Is a block important for awake intubation?

Airway Blocks for Awake Intubation

Effective airway blocks are essential for successful awake intubation as they provide superior intubating conditions with minimal patient discomfort and faster intubation times compared to topical anesthesia alone. 1, 2

Importance of Airway Blocks in Awake Tracheal Intubation (ATI)

Airway blocks offer several advantages during awake intubation:

• Superior anesthesia: Nerve blocks provide more complete and reliable airway anesthesia compared to topical methods alone 2
• Faster intubation: Significantly reduced intubation time (90.2±11.7 seconds with nerve blocks vs. 210.4±10.6 seconds with atomized local anesthesia) 2
• Reduced patient discomfort: Fewer coughing and gagging episodes during the procedure 2
• Hemodynamic stability: Minimal increases in hemodynamic parameters during and after the procedure 1

Recommended Airway Blocks

For complete upper airway anesthesia during awake intubation, the Difficult Airway Society recommends a combination of:

1. Bilateral glossopharyngeal nerve blocks
2. Bilateral superior laryngeal nerve blocks
3. Recurrent laryngeal nerve block (transtracheal injection) 3

Technical Considerations

While the Difficult Airway Society acknowledges that blocks can be associated with higher technical difficulty and potential complications, they note that "in experienced hands, they can provide excellent intubating conditions" 3. Key points:

• Maximum lidocaine dose: Should not exceed 9 mg/kg lean body weight 3
• Vasoconstriction: Phenylephrine 0.5% combined with lidocaine is recommended for nasal routes to reduce epistaxis 3, 4
• Avoid cocaine: Due to potential toxic cardiovascular complications 3, 4
• Consider ultrasound guidance: Particularly helpful in patients with difficult landmarks 5

Comparison with Topical Anesthesia

Research clearly demonstrates the superiority of nerve blocks over topical anesthesia alone:

• Patient comfort: 90% of patients receiving combined nerve blocks report favorable comfort grades 1
• Success rate: Higher first-attempt success rates with nerve blocks 2
• Intubation quality: Better visualization and ease of intubation 6

Practical Approach to Airway Blocks

1. Preparation:

   • Assemble all equipment including nerve block needles, lidocaine, and emergency airway equipment
   • Position patient appropriately (typically head-up position)
   • Provide supplemental oxygen throughout the procedure 3, 4

2. Block sequence:

   • Begin with bilateral glossopharyngeal nerve blocks
   • Proceed to bilateral superior laryngeal nerve blocks
   • Complete with transtracheal (recurrent laryngeal) block 5

3. Verification of adequate topicalization:

   • Test adequacy with an atraumatic instrument (e.g., soft suction catheter) before airway instrumentation 3
   • Proceed with intubation only when patient demonstrates tolerance

Safety Considerations

• Limit attempts: Follow the 3+1 rule (three attempts by initial operator, one by more experienced operator) 3, 4
• Monitor for toxicity: Watch for signs of local anesthetic systemic toxicity and have lipid emulsion available 3
• Maintain oxygenation: Continuous oxygen supplementation is mandatory 3, 4
• Emergency equipment: Have difficult airway equipment immediately available 3

Pitfalls and Caveats

• Risk of over-sedation: Sedation should be used cautiously and not as a substitute for inadequate topicalization 4
• Anatomical variations: Superior laryngeal and glossopharyngeal nerves may have variable locations 5
• Post-procedure monitoring: Patients should remain nil by mouth for at least 2 hours following airway topicalization due to the prolonged effect on laryngeal reflexes 3
• Documentation: Thorough documentation of the technique used is essential for future airway management 3

While some experts may prefer pure topical methods with "spray as you go" techniques 7, the evidence strongly supports the use of combined regional nerve blocks for optimal conditions during awake intubation, particularly in cases of anticipated difficult airways 1, 2.