Local Anesthetic Toxicity (LAST)

 

 

Signs & Symptoms

 

  • Tinnitus, metalic taste, circumoral numbess

  • Altered mental status

  • Seizures

  • Hypotension

  • Bradycardia

  • Ventricular arrhythmias

  • Cardiovascular collapse

 

 

Management

 

  • Stop local anesthetic injection &/or infusion

  • Call for help

  • Initial focus:

    • Airway management: ensure adequate ventilation & oxygenation; 100% FiO2, consider ETT, prevent hypoxia & acidosis (aggravate LAST)

    • Seizure suppression: benzodiazepines preferred, avoid/minimize propofol if hemodynamically unstable; if seizures persist, small doses of succinylcholine to minimize acidosis & hypoxia

    • Alert nearest facility having cardiopulmonary bypass capability

  • Management of cardiac arrhythmias:

    • If pulseless, start CPR

    • ACLS will require adjustment of medications & perhaps prolonged effort

    • Epinephrine doses <1 mcg/kg (small boluses of 10-100 mcg IV)

    • Avoid vasopressin, calcium channel blockers, beta blockers, & local anesthetics

    • If ventricular arrhythmias occur, amiodarone is preferred; avoid lidocaine & procainamide

    • If refractory to treatment, consider cardiopulmonary bypass

  • Lipid emulsion (20%) therapy:

    • Rapidly administer at the first signs of LAST 1.5ml/kg bolus (70kg = 105ml) over 1 minute, then start infusion at 0.25mL/kg/min

    • Repeat bolus once or twice for persistent cardiovascular collapse 

    • May ↑ infusion rate (max 0.5mL/kg/min) if BP remains low

    • Continue infusion for at least 10 minutes after attaining circulatory stability

    • Recommended upper limit 10mL/kg over the first 30 minutes

    • Propofol is not a substitute for lipid emulsion

  • Failure to respond to lipid emulsion & vasopressor therapy should prompt institution of cardiopulmonary bypass (ECMO)