Right-sided double lumen tube (Mallinckrodt - Endobronchial tube) is introduced into the glottis via direct laryngoscopy. After the endotracheal lumen tube has passed the vocal cords, the stylet is removed, and the tube is rotated 90° toward the right and advanced slightly until resistance is encountered. Auscultation is then performed to check the proper side the endobronchial tube was inserted to.