Diffusion of nitrous oxide into the cuff of the endotracheal tube (ETT) results in an increase in cuff pressure. This method was used to test whether tracheal morbidity is related to fill the cuff of the endotracheal tube with alkalinized lidocaine instead of air or lidocaine only.

Adult patients scheduled for total thyroidectomy surgery were randomly enrolled (n = 30 for each group). The ETT cuff was filled with air 6 ml (Group C), with 2% lidocaine 6 ml (Group L), or with alkalinized lidocaine (4 ml or 2 ml of 2% lidocaine) using 2 ml (Group A) or 4 ml (Group B) of 8.4% NaHCO₃. After tracheal extubation, sore throat was evaluated by visual analog scale as the main end-point of the study.

Compared with group air or lidocaine only, the alkalinized-lidocaine groups had a significant reduction in sore throat during the 24-h postoperative period (P < 0.001). The difference was not significant between the two alkalinized lidocaine groups. Cough before tracheal extubation, nausea, postoperative vomiting, dysphonia, and hoarseness after extubation were decreased in the alkalinized-lidocaine groups compared with Group C and L, and a better tolerance was recorded with alkalinized-lidocaine groups compared with Group C and L.

We concluded that use of intracuff alkalinized lidocaine is an effective adjunct to endotracheal intubation instead of air or lidocaine only during nitrous oxide anesthesia, however there were no differences between two alkalinizations.