Nebulization with differently sized 2% lidocaine atomized particles in awake tracheal intubation by video laryngoscopy: a proof-of-concept randomized trial.

Background: Optimization of the individual topicalization technique during awake tracheal intubation (ATI) is critical, but how to accomplish this is still unknown. We hypothesized that there would be a difference between nebulization with different sizes of 2% lidocaine atomized particles in ATI by video laryngoscopy.

Methods: A total of 230 patients scheduled for ATI were recruited from September 2024 through January 2025. Forty-six participants were excluded, and 184 participants were randomly assigned to 4 treatment groups according to the size of the atomized particles of 2% lidocaine: A3 (3-4 μm), A6 (6-7 μm), A9 (9-10 μm), or A11 (11-12 μm).

Results: There were statistically significant differences among the four groups. Post hoc analysis using Dunnett test showed that, compared with the A3 group, the A9 group had greater feelings of comfort (cough score: P = 0.005; reaction score: P = 0.024; discomfort score: P = 0.003). the A9 group had lower heart rates at endotracheal tube insertion(P = 0.015), at inflation of the tracheal tube cuff (P = 0.001) and 1 min after endotracheal tube insertion(P = 0.009); The A9 group had fewer applications of the airway spray and fewer times the patient vomited (P<0.001), but exhibited a longer nebulization time (P<0.0001).

Conclusion: In conclusion, we demonstrated that there were differences between nebulization with different sizes of 2% lidocaine atomized particles in ATI. In addition, 2% lidocaine administered via a nebulizer with 9-10-µm atomized particles performed better during ATI. Therefore, we recommend a nebulizer and the 9-10-µm particle-size range for patients who need ATI.

Trial registration: Clinicaltrials.gov, NCT06420947. Date of Registration: May 12th, 2024.