Lidocaine reduces endotracheal tube associated side effects when instilled over the glottis but not when used to inflate the cuff: A double blind, placebo-controlled, randomized trial.

BACKGROUND: Tracheal intubation results in an alteration of the laryngeal mucosa which can lead to undesirable effects at emergence from anaesthesia. Local anesthetics, when administered topically, may represent an interesting alternative to reduce these side effects.

AIM: In this trial, we aimed to evaluate the effect of lidocaine in preventing tracheal intubation related side effects at emergence from anaesthesia, when instilled onto the glottis before intubation or used to inflate the endotracheal tube cuff.

METHODS: Eighty patients scheduled to elective surgery of less than 120 minutes under general anaesthesia were enrolled in this prospective, randomized, controlled, double blind study. As they receive instillation of 2% lidocaine or saline onto the glottis before intubation, and as they have their endotracheal tube cuff filled with 2% lidocaine or saline, the patients were randomized in four groups. S-S (Saline instillation and saline in the cuff); S-Lido (saline instillation and lidocaine in the cuff); Lido-S (lidocaine instillation and saline in the cuff); Lido-Lido (lidocaine instillation and lidocaine in the cuff). The primary outcome was the incidence of coughing before extubation. The secondary outcomes were sore throat scores at H1 and H24 postoperatively and incidence of dysphagia, dysphonia and laryngeal dyspnea during the first 24 hours.

RESULTS: Coughing occurred in 80%, 70%, 30% and 20% of patients in S-S, S-Lido, Lido-S and Lido-Lido groups respectively. When compared to S-S group, the incidence of coughing was significantly reduced in Lido-S and Lido-Lido groups but not in S-Lido group (p1=0.003; p2=0.0003; p3=0.7 respectively). Sore throat scores at H1 and H24 were significantly lower in Lido-S and Lido-Lido groups (p1=0.00002 and p2=0.01). There was no significant difference between groups regarding the incidence of dysphagia, dysphonia and laryngeal dyspnea.

CONCLUSION: When instilled onto the glottis before intubation, lidocaine reduced both the incidence of coughing and the severity of postoperative sore throat in surgery of less than 120 minutes. Intracuff lidocaine was not effective to reduce neither coughing nor sore throat severity.