critical care medicine
Tracheal Intubation
Insertion Technique for Intubation
 3 attempts) is associated with much higher rates of significant hypoxemia, aspiration, and Cardiac Arrest . In addition to correct positioning, several other general principles are critical for success: Visualizing the epiglottis Visualizing the posterior laryngeal structures (ideally, the vocal cords) Not passing the tube unless tracheal insertion is ensured The conventional laryngoscope is designed to be held in the left hand, and the blade is inserted into the mouth and used as a retractor to displace the mandible and tongue up and away from the laryngoscopist, revealing the posterior pharynx. Avoiding contact with the incisors and not placing undue pressure on laryngeal structures are important. The importance of identifying the epiglottis cannot be overstated.Identifying the epiglottis allows the operator to recognize critical airway landmarks and correctly position the laryngoscope blade. The epiglottis may rest against the posterior pharyngeal wall, where it blends in with the other pink mucus membranes or gets lost in the pool of secretions that invariably exists in the cardiac arrest patient’s airway. Once the epiglottis is found, the operator may use one of 2 techniques to lift it: Typical straight blade approach: The operator picks up the epiglottis with the tip of the laryngoscope blade Typical curved blade approach: The operator indirectly lifts the epiglottis and moves it out of the line of site by advancing the blade into the vallecula and pressing against the hyoepiglottic ligament Success with the curved blade depends on the proper positioning of the blade tip in the vallecula and the direction of the lifting force (see figure). Lifting the epiglottis by either technique reveals the posterior laryngeal structures (arytenoid cartilages, interarytenoid notch), glottis, and vocal cords. If the tip of the blade is too deep, laryngeal landmarks may be entirely bypassed, and the dark, round hole of the esophagus may be mistaken for the glottis opening. If identifying structures is difficult, manipulating the larynx with the right hand placed on the anterior neck (while continuing to hold the laryngoscope in the left hand ) may optimize the laryngeal view (see figure). An assistant can help manipulate the larynx also. Another technique involves lifting the head higher (lifting at the occiput, not atlanto-occipital extension), which distracts the jaw and improves the line of sight. Head elevation is inadvisable in patients with potential cervical spine injury and is difficult in people who are extremely obese (who must be placed in a ramped or head-elevated position beforehand). In an optimal view, the vocal cords are clearly seen. If the vocal cords are not seen, at a minimum, the posterior laryngeal landmarks must be viewed and the tip of the tube must be seen passing above the interarytenoid notch and posterior cartilages. Operators must clearly identify laryngeal landmarks to avoid potentially fatal esophageal intubation. If operators are not confident that the tube is going into the trachea, the tube should not be inserted. Once an optimal view has been achieved, the right hand inserts the tube through the larynx into the trachea (if operators have been applying anterior laryngeal pressure with the right hand, an assistant should continue applying this pressure). If the tube does not pass easily, a 90°counter-clockwise twist of the tube may help it pass more smoothly over the anterior tracheal rings. Before withdrawing the laryngoscope, operators should confirm that the tube is passing between the cords. Appropriate tube depth is usually 21 to 23 cm in adults and 3 times the endotracheal tube size in children (for a 4.0-mm endotracheal tube, 12 cm; for a 5.5-mm endotracheal tube, 16.5 cm). In adults, the tube, if inadvertently advanced, typically migrates into the right mainstem bronchus. Intubation is unsuccessful in 10 to 30% of critically ill patients, so contingency plans should be established. When intubation fails, oxygenation should be prioritized and alternative interventions should be used while minimizing the number of airway interventions in order to minimize trauma and other procedural complications ( Insertion technique references ). Pressure is applied on the neck opposite the direction of lift of the laryngoscope. Arrows show the direction for lift of the laryngoscope and for anterior neck pressure. 1.Frerk C, Mitchell VS, McNarry AF, et al: Difficult Airway Society 2015 guidelines for management of unanticipated difficult intubation in adults.Br J Anaesth115: 827–848, 2015. https://doi.org/10.1093/bja/aev371 2.Higgs A, McGrath BA, Goddard C, et al: Guidelines for the management of tracheal intubation in critically ill adults.Br J Anaesth120:323–352, 2018. doi: 10.1016/j.bja.2017.10.021 