Esophageal intubation: Can it be avoided with the airway scope (Pentax-AWS)?

Airway scope (AWS) is a rigid indirect laryngoscope with integrated tube guidance and can improve laryngeal exposure compared to the conventional direct laryngoscope. It is expected that the clear and improved laryngeal view obtained with AWS can eliminate the risk of esophageal intubation. We, however, experienced 3 cases of esophageal intubation out of 600 clinical cases with AWS in 15 month after its market release. Two cases were by novice anesthesiologists with fewer than 10 intubation experiences with AWS. Although they had had more than 100 intubation experiences with Macintosh laryngoscope, they did not have sharp eye for incorrect intubation with AWS. The third case was performed by an experienced laryngoscopist but it was difficult to identify the glottic opening because patient had distracted airway anatomy due to laryngeal tumor. In all cases esophageal intubation was immediately noticed and airway was secured uneventfully. We conclude that intubation under vision with improved laryngeal view is still not sufficient to prevent esophageal intubation.