Use of the Cook Airway Exchange Catheter to Facilitate Fiberoptic Intubation: Are We Trying to Solve a Problem

To the Editor:—In their report, Ayoub et al. found that advancing the endotracheal tube (ETT) into the trachea over the fiberoptic bronchoscope (FOB) fails in about one third of patients. They also found that by inserting a Cook Airway Exchange Catheter (Cook Critical Care, Bloomington, IN) (CAEC) alongside the FOB, tracheal intubation was successfully accomplished in these patients. They concluded that the presence of the FOB and the CAEC together inside the lumen of the ETT minimized the size of the cleft along the ETT bevel (created by the OD of the FOB and the internal diameter of the ETT), therefore decreasing the likelihood of impingement on the arytenoids cartilages and enhancing the chances of passing the ETT into the trachea. Before this technique becomes an accepted practice, we would like to forward the following comments. First, the authors’ reported 32% failure rate of advancing the ETT over the FOB is unusually high. Had the authors used an appropriate fiberoptic intubation technique, their failure rate would have been extremely low. They used a FOB with an OD of 3.8 mm and ETTs with internal diameters of 7.5 and 8.0 mm. We believe that the great disparity in these diameters contributed to their high incidence of failure in passing the ETT over the FOB. Second, we feel that the authors were biased in their comparison of the success rate using the FOB alone (despite its small diameter) versus the combined use of the FOB and the CAEC. They compared one attempt to advance the ETT over the FOB with up to three attempts when the CAEC was used. If only the first attempts of both techniques were compared, the success rate of using the FOB alone would have been higher (68%) than using both the FOB and the CAEC (9 of 16, or 56%). Third, it is not clear how the authors directed the CAEC through the cords into the trachea. Because the FOB was already in the trachea, it could not have been used to visualize and direct the CAEC toward the cords. For the CAEC to pass through the cords under vision, its tip should be distal to the tip of the FOB. Withdrawing the FOB from the trachea until its tip lies in the pharynx and aligning the CAEC alongside the FOB to introduce both as a unit through the cords is time consuming, carries no guarantee for a successful attempt, and leaves the airway unprotected in the process. Blind insertion of the CAEC with the expectation that it will find its way through the cords can cause, literally, what the authors were trying to avoid, that is, trauma making further attempts at ETT placement more difficult. Fourth, from our experience and the experience of others, difficulty in passing the ETT over the FOB is rarely encountered. The use of a proper technique is the best prophylaxis against failure of ETT advancement over a FOB. Using the largest FOB that fits easily inside an appropriate size ETT, using the jaw thrust maneuver (to decrease the posterior pharyngolaryngeal angle), applying generous lubrication, and placing the ETT in warm water to make it more pliable can ensure almost no failure in ETT advancement. In the rare situation when the ETT cannot be advanced, a gentle 90-degree counterclockwise rotation can be successfully utilized. Introducing another device adjacent to the FOB during intubation can be time consuming, can cause trauma to the airway, and most importantly, should not be an alternative to the use of an appropriate fiberoptic intubation technique.