Reliability of Chest Auscultation in Determining Proper Position of Tracheal Tubes

据报道，插管后呼吸音听诊不可靠主要与墨菲眼的存在有关。本研究旨在确定与没有眼睛的气管插管相比，带墨菲眼的气管插管是否会增加无法识别的支气管插管的风险。本研究表明，听诊器只能在左肺气体流量明显减少时才能识别呼吸音的变化，这表明听诊器无法检测到由于管尖超出隆突而导致的气体流量的轻微减少。使用袖带管，充气的袖带可以密封管和支气管之间的空间，从而完全中断气体流动。然而，无袖管没有可充气的袖带来密封管与支气管之间的空间，因此可以将管尖深深地插入，直到管与支气管之间的间隙消失。因此，听诊在确定气管导管正确位置时的可靠性受到墨菲眼、斜面和袖带的影响。在插管过程中，当呼吸音改变或消失时，应考虑墨菲眼的位置和大小、斜角的形状和袖带的存在，适当地取出插管。这些操作可以防止在口腔颌面外科手术中无意和未被识别的支气管插管。

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.