Figure 49-20 This schematic diagram depicts the complete fiberoptic bronchoscopy picture of left-sided double-lumen endotracheal tubes (both the desired view and the view to be avoided from both of the lumens). A, When the bronchoscope is passed down the left lumen of a left-sided tube, the endoscopist should see a very slight left luminal narrowing and a clear straight-ahead view of the bronchial carina off in the distance. Excessive left luminal narrowing should be avoided. B, When the bronchoscope is passed down the right lumen of a left-sided tube, the endoscopist should see a clear straight-ahead view of the tracheal carina and the upper surface of the blue left endobronchial cuff just below the tracheal carina. Excessive pressure in the endobronchial cuff, as manifested by tracheal carinal deviation to the right and herniation of the endobronchial cuff over the carina, should be avoided. (From Benumof JL: Anesthesia for Thoracic Surgery. Philadelphia, WB Saunders, 1987.)