Figure 49-18 Schematic diagram depicting passage of the left-sided double-lumen endotracheal tube in a supine patient. A, The tube is held with the distal curvature concave anteriorly and the proximal curve concave to the right and in a plane parallel to the floor. The tube is then inserted through the vocal cords until the bronchial cuff passes the vocal cords. The stylet is then removed. B, The tube is rotated 90 degrees counterclockwise so that the distal curvature is concave anteriorly and the proximal curvature is concave to the left and in a plane parallel to the floor. C, The tube is inserted until either mild resistance to further passage is encountered or the end of the common molding of the two lumens is at the teeth. Both cuffs are then inflated, and both lungs are ventilated. Finally, one side is clamped while the other side is ventilated and vice versa. (See the text for further explanation.) (From Benumof JL: Anesthesia for Thoracic Surgery. Philadelphia, WB Saunders, 1987.)