Absorption of lidocaine during aspiration anesthesia of the airway

Study Objective: To determine the optimal solution to use when anesthetizin g the airway by aspiration of lidocaine. Design: Randomized, double-blind clinical study. Setting: University hospital. Patients: 96 adult ASA physical status 1,II, and III patients, scheduled fo r diagnostic flexible bronchoscopy. Interventions: Patients were randomized to receive one of 5 solutions of li docaine: Group A (n = 16): 1 % lidocaine, 0.2 mL . kg(-1); Group B (n = 16) : 1.5 % 0.2 mL . kg(-1) Group C (n = 32): 2 % 0.2 mL . kg(-1); Group D (n = 16): 1 % 0.3 mL . kg(-1), and Group E (n = 16): 2 % 0.3 mL . kg(-1). Fiber optic bronchoscopy was Pe formed after the airway was anesthetized with thi s aspiration technique, using the assigned lidocaine solution. The scope wa s manipulated in the trachea to test for anesthesia. Measurements and Main Results: Successful airway anesthesia was determined by tolerance to bronchoscopy without sustained coughing, and also by the nu mber of lidocaine supplements, if any, that were given via the bronchoscope . Arterial plasma concentrations of lidocaine were measured in 33 patients from Groups C, A and E. All solutions provided equally effective anesthesia of the airway. All patients tolerated endoscopy through the vocal cords, a nd 94 patients required no supplementary anesthesia, or only one dose of li docaine, during bronchoscopy to the carina. The highest peak plasma concent rations of lidocaine were. 5.02 and 6.28 mug . mL. No patient had signs of toxicity. Conclusions: This technique produced anesthesia of the airway to the carina , safely, suitable for awake intubation, in 94 of 95 patients. The use of 1 % lidocaine, 0.2 to mL . kg(-1), so that the volume is 10 to 20 mL, is rec ommended. (C) 2001 by Elsevier Science Inc.