“…10 Measurements of arterial oxygen tension, 6,7 ETN 2 , 11 ETO 2 12,13 concentrations reflect the efficacy of preoxygenation, whereas the slowing of the rate of arterial oxyhemoglobin desaturation during apnea 10,14 is indicative of its efficiency. Since there are many factors that affect the decrease of arterial oxyhemoglobin saturation during apnea, such as capacity of oxygen loading and total oxygen consumption, 10,15,16 it is of utmost importance to maximally preoxygenate the patient to fill the alveolar and arterial compartments with oxygen, especially when difficult ventilation and/ or intubation are anticipated.…”