Management of Unanticipated Difficult Airway in the Prehospital Emergency Setting

We were greatly interested in the recent article of Combes et al.¹ that prospectively validated a prehospital difficult-intubation algorithm. In this clinical study, the tracheal intubation with direct laryngoscope proved impossible in 160 patients. However, of these 160 patients, 15 had a laryngeal view of the Cormack and Lehane (C&L) class I or II, which is generally regarded as an easy laryngoscopy.²The ease of direct laryngoscopy is not synonymous with ease of tracheal intubation, but the laryngeal view obtained by direct laryngoscopy usually is an important determinant of successful intubation. We would like to know the detailed cause of failed intubation in these patients with an easy laryngoscopy. Moreover, the authors did not clearly describe whether their algorithm required for use of an endotracheal tube with a malleable stylet at the initial intubation attempt. In managing difficult intubation, mounting the endotracheal tube onto a stylet and angling the distal tip upward help to guide the tube tip toward the glottis and improve the success rate of tracheal intubation.³ This measure is especially useful when a poor laryngeal view is obtained during direct laryngoscopy or when using a flexible endotracheal tube without a natural anterior curve. In general, when speed of tracheal intubation is important (as in a patient with a full stomach or chest compression), an endotracheal tube should always be equipped with a stylet.⁴

In this difficult-intubation management algorithm, the authors recommended that if the tracheal intubation failed after either two attempts with a C&L class less than IV or a single attempt with a C&L class IV, along with optimal upper airway and head manipulations, the participants were requested to move to the next step of the algorithm, the gum elastic bougie (GEB). GEB-guided intubation was used as first choice and the intubating laryngeal mask airway (ILMA) as a backup. However, what usually determines the successful intubation with the GEB is part or complete visualization of the epiglottis with or without laryngeal structure. For an intubator who has no extensive experience in the GEB-guided intubation, if direct laryngoscopy can not expose any epiglottic structure as an objective mark (e.g., C&L class IV), blindly inserting the GEB into the trachea will be very difficult. In clinical practice, the GEB-guided intubation is really most suitable for patients with a C&L class less than IV.⁵ Thus, we consider that in their difficult-intubation management algorithm, the rescue step to use the GEB-guided intubation as first choice may be suitable only for the patients with a C&L class less than IV. After a single intubation attempt failed in patients with a C&L class IV, the rescue airway algorithm should move directly to the step that uses the ILMA to ventilate the patients and then to intubate the trachea, but not to the step that attempts reintubation with the GEB because it has high risks of failed intubation and increased airway trauma. For this situation, we completely agree with the editorial view of Drs. Isono and Ishikawa that maintenance of oxygenation is the final goal of airway management.⁶

The authors did not clearly state the type of the ILMA used for this difficult-intubation management algorithm. When an ILMA is used as a rescue airway device in the prehospital setting, we recommend use of the ILMA CTrach™ (Laryngeal Mask Company Limited, San Diego, CA) with the integrated fiberoptic channels and a detachable liquid crystal display viewer, rather than the ILMA Fastrach™ (Laryngeal Mask Company Limited). It has been shown that compared with the ILMA Fastrach™, the ILMA CTrach™ can enable a higher first-attempt success rate of tracheal intubation because of the view of the glottis it provides, the way it optimizes placement of the device, and the ability to observe the process of tracheal intubation through the device.⁷ In addition, data from the study of Nickel et al.⁸suggest that the ILMA CTrach™ is a suitable device for emergency airway management in the prehospital setting because it provides ventilation and facilitates intubation with a very high success rate.

Fu-Shan Xue, M.D.*

Xu Liao, M.D.

Yu-Jing Yuan, M.D.

Qiang Wang, M.D.

Jian-Hua Liu, M.D.

*Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, People's Republic of China. fruitxue@yahoo.com.cn

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