Intravenous Lidocaine Infusion for the Management of Early Postoperative Pain: A Comprehensive Review of Controlled Trials.

Previously used as anti-arrhythmic, intravenous lidocaine infusion is becoming popular for use in management of acute pain. There is still much to be understood about its pharmacokinetics and pharmacodynamics, especially with regard to optimal dosing to avoid side effects. In this article, we selected and reviewed randomized controlled trials to summarize the pharmacokinetics, antinociceptive effects, anti-hyperalgesic effects, anti-inflammatory effects, side effects, and role of intravenous lidocaine in the management of early postoperative pain. The mechanisms of action of lidocaine are still unclear but there are many theories postulated. Optimal dosing of lidocaine is not known but general consensus indicates that a loading dose of 1-2 mg/kg, followed by 1-2 mg/kg/hr continuous infusion during early postoperative pain control while recovering from anesthesia to achieve therapeutic levels of 0.5-5 mcg/kg clearly improves analgesia in the immediate postoperative period. Although lidocaine was initially studied and proven to have clear analgesic effects following laparoscopic and open abdominal surgeries, it has now been shown to be applicable in different clinical settings perioperatively including following spinal, breast, ENT and other surgeries. It is generally safe, with hypotension, headache and vomiting being the more common side effects. Serious adverse effects include cardiovascular block and arrhythmias, neuro-excitability and hypersensitivity, although the frequency of these are not known.