Reliability of Chest Auscultation in Determining Proper Position of Tracheal Tubes

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Unreliability of breath sounds auscultation after intubation is reportedly mainly related to the presence of the Murphy eye. This study was performed to ascertain whether cuffed and uncuffed tracheal tubes with the Murphy eyes increases the risk of unrecognized bronchial intubation, compared to tubes without eyes. The present study demonstrates that a stethoscope can recognize the change in breath sounds only when gas flow to the left lung remarkably decreases, indicating that a stethoscope is unable to detect the slight decrease in gas flow resulting from advancement of the tube tip beyond the carina. With use of a cuffed tube, the inflated cuff can seal the space between the tube and the bronchus, with consequent complete interruption of gas flow. However, uncuffed tubes do not have the inflatable cuff that can seal the space between the tube and the bronchus, so the tubetip can be deeply inserted until the gap between the tube and the bronchus is lost. Therefore, the reliability of chest auscultation in determining the proper position of the tracheal tubes is influenced by the Murphy eye, bevel, and cuff. When breath sounds change or disappear during tube advancement, it is necessary to appropriately withdraw the tube, considering the location and size of the Murphy eye, the shape of the bevel, and the presence of the cuff. These maneuvers can prevent inadvertent and unrecognized bronchial intubation during oral and maxillofacial surgery.