The technique of endobronchial lidocaine administration does not influence plasma concentration profiles and pharmacokinetic parameters in humans

Abstract

This study investigated plasma concentration profiles, pharmacokinetic characteristics and side-effects of lidocaine following 3 different administration techniques. Sixty ASA I/II patients undergoing elective ENT-operations were randomised into 4 groups. Lidocaine 1% (1 mg/kg) was administered 50 min before the end of the operation, via a regular endotracheal tube (group 1), a suction-catheter deep endobronchially (group 2), or an EDGAR-(Endobronchial Drug and Gas Application during Resuscitation)-tube characterized by a separate injection channel ending at the orifice of the tube (group 3). For the control group, a regular endotracheal tube was inserted without lidocaine administration (group 4). Anesthesia was induced with propofol (2 mg/kg), sufentanil (0.5 μg/kg), and vecuronium (0.08 mg/kg) and continued as total intravenous anesthesia with propofol (8 mg/kg/h) and oxygen in air (FiO 2 = 0.33). A control and 13 blood samples were taken up to 180 min after lidocaine administration. Lidocaine plasma concentrations were determined using a fluorescence polarization immunoassay (TDxFLx). Heart rate, blood pressure, endtidal Pco 2, and oxygen saturation were similar in all groups investigated. Ventilation was interrupted for 3.6 ± 0.5 s in group 1 and 10.2 ± 0.8 s in group 2, to administer lidocaine. Patients from group 3 were ventilated continuously because of a separate injection channel integrated in the EDGAR-tube. Sore throat was significantly increased in group 2 as compared with groups 1, 3 and 4. Asorption of lidocaine in groups 1–3 resulted in maximal mean plasma concentrations ranging from 0.78 to 0.85 μg/ml after 16.9 to 22.4 min. Significant differences in the plasma concentration profiles and pharmacokinetic parameters of lidocaine were not observed between groups 1–3. In conclusion, drug application via suction-catheter is more irritating, required the longest interruption of ventilation, and might be a potential source of bacterial contamination. In contrast to previous reports, application of lidocaine deep endobronchially has no advantage with respect to the plasma concentration profile and pharmacokinetic parameters including reliability of prompt and complete systemic drug delivery. Thus, deep endobronchial lidocaine administration using a suction-catheter or similar equipment might not be advantageous during resuscitation.