LAUSR

Objectives For endovenous thermal ablation of the saphenous veins, tumescent lidocaine anesthesia is often used. Unfortunately, information is sparse on the pharmacokinetics of lidocaine absorption and its maximum safe dose. The aim of this study was to evaluate plasma concentration of lidocaine on 12 lead electrocardiograms (ECGs) and symptoms over time after the administration of tumescent lidocaine during endovenous thermal ablation procedures in healthy volunteers. Methods An observational study of symptoms, 12 lead ECGs, and serum lidocaine levels were obtained following the administration of either 15 mg/kg lidocaine or 35 mg/kg lidocaine in the perivenous saphenous space under ultrasound guidance. Blood was drawn at regular intervals in heparinized tubes and spun at 3000 r/min for 10 min. The plasma lidocaine levels were plotted vs. time for statistical comparisons. Results With the 35 mg/kg dose, four of 11 participants developed symptoms of lidocaine toxicity at 40 min, which resolved by 180 min. The 35 mg/kg dose resulted in a mean serum lidocaine peak of 2.55 µg/ml at 60 min. The 15 mg/kg dose did not result in any symptoms of lidocaine toxicity, and it resulted in a serum lidocaine plateau of 0.85 µg/ml at 180 min. No significant changes were seen on the 12-lead ECG after the administration of lidocaine at either dose. Conclusions The 15 mg/kg total lidocaine dose did not cause symptoms and appears to be a safe lidocaine dosage for tumescent anesthesia for saphenous endovenous thermal ablations. The 35 mg/kg lidocaine dose is associated with lidocaine toxicity. More study on the maximal safe dose of lidocaine for endovenous thermal ablations is needed.