Local anesthetic systemic toxicity

Revision as of 05:47, 16 July 2015 by Mholtz (talk | contribs)

Background

  • Complication of lidocaine injection (accidental into systemic circulation)
    • 0.2% of nerve blocks
  • Occurs within minutes of injection
    • 75% occuring within 5 minutes

Maximum Doses of Anesthetic Agents

Agent Without Epinephrine With Epinephrine Duration Notes
Lidocaine 5 mg/kg (max 300mg) 7 mg/kg (max 500mg) 30-90 min
  • 1% soln contains 10 mg/ml
  • 2% soln contains 20 mg/ml
Mepivicaine 7 mg/kg 8 mg/kg
Bupivicaine 2.5 mg/kg (max 175mg) 3 mg/kg (max 225mg) 6-8 hr
  • 0.5% soln contains 5 mg/ml
  • May cause cardiac arrest if injected intravascularly
  • Do not buffer with bicarbonate
Ropivacaine 3 mg/kg
Prilocaine 6 mg/kg
Tetracaine 1 mg/kg 1.5 mg/kg 3hrs (10hrs with epi)
Procaine 7 mg/kg 10 mg/kg 30min (90min with epi)

Clinical Features

  • CNS symptoms
    • Agitation
    • Auditory changes
    • Metallic taste
    • Seizures or drowsiness
    • Coma
    • Respiratory arrest
  • Cardiovascular
    • First excitation
      • Tachycardia
      • Ventricular dysrhythmia
      • Hypertension
    • Followed by depression

Differential Diagnosis

  • Anaphylaxis
  • Anxiety

Diagnosis

  • Clinical diagnosis

Workup

  • Directed by clinical picture
  • Blood levels of anesthetic are available, but not clinically useful.

Management

  • Lipid emulsion, 20% solution
    • 1.5 mL/kg bolus over 1 minute
    • Then, 15 mL/kg per hour x 20-minute infusion (0.25 mL/kg/min for 20 min or until hemodynamic stability)
  • Manage seizures with benzodiazepines; propofol is an option but may worsen CV toxicity
  • ACLS modifications per ASRA (Am Soc of Regional Anesthesia):
    • Small initial doses of 100 μg boluses in adults
    • No vasopressin
    • Avoid CCBs and BBs
    • Amiodarone preferred in ventricular dysrhythmias

See Also

External Links

Medscape:Local Anesthetic Toxicity

References