Various pre-oxygenation methods have been described to prolong the non hypoxic apnea time in the obese population. Some proposed pre-oxygenation strategies with the patient in the head up position (beach chair). It is a position derived from the ramped position described as the best to visualized the obese patients' glottis. Others proposed pre-oxygenation strategies with positive pressure ventilation, but only the supine position has been studied concomitantly.