A Study on Lidocaine Pharmacokinetic Behavior Following Endotracheal Administration in ICU

The endotracheal route for drug delivery is a valuable alternative in emergency conditions in which intravenous access is difficult or impossible. Liodcaine is an antiarrhythmic agent with tracheal absorbency, commonly used in cardiac emergenices.

The purpose of this study was to investigate Lidocaine pharmacokinetic behavior following endotracheal administration in critically ill patients.

14 mechanically ventilated critically ill patients received 2mg/kg lidocaine 2% (diluted as necessary with 0.9% Saline up to total volume of 5-10 ml) via an endotracheal tube. Five positive pressure breaths were provided immediately after instillation of the drug into the airway and then patients connected to the ventillator again. Venous blood samples were drawn for 4 hours after lidocaine administration and plasma concentrations determined by HPLC method.

After 5 min, average lidocaine concentrations reached the therapeutic range (1.5-5 μg/ml) and remained in this range for 30 minutes. Volume of distribution (Vd) was found to be 0.7 ± 0.3 L/Kg, and clearance (Cl) 4.29 ± 1.4 ml/min /kg. These valuse are lower than those described previously for healthy volunteers (P< 0.001), but similar to those described in ICU patients (P > 0.05). Half life was 113.1 ± 34.1 min and was not different from parameters published previously for healthy and ICU patients (P > 0.05).

In conclusion, endotracheal administration of Lidocaine can provide therapeutic levels in critically ill patients.It is not definitely clear that the technique of endotracheal drug administration or the unstable physiologic condition of the patients alters the pharmacokinetics of lidocaine.