Figure 49-19 Three major malpositions (involving a whole lung) of a left-sided double-lumen endotracheal tube can occur. The tube can be in too far on the left (both lumens are in the left main stem bronchus), out too far (both lumens are in the trachea), or down the right main stem bronchus (at least the left lumen is in the right main stem bronchus). In each of these three malpositions, the left cuff, when fully inflated, can completely block the right lumen. Inflation and deflation of the left cuff while the left lumen is clamped create a breath sound differential diagnosis of tube malposition. (See the text for a full explanation.) L, left; R, right; ↓, decreased. (From Benumof JL: Anesthesia for Thoracic Surgery. Philadelphia, WB Saunders, 1987.)