Difference between revisions of "Local anesthetic systemic toxicity"

(Management)
 
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==Background==
 
==Background==
 +
*Acronym: LAST
 
*Life-threatening adverse reaction to local anesthetic toxicity.
 
*Life-threatening adverse reaction to local anesthetic toxicity.
*Causes<ref name="Fencl">Fencl JL. Local anesthetic systemic toxicity: perioperative implications. AORN J. 2015 Jun;101(6):697-700.</ref>
 
**Injection of local anesthetic into systemic circulation
 
**Exceeding the maximum dose of local anesthetic (see table below)
 
**Absorption of anesthetic into systemic circulation by injection into extremely vascular area.
 
 
*Incidence = ~0.2% of nerve blocks
 
*Incidence = ~0.2% of nerve blocks
 
*Generally occurs within minutes of injection
 
*Generally occurs within minutes of injection
 +
 +
===Causes<ref name="Fencl">Fencl JL. Local anesthetic systemic toxicity: perioperative implications. AORN J. 2015 Jun;101(6):697-700.</ref>===
 +
*Injection of local anesthetic into systemic circulation
 +
*Exceeding the maximum dose of local anesthetic (see table below)
 +
*Absorption of anesthetic into systemic circulation by injection into extremely vascular area.
  
 
{{Maximum doses of anesthetic agents}}
 
{{Maximum doses of anesthetic agents}}
 +
 +
===Diphenhydramine as Local Anesthetic===
 +
*Injectable 1% diphenhydramine (10 mg/mL) can be used as a local anesthestic alternative to ester/amide anesthetics<ref>Pavlidakey PG et al. Diphenhydramine as an Alternative Local Anesthetic Agent. J Clin Aesthet Dermatol. 2009 Oct; 2(10): 37–40.</ref>
 +
**Sodium channel blocker mechanism
 +
**1-2 mL of 1% diphenhydramine at a time, to not exceed excessive sedation dose
 +
**Typical vial is 50 mg/mL, so to make 10 mg/mL:
 +
***10 mL NS removed from 50 mL vial
 +
***Add 10 mL of 50 mg/mL diphenhydramine to 40 mL of NS
 +
***Sedation is dose related and is similar to what would be expected for IM doses
 +
***Relative contraindications are the same for IM diphenhydramine administration
  
 
==Clinical Features==
 
==Clinical Features==
*CNS symptoms (typically occur before CVS symptoms<ref name="Fencl" />)
+
''Clinical course tends to be a dose-dependant progression from CNS symptoms to CVS symptoms and death<ref>Kamel I, Trehan G, Barnette R. Intralipid Therapy for Inadvertent Peripheral Nervous System Blockade Resulting from Local Anesthetic Overdose. Case Reports in Anesthesiology. 2015;2015:486543. doi:10.1155/2015/486543.</ref>''
**Agitation
+
*CNS symptoms
 +
**[[Agitation]]
 
**Auditory changes
 
**Auditory changes
 
**Metallic taste
 
**Metallic taste
 
**[[Seizures]] or drowsiness
 
**[[Seizures]] or drowsiness
**Coma
+
**[[Coma]]
**Respiratory arrest
+
**[[Respiratory arrest]]
 
*Cardiovascular<ref name="Fencl" />
 
*Cardiovascular<ref name="Fencl" />
 
**Early signs
 
**Early signs
***Tachycardia
+
***[[Tachycardia]]
***Ventricular dysrhythmia
+
***Ventricular [[dysrhythmia]]
***Hypertension
+
***[[Hypertension]]
 
**Late signs
 
**Late signs
***Bradycardia
+
***[[Bradycardia]]
 
***Conduction block
 
***Conduction block
 
***Cardiovascular collapse
 
***Cardiovascular collapse
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*Anaphylaxis
 
*Anaphylaxis
 
*Anxiety
 
*Anxiety
 +
*[[Methemoglobinemia]] - local anesthestics oxidize Fe2+ to Fe3+ in Hb
 +
{{Sodium channel blocking toxidromes}}
  
==Diagnosis==
+
==Evaluation==
 
*Clinical diagnosis
 
*Clinical diagnosis
  
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==Management==
 
==Management==
*Lipid emulsion, 20% solution
+
*Aggressive supportive care (including airway management) and application of ACLS
 +
**Ventilate with 100% FiO2 - bolus dose of 50-100mg IV [[succinylcholine]] paralyzes without depressing CNS or CV<ref>GlobalRPH. Management of Local Anesthetic Emergencies. http://www.globalrph.com/local-anesthetics.htm</ref>
 +
**Hypercapnia, hypoxia, acidosis all worsen toxic effects<ref name="Dillane">Dillane D, Finucane BT. Local anesthetic systemic toxicity. Can J Anaesth. 2010 Apr;57(4):368-80.</ref>
 +
**Manage seizures with [[benzodiazepines]]; [[propofol]] is an option but may worsen cardiovascular toxicity
 +
*Early activation of ECMO or consideration for transfer to ECMO center as cardiac arrest is often refractory to ACLS.
 +
*1 amp of [[sodium bicarbonate]] IV q2 min for:
 +
**VT or VF
 +
**Severe acidosis
 +
*'''[[Intralipid|Lipid emulsion]]''', (Intralipid) 20% solution<ref name="Dillane" />
 +
**Lipid sink, binds to local anesthetic
 
