Podcast 818: Local Anesthetics and LAST

Contributor: Don Stader, MD

Educational Pearls:

• There are two major groups of local anesthetics: Amide and Esther
• To recall what group an anesthetic belongs to, use this memory trick:

Amide has an 'i' in the name and Amide anesthetics have 2 'i's e.g., Lidocaine. Ester has no 'i' and most common Ester anesthetics have only one 'i' e.g., Tetracaine.

• In a true allergy and/or contraindication to both local anesthetic groups, diphenhydramine is an acceptable alternative.
• Epinephrine is administered with local anesthetics to decrease bleeding, increase duration of action, and minimize systemic spread of the anesthetic, thus reducing toxicity.
• Symptoms of Local Anesthetic Systemic Toxicity (LAST) may begin with dizziness, confusion and/or slurred speech, and can progress to cardiovascular collapse and death.
• Treat LAST with lipid emulsion therapy i.e. 'Intralipids' to create a lipid sink that absorbs anesthetic agent
• Administer initial 1.5 ml/kg bolus (approximately 100 ml in 70 mg adult) followed by infusion rate of 0.25 mg/kg/hour. Do not surpass 10 mg/kg total.

References

Dickerson DM, Apfelbaum JL. Local anesthetic systemic toxicity. Aesthet Surg J. 2014;34(7):1111-1119. doi:10.1177/1090820X14543102

Bina B, Hersh EV, Hilario M, Alvarez K, McLaughlin B. True Allergy to Amide Local Anesthetics: A Review and Case Presentation. Anesth Prog. 2018;65(2):119-123. doi:10.2344/anpr-65-03-06

Macfarlane AJR, Gitman M, Bornstein KJ, El-Boghdadly K, Weinberg G. Updates in our understanding of local anaesthetic systemic toxicity: a narrative review. Anaesthesia. 2021;76 Suppl 1:27-39. doi:10.1111/anae.15282

Summarized by Kirsten Hughes, MS4 | Edited by John Spartz MD & Erik Verzemnieks, MD

In an effort to promote diversity, equity, and inclusion in Emergency Medicine, The Emergency Medical Minute is proud to present our 2nd annual Diversity and Inclusion Award. We support increasing the representation of underrepresented groups in medicine and extend this award to individuals applying to emergency medicine residencies during the 2022-2023 cycle. For information on award eligibility and the application process, visithttps://emergencymedicalminute.com/edi-award/

Donate to EMM today!