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Local Anesthetic Systemic Toxicity

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Local Anesthetic Systemic Toxicity, Local Anesthetic Agent Poisoning, LAST Reaction

  • Definitions
  1. LAST
    1. Local Anesthetic Systemic Toxicity
  • Mechanism
  1. Vascular injection of large dose of local anesthetic
  • Risk Factors
  1. Extremes of age
  2. Large region of infiltration
  3. Liver failure (hypoalbuminemia)
  4. Concurrent medications
    1. Beta Blockers
    2. Calcium Channel Blockers
    3. Digoxin
  1. Neurologic
    1. Tinnitus
    2. Dizziness
    3. Circumoral or Tongue numbness
    4. Metallic Taste
    5. Confusion
    6. Seizure
  2. Cardiovascular
    1. Bradycardia
    2. Hypotension
    3. Ventricular arrhythmia (including VT/VF)
    4. AV Block
    5. Palpitations
  • Adverse Effects
  • Bupivicaine
  1. High risk of serious arrhythmia or Cardiac Arrest if injected intravascularly
  2. Bupivicaine (and Ropivacaine) are much more toxic systemically than Lidocaine
    1. Highly lipophilic
    2. High Sodium channel affinity
  • Management
  1. ABC Management
  2. Seizure Management
    1. See Status Epilepticus
    2. Benzodiazepines are preferred first-line agents
    3. Avoid Propofol (due to hemodynamic instability)
  3. Arrhythmia Management
    1. See ABC Management (follow ACLS protocols)
    2. Avoid vasopressin, Calcium Channel Blockers, Beta Blockers
    3. Decrease Epinephrine dose to 1 mcg/kg
    4. Give Sodium Bicarbonate if Wide Complex Tachycardia (similar to Tricyclic Overdose)
  4. Intralipid 20% emulsion
    1. Bolus 1.5 mg/kg (Lean Body Mass) IV push over 2 minutes
      1. May repeat in 2-3 minutes for refractory cardiovascular collapse
      2. If still not effective may start Intralipid infusion as below
    2. Continuous infusion 0.25 ml/kg/min for at least 10 min after circulatory stability
      1. May increase to 0.50 ml/kg/min if persistent Hypotension
      2. May increase to maximum of 10-15 ml/kg
      3. Alternatively, 15 ml/kg may be infused over 1 hour
    3. See Intravenous Lipid Emulsion
    4. Primarily for lipophilic drug toxicity (esp. bupivicaine)
    5. Draw blood tubes before injecting Intralipid (alters lab values)
  • Prevention
  1. Withdraw first, when injecting anesthetic, especially for bupivicaine (to prevent intravascular injection)
  2. Adding Epinephrine to the local anesthetic keeps the agent in the tissues with less systemic absorption
  3. Limit local anesthetic to their maximums (calculate the maximum cc of local anesthetic that may be used)
    1. Lidocaine: 4 mg/kg
    2. Lidocaine with Epinephrine: 7 mg/kg
    3. Bupivicaine: 2 mg/kg
    4. Ropivacaine 3 mg/kg
  4. Be aware of high risk locations for local injections (esp. with bupivicaine)
    1. Intercostal Nerve Blocks
  • References
  1. Acker, Koval and Leeper (2017) Crit Dec Emerg Med 31(4): 3-13
  2. Nordt and Shoenberger in Herbert (2019) EM:Rap 19(2): 4-5
  3. Burch (2011) Am J Health Syst Pharm 68(2):125-9 +PMID:21200058 [PubMed]