THE TECHNIQUE OF ENDOBRONCHIAL LIDOCAINE ADMINISTRATION DOES NOT INFLUENCE PLASMA-CONCENTRATION PROFILES AND PHARMACOKINETIC PARAMETERS IN HUMANS

This study investigated plasma concentration profiles, pharmacokinetic characteristics and side-effects of lidocaine following 3 different a dministration techniques. Sixty ASA I/II patients undergoing elective ENT-operations were randomised into 4 groups. Lidocaine 1% (I mg/kg) w as 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 R esuscitation)-tube characterized by a separate injection channel endin g at the orifice of the tube (group 3). For the control group, a regul ar endotracheal tube was inserted without lidocaine administration (gr oup 4). Anesthesia was induced with propofol (2 mg/kg), sufentanil (0. 5 mu g/kg), and vecuronium (0.08 mg/kg) and continued as total intrave nous 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 l idocaine administration. Lidocaine plasma concentrations were determin ed using a fluorescence polarization immunoassay (TDxFLx). Heart rate, blood pressure, endtidal PCO2, 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. Pa tients from group 3 were ventilated continuously because of a separate injection channel integrated in the EDGAR-tube. Sore throat was signi ficantly increased in group 2 as compared with groups 1, 3 and 4. Asor ption of lidocaine in groups 1-3 resulted in maximal mean plasma conce ntrations ranging from 0.78 to 0.85 mu g/ml after 16.9 to 22.4 min. Si gnificant differences in the plasma concentration profiles and pharmac okinetic parameters of lidocaine were not observed between groups 1-3. In conclusion, drug application via suction-catheter is more irritati ng, required the longest interruption of ventilation, and might be a p otential source of bacterial contamination. In contrast to previous re ports, application of lidocaine deep endobronchially has no advantage with respect to the plasma concentration profile and pharmacokinetic p arameters including reliability of prompt and complete systemic drug d elivery. Thus, deep endobronchial lidocaine administration using a suc tion-catheter or similar equipment might not be advantageous during re suscitation.