liters each one would need to be set at, I just don't know what types of situations I should know to apply different delivery systems at? Any help would be appreciated, thanks?