The complexities of tracheal intubation with direct laryngoscopy and alternative intubation devices

Intubation research on both direct laryngoscopy and alternative intubation devices has focused on laryngeal exposure and not the mechanics of actual endotracheal tube delivery or insertion. Although there are subtleties to tracheal intubation with direct laryngoscopy, the path of tube insertion and the direct line of sight are relatively congruent. With alternative intubation devices, this is not the case. Video or optical elements in alternative intubation devices permit looking around the curve of the tongue, without a direct line of sight to the glottic opening. With these devices, laryngeal exposure is generally the simple part of the procedure, and conversely, tube delivery to the glottic opening and advancement into the trachea are sometimes not straightforward. This article presents the mechanical and optical complexities of endotracheal tube insertion in both direct laryngoscopy and alternative devices. An understanding of these complexities is critical to facilitate rapid tracheal intubation and to minimize unsuccessful attempts.