What is the procedure for all nerve blocks in awake intubation?

Procedure for Nerve Blocks in Awake Intubation

For complete upper airway anesthesia during awake intubation, a combination of bilateral glossopharyngeal nerve blocks, bilateral superior laryngeal nerve blocks, and recurrent laryngeal nerve block should be performed, as this provides excellent intubating conditions with minimal patient discomfort. 1, 2

Pre-Procedure Preparation

• Use a cognitive aid or checklist before and during the procedure 1, 2
• Ensure all necessary equipment is readily available:
  • Flexible bronchoscope or videolaryngoscope
  • Local anesthetics (lidocaine preferred)
  • Oxygen delivery systems
  • Emergency airway equipment
  • Lipid emulsion (for local anesthetic toxicity)
• Calculate maximum lidocaine dose (not to exceed 9 mg/kg lean body weight) 1, 2
• Administer supplemental oxygen throughout the procedure 1

Topicalization and Block Sequence

1. Bilateral Glossopharyngeal Nerve Blocks:

   • Intraoral approach: Apply 2% lidocaine to the posterior tonsillar pillar
   • Use 2 ml of 2% lidocaine per side
   • This blocks sensation to the posterior third of tongue and oropharynx 3, 4

2. Bilateral Superior Laryngeal Nerve Blocks:

   • Identify the greater cornu of hyoid bone
   • Insert needle at the thyrohyoid membrane
   • Inject 2 ml of 2% lidocaine per side
   • This blocks sensation to the base of tongue, epiglottis, and larynx above the vocal cords 3, 4

3. Recurrent Laryngeal Nerve Block (Transtracheal):

   • Insert needle through cricothyroid membrane
   • Aspirate air to confirm position
   • Inject 3-4 ml of 4% lidocaine
   • This blocks sensation below the vocal cords 3, 4

4. Test adequacy of topicalization before airway instrumentation using a soft suction catheter or Yankauer sucker 1

Performance of Awake Intubation

1. Allow 5-10 minutes for blocks to take full effect
2. Proceed with awake intubation using flexible bronchoscope or videolaryngoscope
3. Limit attempts to three, with one further attempt by a more experienced operator (3+1 rule) 1, 2
4. Perform a two-point check to confirm correct tube placement:
   • Visual confirmation of tracheal placement
   • Capnography to exclude esophageal intubation 1
5. Identify the carina before advancing the tube to minimize risk of misplacement 1
6. Only induce anesthesia after confirming correct tube position 1

Monitoring and Safety Considerations

• Monitor for signs of local anesthetic systemic toxicity:
  • Lightheadedness, perioral numbness, tinnitus
  • Seizures, cardiovascular collapse
• Maximum lidocaine dose should not exceed 9 mg/kg lean body weight 1
• Avoid cocaine due to potential cardiovascular complications; use phenylephrine with lidocaine for nasal routes 1, 2
• Monitor oxygen saturation continuously 1, 2
• Consider minimal sedation administered by an independent practitioner, but do not substitute for inadequate topicalization 1

Comparative Efficacy of Nerve Blocks vs. Other Methods

Research demonstrates that nerve blocks provide superior conditions compared to atomized or nebulized lidocaine:

• Significantly faster intubation times (63.8±7.9 seconds vs. 184.9±13.4 seconds) 5
• Better patient comfort and fewer coughing/gagging episodes 5, 6
• More stable hemodynamics and fewer episodes of desaturation 5, 6
• Lower total lidocaine dose required (349 mg vs. 815 mg) 7

Post-Procedure Considerations

• Patients should remain nil by mouth for at least 2 hours following airway topicalization due to prolonged effect on laryngeal reflexes 1
• Document the technique used, including:
  • Oxygenation method
  • Topicalization technique and doses
  • Sedation strategy (if used)
  • Device and tube used
  • Number of attempts 1

Common Pitfalls and Caveats

• Do not exceed the maximum lidocaine dose (9 mg/kg lean body weight)
• Consider the total dose of all local anesthetics administered, regardless of route
• Invasive nerve block techniques should be reserved for those with expertise in their performance 1
• Sedation should not substitute for inadequate topicalization 1
• For patients with difficult landmarks, ultrasound can assist with nerve block placement 3
• Have lipid emulsion available in case of local anesthetic toxicity 1, 2

The evidence strongly supports that nerve blocks provide faster intubation times, better patient comfort, and more stable hemodynamics compared to other topicalization methods for awake intubation, particularly in patients with difficult airways.