Prevention of coughing induced by endotracheal tube during emergence from general anesthesia--a comparison between three different regimens of lidocaine filled in the endotracheal tube cuff

Abstract

Background: "Deep" extubation, administration of intravenous (i.v.) narcotics, i.v. lidocaine and forestalling local spray of lidocaine have been used to help diminish coughing during emergence. However, the respective efficacy of these techniques has not been concluded. Sconzo et al. indicated that endotracheal tube (ETT) cuff might serve as a reservoir for local anesthetic. Alkalizing and warming are two techniques frequently used to increase in the proportion of uncharged drugs available. Matias indicated that alkalization could prompt a 63-fold increase of the rate of diffusion of lidocaine across the ETT cuff. Huang et al. also observed that alkalization together with warming could achieve a 118-fold increase further. However, the in vivo effects of ETT-cuff lidocaine have not been studied.

Methods: Eighty patients of ASA Class I-II undergoing elective surgeries were included. They were randomly assigned into four groups. After tracheal intubation, the ETT cuff was filled with one of the following solutions: normal saline 6 ml (Group A), 4% lidocaine 6 ml at room temperature (Group B), 4% lidocaine 5 ml + 7% sodium bicarbonate 1 ml at room temperature (Group C), and 4% lidocaine 5 ml + 7% sodium bicarbonate 1 ml warmed to 38 degrees C (Group D). Changes of vital signs as well as the times of coughing in the course of extubation and post-extubation complications were recorded. One way ANOVA (SPSS for windows) was used for data analysis.

Results: The respective number of coughing per patient in the experimental groups (Group B, C and D) was significantly less than the saline or control group (mean = 9.70, 9.15 and 3.95, respectively, p < 0.05). The incidence of sore throat in Group C and Group D was significantly less than the control group (35% and 25%, respectively, p < 0.05). Regarding the hemodynamic changes, systolic arterial pressure (SAP) and mean arterial pressure (MAP) were higher in Group B and C (p < 0.05) before extubation.

Conclusions: Alkalized and warmed lidocaine prestored in the endotracheal tube (ETT) cuff can greatly reduce ETT-induced coughing and thus promote a smoother emergence from general anesthesia with endotracheal intubation.