Neck anteflexion method for facilitating videolaryngoscopic tracheal intubation while applying cricoid pressure.


Cricoid pressure is a technique used worldwide to reduce the risk of aspiration during tracheal intubation [1]. Previous studies have shown that cricoid pressure with adequate force does not worsen but rather improves laryngoscopy with the Macintosh laryngoscope (McL) [2]. In contrast, we have shown that cricoid pressure impedes videolaryngoscopic tracheal intubation using the Pentax-AWS Airwayscope® (AWS; Hoya, Tokyo, Japan). One possible reason for the difficulty could be attributed to the indirect video function of the AWS. The AWS obtains images from beneath the line of sight; it is common for the video camera perspective to be facing upward towards the larynx. The trachea descends posteriorly into the thorax. This difference in angles—with the camera coming up from the base of the tongue towards the larynx and the tracheal axis descending away from it—can sometimes make passage of a tube through the glottis difficult using the AWS. Cricoid pressure may exacerbate this potential problem by further increasing the difference in angle as the trachea is pushed downward. Although doctors can get clear view of the glottis and its surrounding structures, deviations that occur during tracheal tube advancement by cricoid pressure may be difficult to image. To circumvent this difficulty, we propose a ‘neck anteflexionmethod.’ As cricoid pressure pushes the trachea downward and deviation appears (Fig. 1a), head elevation after laryngoscopy alleviates the deviation and facilitates smooth tracheal tube passage through the glottis (Fig. 1b).


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