Local Anesthetic Systemic Toxicity – Is Fat The New “Wonder Drug?”

Image Credit: Photo by NIH: https://flic.kr/p/nQg4F7

Author: Jonathan Morgan, MSIV
Lake Erie College of Osteopathic Medicine-Bradenton

The provision of local and regional anesthesia is a core part of emergency medicine. Toxicity as a result of the administration of local anesthetics is exceedingly rare, but it does occur, and may even be more common than malignant hyperthermia.[1] Many outpatient facilities provide local or regional anesthesia and may not be prepared to handle severe toxicity. Emergency physicians should be prepared to deal with this rare but catastrophic outcome if it occurs following anesthesia either in their own department or in another setting.

Local Anesthesia Systemic Toxicity

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Local anesthetic systemic toxicity (LAST) can result from administration of any of the local anesthetics and can be difficult to identify. Classic descriptions include CNS toxicity (altered mental status, agitation, sedation, or seizures) preceding respiratory or cardiac arrest, but the presentation can be quite variable and the first symptom of LAST may be cardiac arrest. Symptoms may appear within a minute, but can also appear more than 5 minutes after injection of an anesthetic. There is a classic prodrome of auditory changes and metallic taste, but one review found that this was present in less than 20% of cases.[2,3]