During unanticipated difficult intubations, emergencies, or when direct laryngoscopy provides a poor view (Cormack-Lehane Grade III) or reveals a very tight glottic opening, it is often beneficial to insert a guiding catheter (“gum elastic bougie” or GEB) prior to attempting endotracheal tube (ETT) placement.

The GEB provides several advantages. It has improved maneuverability compared with an ETT. The GEB’s combination of firmness and an angulated tip provides a means to intubate the glottic opening when it is poorly visualized, if its location can be inferred from the view of the interarytenoid notch or the position of the epiglottis. Additionally, the GEB can provide a tactile clue that it has been placed correctly in the airway, as its stiff end often moves against the cartilagenous tracheal rings. Of note, the GEB can provide a second form of tactile feedback because continuing to insert the bougie will lead to resistance if placed in the trachea. This resistance occurs when the angled tip of the bougie is too wide to fit through the narrowing bronchi. It usually occurs at an insertion depth of 30-35 cm. Generally, no resistance is felt if placed in the esophagus.

The malleable Eschmann introducer with its stiff, angulated distal tip lends itself to this task because it is small enough to be maneuvered in the pharynx where it is used to “probe” for the glottic opening. Its end is firm enough to rattle against the tracheal rings as it is placed in the airway, providing a sense of correct placement. This type of introducer is 60 cm long, 5 mm in diameter, with distal 2.5 cm angulated at approximately 40°. It has markings for every 10 cm.

The Frova intubating introducer similarly facilitates intubation when the glottic view is poor. This device is a hollow cannula with a malleable, removable steel stylet, which permits “jet” (high pressure) ventilation through an adaptor, or oxygen insufflation during intubation attempts. It is 65 cm long, 4.7 mm in diameter, with distal 2.0 cm angulated at 65°. The introducer comes with a rigid stylet that is 10 cm shorter than the introducer thereby decreasing the risk of trauma on insertion.

Airway exchange catheters can also be used as ETT introducers. However, these devices lack a curved tip to provide tactile feedback regarding which lumen is being cannulated.

Numerous case reports and case series attest to the value of the bougie in difficult intubations in the operating room (OR), emergency department, and in the prehospital setting. A significant proportion of these studies were carried out in the United Kingdom.

There have been several papers that have elucidated optimum technique for GEB use. Dogra et al identified several steps that increased success using GEB. These included keeping the laryngoscope blade in the mouth during ETT placement and rotating the tube 90° counterclockwise if the ETT became lodged at the glottic opening.¹ Additionally, Latto et al collected data on 200 cases of GEB use by anesthesiologists in the United Kingdom between October 1997 and August 1998. Of 200 uses, 146 were for “poor view of the larynx” and 46 for “difficulty pushing the tube toward the larynx.” Their survey revealed that 178 cases were intubated on first try with GEB and 15 on the second attempt. Six required more than two attempts, and one attempt at inserting GEB failed. Moreover, “clicks” of the tracheal ring were present in 65% of cases (130) and only 13% had distal resistance. They recommended that the distal end of the GEB be further bent to a more acute angle prior to use, as well as inserting the GEB to 45-cm depth before declaring that the device had encountered no resistance and hence was likely in the esophagus. Furthermore, their survey revealed that in 45% of the cases laryngeal pressure improved the view of the glottic opening, and in 51% there was no change, whereas it worsened the view in only 2% of cases. Hence, they also recommend optimum positioning of the patient along with attempted laryngeal pressure as part of their routine technique to obtain the best glottic view.²

Several case reports show GEB use increases success in difficult airway scenarios. Combes et al trained 40 anesthesiologists on a manikin over 2 months on a difficult airway algorithm where GEB was the first line tool in a “can ventilate, cannot intubate” scenario. In the prospective portion of the study over next 18 months, 89 scenarios occurred, and, in 80 cases, GEB allowed the ETT to be successfully placed.³ Komatsu et al examined the role of GEB in anesthetized patients with simulated restricted neck immobility using a cervical collar. There was a 90% intubation success rate using GEB. Of note, the authors
also reported a 100% success rate with a video laryngoscope.⁴ Nolan and Wilson studied intubation in 157 patients with manual cervical stabilization applied, and found that with GEB, all 78 patients in the GEB group were intubated in less than 45 seconds, and that GEB was used successfully in the 5 intubation failures in the direct laryngoscopy group⁵. Furthermore, Maruyama and colleagues studied the difficulty of intubation using video laryngoscope, GEB, and standard direct laryngoscopy in manikins undergoing chest compressions with or without manual cervical stabilization. These authors found that intubation via video laryngoscope was more readily accomplished than that with GEB, which in turn was easier than standard direct laryngoscopy.⁶

Moreover, several authors have examined GEB use outside the OR. Jabre et al evaluated GEB use in the prehospital setting where intubation was necessary. After training on a manikin, intubation reports were collected for the next 30 months. Of the 1,442 intubations, 41 attempts required GEB placement. It was successfully placed 33 times (78%).⁷ Shah et al⁸ reported use of GEB during intubation for various reasons in 88 cases over 17 months in a large academic emergency medicine department and reported a success rate of 80%. Also, some authors have found GEB useful in modifying other airway techniques. GEB also has been used to assist in cricothyrotomy in an animal laboratory setting⁹