**1.5 mL/kg bolus over 1 minute
 
**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)
+
**Then, 0.25 mL/kg/min for 20 min or until hemodynamic stability achieved
*Manage seizures with benzodiazepines; propofol is an option but may worsen CV toxicity
+
***↑ to 0.5 mL/kg/min if hemodynamic status declines
 +
**Maximum total dose 12 mL/kg.
 +
**Consider drawing extra blood as will interfere with labs
 
*ACLS modifications per ASRA (Am Soc of Regional Anesthesia):
 
*ACLS modifications per ASRA (Am Soc of Regional Anesthesia):
**Small initial doses of 100 μg boluses in adults
+
**Avoid vasopressin
**No vasopressin
+
**Avoid calcium-channel blockers and beta-blockers
**Avoid CCBs and BBs
+
**[[Amiodarone]] preferred in ventricular dysrhythmias
**Amiodarone preferred in ventricular dysrhythmias
+
 
 +
==Disposition==
 +
*Admit
  
 
==See Also==
 
==See Also==
*[[Nerve Blocks (Main)]]
+
*[[Nerve blocks (main)]]
 
*[[Lidocaine]]
 
*[[Lidocaine]]
  
 
==External Links==
 
==External Links==
[http://emedicine.medscape.com/article/1844551-overview Medscape:Local Anesthetic Toxicity]
+
*[http://emedicine.medscape.com/article/1844551-overview Medscape:Local Anesthetic Toxicity]
  
 
==References==
 
==References==
 
<References/>
 
<References/>
  
[[Category:Tox]]
+
[[Category:Toxicology]]
[[Category:Drugs]]
+
[[Category:Pharmacology]]

Latest revision as of 02:02, 8 January 2020

Background

  • Acronym: LAST
  • Life-threatening adverse reaction to local anesthetic toxicity.
  • Incidence = ~0.2% of nerve blocks
  • Generally occurs within minutes of injection

Causes[1]

  • Injection of local anesthetic into systemic circulation
  • Exceeding the maximum dose of local anesthetic (see table below)
  • Absorption of anesthetic into systemic circulation by injection into extremely vascular area.

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)

Diphenhydramine as Local Anesthetic

  • Injectable 1% diphenhydramine (10 mg/mL) can be used as a local anesthestic alternative to ester/amide anesthetics[2]
    • Sodium channel blocker mechanism
    • 1-2 mL of 1% diphenhydramine at a time, to not exceed excessive sedation dose
    • Typical vial is 50 mg/mL, so to make 10 mg/mL:
      • 10 mL NS removed from 50 mL vial
      • Add 10 mL of 50 mg/mL diphenhydramine to 40 mL of NS
      • Sedation is dose related and is similar to what would be expected for IM doses
      • Relative contraindications are the same for IM diphenhydramine administration

Clinical Features

Clinical course tends to be a dose-dependant progression from CNS symptoms to CVS symptoms and death[3]

Differential Diagnosis

  • Anaphylaxis
  • Anxiety
  • Methemoglobinemia - local anesthestics oxidize Fe2+ to Fe3+ in Hb

Sodium Channel Blockade Toxidrome

Evaluation

  • Clinical diagnosis

Workup

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

Management

  • Aggressive supportive care (including airway management) and application of ACLS
    • Ventilate with 100% FiO2 - bolus dose of 50-100mg IV succinylcholine paralyzes without depressing CNS or CV[4]
    • Hypercapnia, hypoxia, acidosis all worsen toxic effects[5]
    • Manage seizures with benzodiazepines; propofol is an option but may worsen cardiovascular toxicity
  • Early activation of ECMO or consideration for transfer to ECMO center as cardiac arrest is often refractory to ACLS.
  • 1 amp of sodium bicarbonate IV q2 min for:
    • VT or VF
    • Severe acidosis
  • Lipid emulsion, (Intralipid) 20% solution[5]
    • Lipid sink, binds to local anesthetic
    • 1.5 mL/kg bolus over 1 minute
    • Then, 0.25 mL/kg/min for 20 min or until hemodynamic stability achieved
      • ↑ to 0.5 mL/kg/min if hemodynamic status declines
    • Maximum total dose 12 mL/kg.
    • Consider drawing extra blood as will interfere with labs
  • ACLS modifications per ASRA (Am Soc of Regional Anesthesia):
    • Avoid vasopressin
    • Avoid calcium-channel blockers and beta-blockers
    • Amiodarone preferred in ventricular dysrhythmias

Disposition

  • Admit

See Also

External Links

References

  1. 1.0 1.1 Fencl JL. Local anesthetic systemic toxicity: perioperative implications. AORN J. 2015 Jun;101(6):697-700.
  2. Pavlidakey PG et al. Diphenhydramine as an Alternative Local Anesthetic Agent. J Clin Aesthet Dermatol. 2009 Oct; 2(10): 37–40.
  3. Kamel I, Trehan G, Barnette R. Intralipid Therapy for Inadvertent Peripheral Nervous System Blockade Resulting from Local Anesthetic Overdose. Case Reports in Anesthesiology. 2015;2015:486543. doi:10.1155/2015/486543.
  4. GlobalRPH. Management of Local Anesthetic Emergencies. http://www.globalrph.com/local-anesthetics.htm
  5. 5.0 5.1 Dillane D, Finucane BT. Local anesthetic systemic toxicity. Can J Anaesth. 2010 Apr;57(4):368-80.