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  • Incidence of local anesthetic systemic toxicity (LAST) after peripheral nerve blocks is higher than after epidural anesthesia.

  • Ultrasound-guided peripheral nerve block is associated with lower incidence of LAST (Odds ratio 0.23).1

  • Use of epinephrine in local anesthetics decreases its systemic absorption.

  • In 1998, Dr. Guy Weinberg first observed that pretreatment or resuscitation with a lipid infusion shifts the dose-response curve to the right in a rat model of bupivacaine-induced asystole.2

  • In 2006, the first case was reported of the successful use of a 20% lipid emulsion (intralipid) in a patient after LAST-induced prolong cardiac arrest.3

  • Since then, lipid emulsion has been used successfully in lipophilic drug overdoses, such as tricyclic antidepressants, bupropion, verapamil, diltiazem, caffeine, and olanzapine.


  • Unrecognized intravascular epidural catheter

  • Extremes of age

  • Nerve block site

  • Patient-related factors: cardiac, renal, and hepatic diseases

  • Multiple procedures: such as labor analgesia to cesarean section, or regional block after cesarean section

  • Multiple routes of administration: local infiltration, irrigation, neuraxial, nerve blocks, and lidocaine patch

  • Repeated use of local anesthetics for infiltration


Mechanism of Lipid Emulsion4

  • Lipid sink

  • Metabolic effect: increases fatty acid uptake by mitochondria

  • Membrane effect: stabilizes the membranes

  • Cytoprotection: via activation of Protein kinase B (PKB), also known as Akt pathway


Lipid emulsion: Intralipid.


The signs, symptoms, and timing of LAST are unpredictable and can be subtle. Wide range of symptoms include:

  • Mental status change including coma and convulsions.

  • Cardiovascular instability to cardiac arrest.

  • Be vigilant. Early diagnosis is the key for successful resuscitation.


  • The LAST Checklist from the American Society of Regional Anesthesia and Pain Medicine (ASRA) summarizes the workflow of resuscitation of LAST and the use of lipid emulsion (Fig. 61-2).5

  • Data are inconsistent regarding whether lipid emulsion is effective to resuscitate the patients with LAST due to lidocaine overdose. The lipid administration proved to be safe; the author would recommend using lipid emulsion to treat lidocaine-induced LAST.

  • Important note for resuscitation: Use smaller than normal dose of epinephrine in the Advanced Cardiovascular Life Support (ACLS). Avoid beta blockers, calcium channel blockers, and vasopressin.


ASRA-copyrighted LAST checklist and resuscitation workflow. (Reproduced with permission from American Society of Regional Anesthesia and Pain Medicine, ©2020.)


1. +
Barrington  MJ, Kluger  R. Ultrasound guidance reduces the risk of local anesthetic systemic toxicity following peripheral nerve blockade. Reg Anesth Pain Med. 2013;38:289–299.  [PubMed: 23788067]
2. +
Weinberg  GL, VadeBoncouer  T, Ramaraju  GA,  et al. Pretreatment or resuscitation with ...

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