After five minutes of 100% oxygen administration, if the patient does not complain of dizziness, headache, nausea or lethargy, the nasal hood and the flow of gas may be discontinued. The proper sequence is removal of the nasal hood, followed by termination of gas flow. This is the reverse of the sequence at the initiation of gas administration. At the start of the procedure, the administration began by turning on the gas flow and then placing the nasal hood over the patient’s nose to prevent patient anxiety due to the inability to inhale gas. Similarly, to the very last moment of the procedure we want to avail the patient of the ability to breathe normally.