What is the use of Lidocaine (Lignocaine)?

From the Guidelines

Lignocaine is recommended as a first-line treatment for ventricular tachycardia (VT) at a dose of 1–3 mg/kg intravenously, with a maximum bolus dose of 100 mg, and a maintenance infusion of 2–4 mg/min, as supported by the most recent and highest quality study 1. When considering the use of lignocaine, it is essential to weigh the benefits against the potential risks, particularly in patients with existing comorbidities. The study published in 2021 1 provides guidelines for the safe use of intravenous lidocaine, including the recommendation to use ideal body weight for dose calculation and to avoid using it in patients weighing less than 40 kg.

Key Considerations

• Lignocaine is a Class Ib antiarrhythmic drug, effective in treating ventricular arrhythmias, but it has no effect on supraventricular tachycardia (SVT) 1.
• The medication can depress myocardial contractility, and toxic levels can produce paraesthesia, drowsiness, muscular twitching, or seizure 1.
• For postoperative pain and recovery, intravenous lidocaine should be used with caution, following the recommended dosing guidelines, and with careful monitoring for signs of toxicity 1.

Administration and Monitoring

• A loading dose of no more than 1.5 mg/kg-1, given as an infusion over 10 min, is recommended, followed by an infusion of no more than 1.5 mg/kg-1.h-1, for no longer than 24 h 1.
• Patients receiving intravenous lignocaine should be managed in a monitored bedspace in a high dependency unit (level 2 care), with particular vigilance in patients with existing comorbidity 1.
• Lipid emulsion 20% should be readily available wherever intravenous lignocaine is used, and staff should know where it is kept, in case of toxicity 1.

From the FDA Drug Label

The safety and effectiveness of lidocaine depend on proper dosage, correct technique, adequate precautions, and readiness for emergencies. The lowest dosage that results in effective anesthesia should be used to avoid high plasma levels and serious adverse effects. Repeated doses of lidocaine may cause significant increases in blood levels with each repeated dose, because of slow accumulation of the drug or its metabolites. Debilitated, elderly patients, acutely ill patients, and children should be given reduced doses commensurate with their age and physical status. Lidocaine should also be used with caution in patients with severe shock or heart block Local anesthetic solutions containing a vasoconstrictor should be used cautiously and in carefully circumscribed quantities in areas of the body supplied by end arteries or having otherwise compromised blood supply. Patients with peripheral vascular disease and those with hypertensive vascular disease may exhibit exaggerated vasoconstrictor response. Ischemic injury or necrosis may result Preparations containing a vasoconstrictor should be used with caution in patients during or following the administration of potent general anesthetic agents, since cardiac arrhythmias may occur under such conditions Careful and constant monitoring of cardiovascular and respiratory (adequacy of ventilation) vital signs and the patient's state of consciousness should be accomplished after each local anesthetic injection It should be kept in mind at such times that restlessness, anxiety, tinnitus, dizziness, blurred vision, tremors, depression or drowsiness may be early warning signs of central nervous system toxicity. Since amide-type local anesthetics are metabolized by the liver, lidocaine should be used with caution in patients with hepatic disease Patients with severe hepatic disease, because of their inability to metabolize local anesthetic normally, are at a greater risk of developing toxic plasma concentrations Lidocaine should also be used with caution in patients with impaired cardiovascular function since they may be less able to compensate for functional changes associated with the prolongation of A-V conduction produced by these drugs

The main uses and precautions of lignocaine (lidocaine) are:

• Proper dosage and technique are crucial for safe and effective use
• Caution is advised in patients with severe shock, heart block, peripheral vascular disease, hypertensive vascular disease, hepatic disease, and impaired cardiovascular function
• Monitoring of cardiovascular and respiratory vital signs and the patient's state of consciousness is necessary after each injection
• Early warning signs of central nervous system toxicity include restlessness, anxiety, tinnitus, dizziness, blurred vision, tremors, depression, or drowsiness
• Reduced doses are recommended for debilitated, elderly, acutely ill, and child patients 2

From the Research

Lignocaine Overview

• Lignocaine, also known as lidocaine, is a local anaesthetic and antiarrhythmic drug 3.
• It is commonly used to prevent ventricular fibrillation in patients with acute myocardial infarction, although its efficacy is still debated 3.
• Lignocaine is eliminated primarily by hepatic metabolism and its clearance can be affected by disease states such as cardiac failure or liver disease 3.

Administration and Dosage

• The administration of lignocaine as a local anaesthetic may result in blood lignocaine concentrations in the antiarrhythmic or even toxic ranges 3.
• The recommended dosage for a healthy adult patient is four and a half 2 ml (or 2.2-ml) cartridges of lignocaine with adrenaline (180-198 mg lignocaine or 2.57-2.82 mg/kg body weight) 4.
• For medically compromised patients, minimal doses of lignocaine and adrenaline should be used, and especial caution is necessary in patients likely to react adversely to the exogenous adrenaline of the dual formulation 4.

Antiarrhythmic Effects

• Lignocaine is classified as a class Ib anti-arrhythmic that blocks voltage- and pH-dependent sodium channels, exhibiting well-investigated anti-arrhythmic effects 5.
• It increases the ventricular fibrillatory threshold and can interrupt life-threatening tachycardias caused by re-entrant mechanisms, especially in ischemic tissue 5.
• Lignocaine has come back into focus for the treatment of acute sustained ventricular tachyarrhythmias 5.

Side Effects and Toxicity

• Lignocaine toxicity can occur, especially with high doses or in patients with liver disease, and may manifest as neurologic manifestations, including altered mental status and seizure 6.
• Subcutaneous lidocaine administration can contribute to the occurrence of asystole during permanent pacemaker implantation, and it is advisable to limit the amount of lidocaine administered to the minimum necessary to achieve adequate local anesthesia 7.