Ottawa Anesthesia Primer. Patrick Sullivan

       Fig. 6.13 Laryngeal anatomy. The epiglottis is shown in both the ‘open’ (left image) and ‘closed’ (right image) position. The cuneiform (medial) and corniculate (lateral) cartilages form the aryepiglottic folds.

       Fig. 6.14 The ‘BURP’ maneuver refers to a Backward, Upward and Rightward Pressure being applied to the thyroid cartilage. It differs from cricoid pressure (Fig. 9.1) in that the pressure is applied on the thyroid cartilage rather than the cricoid cartilage. It’s purpose is to facilitate visualization of the glottis by the endoscopist.

       IV. Insertion of the ETT:

      Intubation is performed with the left hand controlling the laryngoscope blade while the right hand opens the patient’s mouth and then passes the ETT tip through the laryngeal inlet under direct visualization. When a limited laryngeal view is encountered, the epiglottis can be used as a landmark for guiding the ETT between the hidden vocal cords. The tip of the ETT is passed underneath the epiglottis and anterior to the esophageal inlet. Note that the glottis lies anterior to the esophagus (or above the esophagus during laryngoscopy). When the epiglottis partially obscures the view of the glottis, an assistant can be asked to apply pressure to the thyroid cartilage by displacing it in a direction that is backwards, upward, and towards the right side of the patient. This maneuver is called the “BURP” maneuver (Fig. 6.14). It is used to move the larynx in a manner that improves the clinician’s view of the glottis. The BURP maneuver should not be confused with the application of cricoid pressure. Cricoid pressure is discussed in Chapter 9: Rapid Sequence Induction.

      A malleable stylet that is shaped to form a distal anterior curve of approximately 35° can be helpful to guide the ETT tip through the laryngeal inlet and should be used for all difficult and/or emergency intubations. Use of an endotracheal stylet that is configured with a more acute 90° “hockey stick” configuration is discouraged as this may result in trauma to the anterior trachea on insertion as well as ETT displacement when the stylet is removed.

      When there is a limited view of the ETT passing through the vocal cords, the Ford Maneuver can help with visual confirmation of its correct placement in the glottis immediately after intubation. The maneuver is performed by displacing the glottis posteriorly using downward pressure on the ETT while lifting with the laryngoscope to expose the glottis and ETT. This maneuver is useful in the patient with a grade 3 or 4 larynx when difficulty is encountered visualizing the glottic structures.

      The cuff of the ETT should be observed to pass between the vocal cords and should be positioned just inferior (approximately 2 cm) to the vocal cords. Before withdrawing the laryngoscope blade from the patient’s mouth, it is helpful to note the length of the ETT at the patient’s lips using the cm markers on the ETT. This will be useful information should the ETT move before it can be secured. The usual distance from the tip of the ETT to the patient’s mouth is approximately 21 - 24 cm in adult males and 18 – 22 cm in adult females. The ETT cuff is inflated with just enough air to create a seal around the ETT during positive pressure ventilation. A cuff leak may be detected by listening at the patient’s mouth or over the larynx.

      Bimanual laryngoscopy is an essential maneuver to improve the glottic view when an inadequate view is obtained on first attempt. The maneuver is performed by the clinician using the left hand to lift the laryngoscope blade while the right thumb and forefinger are used to manipulate the thyroid cartilage externally by pushing it posteriorly or to the right to obtain a better view of the glottis. Once an optimal view is obtained, an assistant’s hand replaces the clinician’s right hand to maintain the thyroid manipulation. The clinician then uses the right hand to direct the ETT into the glottis.

       V. Confirmation of correct ETT placement:

      Immediate absolute proof that the ETT is in the tracheal lumen can be obtained by observing the ETT pass through the vocal cords, by observing ETCO₂ returning with each respiration, or by visualizing the tracheal lumen through the ETT using a fiberoptic scope. Indirect confirmation that the trachea is intubated with a tracheal tube includes: listening over the epigastrium for the absence of breath sounds with ventilation, observing the chest rise and fall with positive pressure ventilation, observing condensation on the ETT, balloting the endotracheal cuff in the neck, and listening to the apex of each lung field for breath sounds with ventilation. There are reports of physicians auscultating “distant breath sounds” in each lung field when in fact the ETT was incorrectly placed in the esophagus. Hence, listening to the lung fields may reveal bronchospasm or evidence of an endobronchial intubation, but it cannot be relied on as absolute proof that the ETT is correctly positioned in the trachea.

      If the ETT is positioned in the tracheal lumen and the patient is breathing spontaneously, the reservoir bag will fill and empty with respiration. An awake patient will not be able to vocalize with an ETT positioned in the tracheal lumen. On an anterior-posterior chest x-ray, the tip of the ETT should be located between the midpoint of the thoracic inlet and the carina.

      Decreased air entry to one lung field may indicate that the ETT is in a mainstem bronchus (usually the right mainstem bronchus). In this situation, the patient may become increasingly hypoxic or continue to cough. An endobronchial intubation may be suspected when one side of the chest is observed moving more than the other with ventilation. In this situation, the airway pressures may be higher than normal (> 25 cm H₂O), and an abnormally distant ETT position at the patient’s lips will be noted.

      Clinical Pearl: “If in doubt, take it out”

      This is prudent advice for anyone who has just attempted tracheal intubation and is unsure and unable to confirm tracheal placement. In this case, rather than risk hypoxic injury and gastric aspiration, it is better to remove the ETT, resume mask ventilation with 100% oxygen, stabilize the patient, and call for help.

      Clinical Pearl: “If in doubt, leave it in”

      This advice applies to the clinician who is considering tracheal extubation in a patient whose trachea has been intubated for a prolonged period of time. When the clinician questions whether the patient’s trachea can be safely extubated (see Chapter 7: extubation criteria), it is generally safer to delay extubation, continue to support ventilation, and ensure hemodynamic stability, analgesia, sedation, and oxygenation rather than perform premature tracheal extubation.

       Difficulty with Intubation:

      Repeat intubation attempts should be avoided unless there is a different tactic to improve the chance of success. Persistent repeat attempts at intubation traumatize the patient’s airway,