A 62-year-old man is brought to Accident and emergency following assault to the head. He has a face mask and reservoir bag delivering 15L/min of oxygen, a stiff cervical collar and is attached to an intravenous drip. He has no spontaneous eye opening except to pain, makes incomprehensible sounds, and does not obey commands. He demonstrates flexion withdrawal to painful stimuli. On suction, he has no gag reflex. What is the next best step in management of this patient?