Patients will be excluded from the primary outcome analysis, but included in the intention to treat analysis for the secondary outcome if they are not pre-oxygenated to the standard RSI protocol of 3 minutes with 100% FiO2 by means of bag valve mask, HFNC and/or non-rebreather; patients will be excluded from the study in general if they are in cardiac or traumatic arrest or they are intubated without an apneic period (awake intubation)