Does the Murphy eye reduce the reliability of chest auscultation in detecting endobronchial intubation?

Bilateral breath sounds are routinely auscultated after endotracheal intubation to verify that the endotracheal tube (ETT) tip is properly positioned. We conducted the present study to ascertain whether the eye of the Murphy tube has an influence on the reliability of auscultation of breath sounds in detecting endobronchial intubation. Twenty patients undergoing scheduled oral and maxillofacial surgery participated in this study. After the induction of general anesthesia, either the Magill tube or the Murphy tube was inserted through the nose into the trachea. The fiberoptic bronchoscope was inserted through the ETT, and the distance from the nares to the carina of the trachea was measured. When breath sounds from the left side of the chest changed and disappeared while the ETT was being advanced, the distance from the nares to the ETT tip was measured. Unilateral auscultatory change was not observed until the ETT tip was advanced beyond the carina and inserted 1.5+/-0.4 cm into the right mainstem bronchus when the Magill tube was used and 2.0+/-0.4 cm when the Murphy tube was used (P < 0.01). Breath sounds disappeared when the ETT tip was further advanced up to 3.2+/-0.3 cm from the carina. We demonstrated that the eye of the Murphy tube reduces the reliability of chest auscultation in detecting endobronchial intubation.

The Murphy eye was designed to allow ventilation of the lung when the bevel of the endotracheal tube is occluded. We demonstrated that the eye of the Murphy tube reduces the reliability of chest auscultation in detecting endobronchial intubation.