To the Editor:—
The article by Johnsen et al. 1once again highlights a problem commonly faced by practitioners using a fiberoptic scope to intubate the trachea, i.e. , resistance to passage of the endotracheal tube. As they discuss, this is usually attributed to the endotracheal tube being caught on structures of the supraglottic airway.2–6Johnson et al. correctly report that when oral fiberoptic intubation is attempted, the most common cause of obstruction to endotracheal tube placement is the right arytenoid cartilage. The article that best describes the anatomical reasons for endotracheal tube obstruction is based on observation of obstruction to endotracheal tube placement in an intubating mannequin.3Unfortunately, Johnson et al. neglect to credit this investigation, which found the same cause of obstruction, albeit not in human subjects, as they now report. In addition, as we reported in a letter to the editor of this journal, we have had years of experience with a high degree of successful oral endotracheal tube passage over the fiberscope in children and adults using the method of beginning with the bevel in the down position or facing posteriorly.7For example, in one of our recent publications examining the best method to teach fiberoptic intubation to residents, we found a high degree of successful initial endotracheal tube passage over the fiberscope. By paying strict attention to bevel orientation, we had only 3 failures of 300 intubation attempts that were secondary to inability to pass the endotracheal tube.8Overall, intubation was successful in 292 of 300 attempts; the 5 additional failures were secondary to being unable to correctly place the fiberscope.8This is a far higher success rate than the 50% obstruction Johnson et al. report when the bevel orientation is not down or posterior. It should also be noted that anatomical obstruction for nasal intubation differs.3In this case, obstruction is usually secondary to the epiglottis, and, as we have advocated and continue to teach, when nasal intubation is performed, the bevel orientation should be up or facing anteriorly to assure the highest rate of successful endotracheal tube passage. An easy mnemonic to assist in remembering the endotracheal tube orientation is “UNDO your troubles with the tube”—i.e. , bevel U p for N asal fiberoptic intubation and bevel D own for O ral fiberoptic intubation.
*Feinberg School of Medicine, Northwestern University, Chicago, Illinois. firstname.lastname@example.org