This can be achieved whether you use a mask, NPPV, or BVM; a good seal can still be obtained. Alternatively, you can use the high flow nasal cannula technique for preoxygenation.
Normal adjunctive airway techniques/equipment (jaw thrust, oropharyngeal airway) remain useful. In particular, nasal trumpet can maintain patencny of at least one nare.
Consider taping cannula to face to prevent dislodgement.
Apneic oxygenation
ECG axis
Mask squeeze
Lung recruitment maneuver
Breath-holding spell
Hypopyon
Ventilation modes
CO2 narcosis