LAST is a severe consequence of local anaesthetic toxicity.

Agent Max Dose w/ Epi Max Dose w/o Epi Duration of Action
Lidocaine 7 mg/kg 5 mg/kg 30-90 minutes
Bupivicaine 3 mg/kg 2.5 mg/kg 6-8 hours

Clinical Manifestations

  1. CNS excitatory effects due to inhibition of cortical inhibitory pathways.
    1. Perioral numbeness, metallic taste
    2. mental status changes or anxiety
    3. visual changes
    4. muscle twitching
    5. seizures
  2. CNS depression
    1. somnolence
    2. coma
    3. respiratory depression
  3. cardiovascular effects
    1. hypertension/tachycardia are rare
    2. hypotension and bradycardia are more common
    3. ventricular arrythmias, asystolic cardiac arrest

Management of LAST

  1. Stop injections
  2. Call for help, establish IV access
  3. Arrange cardiopulmonary bypass if required.
  4. Airway management
  5. Seizure treatment - IV benzodiazepines are first-line.
  6. Arrhythmia and cardiac arrest management
    1. Amiodarone is first-line antiarrhythmic. Avoid lidocaine and other class I antiarrhythmics
    2. Reduce the bolus dose of epinephrine to <= 1 mcg/kg to avoid arrhythmogenic effects.
    3. Avoid vasopressin.
  7. Lipid rescue therapy (20% emulsion) is indicated with CV instability or with significant neurotoxicity. See Lipid Emulsion
  8. Transfer to monitored setting (ICU).