Local Anesthetic Toxicity (LAST)
Signs & Symptoms
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Tinnitus, metalic taste, circumoral numbess
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Altered mental status
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Seizures
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Hypotension
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Bradycardia
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Ventricular arrhythmias
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Cardiovascular collapse
Management
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Stop local anesthetic injection &/or infusion
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Call for help
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Initial focus:
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Airway management: ensure adequate ventilation & oxygenation; 100% FiO2, consider ETT, prevent hypoxia & acidosis (aggravate LAST)
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Seizure suppression: benzodiazepines preferred, avoid/minimize propofol if hemodynamically unstable; if seizures persist, small doses of succinylcholine to minimize acidosis & hypoxia
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Alert nearest facility having cardiopulmonary bypass capability
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Management of cardiac arrhythmias:
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If pulseless, start CPR
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ACLS will require adjustment of medications & perhaps prolonged effort
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Epinephrine doses <1 mcg/kg (small boluses of 10-100 mcg IV)
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Avoid vasopressin, calcium channel blockers, beta blockers, & local anesthetics
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If ventricular arrhythmias occur, amiodarone is preferred; avoid lidocaine & procainamide
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If refractory to treatment, consider cardiopulmonary bypass
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Lipid emulsion (20%) therapy:
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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
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Repeat bolus once or twice for persistent cardiovascular collapse
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May ↑ infusion rate (max 0.5mL/kg/min) if BP remains low
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Continue infusion for at least 10 minutes after attaining circulatory stability
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Recommended upper limit 10mL/kg over the first 30 minutes
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Propofol is not a substitute for lipid emulsion
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Failure to respond to lipid emulsion & vasopressor therapy should prompt institution of cardiopulmonary bypass (ECMO)