Comparison of 40 and 100 mg of laryngotracheal lidocaine instillation to prevent cough during emergence from general anesthesia: A randomized controlled trial

Abstract

BackgroundPrevious studies have found that laryngotracheal instillation of 100–160 mg of lidocaine could alleviate cough. The objective of this study was to examine whether a smaller dosage (40 mg) of lidocaine can produce a noninferior result compared with the usual dosage. MethodThis study included 275 patients aged 18–60 years with an American Society of Anesthesiologists class I-III who were undergoing elective surgery under general anesthesia with a tracheal tube. All patients were randomly divided into two groups. Two milliliters of 2% lidocaine (40 mg) diluted with 3 ml of sterile water to make up a 5-ml solution for the L40 group was prepared to be identical with a 5-ml solution of 2% lidocaine (100 mg) for the L100 group. The 5-ml solutions were divided into halves and injected using 3-ml syringes through each of the two ports of a laryngotracheal instillation of the topical anesthesia tube at the end of surgical closure. The severity of cough and complications during extubation and stay in the postanesthetic care unit were recorded. ResultsA total of 275 patients were enrolled, and five patients were excluded. The incidence of total cough was significantly higher in the L40 group (71.1%) than in the L100 group (52.6%) (P = 0.003). However, the incidence of cough grades 1 and 2 was comparable between the two groups (75.6% and 76.8%, respectively; P = 0.464). Sore throat and swallowing difficulty were common complications, but there were no statistical differences. ConclusionThe incidence of cough with lidocaine 40 mg administered intratracheally was significantly higher than that with lidocaine 100 mg during extubation. Thai Clinical Trial Registry numberTCTR 20200811001 (www.thaiclinicaltrials.org).