What anatomical landmark is most important to visualize during intubation?

Visualizing the Glottic Opening is the Most Important Anatomical Landmark During Intubation

The most important anatomical landmark to visualize during intubation is the glottic opening (vocal cords), as this confirms the correct pathway for endotracheal tube placement and reduces the risk of failed intubation and associated complications 1.

Understanding Laryngeal Visualization

During direct laryngoscopy, visualization of key anatomical structures follows a sequential pattern:

1. Epiglottis - Often the first visible structure when inserting the laryngoscope
2. Vocal cords - The critical landmark indicating the entrance to the trachea
3. Arytenoid cartilages - Posterior landmarks that help orient toward the glottis

Cormack-Lehane Grading System

The Cormack-Lehane grading system describes the view obtained during laryngoscopy:

• Grade 1: Full view of vocal cords
• Grade 2: Partial view of vocal cords
• Grade 3a: Only epiglottis visible, can be lifted
• Grade 3b: Only epiglottis visible, cannot be lifted
• Grade 4: Neither epiglottis nor glottis visible

Importance of Visualizing the Glottic Opening

Visualization of the glottic opening is crucial for several reasons:

• Confirms correct tube placement: Direct visualization of the tracheal tube passing through the vocal cords is one of the most reliable methods to confirm proper placement 1
• Prevents esophageal intubation: Esophageal intubation remains a cause of mortality, and direct visualization helps avoid this complication 1
• Reduces airway trauma: Multiple and prolonged attempts at laryngoscopy are associated with significant morbidity and mortality 1
• Facilitates first-attempt success: Clear visualization of the glottis significantly improves first-attempt success rates

Techniques to Improve Glottic Visualization

When initial laryngoscopy yields a poor view:

1. Optimize head position: The "sniffing position" (head extension and neck flexion) improves the line of sight 1

2. External laryngeal manipulation (OELM or BURP):

   • OELM (Optimal External Laryngeal Manipulation)
   • BURP (Backward, Upward, and Rightward Pressure on the thyroid cartilage) 1

3. Consider releasing cricoid pressure: Cricoid pressure may impair the view and should be reduced or released if visualization is difficult 1

4. Use of alternative equipment:

   • Videolaryngoscopes provide improved views of the glottis compared to direct laryngoscopy 1
   • Tracheal tube introducer (bougie) when only partial visualization is possible 1

When Glottic Visualization is Difficult

If the glottic opening cannot be visualized (Cormack-Lehane grade 3b or 4):

• Avoid blind attempts: The success rate of blind insertion is low and the risk of airway trauma is high 1
• Consider epiglottis lifting: When only the epiglottis is visible, using a stylet to lift the epiglottis can significantly improve intubation success 2
• Switch to alternative approach: After two failed attempts, consider implementing a secondary intubation plan such as using a supraglottic airway device as a conduit for intubation 1

Verification of Tube Placement

After intubation, a two-point check should be performed:

1. Visual confirmation: Direct visualization of the tube passing through the vocal cords
2. Capnography: A sustained capnographic trace is the most reliable method of confirming tracheal intubation 1

Common Pitfalls to Avoid

• Excessive force: Applying too much force during laryngoscopy can cause dental or soft tissue damage
• Multiple attempts: Limit direct laryngoscopy attempts to avoid trauma and development of a "can't ventilate" situation 1
• Ignoring the epiglottis: When the vocal cords cannot be visualized, the epiglottis becomes an important landmark to guide tube placement 2
• Relying solely on capnography: In spontaneously breathing patients, a capnographic trace may be seen even with supraglottic placement 1

By prioritizing visualization of the glottic opening during intubation, clinicians can maximize success rates while minimizing complications that directly impact patient morbidity and mortality.