Fig. 3. Tube misplacement during one-lung ventilation may lead to hypoxemia. The correct position (  A^L ) and possible misplacements (  B^L –  C^L ) of the left-sided double-lumen tube are shown. In the lower four figures, correct position (  A^R ) and possible misplacements (  B^R –  D^R ) of the right sided double-lumen tubes are shown.