A comparison of the endotracheal tube and the laryngeal mask airway as a route for endobronchial lidocaine administration.

Abstract

Drug administration via the endotracheal tube is recommended as a second-line approach in emergency settings such as cardiac arrest. It is unknown what amount of drugs are absorbed when they are given through the laryngeal mask airway as compared with the endotracheal tube. We administered lidocaine at a dose of 2 mg/kg diluted in 10 mL normal saline to 20 anesthetized patients undergoing routine surgical procedures. Ten patients received lidocaine into the endotracheal tube and 10 patients received lidocaine into the laryngeal mask airway. Blood samples were taken for measurement of lidocaine plasma concentrations, and the pharmacokinetics were calculated. Therapeutic plasma concentrations (>1.4 microg/mL) could be achieved in 10 of 10 patients after endotracheal tube instillation but in only 4 of 10 patients after laryngeal mask instillation (P < 0.05). Peak lidocaine concentrations (2.47 and 1.09 microg/mL) (P < 0.05) and the area under the time versus plasma concentration curve (117.7 and 91.2 microg x min x mL(-1)) (P < 0.05) were higher after lidocaine administration into the endotracheal tube than into the laryngeal mask airway. In conclusion, the laryngeal mask airway is not a reliable route for the recommended dose of endobronchial lidocaine administration compared with the endotracheal tube.