What is the recommended technique and dosage for using nebulized lidocaine in awake intubation?

Nebulized Lidocaine for Awake Intubation

For awake intubation in adults, use nebulized lidocaine 4% at a dose of 200 mg (5 mL) combined with spray-as-you-go technique, ensuring the total topical dose does not exceed 9 mg/kg lean body weight. 1

Recommended Technique

Nebulization Protocol

• Administer 200 mg of 4% lidocaine via nebulizer using oxygen at 10 L/min as the driving gas through a standard mouthpiece 2
• Allow 15 minutes for nebulization to achieve adequate mucosal anesthesia 3
• Nebulization alone produces very low plasma concentrations (mean peak 0.29 mg/L at 30 minutes), well below the toxic threshold of 5 mg/L 4

Supplemental Topicalization

• Combine nebulization with spray-as-you-go technique for optimal conditions 2
• Apply supplemental lidocaine directly to the vocal cords and trachea via the fiberoptic bronchoscope working channel as needed 2
• The combination approach provides superior airway anesthesia compared to nebulization alone 5

Concentration Selection

• Use 2% lidocaine for atomized/spray applications rather than 1%, as 2% provides superior intubating conditions with better patient tolerance and shorter procedural times 6
• Lower concentrations (1%) are equally effective as higher concentrations (2%) for cough suppression during bronchoscopy, but for awake intubation specifically, 2% atomized lidocaine demonstrates better efficacy 5, 6
• 4% lidocaine is appropriate for nebulization and has been shown to provide better patient comfort than 2% nebulized lidocaine (Puchner scale 1.30 vs 2.23) 7

Maximum Dosing Limits

Adult Dosing

• Maximum total topical dose: 9 mg/kg lean body weight 1
• The Difficult Airway Society guidelines explicitly recommend up to 9 mg/kg based on lean body weight for awake tracheal intubation 1
• British Thoracic Society data supports doses up to 15.4 mg/kg without serious adverse events, though subjective toxicity symptoms (dizziness, euphoria) occurred at ≥9.6 mg/kg 5
• Cardiac and neurological toxicity typically occurs when serum levels exceed 5 mg/L or topical doses exceed 7 mg/kg 5

Pediatric Dosing (if applicable)

• Maximum dose: 5 mg/kg ideal body weight for procedures up to 2 hours 8
• Reduce to 4 mg/kg ideal body weight in infants <6 months, underweight children, or those with hepatic disease 8
• Use 1% or 2% solutions in children <10 kg to provide adequate volume 8
• Never use concentrations >4% in children 8

Safety Considerations

Monitoring for Toxicity

• Early warning signs include: circumoral numbness, facial tingling, metallic taste, dizziness, and euphoria 5
• These symptoms should prompt immediate cessation of further lidocaine administration 5
• Patients require observation for 30-60 minutes post-topicalization, as systemic absorption may manifest later 8

Special Populations Requiring Caution

• Patients with congestive heart failure have increased risk of cardiac toxicity 5
• Hepatic dysfunction impairs lidocaine metabolism and prolongs elimination half-life 8
• Infants <6 months have immature hepatic enzymes and require dose reduction 8

Documentation and Preparation

• Document total lidocaine dose clearly in the patient record 8
• Pre-operative team brief is essential when both anesthetist and surgeon plan to use lidocaine to avoid cumulative overdose 8
• 20% intravenous lipid emulsion must be immediately available in all locations where lidocaine topicalization occurs 8

Post-Procedure Management

Recovery Protocols

• Patients should fast for at least 1 hour after airway topicalization 8
• Extend fasting time if the patient is at significant aspiration risk 8
• Duration of lidocaine action is approximately 30-60 minutes, though oral mucosal effects may resolve in <15 minutes 8
• Patients should be nursed in recovery by appropriate practitioners who are aware of signs of aspiration and local anesthetic systemic toxicity 8

Common Pitfalls to Avoid

• Do not use lidocaine solutions with vasoconstrictors (e.g., epinephrine/adrenaline) for airway topicalization in children due to risk of hypertensive crises and cardiac arrest 8
• Avoid using sedation as a substitute for inadequate topicalization—effective airway anesthesia must be established first 1
• Do not exceed three intubation attempts (plus one by a more experienced operator) even with adequate topicalization 1
• Never induce general anesthesia until tracheal tube position is confirmed by both visual confirmation and capnography 1