Plasma Lidocaine Level, Analgesic Effect and Side Effect during Intravenous Lidocaine Infusion for Chronic ain Management

Song, Sun Ok; Jeon, Dong Seok; Choi, Sae Young

Abstract

BACKGROUND: Lidocaine administered intravenously (IV lidocaine) is efficacious in the treatment of thic pain. There are many differences in doses and methods of IV lidocaine therapy. We have made a ous clinical report of IV lidocaine infusion for chronic pain patients. The aims of this study were to evaluate the plasma concentration of lidocaine, and the analgesic effect and safety of our method of IV idocaine infusion.
METHODS
Sixteen neuropathic pain patients received IV lidocaine infusion. Lidocaine of 5 mg/kg ixed in 150 ml of normal saline was infused over 40 min at a rate with 300 ml/h for the initial 10 min, and the remaining at 200 ml/h. Blood sampling, for the analysis of plasma lidocaine concentration, pain score by numerical rating scale, blood pressure and heart rate were obtained before the infusion and at 20, 40, 60, 90 and 120 min following the start of infusion.
RESULTS
Thirteen patients (81.3%) had analgesic effects in IV lidocaine infusion. Mean plasma caine concentrations were 0, 2.0, 2.7, 2.2, 1.5, 1.1 ug/ml, and mean pain scores were 7.6, 5.6, 3.7, 3.1, 3.0, and 3.1 before the infusion and at 20, 40, 60, 90 and 120 min following the start of infusion. Plasma aine over 2 microgram/ml revealed an analgesic effect, and pain scores precipitously dropped around 40 min following the start of infusion. There were no significant changes of blood pressure and heart rate. Side effects were mild in terms of sedation, dizziness, light-headedness, nausea and metallic taste.
CONCLUSIONS
These results suggest that our method of IV lidocaine infusion -within therapeutic nge of lidocaine not to allow toxic plasma concentration, and with any effective analgesia, little modynamic change and minimal side effects- is a useful and a safe diagnostic and therapeutic modality for hronic neuropathic pain.