Lidocaine, an amino-amide local anesthetic, effectively reduces opioid requirements and their associated side effects due to its significant analgesic properties. Recommended dosing begins with a loading dose of 1-2 mg/kg, followed by a continuous infusion rate of 1-2 mg/kg/hr, which should be halved every 6 hours. Its use in abdominal surgeries has been linked to reduced ileus and postoperative nausea and vomiting (PONV), demonstrating comparable efficacy to epidural local anesthetic delivery. Additionally, lidocaine may offer neuroprotective benefits, potentially mitigating early post-operative cognitive dysfunction, and is also effective in treating neuropathic pain.
Given its hepatic metabolism, lidocaine infusion rates must be adjusted in cases of low cardiac output to avoid toxicity. Notable side effects include perioral paresthesia, metallic taste, tinnitus, and the risk of seizures. Toxicity under anesthesia might only present as bradycardia and wide QRS complexes, with potential for cardiac arrest at extreme plasma levels above 5 mcg/ml. A standard regimen leading to a plasma concentration of approximately 2 mcg/ml involves a bolus dose of 1 mg/kg followed by an infusion of 1.5 mg/kg/hr, thus incorporating a margin of safety.
For cases of suspected local anesthetic systemic toxicity, the recommended treatment involves an initial bolus of 1.5 ml/kg of intralipid, followed by an infusion of 0.25 ml/kg/min. IV lidocaine infusions have demonstrated benefits such as decreased opioid consumption, reduced postoperative pain, shortened hospital stays, and earlier return of bowel function in open abdominal procedures. This has raised questions about the necessity of epidural infusions of local anesthetics in some surgical contexts. Despite findings from Terwaki et al. suggesting IV lidocaine infusion might be less effective than epidural analgesia in reducing opioid use in major abdominal surgery, lidocaine is associated with significant improvements in various recovery aspects, supporting its value in perioperative pain management strategies.
